EVALUATION KIT AVAILABLE
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MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
General Description
Benefits and Features
The MAX20461 combines a 3A high-efficiency, automotive-grade, step-down converter, a USB Type-C/BC1.2
host charger emulator, and high bandwidth USB protection switches for automotive USB 2.0 host applications.
The device also includes a USB load current-sense amplifier and a configurable feedback-adjustment circuit that
provides automatic USB voltage compensation for voltage
drops in captive cables often found in automotive applications. The device limits the USB load current using both
a fixed internal peak-current threshold and a user-configurable external current-sense USB load threshold.
● One-Chip Type-C Solution Directly from Car Battery to
Portable Device
• MAX20461: USB Type-C Compliant DFP Controller
with VCONN Protection
• MAX20461A: USB Type-C Compliant DFP
Controller
• 1GHz Bandwidth USB 2.0 Data Switches
• 4.5V to 28V Input (40V Load Dump), Synchronous
Buck Converter
• 5V to 7V, 3A Output Capability
The MAX20461 is optimized for high-frequency operation
and includes programmable frequency selection from
310kHz to 2.2MHz, allowing optimization of efficiency,
noise, and board space based on the application requirements. The fully synchronous DC-DC converter integrates
high-side and low-side MOSFETs with an external SYNC
input/output, and can be configured for spread-spectrum
operation.
The MAX20461 allows flexible configuration and advanced diagnostic options for both standalone and supervised applications. The device can be programmed using
either external programming resistors and/or internal I2C
registers via the I2C bus.
The MAX20461 is available in a small 5mm x 5mm 32-pin
TQFN package and is designed to minimize required external components and layout area.
Applications
● Automotive Radio and Navigation
● USB Port for Host and Hub Applications
● Automotive Connectivity/Telematics
● Optimal USB Charging and Communication for
Portable Devices
• User-Programmable Voltage Gain Adjusts Output
for Up to 474mΩ Cable Resistance
• User-Programmable USB Current Limit
• Type-C Cable Orientation Indicator for USB3
Applications
• Supports USB BC1.2 CDP and SDP Modes
• Compatible with USB On-the-Go Specification and
Apple CarPlay®
● Low-Noise Features Prevent Interference with AM
Band and Portable Devices
• Fixed-Frequency 310kHz to 2.2MHz Operation
• Fixed-PWM Option at No Load
• Spread Spectrum for EMI Reduction
• SYNC Input/Output for Frequency Parking
● Robust Design Keeps Vehicle System and Portable
Device Safe in an Automotive Environment
• Short-to-Battery Protection on VBUS, HVD± Pins
• CC1 and CC2 Tolerant to 20V Transients
• Advanced Diagnostics Through I2C Bus
• ±25kV Air/±8kV Contact ISO 10605 (330pF, 2kΩ)*
• ±15kV Air/±8kV Contact ISO 10605 (330pF, 2kΩ)**
• ±15kV Air/±8kV Contact ISO 10605 (330pF, 330Ω)*
• ±15kV Air/±8kV Contact IEC 61000-4-2 (150pF,
330Ω)*
• Overtemperature Protection, Warning, and
Intelligent Current Foldback
• -40°C to +125°C Operating Temperature Range
*Tested in Typical Application Circuit as used on the
MAX20461 Evaluation Kit with 1m captive cable.
**Tested in Typical Application Circuit as used on the
MAX20461 Evaluation Kit without 1m captive cable.
Ordering Information appears at end of datasheet.
Apple and CarPlay are registered trademarks of Apple Inc.
19-100338; Rev 5; 5/21
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Simplified Block Diagram
RADIO
HEAD
MAX20461
DC-DC +
USB TYPE-C
VBUS
VBAT
USB
PHY
D-
HVD-
D+
HVD+
VCONN
RADIO
HEAD
USB
PHY
USB TYPE-C
CONNECTOR
PORTABLE
DEVICE
USB TYPE-C
CONNECTOR
PORTABLE
DEVICE
CC
MAX20461A
DC-DC +
USB TYPE-C
VBUS
VBAT
CAPTIVE
CABLE
D-
HVD-
D+
HVD+
CAPTIVE
CABLE
CC
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Maxim Integrated | 2
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
TABLE OF CONTENTS
General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Benefits and Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Simplified Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
32 Pin TQFN 5x5x0.75mm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Typical Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Pin Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
MAX20461 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
MAX20461A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Functional Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
On-Channel -3dB Bandwidth and Crosstalk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
On-Capacitance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
DCDC_ON Reset Behavior and Timing Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
ADC Timing Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
ATTACH Logic Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Cable Attach-Detach and SENSN Discharge Timing Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Detailed Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Detailed Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
USB Type-C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Configuration Channel (CC1 and CC2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
CC Polarity Output Pin (CC_POL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
VCONN (MAX20461 Only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
VBUS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
External FET Gate Drive (G_DMOS Pin) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Legacy Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Power-Up and Enabling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
System Enable (HVEN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
DC-DC Enable (ENBUCK) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.3V Input (IN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Linear Regulator Output (BIAS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Power-On Sequencing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Step-Down DC-DC Regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Step-Down Regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Wide Input Voltage Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Maximum Duty-Cycle Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
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Maxim Integrated | 3
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
TABLE OF CONTENTS (CONTINUED)
Output Voltage (SENSP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Soft-Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Reset Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Reset Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Switching Frequency Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Switching Frequency Synchronization (SYNC Pin) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Forced-PWM Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Intelligent Skip-Mode Operation and Attach Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Spread-Spectrum Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Current Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Output Short-Circuit Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Thermal Overload Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Pre-Thermal Overload Warning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Automatic Thermal Foldback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
USB Current Limit and Output Voltage Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Current-Sense Amplifier (SENSP, SENSN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
USB DC Current Limit Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Voltage Feedback Adjustment Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Remote Sense Feedback Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
High Voltage Modes Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
USB Protection Switches and BC1.2 Host Charger Emulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
USB Protection Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
USB Host Charger Emulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
USB On-The-Go and Dual-Role Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
I2C, Control, and Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
I2C Configuration (CONFIG1 and I2C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Standalone Configuration (CONFIG1–CONFIG3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
I2C Diagnostics and Event Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Interrupt and Attach Output (INT(ATTACH)) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
I2C Output Voltage and Current Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
I2C Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Bit Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
STOP and START Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Early STOP Condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Clock Stretching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
I2C General Call Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
I2C Slave Addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Acknowledge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Write Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
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Maxim Integrated | 4
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
TABLE OF CONTENTS (CONTINUED)
Read Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Fault Detection and Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Fault Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Fault Output Pin (FAULT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Summary Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Register Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Applications Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
DC-DC Switching Frequency Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
DC-DC Input Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
DC-DC Output Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
DC-DC Output Inductor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Layout Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Determining USB System Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
USB Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
USB Output Current Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
USB Voltage Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Tuning of USB Data Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
USB Data Line Common-Mode Choke Placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
ESD Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
ESD Test Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Human Body Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
IEC 61000-4-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Typical Application Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Typical Application Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
www.maximintegrated.com
Maxim Integrated | 5
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
LIST OF FIGURES
Figure 1. Type-C Pullup Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Figure 2. USB Type-C Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Figure 3. Remote Cable-Sense Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Figure 4. Data Switch and Charge-Detection Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Figure 5. I2C Timing Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Figure 6. START, STOP and REPEATED START Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Figure 7. Acknowledge Condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Figure 8. Data Format of I2C Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Figure 9. DC Voltage Adjustment Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Figure 10. Increase in SENSP vs. USB Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Figure 11. Tuning of Data Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Figure 12. Near-Eye Diagram (with No Switch) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Figure 13. Untuned Near-Eye Diagram (with MAX20461) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Figure 14. Human Body ESD Test Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Figure 15. IEC 61000-4-2 ESD Test Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Figure 16. Human Body Current Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Figure 17. IEC 61000-4-2 Current Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
www.maximintegrated.com
Maxim Integrated | 6
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
LIST OF TABLES
Table 1. Charge Detection Precedence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Table 2. CC Pulldown Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table 3. CC Pulldown Response (MAX20461A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table 4. Type-C Source VCONN Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Table 5. DC-DC Converter Intelligent Skip Mode Truth Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Table 6. Data Switch Mode Truth Table (I2C Variants) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Table 7. Data Switch Mode Truth Table (Standalone Variants) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Table 8. CONFIG1 Pin Table (I2C Version) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Table 9. CONFIG1 Pin Table (Standalone Variants) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Table 10. CONFIG2 and CONFIG3 Pin Table (Standalone Variants) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Table 11. I2C Slave Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Table 12. Fault Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Table 13. Recommended Output Filters For ILOAD of 3A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
www.maximintegrated.com
Maxim Integrated | 7
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Absolute Maximum Ratings
SUPSW to PGND ................................................... -0.3V to +40V
HVEN to PGND ....................................... -0.3V to VSUPSW+0.3V
LX to PGND (Note 1) ............................... -0.3V to VSUPSW+0.3V
SYNC to AGND ............................................-0.3V to VBIAS+0.3V
SENSN, SENSP, VBMON to AGND ...... -0.3V to VSUPSW+0.3V
AGND to PGND ..................................................... -0.3V to +0.3V
BST to PGND ........................................................ -0.3V to +46V
BST to LX ................................................................. -0.3V to +6V
IN, CONFIG1, ENBUCK, SDA (CONFIG2), SCL (CONFIG3),
BIAS, BCMODE, FAULT, CC_POL (SHIELD), CC1, CC2,
VCONN, INT(ATTACH) to AGND .............................. -0.3V to +6V
HVDP, HVDM to AGND.......................................... -0.3V to +18V
DP, DM to AGND..............................................-0.3V to VIN+0.3V
G_DMOS to AGND................................................. -0.3V to +16V
LX Continuous RMS Current .................................................3.5A
Output Short-Circuit Duration......................................Continuous
Thermal Charactaristics
Continuous Power Dissipation - Single Layer Board (TA =
+70°C, 32-TQFN (derate 21.3mW/°C above +70°C)) .... 1702.1
mW
Continuous Power Dissipation - Multi Layer Board (TA =
+70°C, 32-TQFN (derate 34.5mW/°C above +70°C)) .... 2758.6
mW
Operating Temperature Range .......................-40°C to +125°C
Junction Temperature ................................................... +150°C
Storage Temperature Range...........................-40°C to +150°C
Lead Temperature (soldering, 10s) ............................... +300°C
Soldering Temperature (reflow)..................................... +260°C
Note 1: Self-protected from transient voltages exceeding these limits for ≤ 50ns in circuit under normal operation.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the
device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for
extended periods may affect device reliability.
Package Information
32 Pin TQFN 5x5x0.75mm
Package Code
T3255+4C
Outline Number
21-0140
Land Pattern Number
90-0012
Thermal Resistance, Single-Layer Board:
Junction to Ambient (θJA)
47 °C/W
Junction to Case (θJC)
1.70 °C/W
Thermal Resistance, Four-Layer Board:
Junction to Ambient (θJA)
29 °C/W
Junction to Case (θJC)
1.70 °C/W
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates
RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status.
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal
considerations, refer to www.maximintegrated.com/thermal-tutorial.
www.maximintegrated.com
Maxim Integrated | 8
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Electrical Characteristics
(VSUPSW = 14V, VIN = 3.3V, VENBUCK = 3.3V, VVCONN = 5V, Temperature = TA = TJ = -40°C to +125°C, unless otherwise noted.,
Actual typical values may vary and are not guaranteed.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
28
V
40
V
20
μA
Power Supply and Enable
Supply Voltage Range
VSUPSW
Load Dump Event
Supply Voltage Range
VSUPSW_LD
(Note 2)
4.5
< 1s
Supply Current - Off
State
ISUPSW
VSUPSW = 18V; VHVEN = 0V; VIN = 0V;
VCONN = 0V, Off State
10
Supply Current - Buck
Off
ISUPSW
VHVEN = 14V; VENBUCK = 0V
1.1
mA
Supply Current - Skip
Mode
ISUPSW
VHVEN = 14V; buck switching; no load
1.8
mA
Supply Current - FPWM
ISUPSW
VHVEN = 14V; buck switching; no load
BIAS Voltage
VBIAS
5.75V ≤ VSUPSW ≤ 28V
BIAS Current Limit
BIAS Undervoltage
Lockout
VUV_BIAS
VBIAS rising
28
4.5
4.7
50
150
3.0
3.3
BIAS Undervoltage
Lockout Hysteresis
SUPSW Undervoltage
Lockout
VUV_SUPSW
VSUPSW rising
3.9
IN Overvoltage Lockout
IN Input Current
VIN
3
VIN rising
VHVEN_R
HVEN Falling Threshold
VHVEN_F
tHVEN_R
HVEN Delay Falling
tHVEN_F
HVEN Input Leakage
V
V
3.6
V
3.8
4
4.3
V
10
µA
0.6
1.5
2.4
V
0.4
V
15
μs
VHVEN
HVEN Delay Rising
V
V
4.42
IIN
HVEN Rising Threshold
HVEN Hysteresis
3.6
0.2
VIN_OVLO
V
mA
0.2
SUPSW Undervoltage
Lockout Hysteresis
IN Voltage Range
mA
5.25
0.2
2.5
5
12
V
25
μs
10
µA
10
13.0
V
100
250
kΩ
VHVEN = VSUPSW = 18V, VHVEN = 0V
G_DMOS Pin
G_DMOS Unloaded
Output Voltage
VG_DMOS_OC
G_DMOS Output
Impedance
RG_DMOS_OC
G_DMOS DC Output
Current
IG_DMOS_SC
VG_DMOS to VBIAS, internal discharge
path 2MΩ to GND
7
G_DMOS to BIAS
20
μA
USB Type C / Power Requirements (MAX20461 Only)
VCONN Source Voltage
Input
VVCONN_IN
1W (3.3V/305mA, 5.5V/185mA) (Note 3)
VCONN On Resistance
RON_VCONN
Resistance from VCONN to CC1 and
CC2, VCONN = 5V
www.maximintegrated.com
3.3
600
5.5
V
1200
mΩ
Maxim Integrated | 9
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Electrical Characteristics (continued)
(VSUPSW = 14V, VIN = 3.3V, VENBUCK = 3.3V, VVCONN = 5V, Temperature = TA = TJ = -40°C to +125°C, unless otherwise noted.,
Actual typical values may vary and are not guaranteed.)
PARAMETER
VCONN Current Limit
VCONN UVLO
Threshold
VCONN to CC1/CC2
Discharge Resistance
SYMBOL
ILIM_VCONN
CONDITIONS
MIN
TYP
Measured on CC1 and CC2.
3.60V ≤ VCONN ≤ 5.5V
310
400
2.2
2.45
2.65
V
3
6.2
kΩ
VVCONN_UVL
O
RDCH
MAX
UNITS
mA
USB Type C / Current Level Characteristics
CC DFP 0.5A Current
Source
IDFP0.5_CC
4.0V < VBIAS < 5.5V, ±20%
64
80
96
µA
CC DFP 1.5A Current
Source
IDFP1.5_CC
4.0V < VBIAS < 5.5V, ±8%
166
180
194
µA
CC DFP 3.0A Current
Source
IDFP3.0_CC
4.0V < VBIAS < 5.5V, ±8%
304
330
356
µA
USB Type C / Timing Characteristics
Type-C CC Pin
Detection Debounce
tCCDEBOUNCE
Final transition to Attached states
160
ms
RL = RS = 50Ω
1000
MHz
DP, DM Analog USB Switches
On-Channel -3dB
Bandwidth
BW
Analog Signal Range
0
Protection Trip
Threshold
VOV_D
Protection Response
Time
tFP_D
VIN = 4.0V, VHVD± = 3.3V to 4.3V step,
RL = 15kΩ on D±, delay to VD± < 3V
2
RON_SA
IL = 10mA, VD± = 0V to VIN, VIN = 3.0V
to 3.6V
4
On-Resistance Switch A
On-Resistance Match
between Channels
Switch A
On-Resistance Flatness
Switch A
∆RON_SA
RFLAT(ON)A
3.65
IL = 10mA, VD± = 1.5V or 3.0V
IL = 10mA,VD_ = 0V or 0.4V
On Resistance of
HVD+/HVD- short
RSHORT
VDP = 1V, IDM = 500μA
HVD+/HVD- OnLeakage Current
IHVD_ON
VHVD± = 3.6V or 0V
HVD+/HVD- OffLeakage Current
IHVD_OFF
VHVD± = 18V, VD± = 0V
ID_OFF
VHVD± = 18V, VD± = 0V
D+/D- Off-Leakage
Current
3.85
3.6
V
4.1
V
µs
8
Ω
0.2
Ω
0.01
90
-7
-1
Ω
180
Ω
7
µA
150
µA
1
µA
Current-Sense Amplifier (SENSP, SENSN) and Analog Inputs (VBMON)
10mV < VSENSP - VSENSN < 110mV,
GAIN[4:0] = 0b11111
Gain
Cable Compensation
LSB
www.maximintegrated.com
RLSB
19.4
V/V
18
mΩ
Maxim Integrated | 10
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Electrical Characteristics (continued)
(VSUPSW = 14V, VIN = 3.3V, VENBUCK = 3.3V, VVCONN = 5V, Temperature = TA = TJ = -40°C to +125°C, unless otherwise noted.,
Actual typical values may vary and are not guaranteed.)
PARAMETER
Overcurrent Threshold
SYMBOL
ILIM_SET
SENSN / VBMON
Discharge Current
ISENSN_DIS
Startup Wait Time
tBUCK_WAIT
SENSN / VBMON
Discharge Time
Forced Buck Off-Time
tDIS_POR
CONDITIONS
MIN
TYP
MAX
ILIM[2:0] = 0b111, RSENSE = 33mΩ
3.04
3.14
3.30
ILIM[2:0] = 0b110, RSENSE = 33mΩ
2.6
2.75
2.9
ILIM[2:0] = 0b101, RSENSE = 33mΩ
2.1
2.25
2.4
ILIM[2:0] = 0b100, RSENSE = 33mΩ
1.62
1.7
1.78
ILIM[2:0] = 0b011, RSENSE = 33mΩ
1.05
1.13
1.21
ILIM[2:0] = 0b010, RSENSE = 33mΩ
0.8
0.86
0.92
ILIM[2:0] = 0b001, RSENSE = 33mΩ
0.55
0.6
0.65
ILIM[2:0] = 0b000, RSENSE = 33mΩ
0.3
0.33
0.36
11
18
32
100
Discharge after POR
1
tDIS_CD
DCDC_ON toggle
2
tDIS_DET
Type-C detach
tBUCKOFF_CD
DCDC_ON toggle; see reset criteria
tBUCKOFF_DE
Type-C detach
T
Attach Comparator Load
Current Rising
Threshold
Common mode input = 5.15V
Attach Comparator
Hysteresis
Common mode input = 5.15V
5
UNITS
A
mA
ms
s
100
ms
2
s
100
ms
16
28
2.5
mA
mA
SENSN Undervoltage
Threshold (Falling)
VUV_SENSN
4
4.375
4.75
V
SENSN Overvoltage
Threshold (Rising)
VOV_SENSN
7
7.46
7.9
V
SENSN Short Circuit
Threshold (Falling)
VSHT_SENSN
1.75
2
2.25
V
SENSN Undervoltage
Fault Blanking Time
SENSN Overvoltage
Fault Blanking Time
16
tB,OV_SENSN
SENSN Discharge
Threshold Falling
From overvoltage condition to FAULT
asserted
VSENSN Falling
0.47
ms
3
6
µs
0.51
0.57
V
0.75
V
2.065
V/V
Remote Feedback Adjustment
SHIELD Input Voltage
Range
0.1
Gain
1.935
Input Referred Offset
Voltage
2
±2.0
mV
Digital Inputs (SDA, SCL, ENBUCK, BCMODE)
Input Leakage Current
www.maximintegrated.com
VPIN = 5.5V, 0V
-5
5
µA
Maxim Integrated | 11
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Electrical Characteristics (continued)
(VSUPSW = 14V, VIN = 3.3V, VENBUCK = 3.3V, VVCONN = 5V, Temperature = TA = TJ = -40°C to +125°C, unless otherwise noted.,
Actual typical values may vary and are not guaranteed.)
PARAMETER
SYMBOL
Logic High
VIH
Logic Low
VIL
CONDITIONS
MIN
TYP
MAX
1.6
UNITS
V
0.5
V
USB 2.0 Host Charger Emulator (HVD+/HVD-, D+/D-)
Input Logic High
VIH
Input Logic Low
VIL
Data Sink Current
IDAT_SINK
Data Detect Voltage
High
VDAT_REFH
Data Detect Voltage
Low
VDAT_REFL
Data Detect Voltage
Hysteresis
VDAT_HYST
Data Source Voltage
VDAT_SRC
2.0
VDAT_SINK = 0.25V to 0.4V
50
V
100
0.8
V
150
μA
0.4
V
0.25
60
ISRC = 200μA
0.5
V
mV
0.7
V
Synchronous Step-Down DC-DC Converter
PWM Output Voltage
Skip Mode Output
Voltage
Load Regulation
VSENSP
VSENSP_SKIP
RLR
7V ≤ VSUPSW ≤ 28V, No Load
5.15
V
7V ≤ VSUPSW ≤ 18V, No Load (Note 2)
5.25
V
51
mΩ
7V ≤ VSUPSW ≤ 18V, for 5V nominal
output setting
Output Voltage
Accuracy
8V ≤ VSUPSW ≤ 18V, 2.4A, VSENSP VSENSN = 79.2mV , GAIN[4:0] =
0b11111 cable compensation.
Spread Spectrum
Range
SS Enabled
SYNC Switching
Threshold High
VSYNC_HI
Rising
SYNC Switching
Threshold Low
VSYNC_LO
Falling
SYNC Internal Pulldown
6.33
6.68
±3.4
V
%
1.4
V
0.4
V
200
kΩ
(Note 4)
1
Cycles
RONH
ILX = 1A
54
95
mΩ
Low-Side Switch OnResistance
RONL
ILX = 1A
72
135
mΩ
BST Input Current
IBST
VBST – VLX = 5V, High-side on
2.2
SYNC Input Clock
Acquisition Time
tSYNC
High-Side Switch OnResistance
LX Current-Limit
Threshold
Skip Mode Peak-Current
Threshold
All Other Variants
5
MAX20461AATJM, MAX20461AATJP
6
ISKIP_TH
1
Negative Current Limit
Soft-Start Ramp Time
LX Rise Time
www.maximintegrated.com
tSS
(Note 4)
mA
A
A
1.2
A
8
ms
3
ns
Maxim Integrated | 12
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Electrical Characteristics (continued)
(VSUPSW = 14V, VIN = 3.3V, VENBUCK = 3.3V, VVCONN = 5V, Temperature = TA = TJ = -40°C to +125°C, unless otherwise noted.,
Actual typical values may vary and are not guaranteed.)
PARAMETER
SYMBOL
LX Fall Time
CONDITIONS
MIN
(Note 4)
BST Refresh Algorithm
Low-Side Minimum OnTime
TYP
MAX
UNITS
4
ns
60
ns
CC_POL, FAULT, INT (ATTACH), SYNC Outputs
Output-High Leakage
Current
FAULT, INT(ATTACH), CC_POL = 5.5V
Output Low Level
Sinking 1mA
SYNC Output High
Level
Sourcing 1mA, SYNC configured as
output
-10
10
µA
0.4
V
VBIAS 0.4
V
Config Resistors Converter
CONFIG1-3 Current
Leakage
VCONFIG = 0V to 4V
Minimum Window
Amplitude
-4
±5
µA
4
%
ADC
Resolution
8
Bits
ADC Gain Error
±2
LSBs
±1
LSB
Offset Error
Offset_ADC
Oscillators
Internal High-Frequency
Oscillator
HFOSC
7
8
9
MHz
Buck Oscillator
Frequency
fSW
FSW[2:0] = 0b000
1.95
2.2
2.45
MHz
Buck Oscillator
Frequency
fSW
FSW[2:0] = 0b101
340
410
480
kHz
Thermal Overload
Thermal Warning
Temperature
140
°C
Thermal Warning
Hysteresis
10
°C
Thermal Shutdown
Temperature
165
°C
Thermal Shutdown
Hysteresis
10
°C
I 2C
Serial Clock Frequency
fSCL
Bus Free Time Between
STOP and START
Condition
tBUF
1.3
µs
START Condition Setup
Time
tSU:STA
0.6
µs
www.maximintegrated.com
400
kHz
Maxim Integrated | 13
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Electrical Characteristics (continued)
(VSUPSW = 14V, VIN = 3.3V, VENBUCK = 3.3V, VVCONN = 5V, Temperature = TA = TJ = -40°C to +125°C, unless otherwise noted.,
Actual typical values may vary and are not guaranteed.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
START Condition Hold
Time
tHD:STA
0.6
µs
STOP Condition Setup
Time
tSU:STO
0.6
µs
tLOW
1.3
µs
Clock Low Period
Clock High Period
tHIGH
0.6
µs
Data Setup Time
tSU:DAT
100
ns
Data Hold Time
tHD:DAT
Pulse Width of Spike
Suppressed
From 50% SCL falling to SDA change
tSP
0.3
0.6
µs
50
ns
±2
kV
ESD Protection (All Pins)
ESD Protection Level
VESD
Human Body Model
ESD Protection (HVDP, HVDM, CC1, CC2)
ISO 10605 Air Gap (330pF, 2kΩ)
ESD Protection Level
VESD
±25
ISO 10605 Contact (330pF, 2kΩ)
±8
IEC 61000-4-2 Air Gap (150pF, 330Ω)
±15
IEC 61000-4-2 Contact (150pF, 330Ω)
±8
ISO 10605 Air-Gap (330pF, 330Ω)
±15
ISO 10605 Contact (330pF, 330Ω)
±8
kV
Note 2: Device is designed for use in applications with continuous operation of 14V. Device meets electrical table up to maximum
supply voltage.
Note 3: The IR drop of the system must be considered when selecting the VCONN pin source voltage.
Note 4: Guaranteed by design and bench characterization; not production tested.
www.maximintegrated.com
Maxim Integrated | 14
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Typical Operating Characteristics
EFFICIENCY (%)
(TA = +25°C, unless otherwise noted.)
www.maximintegrated.com
Maxim Integrated | 15
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
www.maximintegrated.com
Maxim Integrated | 16
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
www.maximintegrated.com
Maxim Integrated | 17
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Pin Configurations
PGND
PGND
LX
LX
BST
ENBUCK
BCMODE
TOP VIEW
CONFIG1
MAX20461
24
23
22
21
20
19
18
17
HVEN
25
16
SDA (CONFIG2)
SUPSW
26
15
SCL (CONFIG3)
SUPSW
27
14
FAULT
VBMON
28
13
SYNC
SENSP
29
12 INT(ATTACH)
SENSN
30
11 IN
G_DMOS
31
BIAS
32
MAX20461
10 DM
9
DP
HVDP
CC_POL (SHIELD)
BCMODE
8
ENBUCK
AGND
HVDM
CC2
7
BST
VCONN
6
LX
CC1
5
LX
4
PGND
3
PGND
2
CONFIG1
1
AGND
+
24
23
22
21
20
19
18
17
TQFN
5mm x 5mm
MAX20461A
TOP VIEW
HVEN
25
16
SDA (CONFIG2)
SUPSW
26
15
SCL (CONFIG3)
SUPSW
27
14
FAULT
VBMON
28
13
SYNC
SENSP
29
12 INT(ATTACH)
SENSN
30
11 IN
G_DMOS
31
BIAS
32
MAX20461A
10 DM
+
2
3
4
5
6
7
8
AGND
CC1
AGND
CC2
AGND
HVDM
HVDP
CC_POL (SHIELD)
9
1
DP
TQFN
5mm x 5mm
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Maxim Integrated | 18
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Pin Description
PIN
NAME
FUNCTION
MAX20461
MAX20461A
1, 5
1, 3, 5
AGND
2
2
CC1
3
—
VCONN
4
4
CC2
6
6
HVDM
High-Voltage-Protected USB Differential Data D- Output. Connect HVD- to the
downstream USB connector D- pin.
7
7
HVDP
High-Voltage-Protected USB Differential Data D+ Output. Connect HVD+ to the
downstream USB connector D+ pin.
8
8
CC_POL
(SHIELD)
9
9
DP
USB Differential Data D+ Input. Connect D+ to the low-voltage USB transceiver
D+ pin.
10
10
DM
USB Differential Data D- Input. Connect D- to the low-voltage USB transceiver Dpin.
11
11
IN
Logic Enable Input. Connect to I/O voltage of USB transceiver. IN is also used for
clamping during overvoltage events on HVD+ or HVD-. Connect a 1µF-10µF
ceramic capacitor from IN to GND.
12
12
INT
(ATTACH)
13
13
SYNC
Switching frequency Input/Output for synchronization with other supplies. See
Applications Information section.
14
14
FAULT
Active-low, open-drain,fault indicator output. Connect a 100kΩ pullup resistor to
the IN pin.
15
15
SCL
(CONFIG3)
In I2C variants, this serves as the I2C SCL Pin. In standalone variants, this serves
as CONFIG3 pin. See Table 10.
16
16
SDA
(CONFIG2)
In the I2C variants, this serves as the I2C SDA Pin. In standalone variants, this
serves as CONFIG2 pin. See Table 10.
17
17
BCMODE
This pin selects between the two modes of data switch operation. The modes are
defined in the Data Switch Mode Truth Table.
18
18
ENBUCK
DC-DC Enable Input. Drive high/low to enable/disable the buck converter.
19
19
BST
20, 21
20, 21
LX
22, 23
22, 23
PGND
24
24
CONFIG1
25
25
HVEN
26, 27
26, 27
SUPSW
Internal High-Side Switch Supply Input. VSUPSW provides power to the internal
switch and LDO. Connect a 10μF ceramic capacitor in parallel with a 47μF
electrolytic capacitor from SUPSW to PGND. See the DC-DC Input Capacitor
section.
28
28
VBMON
USB VBUS monitor.
www.maximintegrated.com
Analog Ground.
Type-C Configuration Channel (CC).
Power Source. Supplies power to the unused CC pin if required.
Type-C Configuration Channel (CC).
In USB-C Configuration, CC_POL Output. In BC1.2 only variant, remote feedback
input. See Figure 3.
In I2C variants, functions as an active-low INT pin. In standalone variants,
functions as active-low Attach. Connect a 100kΩ pullup resistor to IN.
High-Side Driver Supply. Connect a 0.1μF capacitor from BST to LX.
Inductor connection. Connect an inductor from LX to the DC-DC converter output
(SENSP).
Power Ground.
Configuration. Connect a resistor to GND to set default configuration. See Table 8
and Table 9.
Active-high system enable pin. HVEN is battery-voltage tolerant.
Maxim Integrated | 19
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Pin Description (continued)
PIN
MAX20461
MAX20461A
NAME
FUNCTION
29
29
SENSP
DC-DC converter feedback input and current-sense amplifier positive input. DCDC bulk capacitance placed here. Connect to positive terminal of current-sense
resistor (RSENSE) and the main output of the converter. Used for internal voltage
regulation loop.
30
30
SENSN
Current-sense amplifier negative input. Connect to negative terminal of currentsense resistor (RSENSE).
31
31
G_DMOS
Gate drive output. Optionally connect to the gate of an external N-channel FET,
otherwise terminate with 10pF.
32
32
BIAS
5V linear regulator output. Connect a 2.2µF ceramic capacitor from BIAS to GND.
BIAS powers the internal circuitry.
EP
EP
EP
Exposed pad. Connect EP to multiple GND planes with 3 x 3 via grid (minimum).
Functional Diagrams
On-Channel -3dB Bandwidth and Crosstalk
+3.3V
NETWORK ANALYZER
IN
D+ (D-)
+14V
VIN
50Ω
50Ω
SUPSW
+3.3V
HVD+ (HVD-)
VOUT
MEAS
REF
ON-LOSS = 20log
VOUT
VIN
CROSSTALK = 20log
VOUT
VIN
ON-LOSS1 = 20log
HVD+
D+
ON-LOSS2 = 20log
HVDD-
ENBUCK
50Ω
50Ω
CROSSTALK1 = 20log
HVD+
D-
CROSSTALK2 = 20log
HVDD+
GND
ON-LOSS IS MEASURED BETWEEN D+ AND HVD+, OR D- AND HVD-.
CROSSTALK IS MEASURED FROM ONE CHANNEL TO THE OTHER CHANNEL.
SIGNAL DIRECTION THROUGH SWITCH IS REVERSED; WORST VALUES ARE RECORDED.
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Maxim Integrated | 20
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
On-Capacitance
+3.3V
IN
+14V
D_ OR
HVD_
SUPSW
CAPACITANCE
METER
+3.3V
ENBUCK
GND
DCDC_ON Reset Behavior and Timing Diagram
HVEN
DCDC_ON TOGGLE
< 2s
DCDC_ON TOGGLE
> 2s
DCDC_ON
RD ALREADY ATTACHED &
I2C CONFIGURED BIT = 1
ON
USB SIGNAL
CHAIN ACTIVE
OFF
ON
SENSN
DISCHARGE
tDIS_CD
tDIS_CD
OFF
ON
BUCK
CONTROL
OFF
tBUCK_WAIT +
tDIS_POR
tCCDEBOUNCE
www.maximintegrated.com
tBUCKOFF_CD +
tCCDEBOUNCE
tCCDEBOUNCE
Maxim Integrated | 21
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
ADC Timing Diagram
ADC_REQ
ADC_USBV
ADC_USBI
ADC_TEMP
ADC_DONE
INT
EN_ADC_DONE
MASTER WRITES
ADC_REQ
www.maximintegrated.com
SAMPLE READY
IRQ_0 READ
MASTER WRITES
ADC_REQ
AND
EN_ADC_DONE
SAMPLE READY
IRQ_0 READ
Maxim Integrated | 22
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
ATTACH Logic Diagram
SOFT START DONE
CC_ATTACH
LDO
SWITCHOVER
CC_ENB
500ms
ASSERTION
DELAY
DCDC ENABLE
CC_ENB
0
ENABLE FPWM
1ms
ASSERTION
DELAY
CURRENT SENSE
ATTACH CRITERIA
1
BC_ATTACH
USB2 DATA-LINE
ATTACH CRITERIA
INT
1
INT (ATTACH)
PIN
0
CD[1]
STANDALONE
CD[0]
Cable Attach-Detach and SENSN Discharge Timing Diagram
PASSENGER PHONE [RD] & PASSENGER POWERED CABLE [RA]
WITH VCONN CONSIDERATIONS
DCDC_ON low for ≥ 2s
RD
DETACH
DCDC_ON
VBIAS
CC1
0
VBIAS
CC2
RD
ATTACH
RA
ATTACH
0
PASSENGER PHONE [RD] & PASSENGER UN-POWERED CABLE
DCDC_ON low for ≥ 2s
RD
DETACH
RD
ATTACH
CC2 DRIVEN
VCONN
pin = 5V
CC2 DRIVEN
VCONN
pin = 0V
CC2 UNUSED
SENSN
G_DMOS
SENSN
DISCHARGE
tCCDEBOUNCE
RA ATTACH Region
www.maximintegrated.com
11ms
DEBOUNCE
tCCDEBOUNCE
tDIS_DET
11ms
DEBOUNCE
tDIS_DET
Maxim Integrated | 23
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Detailed Block Diagram
CC2
CC1
VBMON
AGND
VCONN
IN
BC1.2 (CDP, SDP)
HOST CHARGER
EMULATION
MAX20461
USB TYPE-C DFP AND
ORIENTATION
DETECTION
HVDM
HVDP
G_DMOS
DM
DP
CHARGE PUMP
SENSN MON
SENSN
CURRENT-SENSE AMP
SENSP
7.46V
BST
REMOTE
CABLE
SENSE
SUPSW
HS_CS
3.5A FPWM
BUCK
CONVERTER
UV
4.37V
DISCH
0.5V
I/O CONTROL
AND
DIAGNOSTICS
BCMODE
FAULT
INT (ATTACH)
ENBUCK
USB
OVERCURRENT
THRESHOLD
ADC
TEMP
MONITOR
HVEN
CC_POL/SHIELD
OSC
PGND
SCL (CONFIG3)
2.0V
FEEDBACK
ADJUSTMENT
LX
SDA (CONFIG2)
SHORT
BIAS
LDO
BIAS
CONFIG1
OV
SYNC
LS_CS
www.maximintegrated.com
Maxim Integrated | 24
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
CC2
CC1
VBMON
AGND
USB TYPE-C DFP AND
ORIENTATION
DETECTION
IN
BC1.2 (CDP, SDP)
HOST CHARGER
EMULATION
MAX20461A
HVDM
HVDP
G_DMOS
DM
DP
CHARGE PUMP
SENSN MON
SENSN
CURRENT-SENSE AMP
SENSP
7.46V
UV
FEEDBACK
ADJUSTMENT
REMOTE
CABLE
SENSE
SUPSW
HS_CS
4.37V
DISCH
0.5V
I/O CONTROL
AND
DIAGNOSTICS
BCMODE
FAULT
INT (ATTACH)
ENBUCK
USB
OVERCURRENT
THRESHOLD
3.5A FPWM
BUCK
CONVERTER
LX
SCL (CONFIG3)
2.0V
BST
ADC
TEMP
MONITOR
HVEN
CC_POL/SHIELD
OSC
PGND
SDA (CONFIG2)
SHORT
BIAS
LDO
BIAS
CONFIG1
OV
SYNC
LS_CS
www.maximintegrated.com
Maxim Integrated | 25
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Detailed Description
The MAX20461 combines a 5V/3A automotive-grade step-down converter, a USB host charger emulator, and USB
protection switches. The device variants offer options for both standalone/GPIO and I2C configuration and control. This
device family is designed for high-power USB ports in automotive radio, navigation, connectivity, USB hub, and dedicated
charging applications.
The MAX20461 features high-voltage, high-ESD, 1GHz bandwidth data switches. MAX20461 protects up to 18V and
includes internal ESD protection circuitry.
The data switches of all device variants protect the sensitive 3.3V pins of the USB transceiver and support USB LowSpeed (1.5Mbps), Full-Speed (12Mbps) and Hi-Speed (480Mbps) communication modes. The internal host charger
port-detection circuitry offers automatic sensing and conformance to multiple standards, including USB Type-C 3.0A/
1.5A/0.5A and USB-IF BC1.2 CDP/SDP modes. All variants enable USB-IF OTG, Apple CarPlay, and Android Auto
conformance, while retaining industry-leading protection features and automotive-grade robustness.
The high-efficiency step-down DC-DC converter operates with an input voltage up to 28V, and is protected from load
dump transients up to 40V. The DC-DC converter can be programmed from 310kHz to 2.2MHz switching frequency, or
synced to 248kHz to 2.2MHz switching frequency. The converter can deliver 3A of continuous current at 125°C.
The MAX20461 features a high-side current-sense amplifier and a programmable feedback-adjustment circuit that
provides automatic USB voltage adjustment to compensate for voltage drops in captive cables associated with
automotive applications. The precision current sense allows for an accurate DC output current limit that minimizes the
solution component size and cost.
USB Type-C
USB Type-C introduces a new connector, cable, and detection mechanism while maintaining backwards compatibility
with the existing USB ecosystem. The small-form-factor Type-C connector is reversible and bidirectional, which
eliminates the Type A/Type B distinction. To maintain the USB host/device relationship, Type-C requires a configuration
channel (CC). The CC pins are used to advertise and detect current capabilities and for the host to detect the cable
orientation, which is required for USB3 and active cables.
A Type-C implementation supports, but does not require, USB Power Delivery, BC1.2, and USB3. For backwards
compatibility, a USB3 implementation also requires an independent USB 2.0 channel. It is also advisable to implement
BC1.2 detection, in addition to CC detection, on HVDP/HVDM. This ensures the highest possible charge current when a
legacy adapter is used. Table 1 shows the precedence of power negotiation as mandated by USB-IF. See USB Type-C
2.0 for details.
The MAX20461 provides an integrated Type-C 5V solution tailored to the automotive market. The device integrates all
control and power circuitry necessary to maintain a 5V/3A downstream facing port (DFP) at the end of a captive-cable.
It also provides BC1.2 charge detection, USB 2.0 data protection, and support for USB3 cable orientation detection and
VCONN power.
Table 1. Charge Detection Precedence
PRECEDENCE
Highest
↓
Lowest
NOMINAL VOLTAGE
MAXIMUM CURRENT
USB Type-C @ 3A Advertisement
MODE OF OPERATION
5V
3A
USB Type-C @ 1.5A Advertisement
5V
1.5A
USB BC1.2
5V
≤ 1.5A
USB 3.1
5V
900 mA
USB 2.0
5V
500 mA
Default USB Power
Configuration Channel (CC1 and CC2)
The CC pins utilize combinations of pullups and pulldowns to detect Type-C device attachment, advertise the current
capabilities of the source, and detect the type and orientation of the cable and the device. There are three possible pullup
resistors (RP) that represent the three source current capabilities: 0.5A, 1.5A, and 3A. There are also two possible device
pulldown resistors (RA and RD) to provide device and cable information to the host. Figure 1 shows how these are used
www.maximintegrated.com
Maxim Integrated | 26
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
for Type-C detection on the CC pins. This configuration allows for simultaneous advertisement and detection. The TypeC specification also allows for dynamic RP changes without any resets. Table 2, Table 3 and Cable Attach-Detach and
SENSN Discharge Timing Diagram detail how the MAX20461 responds to the various combinations or RA and RD.
Table 2. CC Pulldown Response
CC1
CC2
TYPE-C STATUS
Open
Open
Nothing attached
RD
Open
Open
RD
Open
RA
RA
Open
Sink attached
Powered cable without Sink attached
MAX20461 ACTION TAKEN
VBUS
VCONN
CC_ATTACH
CC_POL
CC_PIN_STATE
Off
Off
0
0
0b00
On
Off
1
1
0b01
On
Off
1
0
0b10
Off
Off
0
0
0b00
Off
Off
0
0
0b00
On
On CC2
1
1
0b01
On
On CC1
1
0
0b10
RD
RA
RA
RD
RD
RD
Debug Accessory attached
Off
Off
0
0
0b00
RA
RA
Audio Adapter Accessory attached
Off
Off
0
0
0b00
Powered cable with Sink attached
Table 3. CC Pulldown Response (MAX20461A)
CC1
CC2
TYPE-C STATUS
Open
Open
Nothing attached
RD
Open
Open
RD
Open
RA
RA
Open
RD
RA
MAX20461A ACTION TAKEN
Sink attached
Powered cable without Sink attached
Powered cable with Sink attached
VBUS
CC_ATTACH
CC_POL
CC_PIN_STATE
Off
0
0
0b00
On
1
1
0b01
On
1
0
0b10
Off
0
0
0b00
Off
0
0
0b00
On
1
1
0b01
RA
RD
On
1
0
0b10
RD
RD
Debug Accessory attached
Off
0
0
0b00
RA
RA
Audio Adapter Accessory attached
Off
0
0
0b00
SOURCE MONITORS
FOR CONNECTION
AND ORIENTATION
SINK MONITORS FOR
CURRENT CAPABILITY
BIAS
CC
RP
RP
SOURCE MONITORS
FOR CONNECTION
AND ORIENTATION
RA
RD
RA
RD
SINK MONITORS FOR
CURRENT CAPABILITY
Figure 1. Type-C Pullup Model
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Maxim Integrated | 27
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
CC Polarity Output Pin (CC_POL)
The MAX20461 features an open-drain, active-low CC polarity output. The pin will assert low when RD is detected on
CC2. See Table 2.
VCONN (MAX20461 Only)
While there are two CC pins that must be monitored on the host receptacle, there is only one CC wire running through
the Type-C cable. This allows orientation to be determined, and leaves the second CC pin available for other uses. The
Type-C specification allows the unused CC pin to operate as VCONN, which is a low power source intended to power
active cables that can include authentication ICs or superspeed muxes.
The MAX20461 includes complete support for VCONN power control and protection. When a power source within
the acceptable operating voltage is connected to the VCONN pin, MAX20461 can connect the voltage source to the
appropriate CC pin. Back-to-back VCONN FETs provide overvoltage and overcurrent protection to the VCONN source in
addition to controlling the application of VCONN per the Type-C specification.
Table 4. Type-C Source VCONN Requirements
PORT FEATURES
D+/D-
SSTX/SSRX, VPD
>3A
VCONN REQUIREMENTS
No
No
No
Not required
Yes
No
No
Not required
Yes
Yes
No
1W, 3V-5.5V
VBUS
Type-C includes new requirements for VBUS, even when operating exclusively in 5V mode. When no device is attached
to the CC pins, the host must switch the VBUS source off so that near zero volts is present at the receptacle pin. To
achieve this, the MAX20461 disables the external FET gate drive and turns off the buck converter when in a detached
state, reducing quiescent current. The MAX20461 integrates control and discharge circuits to ensure all Type-C timing
requirements are met. Throughout this document, the term VBUS is used loosely to refer to voltage at SENSP, SENSN
or VBMON. When more precision is required, the specific pin name is referenced.
External FET Gate Drive (G_DMOS Pin)
The MAX20461 includes a gate drive for an optional external FET that can be used to isolate the bulk capacitance when
VBUS is not being sourced. If used, connect the G_DMOS pin to the gate of the external FET. If not used, terminate
G_DMOS with a 10pF capacitor. G_DMOS activates prior to soft-start, and turns off after discharge. If VBUS short-tobattery is required, the FET should be appropriately rated. The external DMOS device must be a 20V VGS type. The
charge pump generates at least 7V.
Legacy Devices
The Type-C specification ensures interoperability with Type-A and Type-B devices by defining requirements for legacy
adapters. As a DFP, relevant adapters connect from the Type-C receptacle to either a Type-B plug or to a Type-A
receptacle, which can then be used with any legacy Type-A cable. A compliant legacy adapter of this type must include
an RD termination inside the adapter. In this case, the MAX20461 detects a Type-C attachment whenever the adapter
is connected, regardless of whether a portable device is connected. The portable device sees the DFP as a BC1.2 port
(when configured as such).
Power-Up and Enabling
System Enable (HVEN)
HVEN is used as the main enable to the device and initiates system start-up and configuration. If HVEN is at a logic-low
level, SUPSW power consumption is reduced and the device enters a standby, low quiescent current level. HVEN is
compatible with inputs from 3.3V logic up to automotive battery. After a system reset (e.g., HVEN toggle, BIAS UV), the
I2C variant asserts the INT pin to indicate that the IC has not been configured. The buck converter is forced off until the
CONFIGURED bit of SETUP_4 is written to a 1. This ensures that a portable device cannot attach before the IC registers
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Maxim Integrated | 28
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
BIAS
RP
CC2_VCONN_EN
RP
CC1_VCONN_EN
CC1_RP_EN
CC2_RP_EN
CC1
VCONN
CC2
VCONN ILIM
5.5V CLAMPS
CC1_VRA_RD
VCONN_UVLO
CC1_VOPEN
CC2_VRA_RD
CC2_VOPEN
Type C
Control Logic
CC1_VCONN_EN
CC2_VCONN_EN
CC1_RP_EN
VRA_RD
VBMON
CC2_RP_EN
VOPEN
VSAFE0V
RP
ENBUCK
CC_CUR_SRC[1:0]
VRA_RD
DCDC_ON
VOPEN
G_DMOS
EN_DCDC
RP Enable
CC_ENB
BUCK CONTROL
FAULT RETRY TIMER EXPIRED
STARTUP/DISCHARGE TIMER EXPIRED
ALLOW DCDC
DCDC_ON RETRY TIMER EXPIRED
Figure 2. USB Type-C Block Diagram
are correctly set for the application.
DC-DC Enable (ENBUCK)
The buck regulator on the MAX20461 is controlled by the ENBUCK pin for standalone variants, and by both the ENBUCK
pin and the I2C interface for I2C variants. DCDC_ON, the logical AND of ENBUCK and EN_DCDC, determines if the
buck converter can be enabled by the Type-C control logic. On standalone variants, EN_DCDC is always high and only
ENBUCK can be used to enable the buck converter. On I2C variants, setting ENBUCK low overrides an I2C EN_DCDC
enable command, which allows compatibility with USB hub controllers. For a typical USB hub application, connect
ENBUCK to the enable output of the USB hub controller. This allows the USB hub controller to enable and disable the
USB power port using software commands. ENBUCK can be directly connected to the BIAS or IN pin for applications
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Maxim Integrated | 29
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
that do not require GPIO control of the DC-DC converter enable.
3.3V Input (IN)
IN is used to clamp the D+ and D- pins during an ESD or overvoltage event on the HVD+ and HVD- pins. This clamping
protects the downstream USB transceiver. The presence of these clamping diodes requires that IN remain set to 3.3V at
all times for USB communication to occur. The IN pin features an overvoltage lockout that disables the data switches if
IN is above VIN_OVLO. Bypass IN with a 1μF ceramic capacitor, place it close to the IN pin, and connect it to the same
3.3V supply that is shared with the multimedia processor or hub transceiver.
Linear Regulator Output (BIAS)
BIAS is the output of a 5V linear regulator that powers the internal logic and control circuitry for the device. BIAS is
internally powered from SUPSW or SENSP and automatically powers up when HVEN is high and SUPSW voltage
exceeds VUV_SUPSW. The BIAS output contains an undervoltage lockout that keeps the internal circuitry disabled when
BIAS is below VUV_BIAS. The linear regulator automatically powers down when HVEN is low, and a low shutdown current
mode is entered. Bypass BIAS to GND with a 2.2μF ceramic capacitor.
Power-On Sequencing
HVEN, ENBUCK and IN do not have a power-up sequence requirement by design. However, the desired system
behavior should be considered for the state of these pins at startup. The D+ and D- pins are clamped to IN, therefore IN
should be set to 3.3V before any USB communication is required. It is recommended that IN is set to 3.3V before HVEN
is set high. ENBUCK acts as the master disable for the DC-DC converter. If ENBUCK is low when HVEN is set high, all
variants keep the buck converter in the disabled state until ENBUCK is set high.
Step-Down DC-DC Regulator
Step-Down Regulator
The MAX20461 features a current-mode, step-down converter with integrated high-side and low-side MOSFETs. The
low-side MOSFET enables fixed-frequency, forced-PWM operation under light loads. The DC-DC regulator features a
cycle-by-cycle current limit and intelligent transition from skip mode to forced-PWM mode that makes the device ideal for
automotive applications.
Wide Input Voltage Range
The device is specified for a wide 4.5V to 28V input voltage range. SUPSW provides power to the internal BIAS linear
regulator and internal power switch. Certain conditions such as cold cranking can cause the voltage at the output to drop
below the programmed output voltage. Under such conditions, the device operates in a high duty-cycle mode to facilitate
minimum dropout from input to output.
Maximum Duty-Cycle Operation
The MAX20461 has a maximum duty cycle of 98% (typ). The IC monitors the off-time (time for which the low-side FET
is on) in both PWM and skip modes for every switching cycle. Once the off-time of 150ns (typ) is detected continuously
for 7.5μs, the low-side FET is forced on for 60ns (typ) every 7.5μs. The input voltage at which the device enters dropout
changes depending on the input voltage, output voltage, switching frequency, load current, and design efficiency. The
input voltage at which the devices enter dropout can be approximated as:
VSUPSW =
(
VOUT + ILOAD × RONH
0.98
)
Note: The equation above does not take into account the efficiency and switching frequency but will provide a good firstorder approximation. Use the RONH (max) in the Electrical Characteristics table.
Output Voltage (SENSP)
The device features a precision internal feedback network that is connected to SENSP and that is used to set the output
voltage of the DC-DC converter. The network nominally sets the average DC-DC converter output voltage to the voltage
that corresponds to the VOUT configuration register, with a default value of 5.15V.
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Maxim Integrated | 30
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Soft-Start
When the DC-DC converter is enabled, the regulator soft-starts by gradually ramping up the output voltage from 0V to
5.15V over approximately 8ms. This soft-start feature reduces inrush current during startup. Soft-start is guaranteed into
compliant USB loads (see the USB Loads section).
Reset Behavior
The MAX20461 implements a discharge function on SENSN any time that the DC-DC regulator is disabled for any
reason. When the discharge function is activated, current (ISENSN_DIS) is drained through a current-limited FET, and a
reset timer is also started. This timer prevents the DC-DC regulator from starting up again until the timer has expired.
This allows for easy compatibility with USB specifications and removes the need for long discharge algorithms to be
implemented in system software. See the relevant Functional Diagrams and Figure 2 for reset timer details.
Reset Criteria
The MAX20461 DC-DC converter automatically resets for all undervoltage, overvoltage, overcurrent and
overtemperature fault conditions. See Table 12 for details. The fault retry timer is configurable in the SETUP_3 register.
This timer is activated after a fault condition is removed and prevents the buck converter from switching on until the timer
expires.
Another internal retry timer is enabled after DCDC_ON is set low or a Type-C detach event. DCDC_ON toggle causes
buck shutdown and prevent the buck from switching on until tBUCKOFF_CD expires. A Type-C detach event will cause
buck shutdown and prevent the buck from switching on until tBUCKOFF_DET expires.
Switching Frequency Configuration
The DC-DC switching frequency can be referenced to an internal oscillator or from an external clock signal on the SYNC
pin. The internal oscillator frequency is set by the FSW[2:0] bits of the SETUP_1 register, which has a POR value
corresponding to 2.2MHz. The internal oscillator can be programmed via I2C to eight discrete values from 310kHz to
2.2MHz. For standalone variants, FSW configuration value is loaded from the CONFIG1 pin at startup with four discrete
values from 310kHz to 2.2MHz available.
Switching Frequency Synchronization (SYNC Pin)
When the SYNC pin is configured to operate as an output, skip mode operation is disallowed, and the internal oscillator
drives the SYNC pin. This allows other devices to synchronize with the MAX20461 180 degrees out of phase for EMI
reduction.
When SYNC is configured as an input, the SYNC pin becomes a logic-level input that can be used for both operatingmode selection and frequency control. Connecting SYNC to GND or an external clock enables fixed-frequency, forcedPWM mode. Connecting SYNC to a logic-high signal allows intelligent skip-mode operation (Type-A mode, i.e. CC_ENB
= 1) or FPWM mode (default Type-C mode, i.e. CC_ENB = 0). The device can be externally synchronized to frequencies
within ±20% of the programmed internal oscillator frequency.
Forced-PWM Operation
In forced-PWM mode, the device maintains fixed-frequency PWM operation over all load conditions, including no-load
conditions.
Intelligent Skip-Mode Operation and Attach Detection
When the SYNC pin is configured as an input and CC_ENB = 1 (via I2C only), but neither a clocked signal nor a logiclow level exists on the SYNC pin, the MAX20461 operates in skip mode at very light load/no load conditions. Intelligent
device attach detection is used to determine when a device is attached to the USB port. The device intelligently exits
skip mode and enters forced-PWM mode when a device is attached and remains in forced-PWM mode as long as the
attach signal persists. This minimizes the EMI concerns caused by automotive captive USB cables and poorly shielded
consumer USB cables. The device attach event is also signaled by the ATTACH pin (standalone variants) or ATTACH
bits (I2C variants). The criteria for device attach detection and intelligent skip-mode operation are shown in Table 5. Note
that when operating in Type-C mode, the buck only switches on when a Type-C device is attached. This means skip
mode cannot be entered if CC_ENB = 0.
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Maxim Integrated | 31
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Table 5. DC-DC Converter Intelligent Skip Mode Truth Table
CC_ENB
SYNC
PIN
SYNC_
DIR BIT
DATA SWITCH CHARGE
DETECTION MODE
CDP ATTACH
DETECTION
CURRENT SENSE
ATTACH DETECTION
DC-DC CONVERTER
OPERATION
0
x
x
x
x
x
Forced-PWM Mode:
Type-C Device Attached
1
x
1
x
x
x
Forced-PWM Mode:
Continuous
1
0
0
x
x
x
Forced-PWM Mode:
Continuous
1
Clocked
0
x
x
x
Forced-PWM Mode:
Continuous
1
1
0
High-Speed Pass Thru
(SDP) Mode
x
0
Intelligent Skip Mode: No
Device Attached
1
1
0
High-Speed Pass Thru
(SDP) Mode
x
1
Forced-PWM Mode:
Device Attached
1
1
0
BC1.2 Auto CDP Mode
0
0
Intelligent Skip Mode: No
Device Attached
1
1
0
BC1.2 Auto CDP Mode
1
x
Forced-PWM Mode:
Device Attached
1
1
0
BC1.2 Auto CDP Mode
x
1
Forced-PWM Mode:
Device Attached
Spread-Spectrum Option
Spread-spectrum operation is offered to improve the EMI performance of the MAX20461. Spread-spectrum operation
is enabled by the SS_EN bit of the SETUP_0 register, which is preloaded on startup from the CONFIG1 pin for both
standalone and I2C variants. The internal operating frequency modulates the switching frequency by up to ±3.4% relative
to the internally generated operating frequency. This results in a total spread-spectrum range of 6.8%. Spread-spectrum
mode is only active when operating from the internal oscillator. Spread-spectrum clock dithering is not possible when
operating from an external clock.
Current Limit
The MAX20461 limits the USB load current using both a fixed internal peak current threshold of the DC-DC converter,
as well as a user-programmable external DC load current-sense amplifier threshold. This allows the current limit to be
adjusted between 300mA to 3A depending on the application requirements, while protecting the system in the event of a
fault. Upon exceeding either the DC-DC peak or user-programmable current thresholds, the high-side FET is immediately
switched off and current-limit algorithms are initiated. When the external current limit lasts for longer than 16ms, the
FAULT pin asserts and the VBUS_ILIM bit of the IRQ_1 register is set. Once the load current exceeds the programmed
threshold, the DC-DC converter acts as a constant-current source. This may cause the output voltage to droop. The
ILIM_ITRIP bit of the SETUP_2 register determines the output voltage droop required to initiate a DC-DC converter reset
during VBUS_ILIM. When ILIM_ITRIP = 0, the USB current limit is detected for 16ms and the output voltage falls below
VUV_SENSN, the DC-DC converter resets. The DC-DC converter also resets if the internal LX peak current threshold is
exceeded for four consecutive switching cycles and the output voltage droops to less than 2.0V.
In some cases, the designer may want to increase the load to 160%, refer to USB Output Current Limit for details.
Output Short-Circuit Protection
The DC-DC converter output (SENSP, SENSN) is protected against both short-to-ground and short-to-battery conditions.
If a short-to-ground or undervoltage condition is encountered, the DC-DC converter immediately resets, asserts the
FAULT pin, flags the fault in the IRQ_1 register, and then reattempts soft-start after the reset delay. This pattern repeats
until the short circuit has been removed.
If a short-to-battery is encountered (VSENSN > VOV_SENSN), the buck converter shuts down, G_DMOS is disabled, the
FAULT pin is asserted, and the fault is flagged in the IRQ_1 register. The buck converter stays shut down until the fault
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Maxim Integrated | 32
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
condition resolves and the 2s timer expires.
Thermal Overload Protection
Thermal overload protection limits the total power dissipated by the device. A thermal-protection circuit monitors the die
temperature. If the die temperature exceeds +165°C, the device shuts down, so it can cool. Once the device has cooled
by 10°C, the device is enabled again. This results in a pulsed output during continuous thermal overload conditions,
protecting the device during fault conditions. For continuous operation, do not exceed the absolute maximum junction
temperature of +150°C. See the Thermal Considerations section for more information.
Pre-Thermal Overload Warning
The MAX20461 I2C variant features a thermal overload warning flag which sets the THM_WARN bit of the IRQ_2 register
when the die temperature crosses +140°C. This allows a system software implementation of thermal foldback or load
shedding algorithms to prevent a thermal overload condition.
Automatic Thermal Foldback
All MAX20461 variants implement a thermal foldback feature which, when enabled, reduces the Type-C current
advertised on the CC pins by RP. When THM_WARN = 1, the RP current advertisement reduces to the setting
immediately below what is set in CC_CUR_SRC[1:0]. When the die temperature drops below the thermal warning
threshold, RP returns to its original setting based on CC_SRC_CUR[1:0].
Note that Type-C allows for dynamic RP changes in the Attached.SRC state without reinitializing detection. The
MAX20461 thermal foldback does not: force BUS to reset, change the BC1.2 mode, or reduce the USB current
limit. Alternative thermal foldback algorithms are available and can be performed in system software. Contact Maxim
Applications for support.
USB Current Limit and Output Voltage Adjustment
Current-Sense Amplifier (SENSP, SENSN)
MAX20461 features an internal USB load current-sense amplifier to monitor the DC load current delivered to the USB
port. The VSENSE voltage (VSENSP - VSENSN) is used internally to provide precision DC current-limit and voltagecompensation functionality. A 33mΩ sense resistor (RSENSE) should be placed between SENSP and SENSN.
In some cases, the designer may want to increase the load to 160%, refer to USB Output Current Limit for details.
USB DC Current Limit Configuration
The MAX20461 allows configuration of the precision DC current limit by the ILIM[2:0] bits of the SETUP_2 register. I2C
configuration enables selection of eight discrete DC current limit values. See SETUP_2 for current limit configuration
values.
Standalone variants of the device allow selection of a subset of the eight available current limit options by reading the
CONFIG3 resistor. See Table 10 and the Applications Information section for more information.
In some cases, the designer may want to increase the load to 160%, refer to USB Output Current Limit for details.
Voltage Feedback Adjustment Configuration
The MAX20461 compensates voltage drop for up to 474mΩ of USB cable in typical USB charging applications. I2C
variants of the device allow this configuration by the GAIN[4:0] bits of the SETUP_1 register. See GAIN[4:0] for voltage
gain configuration. Standalone variants of the device allow configuration by the CONFIG2 resistor, which sets GAIN[3:0],
and the CONFIG3 resistor, which sets GAIN[4]. See the SETUP_1 register map and the Applications Information section
for more information.
In some cases, the designer may want to increase the load to 160%, refer to USB Output Current Limit for details.
Remote Sense Feedback Adjustment
The remote-sense feature (available by custom order only) provides another option to adjust the output voltage by
sensing the ground node on the USB port at the far-end of the captive cable; either with the cable shield or with an
additional sensing wire. This feature automatically senses the cable resistance and adjusts the voltage compensation
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Maxim Integrated | 33
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
without changing the GAIN[4:0] setting.
The user needs to compensate the voltage drop because of the sense resistor, the load line behavior of the buck, and
any difference between the VBUS and GND conductors. See Figure 3 and contact the factory for support and how to
order.
CAPTIVE
USB CABLE
+ VDUT -
REGULATED FOR
ILOAD and RCABLE
MAX20461
HVBUS
HVDHVD+
AGND
SHEILD
GAIN[4:0] =
RVBUS
DM
PORTABLE
DEVICE
DP
RGND
USB SHEILD OR
SENSE WIRE
CANNOT CONNECT TO IC GND
Figure 3. Remote Cable-Sense Diagram
High Voltage Modes Configuration
I2C variants of the MAX20461 allow high output voltage mode configurations for flexible use in higher power charging
applications, and for load-dump protected battery pass-through output to automotive modules. Contact factory for
support.
USB Protection Switches and BC1.2 Host Charger Emulation
USB Protection Switches
MAX20461 provides automotive-grade ESD and short-circuit protection for the low-voltage USB data lines of highintegration multimedia processors. HVDP/HVDM protection consists of ESD and OVP (overvoltage protection) for
1.5Mbps, 12Mbps, and 480Mbps USB transceiver applications. This is accomplished with a very low-capacitance FET in
series with the D+ and D- data path.
The MAX20461 does not require an external ESD array, and protects the HVD+ and HVD- pins to ±15kV Air-Gap/±8kV
Contact Discharge with the 150pF/330Ω IEC 61000-4-2 model and the 330pF/330Ω model, as well as protecting up
to ±25kV Air-Gap/±8kV Contact Discharge with the 330pF/2kΩ ISO 10605 model. The MAX20461 provides robust,
automotive-grade protection while maintaining a 1GHz -3dB insertion loss. This ensures optimum eye diagram at the end
of a captive cable.
The HVD+ and HVD- short-circuit protection features include protection for a short to the USB +5V BUS and a short to
the +18V car battery. These protection features prevent damage to the low-voltage USB transceiver when shorts occur
in the vehicle harness or customer USB connector/cable. Short-to-GND protection is provided by the upstream USB
transceiver.
USB Host Charger Emulator
The USB protection switches integrate the latest USB-IF Battery Charging Specification Revision 1.2 CDP and SDP
circuitry.
Table 6. Data Switch Mode Truth Table (I2C Variants)
PART NUMBER
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DEVICE INPUTS
SA
SB
DATA SWITCH MODE
Maxim Integrated | 34
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Table 6. Data Switch Mode Truth Table (I2C Variants) (continued)
MAX20461ATJA,
MAX20461AATJA,
MAX20461AATJM
HVEN
IN
CD[1]
CD[0]
BCMODE
0
X
X
X
X
1
0
X
X
1
Invalid Mode (IN = 3.3V required for all modes)
1
0
0
X
0
Invalid Mode (IN = 3.3V required for all modes)
1
1
0
0
0
1
0
Hi-Speed Pass-Through (SDP)
On if
CDP = 1
BC1.2 Auto-CDP (CDP)
On if
CDP = 1
BC1.2 Auto-CDP (CDP)
0
0
1
1
0
1
0
On if
CDP = 0
1
1
X
X
1
On if
CDP = 0
Off
Table 7. Data Switch Mode Truth Table (Standalone Variants)
PART NUMBER
MAX20461ATJD,
MAX20461AATJD,
MAX20461AATJP
DEVICE INPUTS
HVEN
IN
BCMODE
0
X
X
1
0
X
1
1
0
1
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1
1
SA
SB
DATA SWITCH MODE
0
0
Off
Invalid Mode (IN = 3.3V required for all modes)
1
0
Hi-Speed Pass-Through (SDP)
On if CDP = 0
On if
CDP = 1
BC1.2 Auto-CDP (CDP)
Maxim Integrated | 35
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
IN
SA
DP
HVDP
ESD
POTECTION
SA
DM
HVDM
ESD
POTECTION
SB
DEVICE
USB 2.0
DISCONNECT
HOST CHARGER FOR 500ms
EMULATION
SB
R
LS/FS DETECTION
ON HVDP/HVDM
CD[1:0]
HVDP/HVDM OV
IN OV
Q
CDP
ATTACH
BCMODE
HVEN
S
FAULT/ERROR
CONTROL
LOGIC
SA
SB
CDP
MAX20461
Figure 4. Data Switch and Charge-Detection Block Diagram
USB On-The-Go and Dual-Role Applications
The MAX20461 is fully compatible with USB on-the-go (OTG) and dual-role applications. A negotiated role swap (HNP
or Apple CarPlay) requires no software interaction with the IC. When there is no negotiation before the SOC enters
peripheral mode, the MAX20461 must be in Hi-Speed pass-through (SDP mode) before and during the role swap.
All variants default to SDP mode on startup if the BCMODE pin is logic-low. This configuration allows a role swap
immediately on startup without microcontroller interaction.
I2C, Control, and Diagnostics
I2C Configuration (CONFIG1 and I2C)
The MAX20461 I2C variants allow basic device configuration through a resistor placed to GND on the CONFIG1 pin. The
configuration parameters correlating to the chosen resistor are pre-loaded into their respective I2C registers on startup
when HVEN is toggled high. After startup, the user is free to change the affected I2C registers as desired.
For I2C variants, CONFIG1 sets the startup value of the DC-DC spread-spectrum enable bit SS_EN and the SYNC
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Maxim Integrated | 36
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
direction control bit SYNC_DIR. CONFIG1 also sets the LSBs of the I2C slave address. The configuration table for the
I2C variant CONFIG table is shown in Table 8.
Table 8. CONFIG1 Pin Table (I2C Version)
RESISTANCE (Ω, typ)
STEP
SS_EN
SYNC_DIR
I2C_ADDR LSBs
Short to GND
0
1 (ON)
1 (IN)
00
619
1
1 (ON)
1 (IN)
01
976
2
1 (ON)
1 (IN)
10
1370
3
1 (ON)
1 (IN)
11
1820
4
1 (ON)
0 (OUT)
00
2370
5
1 (ON)
0 (OUT)
01
3090
6
1 (ON)
0 (OUT)
10
3920
7
1 (ON)
0 (OUT)
11
4990
8
0 (OFF)
1 (IN)
00
6340
9
0 (OFF)
1 (IN)
01
8250
10
0 (OFF)
1 (IN)
10
11000
11
0 (OFF)
1 (IN)
11
15400
12
0 (OFF)
0 (OUT)
00
23700
13
0 (OFF)
0 (OUT)
01
44200
14
0 (OFF)
0 (OUT)
10
Short to BIAS
(or R > 71.5kΩ)
15
0 (OFF)
0 (OUT)
11
Standalone Configuration (CONFIG1–CONFIG3)
The MAX20461 standalone variants allow full device configuration from three resistors placed among the three CONFIG
pins and GND. For standalone variants, SDA and SCL serve as CONFIG2 and CONFIG3, respectively.
CONFIG1 sets the internal oscillator switching frequency, SYNC pin direction, and DC-DC spread spectrum mode.
CONFIG2 sets the 4 LSBs of the voltage adjustment gain (GAIN[3:0]). CONFIG3 sets the USB DC current limit, typeC current advertisement, automatic thermal foldback, and MSB of voltage adjustment gain (GAIN[4]). See tables below
for standalone variant CONFIG options. See the Applications Information section for setting selection and Ordering
Information for variant part number information.
In some cases, the designer may want to increase the load to 160%, refer to USB Output Current Limit for details.
Table 9. CONFIG1 Pin Table (Standalone Variants)
RESISTANCE (Ω, typ)
STEP
SS_EN
SYNC_DIR
FSW (kHz)
Short to GND
0
ON
IN
2200
619
1
ON
IN
488
976
2
ON
IN
350
1370
3
ON
IN
310
1820
4
ON
OUT
2200
2370
5
ON
OUT
488
3090
6
ON
OUT
350
3920
7
ON
OUT
310
4990
8
OFF
IN
2200
6340
9
OFF
IN
488
8250
10
OFF
IN
350
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MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Table 9. CONFIG1 Pin Table (Standalone Variants) (continued)
RESISTANCE (Ω, typ)
STEP
SS_EN
SYNC_DIR
FSW (kHz)
11000
11
OFF
IN
310
15400
12
OFF
OUT
2200
23700
13
OFF
OUT
488
44200
14
OFF
OUT
350
Short to BIAS
(or R > 71.5kΩ)
15
OFF
OUT
310
Table 10. CONFIG2 and CONFIG3 Pin Table (Standalone Variants)
CONFIG2
CONFIG3
RESISTANCE (Ω, typ)
STEP
GAIN[3:0]
THM_FLDBK_EN
GAIN[4]
CURRENT LIMIT
ILIM_SET (A)
TYPE-C MODE
CC_SRC_CUR (A)
Short to GND
0
0b0000
ON
0
0.55
0.5
619
1
0b0001
ON
0
1.62
1.5
976
2
0b0010
ON
0
2.60
1.5
1370
3
0b0011
ON
0
3.04
3.0
1820
4
0b0100
ON
1
0.55
0.5
2370
5
0b0101
ON
1
1.62
1.5
3090
6
0b0110
ON
1
2.60
1.5
3920
7
0b0111
ON
1
3.04
3.0
4990
8
0b1000
OFF
0
0.55
0.5
6340
9
0b1001
OFF
0
1.62
1.5
8250
10
0b1010
OFF
0
2.60
1.5
11000
11
0b1011
OFF
0
3.04
3.0
15400
12
0b1100
OFF
1
0.55
0.5
23700
13
0b1101
OFF
1
1.62
1.5
44200
14
0b1110
OFF
1
2.60
1.5
Short to BIAS
(or R > 71.5kΩ)
15
0b1111
OFF
1
3.04
3.0
I2C Diagnostics and Event Handling
The I2C-based diagnostic functionality is independent of the FAULT pin. Setting the IRQMASK bit for a specific fault
condition does not mask the FAULT pin for the respective fault. IRQMASK register functionality affects only the behavior
of the INT pin. This allows the FAULT pin to be tied to over-current fault input of a hub controller or SoC, while the I2C
interface is simultaneously used by the system software for advanced diagnostic functionality.
Interrupt and Attach Output (INT(ATTACH))
The MAX20461 INT(ATTACH) pin functions as an interrupt (INT) for I2C variants. The INT pin asserts an interrupt based
on the configuration of the IRQ_MASK_0, IRQ_MASK_1, and IRQ_MASK_2 registers. Interrupt configuration allows the
INT pin to assert any of the featured fault detection, as well as on device attachment, and USB voltage/current ADC
conversion completion. The INT pin only asserts while a masked IRQ bit is asserted, which means its behavior is also
dependent on the AUTOCLR bit.
Standalone variants of the MAX20461 feature an open-drain, active-low, ATTACH output that serves as the attach
detection pin. For standalone variants, the ATTACH pin can be used for GPIO input to a microprocessor, or to drive an
LED for attach/charge indication.
The INT(ATTACH) assertion logic is shown in ATTACH Logic Diagram.
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MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
I2C Output Voltage and Current Measurement
The MAX20461 I2C variant allows measurement of the instantaneous SENSN voltage, DC output current, and die
temperature using an integrated ADC. To initiate a measurement, set the ADC_REQ bit of the ADC_REQUEST register.
The ADC_REQ bit is cleared by the IC once the measurement is complete and the ADC samples are available.
Additionally, the ADC_DONE bit of the IRQ_0 register will be set when the sample is available. ADC_DONE can be
masked to assert an interrupt when the sample is ready.
The sampled measurements can be read from the ADC_USBV, ADC_USBI, and ADC_TEMP registers. The new sample
persists in the register until another sample request is initiated by setting the ADC_REQ bit.
All measurements provide 8 bits of resolution. The measured SENSN voltage has a range of 0V to 19.8V. Convert the
sample to a voltage as follows
19.8V
VSENSN = 256 · ADC_USBV (Volts).
The measured SENSE voltage has a range from 0 to 116mV. Convert the sample to a current as follows
116mV
ADC_USBI
ILOAD = 256 · R
(Amps).
SENSE
The measured die temp has a range from -40ºC to 170ºC and a temperature resolution of 3.5ºC. Convert the sample to
a die temperature by TJ = 3.5ºC · ADC_TEMP - 270 (ºC).
I2C Interface
The MAX20461 features an I2C, 2-wire serial interface consisting of a serial-data line (SDA) and a serial clock line (SCL).
SDA and SCL facilitate communication between the MAX20461 and the master at clock rates up to 400kHz. The master,
typically a microcontroller, generates SCL and initiates data transfer on the bus. Figure 5 shows the 2-wire interface
timing diagram.
A master device communicates to the MAX20461 by transmitting the proper address followed by the data word. Each
transmit sequence is framed by a START (S) or REPEATED START (Sr) condition and a STOP (P) condition. Each word
transmitted over the bus is 8 bits long and is always followed by an acknowledge clock pulse. The MAX20461 SDA line
operates as both an input and an open-drain output. A pullup resistor greater than 500Ω is required on the SDA bus.
The MAX20461 SCL line operates as an input only. A pullup resistor greater than 500Ω is required on SCL if there are
multiple masters on the bus, or if the master in a single-master system has an open-drain SCL output. Series resistors in
line with SDA and SCL are optional. The SCL and SDA inputs suppress noise spikes to assure proper device operation
even on a noisy bus.
SDA
tBUF
tSU, DAT
tSU,STA
tLOW
tHD,DAT
tHD,DAT
tSP
tSU,STO
SCL
tHIGH
tHD,STA
tR
START CONDITION
tF
REPEATED START
CONDITION
STOP
CONDITION
START
CONDITION
Figure 5. I2C Timing Diagram
Bit Transfer
One data bit is transferred during each SCL cycle. The data on SDA must remain stable during the high period of the
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MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
SCL pulse. Changes in SDA while SCL is high are considered control signals (see the STOP and START Conditions
section). SDA and SCL idle high when the I2C bus is not busy.
STOP and START Conditions
A master device initiates communication by issuing a START condition. A START condition is a high-to-low transition
on SDA with SCL high. A STOP condition is a low-to-high transition on SDA while SCL is high (Figure 6). A START (S)
condition from the master signals the beginning of a transmission to the MAX20461. The master terminates transmission,
and frees the bus, by issuing a STOP (P) condition. The bus remains active if a REPEATED START (Sr) condition is
generated instead of a STOP condition.
S
Sr
P
SDA
tSU:STA
tSU:STO
SCL
tHD:STA
tHD:STA
Figure 6. START, STOP and REPEATED START Conditions
Early STOP Condition
The MAX20461 recognizes a STOP condition at any point during data transmission, unless the STOP condition occurs
in the same high pulse as a START condition.
Clock Stretching
In general the clock signal generation for the I2C bus is the responsibility of the master device. The I2C specification
allows slow slave devices to alter the clock signal by holding down the clock line. The process in which a slave device
holds down the clock line is typically called clock stretching. The MAX20461 does not use any form of clock stretching to
hold down the clock line.
I2C General Call Address
The MAX20461 does not implement the I2C specifications general call address. If the MAX20461 sees the general call
address (0b0000_0000), it does not issue an acknowledge.
I2C Slave Addressing
Once the device is enabled, the I2C slave address is set by the CONFIG1 pin.
The address is defined as the 7 most significant bits (MSBs) followed by the R/W bit. Set the R/W bit to 1 to configure
the device to read mode. Set the R/W bit to 0 to configure the device to write mode. The address is the first byte of
information sent to the device after the START condition.
Table 11. I2C Slave Addresses
CONFIG1 CODE
A6
A5
A4
A3
A2
A1
A0
7-BIT ADDRESS
WRITE
READ
0b00
0
1
1
0
0
0
0
0x30
0x60
0x61
0b01
0
1
1
0
0
0
1
0x31
0x62
0x63
0b10
0
1
1
0
0
1
0
0x32
0x64
0x65
0b11
0
1
1
0
0
1
1
0x33
0x66
0x67
Acknowledge
The acknowledge bit (ACK) is a clocked 9th bit that the device uses to handshake receipt each byte of data (Figure
7). The device pulls down SDA during the master generated 9th clock pulse. The SDA line must remain stable and
low during the high period of the acknowledge clock pulse. Monitoring ACK allows for detection of unsuccessful data
transfers. An unsuccessful data transfer occurs if a receiving device is busy or if a system fault has occurred. In the event
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MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
of an unsuccessful data transfer, the bus master can reattempt communication.
Not Acknowledge (nA)
S
Acknowledge (A)
SDA
tSU:DAT
1
SCL
2
tHD:DAT
8
9
Figure 7. Acknowledge Condition
Write Data Format
A write to the device includes transmission of a START condition, the slave address with the write bit set to 0, one byte
of data to a register address, one byte of data to the command register, and a STOP condition. Figure 8 illustrates the
proper format for one frame.
Read Data Format
A read from the device includes transmission of a START condition, the slave address with the write bit set to 0, one
byte of data from a register address, restart condition, the slave address with read bit set to 1, one byte of data to the
command register, and a STOP condition. Figure 8 illustrates the proper format for one frame.
Write Byte
S
Slave
Address
0 A
Register
Address
A
Data Byte
A P
Data Byte1
A
Write Sequential Bytes
S
Slave
Address
0 A
Register
Address
A
0 A
Register
Address
A Sr
Slave
Address
1 A
Data Byte
N
P
A
A Sr
Slave
Address
1 A
Data Byte 1
...
...
Data Byte N
A P
Read Byte
S
Slave
Address
Read Sequential Bytes
S
Slave
Address
0 A
Register
Address
Data Byte N
N
P
A
Figure 8. Data Format of I2C Interface
Fault Detection and Diagnostics
Fault Detection
The MAX20461 features advanced device protection features with automatic fault handing and recovery. Table 12
summarizes the conditions that generate a fault, and the actions taken by the device. For all variants, the FAULT output
remains asserted as long as a fault condition persists.
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Maxim Integrated | 41
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
For I2C variants, the IRQ registers provide detailed information on the source of the fault condition, and the IRQMASK
registers allow selection of the criteria for assertion of the I2C Interrupt pin, INT. The IRQ register bits clear when read.
However, the IRQ bits that represent a present fault condition continue to reassert after they are cleared, so long as the
fault condition persists. If the IRQMASK registers are configured to assert INT for a present fault, the INT pin deasserts
when the IRQ register that asserted the interrupt is read. The INT pin subsequently reasserts if the fault condition persists.
Fault Output Pin (FAULT)
The MAX20461 features an open-drain, active-low FAULT output. The MAX20461 is designed to eliminate false FAULT
reporting by using an internal deglitch and fault blanking timer. This ensures FAULT is not incorrectly asserted during
normal operation such as starting into high-capacitance loads. The FAULT pin can be tied directly to the over-current
fault input of a hub controller or SoC.
Table 12. Fault Conditions
IRQ REGISTER
BITS (I2C ONLY)
DEBOUNCE
PRIOR TO
ACTION
Thermal
Shutdown
THM_SHD
Immediate
Thermal
Warning/
Foldback
THM_WARN
20 ms
IN_OV
Immediate
Assert FAULT pin and associated IRQ bit, shut down DC-DC converter, open
data switches, disable RP, and reset BC1.2. When fault resolves and
RETRY_TMR expires, release FAULT pin, close data switches, enable RP and
the DC-DC converter.
EVENT
IN
Overvoltage
ACTION TAKEN
Assert FAULT pin and associated IRQ bit, shut down DC-DC converter, open
data switches, and disable RP. When fault resolves and RETRY_TMR expires,
release FAULT pin, enable RP and the DC-DC converter.
Assert associated IRQ bit and reduce Type-C RP by one step. When fault
resolves and RETRY_TMR expires, reset Type-C to CC_SRC_CUR.
HVDP/
HVDM
Overvoltage
DATA_OV
Immediate
Assert FAULT pin and associated IRQ bit, shut down DC-DC converter, open
data switches, disable RP, and reset BC1.2. When fault resolves and
RETRY_TMR expires, release FAULT pin, close data switches, enable RP and
the DC-DC converter.
USB DC
Overcurrent
VBUS_ILIM
16 ms
Assert FAULT pin and associated IRQ bit after overcurrent condition persists for
16ms. When overcurrent resolves and RETRY_TMR expires, release FAULT
pin.
USB DC
Overcurrent
and SENSN
< 4.38V
SENSN <
4.38V
USB DC
Overcurrent
and SENSN
< 2V
VBUS_ILIM_UV
16 ms
ILIM_ITRIP = 0:
Assert FAULT pin and associated IRQ bit, shut down DC-DC converter, and
disable RP after overcurrent and undervoltage condition persists for 16ms.
Release FAULT pin, enable RP and DC-DC converter once RETRY_TMR
expires after shutdown.
I2C variant and ILIM_ITRIP = 1:
Assert FAULT pin and associated IRQ bit after overcurrent condition persists for
16ms. When overcurrent resolves and RETRY_TMR expires, release FAULT
pin.
VBUS_UV
16 ms
Assert FAULT pin and associated IRQ bit after undervoltage condition persists
for 16ms. When undervoltage resolves and RETRY_TMR expires, release
FAULT pin.
VBUS_SHT_GND
Immediate
Assert FAULT pin and associated IRQ bit, shut down DC-DC converter, open
data switches, and disable RP. Release FAULT pin, enable RP and DC-DC
converter once RETRY_TMR expires after shutdown.
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MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Table 12. Fault Conditions (continued)
EVENT
IRQ REGISTER
BITS (I2C ONLY)
DEBOUNCE
PRIOR TO
ACTION
LX
Overcurrent
for 4
Consecutive
Cycles
and SENSN
< 2V
VBUS_SHT_GND
Immediate
Assert FAULT pin and associated IRQ bit, shut down DC-DC converter, open
data switches, and disable RP. Release FAULT pin, enable RP and DC-DC
converter once RETRY_TMR expires after shutdown.
SENSN
Overvoltage
VBUS_OV
Immediate
Assert FAULT pin and associated IRQ bit, shut down DC-DC converter, open
data switches, and disable RP. When fault resolves and RETRY_TMR expires,
release FAULT pin, enable RP, DC-DC converter, and data switches.
VCONN
Overcurrent
VCONN_ILIM
1 ms
Assert FAULT pin and associated IRQ bit, open VCONN FET. After overcurrent
no longer exists and RETRY_TMR expires, release FAULT pin. VCONN can only
be re-enabled by passing through the unattached state.
VBUS Preon
Overvoltage
VBUS_PRE_OV
16 ms
Assert FAULT pin and associated IRQ bit after overvoltage condition persists for
16ms. After overvoltage no longer exists and RETRY_TMR has expired, release
FAULT pin.
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ACTION TAKEN
Maxim Integrated | 43
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Register Map
Summary Table
ADDRESS
NAME
MSB
LSB
USER_CMDS
–
THM_FL
DBK_EN
EN_DCD
C
0x00
SETUP_0[7:0]
0x01
SETUP_1[7:0]
0x02
SETUP_2[7:0]
0x03
SETUP_3[7:0]
0x04
SETUP_4[7:0]
–
–
–
0x05
ADC_REQUEST[7:0]
–
–
0x06
CC_REQUEST[7:0]
–
0x07
IRQ_MASK_0[7:0]
0x08
FSW[2:0]
–
–
SYNC_D
IR
VOUT[2:0]
SS_EN
GAIN[4:0]
ILIM_ITR
IP
–
–
ILIM[2:0]
CC_ENB
CC_VCO
NN_EN
–
–
–
–
CONFIG
URED
–
–
–
–
–
ADC_RE
Q
–
–
–
–
–
CC_FOR
CE_ERR
CC_SRC
_RST
IRQ_AU
TOCLR
–
EN_CC_
STATE_
EV
EN_CC_
ATTACH
_IRQ
EN_BC_
ATTACH
_IRQ
EN_CC_
ATTACH
_EV
EN_BC_
ATTACH
_EV
EN_ADC
_DONE
IRQ_MASK_1[7:0]
–
EN_VBU
S_PRE_
OV
EN_VBU
S_ILIM_
UV
EN_VBU
S_ILIM
EN_VBU
S_OV
EN_VBU
S_UV
EN_VBU
S_SHT_
GND
EN_THM
_SHD
0x09
IRQ_MASK_2[7:0]
–
–
EN_VBU
S_PREB
IAS
EN_VCO
NN_ERR
EN_THM
_WARN
EN_IN_
OV
EN_DAT
A_OV
EN_VCO
NN_ILIM
0x0A
IRQ_0[7:0]
UNCON
FIGURE
D
–
CC_STA
TE_EV
CC_ATT
ACH_IR
Q
BC_ATT
ACH_IR
Q
CC_ATT
ACH_EV
BC_ATT
ACH_EV
ADC_DO
NE
0x0B
IRQ_1[7:0]
–
VBUS_P
RE_OV
VBUS_IL
IM_UV
VBUS_IL
IM
VBUS_O
V
VBUS_U
V
VBUS_S
HT_GND
THM_SH
D
0x0C
IRQ_2[7:0]
–
–
VBUS_P
REBIAS
VCONN_
ERR
THM_W
ARN
IN_OV
DATA_O
V
VCONN_
ILIM
0x0D
STATUS_0[7:0]
–
–
–
CC_ATT
ACH
BC_ATT
ACH
VBMON
_SAFE
VCONN_
READY
VBUS_S
TAT
0x0E
STATUS_1[7:0]
–
–
0x10
ADC_0[7:0]
ADC_USBI[7:0]
0x11
ADC_1[7:0]
ADC_USBV[7:0]
0x12
ADC_2[7:0]
ADC_TEMP[7:0]
RETRY_TMR[1:0]
CD[1:0]
CC_PIN_STATE[1:0
]
CC_SRC_CUR[1:0]
CC_STATE[3:0]
Register Details
SETUP_0 (0x0)
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Maxim Integrated | 44
MAX20461
BIT
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
7
6
5
Field
–
THM_FLDB
K_EN
EN_DCDC
VOUT[2:0]
Reset
–
0b0
0b1
0b000
Access
Type
–
Write, Read
Write, Read
Write, Read
BITFIELD
THM_FLDBK
_EN
EN_DCDC
VOUT
BITS
4
3
2
DESCRIPTION
1
0
SYNC_DIR
SS_EN
Write, Read
Write, Read
DECODE
6
Lowers the Type-C advertised current
capability when thermal warning is tripped.
0 = Disable Thermal Foldback
1 = Enable Thermal Foldback
5
DC/DC Converter Enable. Internally AND'ed
with the ENBUCK pin.
0 = Disable VBUS Buck Converter
1 = Enable VBUS Buck Converter
VBUS Output Level Selection
0b000 = 5V
0b001 = 9V
0b010 = 12V
0b011 = 15V
0b100 = 18V (protected battery pass-through)
0b101 = 5V
0b110 = 5V
0b111 = 5V
4:2
SYNC_DIR
1
SYNC Pin Direction Selection
Initial value set by CONFIG1 resistor.
0 = Output
1 = Input
SS_EN
0
Spread Spectrum Enable
Initial value set by CONFIG1 resistor.
0 = Disable Spread Spectrum Function
1 = Enable Spread Spectrum Function
SETUP_1 (0x1)
BIT
7
6
5
4
3
2
1
Field
FSW[2:0]
GAIN[4:0]
Reset
0b000
0b00000
Write, Read
Write, Read
Access
Type
BITFIELD
FSW
BITS
7:5
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DESCRIPTION
DC/DC Convertor Switching Frequency
Selection
0
DECODE
0b000 = 2200 kHz
0b001 = 1200 kHz
0b010 = 790 kHz
0b011 = 600 kHz
0b100 = 488 kHz
0b101 = 410 kHz
0b110 = 350 kHz
0b111 = 310 kHz
Maxim Integrated | 45
MAX20461
BITFIELD
GAIN
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
BITS
4:0
DESCRIPTION
DECODE
The gain of the voltage correction applied to
the buck converter output (based on DC load
sensed by current sense amp). RSENSE =
33mΩ.
0: 0mΩ
1: 18mΩ
2: 36mΩ
3: 54mΩ
4: 72mΩ
5: 90mΩ
6: 108mΩ
7: 126mΩ
8: 144mΩ
9: 162mΩ
10: 180mΩ
11: 198mΩ
12: 216mΩ
13: 234mΩ
14: 252mΩ
15: 270mΩ
16: 288mΩ
17: 306mΩ
18: 324mΩ
19: 342mΩ
20: 360mΩ
21: 378mΩ
22: 396mΩ
23: 414mΩ
24: 432mΩ
25: 450mΩ
26: 468mΩ
27: 486mΩ
28: 504mΩ
29: 522mΩ
30: 540mΩ
31: 558mΩ
SETUP_2 (0x2)
7
6
5
4
3
Field
BIT
–
–
–
ILIM_ITRIP
–
ILIM[2:0]
Reset
–
–
–
0b0
–
0b111
Access
Type
–
–
–
Write, Read
–
Write, Read
BITFIELD
ILIM_ITRIP
ILIM
BITS
4
2:0
DESCRIPTION
Determines the buck's retry behavior under
USB DC current limit conditions.
USB DC Current-Limit Threshold, RSENSE =
33mΩ.
2
1
0
DECODE
0 = VBUS_ILIM_UV fault enabled.
1 = VBUS_ILIM_UV fault disabled.
USB DC Current-Limit Threshold (min in Amps)
0b000 = 0.3
0b001 = 0.55
0b010 = 0.8
0b011 = 1.05
0b100 = 1.62
0b101 = 2.1
0b110 = 2.6
0b111 = 3.04
SETUP_3 (0x3)
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Maxim Integrated | 46
MAX20461
BIT
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
7
6
Field
RETRY_TMR[1:0]
Reset
0b00
Access
Type
BITFIELD
RETRY_TM
R
5
Write, Read
BITS
3
2
CC_ENB
CC_VCON
N_EN
CC_SRC_CUR[1:0]
0b0
0b1
0b01
Write, Read
Write, Read
Write, Read
CD[1:0]
Write, Read
7:6
4
DESCRIPTION
5:4
CC_ENB
3
CC_VCONN
_EN
2
CC_SRC_C
UR
Determines the length of the RETRY timer
after a fault condition.
This register is pre-loaded based on the part
number variant and the status of the
BCMODE pin.
0b00 = 2.0s
0b01= 1.0s
0b10 = 0.5s
0b11= 16ms
0b00 = High Speed Pass Through (SDP)
0b01 = Auto-CDP
0b10 = Reserved
0b11 = Reserved
0 = Enable
1 = Disable
Disable Type-C Detection
MAX20461A: Not Used
MAX20461: Enable VCONN pass-through
1:0
0
DECODE
BC1.2 Charge Detection Configuration
Selection.
CD
1
Type-C DFP source pullup current
advertisement (RP)
0 = Disable VCONN pass-through.
1 = Enable VCONN pass-through.
00 = 0.5A
01 = 1.5A
10 = 3.0A
11 = 0.5A
SETUP_4 (0x4)
BIT
7
6
5
4
3
2
1
0
Field
–
–
–
–
–
–
–
CONFIGUR
ED
Reset
–
–
–
–
–
–
–
0b0
Access
Type
–
–
–
–
–
–
–
Write, Read
BITFIELD
BITS
DESCRIPTION
DECODE
I2C configuration complete indicator
CONFIGURE
D
0
Upon power-up, the buck converter is
prevented from turning on until this bit is
written to a one, indicating the part is fully
configured for its intended mode of operation.
0 = I2C Configuration Pending
1 = I2C Configuration Complete
ADC_REQUEST (0x5)
7
6
5
4
3
2
1
0
Field
BIT
–
–
–
–
–
–
–
ADC_REQ
Reset
–
–
–
–
–
–
–
0b0
Access
Type
–
–
–
–
–
–
–
Write, Read
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Maxim Integrated | 47
MAX20461
BITFIELD
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
BITS
DESCRIPTION
DECODE
ADC V/I Sample Request
ADC_REQ
0
When a one is written, ADC V/I sampling is
initiated. This bit is cleared once the
requested sampling is complete and the ADC
results are updated. The status of the ADC
conversion (data ready) can be monitored in
the IRQ0 register.
0 = No ADC Sample Requested
1 = ADC Sample Requested
CC_REQUEST (0x6)
BIT
7
6
5
4
3
2
1
0
CC_SRC_R
ST
Field
–
–
–
–
–
–
CC_FORCE
_ERR
Reset
–
–
–
–
–
–
0b0
0b0
Access
Type
–
–
–
–
–
–
Write, Read
Write, Read
BITFIELD
BITS
DESCRIPTION
DECODE
Type-C Force Error Request
CC_FORCE_
ERR
1
This is a request bit (write-only). Forces the
Type-C state machine to go through error
recovery. This bit will always read back zero.
0 = No change to current operating state.
1 = Force transition to error recovery state.
Type-C Force Source Reset Request
CC_SRC_RS
T
0
This is a request bit (write-only). The Type-C
state machine will be forced back to the
UnAttached.SRC state, restarting Type-C
detection. This bit will always read back zero.
0 = No change to current operating state
1 = Force transition to UnAttached.SRC state
IRQ_MASK_0 (0x7)
A Read-Write register that configures which of the conditions in the IRQ_0 register will assert an Interrupt. See the
IRQ_0 register for condition descriptions.
BIT
7
6
5
4
3
2
1
0
Field
IRQ_AUTO
CLR
–
EN_CC_ST
ATE_EV
EN_CC_AT
TACH_IRQ
EN_BC_AT
TACH_IRQ
EN_CC_AT
TACH_EV
EN_BC_AT
TACH_EV
EN_ADC_D
ONE
Reset
0b0
–
0b0
0b0
0b0
0b0
0b0
0b0
Write, Read
–
Write, Read
Write, Read
Write, Read
Write, Read
Write, Read
Write, Read
Access
Type
BITFIELD
BITS
DESCRIPTION
DECODE
IRQ_AUTOC
LR
7
IRQ Auto Clear
0 = IRQ register flags are latched on until read.
1 = IRQ register flags are automatically cleared
when the error condition is removed.
EN_CC_STA
TE_EV
5
CC_STATE Interrupt Enable
0 = Not included in Interrupt
1 = Included in Interrupt
EN_CC_ATT
ACH_IRQ
4
Type-C ATTACH STATUS Interrupt Enable
0 = Not included in Interrupt
1 = Included in Interrupt
EN_BC_ATT
ACH_IRQ
3
BC1.2 ATTACH STATUS Interrupt Enable
0 = Not included in Interrupt
1 = Included in Interrupt
www.maximintegrated.com
Maxim Integrated | 48
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
BITFIELD
BITS
DESCRIPTION
DECODE
EN_CC_ATT
ACH_EV
2
Type-C ATTACH EVENT Interrupt Enable
0 = Not included in Interrupt
1 = Included in Interrupt
EN_BC_ATT
ACH_EV
1
BC1.2 ATTACH EVENT Interrupt Enable
0 = Not included in Interrupt
1 = Included in Interrupt
EN_ADC_D
ONE
0
ADC_DONE Interrupt Enable
0 = Not included in Interrupt
1 = Included in Interrupt
IRQ_MASK_1 (0x8)
A Read-Write register that configures which of the conditions in the IRQ_1 register will assert an Interrupt. See the
IRQ_1 register for condition descriptions.
BIT
7
6
5
4
3
2
1
0
Field
–
EN_VBUS_
PRE_OV
EN_VBUS_I
LIM_UV
EN_VBUS_I
LIM
EN_VBUS_
OV
EN_VBUS_
UV
EN_VBUS_
SHT_GND
EN_THM_S
HD
Reset
–
0x0
0b0
0b0
0b0
0b0
0b0
0b0
Access
Type
–
Write, Read
Write, Read
Write, Read
Write, Read
Write, Read
Write, Read
Write, Read
BITFIELD
BITS
DESCRIPTION
DECODE
EN_VBUS_P
RE_OV
6
VBUS_PRE_OV Interrupt Enable
0 = Not included in Interrupt
1 = Included in Interrupt
EN_VBUS_IL
IM_UV
5
VBUS_ILIM_UV Interrupt Enable
0 = Not included in Interrupt
1 = Included in Interrupt
EN_VBUS_IL
IM
4
VBUS_ILIM Interrupt Enable
0 = Not included in Interrupt
1 = Included in Interrupt
EN_VBUS_O
V
3
VBUS_OV Interrupt Enable
0 = Not included in Interrupt
1 = Included in Interrupt
EN_VBUS_U
V
2
VBUS_UV Interrupt Enable
0 = Not included in Interrupt
1 = Included in Interrupt
EN_VBUS_S
HT_GND
1
VBUS_SHT_GND Interrupt Enable
0 = Not included in Interrupt
1 = Included in Interrupt
EN_THM_SH
D
0
THM_SHD Interrupt Enable
0 = Not included in Interrupt
1 = Included in Interrupt
IRQ_MASK_2 (0x9)
A Read-Write register that configures which of the conditions in the IRQ_2 register will assert an Interrupt. See the
IRQ_2 register for condition descriptions.
BIT
7
6
5
4
3
2
1
0
EN_VCON
N_ERR
EN_THM_
WARN
EN_IN_OV
EN_DATA_
OV
EN_VCON
N_ILIM
Field
–
–
EN_VBUS_
PREBIAS
Reset
–
–
0b0
0b0
0b0
0b0
0b0
0x0
Access
Type
–
–
Write, Read
Write, Read
Write, Read
Write, Read
Write, Read
Write, Read
BITFIELD
BITS
EN_VBUS_P
REBIAS
5
www.maximintegrated.com
DESCRIPTION
VBUS_PREBIAS Interrupt Enable
DECODE
0 = Not included in Interrupt
1 = Included in Interrupt
Maxim Integrated | 49
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
BITFIELD
BITS
DESCRIPTION
DECODE
EN_VCONN
_ERR
4
EN_THM_W
ARN
3
THM_WARN Interrupt Enable
0 = Not included in Interrupt
1 = Included in Interrupt
EN_IN_OV
2
IN_OV Interrupt Enable
0 = Not included in Interrupt
1 = Included in Interrupt
EN_DATA_O
V
1
DATA_OV Interrupt Enable
0 = Not included in Interrupt
1 = Included in Interrupt
EN_VCONN
_ILIM
0
MAX20461A: Not Used
MAX20461: VCONN_ERR Interrupt Enable
MAX20461A: Not Used
0 = Not included in Interrupt
1 = Included in Interrupt
0 = Not included in Interrupt
1 = Included in Interrupt
MAX20461: VCONN_ILIM Interrupt Enable
IRQ_0 (0xA)
A read only register that includes flags which indicate a number of operating conditions. These flags can assert an
interrupt by setting the corresponding bit in the MASK register.
IRQ_0 holds notifications of expected operations rather than error/fault conditions.
BIT
Field
Reset
Access
Type
BITFIELD
UNCONFIGU
RED
7
6
5
4
3
2
1
0
UNCONFIG
URED
–
CC_STATE
_EV
CC_ATTAC
H_IRQ
BC_ATTAC
H_IRQ
CC_ATTAC
H_EV
BC_ATTAC
H_EV
ADC_DON
E
0b0
–
0b0
0b0
0b0
0b0
0b0
0b0
–
Read
Clears All
Read
Clears All
Read
Clears All
Read
Clears All
Read
Clears All
Read
Clears All
Read
Clears All
BITS
7
DESCRIPTION
I2C Unconfigured Indicator Bit
DECODE
0 = Device is fully configured
(CONFIGURED written to 1)
1 = Device is not fully configured
(CONFIGURED has not been written to 1)
Type-C State Change Indicator
CC_STATE_
EV
5
Clear on Read. Not affected by
IRQ_AUTOCLR.
0 = No change in Type-C state since last read
1 = Type-C state has changed since last read
Type-C ATTACH Indicator
CC_ATTACH
_IRQ
4
BC_ATTACH
_IRQ
3
This bit indicates a Type-C device attach is
observed via the CC Pins. Applies to
Attached.SRC states. Further attach details
can be read in the STATUS registers.
0 = No Type-C device attached
1 = Type-C device attached
BC1.2 ATTACH Indicator
www.maximintegrated.com
This bit indicates a BC1.2 device attach is
observed via the HVDP/HVDM pins.
0 = No device attached
1 = Device attached
Maxim Integrated | 50
MAX20461
BITFIELD
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
BITS
DESCRIPTION
DECODE
Type-C ATTACH Event Detected
CC_ATTACH
_EV
2
This bit indicates a Type-C device attach was
initiated and/or terminated as observed via
the CC Pins.This bit differs from
CC_ATTACH (which indicates the current
Type-C attach status in real time) in that it is
issued only when the status changes from
unattached to attached or vice-versa.
0 = No attach or detach event detected since least
read
1 = New attach and/or detach event detected
Clear on Read. Not affected by
IRQ_AUTOCLR.
BC1.2 ATTACH Event Detected
BC_ATTACH
_EV
1
This bit indicates a BC1.2 device attach was
initiated and/or terminated as observed via
the HVDP/HVDM pins.This bit differs from
BC_ATTACH (which indicates the current
BC1.2 attach status in real time) in that it is
issued only when the status changes from
unattached to attached or vice-versa.
0 = No attach or detach event detected since least
read
1 = New attach and/or detach event detected
Clear on Read. Not affected by
IRQ_AUTOCLR.
ADC_DONE
0
ADC Meaurement Complete Indicator.
Clear on Read.
0 = No new data available since least read
1 = New data available
IRQ_1 (0xB)
A read only register that includes flags which indicate a number of error conditions. These flags can assert an interrupt
by setting the corresponding bit in the MASK register.
BIT
7
6
5
Field
–
VBUS_PRE
_OV
VBUS_ILIM
_UV
VBUS_ILIM
Reset
–
0b0
0b0
Access
Type
–
Read
Clears All
Read
Clears All
BITFIELD
BITS
4
3
2
1
0
VBUS_OV
VBUS_UV
VBUS_SHT
_GND
THM_SHD
0b0
0b0
0b0
0b0
0b0
Read
Clears All
Read
Clears All
Read
Clears All
Read
Clears All
Read
Clears All
DESCRIPTION
DECODE
VBUS Pre-Overvoltage Fault Detected
VBUS_PRE_
OV
6
Asserts if overvoltage exists on VBMON
when Type-C is enabled and no Type-C
device is attached.
0 = No event
1 = Event detected
Clear on Read if condition is resolved.
VBUS_ILIM_
UV
5
VBUS_ILIM
4
VBUS Current Limit and SENSN UV Fault
Detected
Disabled when ILIM_ITRIP = 1. Clear on
Read if condition is resolved.
VBUS Current Limit Condition Detected
www.maximintegrated.com
Disabled when ILIM_ITRIP = 0. Clear on
Read if condition is resolved.
0 = No event
1 = Event detected
0 = No event
1 = Event detected
Maxim Integrated | 51
MAX20461
BITFIELD
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
BITS
DESCRIPTION
DECODE
VBUS_OV
3
VBUS Overvoltage Fault Detected
Detected on SENSN pin. Clear on Read if
condition is resolved.
0 = No event
1 = Event detected
VBUS_UV
2
VBUS Under Voltage Fault Detected
Detected on SENSN pin. Clear on Read if
condition is resolved.
0 = No event
1 = Event detected
VBUS_SHT_
GND
1
VBUS Short to Ground Fault Detected
Detected on SENSN pin. Clear on Read if
condition is resolved.
0 = No event
1 = Event detected
THM_SHD
0
Over Temperature Fault Detected
Asserts when the die temperature exceeds
165°C (typ). Clear on Read if condition is
resolved.
0 = No event
1 = Event detected
IRQ_2 (0xC)
A read only register that includes flags which indicate a number of error conditions. These flags can assert an interrupt
by setting the corresponding bit in the MASK register.
BIT
7
6
5
4
3
2
1
0
Field
–
–
VBUS_PRE
BIAS
VCONN_E
RR
THM_WAR
N
IN_OV
DATA_OV
VCONN_ILI
M
Reset
–
–
0b0
0b0
0b0
0b0
0b0
0b0
–
Read
Clears All
Read
Clears All
Read
Clears All
Read
Clears All
Read
Clears All
Read
Clears All
Access
Type
BITFIELD
VBUS_PREB
IAS
–
BITS
DESCRIPTION
VBUS Pre-Bias
5
Asserts if Type-C is enabled and VBMON >
VSAFE0V when no Type-C device is attached.
DECODE
0 = No event
1 = Event detected
MAX20461A: Not Used
VCONN_ER
R
4
MAX20461: VCONN input requested and the
VCONN source is not within operating range.
0 = No event
1 = Event detected
THM_WARN
3
Thermal Warning Condition Detected
Asserts when the temperature has reached
140°C (typ).
If thermal foldback is enabled, the Type-C
current advertisement is lowered one step
while this bit is asserted.
Clear on Read if condition is resolved.
IN_OV
2
IN Pin Overvoltage Fault Detected
Clear on Read if condition is resolved.
0 = No event
1 = Event detected
DATA_OV
1
DATA Pin Overvoltage Fault Detected
Clear on Read if condition is resolved.
0 = No event
1 = Event detected
0 = No event
1 = Event detected
MAX20461A: Not Used
VCONN_ILI
M
0
www.maximintegrated.com
MAX20461: VCONN Overcurrent Fault
Detected
The VCONN overcurrent monitor is only active
when VCONN is being sourced to a CC pin. It
is not active on the opposite CC pin.
Clear on Read if condition is resolved.
0 = No event
1 = Event detected
Maxim Integrated | 52
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
STATUS_0 (0xD)
A read only register that includes information on the current status of the IC.
BIT
7
6
5
4
3
2
1
0
BC_ATTAC
H
VBMON_S
AFE
VCONN_R
EADY
VBUS_STA
T
Field
–
–
–
CC_ATTAC
H
Reset
–
–
–
0b0
0b0
0b0
0b0
0b0
Access
Type
–
–
–
Read Only
Read Only
Read Only
Read Only
Read Only
BITFIELD
BITS
CC_ATTACH
4
Type-C ATTACH Status Indicator
This bit indicates the current Type-C attach
status via the CC pins. More details can be
read in the STATUS_1 register.
0 = No Type-C device currently attached
1 = Type-C device currently attached
3
BC1.2 ATTACH Status Indicator
This bit indicates the current device attach
status via the HVDP/HVDM pins. More details
can be read in the STATUS_1 register.
0 = No device currently attached
1 = Device currently attached
2
VBMON (VBUS) Safe Status Indicator
Determines if the DC-DC converter can be
turned on after a Type-C attach. Only
applicable with Type-C enabled.
0 = VBUS > VSAFE0V
1 = VBUS < VSAFE0V
BC_ATTACH
VBMON_SA
FE
DESCRIPTION
DECODE
MAX20461A: Not Used
VCONN_RE
ADY
1
MAX20461: VCONN Detect Status Indicator
Asserts when Type-C is enabled and a
VCONN source is detected on the VCONN pin.
VBUS_STAT
0
Type-C VBUS Status Indicator
0 = VCONN not observed
1 = VCONN > VVCONN_DET
0 = VBUS not applied to receptacle
1 = VBUS applied to receptacle (Attached.SRC)
STATUS_1 (0xE)
A read only register that includes information on the current status of the IC.
7
6
Field
BIT
–
–
CC_PIN_STATE[1:0]
CC_STATE[3:0]
Reset
–
–
0b00
0b0000
Access
Type
–
–
Read Only
Read Only
BITFIELD
CC_PIN_ST
ATE
CC_STATE
BITS
5:4
3:0
www.maximintegrated.com
5
4
DESCRIPTION
3
2
1
0
DECODE
Type-C Active CC Pin/Orientation Indicator
0b00 = No Attach
0b01 = RD detected on CC1
0b10 = RD detected on CC2
0b11 = Not used
Type-C Functional Status/State Indicator
0b0000 = Disabled
0b0010 = ErrorRecovery
0b0011 = Unattached.SRC
0b0110 = AttachWait.SRC
0b1000 = Attached.SRC (CC2)
0b1100 = Attached.SRC (CC1)
Maxim Integrated | 53
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
ADC_0 (0x10)
BIT
7
6
5
4
3
Field
ADC_USBI[7:0]
Reset
0x00
Access
Type
BITFIELD
ADC_USBI
2
1
0
Read Only
BITS
7:0
DESCRIPTION
DECODE
USB Load Current ADC Measurement Result
ILOAD = ((116mV/256) * ADC_USBI)/RSENSE
(amperes)
ADC_1 (0x11)
BIT
7
6
5
4
3
Field
ADC_USBV[7:0]
Reset
0x00
Access
Type
BITFIELD
ADC_USBV
2
1
0
Read Only
BITS
7:0
DESCRIPTION
DECODE
USB Voltage ADC Measurement Result
VSENSP = (19.8V/256) * ADC_USBV (volts), when
VOUT[2:0] = 0b000
ADC_2 (0x12)
BIT
7
6
5
4
3
Field
ADC_TEMP[7:0]
Reset
0x00
Access
Type
BITFIELD
ADC_TEMP
2
1
0
Read Only
BITS
7:0
www.maximintegrated.com
DESCRIPTION
Die Temp ADC Measurement Result
DECODE
Die Temp = 3.5°C * ADC_TEMP - 270 (°C)
Maxim Integrated | 54
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Applications Information
DC-DC Switching Frequency Selection
The switching frequency (fSW) for MAX20461 is programmable via the CONFIG1 resistor (on standalone variants) or by
I2C register writes.
Higher switching frequencies allow for smaller PCB area designs with lower inductor values and less output capacitance.
Consequently, peak currents and I2R losses are lower at higher switching frequencies, but core losses, gate charge
currents, and switching losses increase.
To avoid AM band interference, operation between 500kHz and 1.8MHz is not recommended.
DC-DC Input Capacitor Selection
The input capacitor supplies the instantaneous current needs of the buck converter and reduces the peak currents drawn
from the upstream power source. The input bypass capacitor is a determining factor in the input voltage ripple.
The input capacitor RMS current rating requirement (IIN(RMS)) is defined by the following equation:
IIN(RMS) = ILOAD
√VSENSP × (VSUPSW − VSENSP)
VSUPSW
IIN(RMS) has a maximum value when the input voltage equals twice the output voltage (VSUPSW = 2 · VSENSP), so
1
IIN(MAX) = 2 · ILOAD(MAX). ILOAD is the measured operating load current, while ILOAD(MAX) refers to the maximum load
current.
Choose an input capacitor that exhibits less than 10ºC self-heating temperature rise at the RMS input current for optimal
long-term reliability.
The input voltage ripple is composed of VQ (caused by the capacitor discharge) and VESR (caused by the ESR of the
capacitor). Use low-ESR ceramic capacitors with high ripple current capability at the input. Assume the contribution from
the ESR and capacitor discharge is equal to 50%. Calculate the input capacitance and ESR required for a specified input
voltage ripple using the following equations:
ESRIN =
ΔVESR
ΔIL
ILOAD MAX +
(
) 2
where:
ΔIL =
(VSUPSW − VSENSP) × VSENSP
VSUPSW × fSW × L
and:
CIN =
(
)
ILOAD MAX × D 1 − D
VSENSP
(
)
where D = V
ΔVQ × fSW
SUPSW
Where D is the buck converter duty cycle.
Bypass SUPSW with 0.1μF parallel to 10μF of ceramic capacitance close to the SUPSW and PGND pins. The ceramic
di
input capacitor of a buck converter has a high dt , minimize the PCB current-loop area to reduce EMI. Bypass SUPSW
with 47μF of bulk electrolytic capacitance to dampen line transients.
DC-DC Output Capacitor Selection
To ensure stability and compliance with the USB and Apple specifications, follow the recommended output filters listed in
Table 13. For proper functionality, a minimum amount of ceramic capacitance must be used regardless of fSW. Additional
capacitance for lower switching frequencies can be low-ESR electrolytic types (< 0.25Ω).
www.maximintegrated.com
Maxim Integrated | 55
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
DC-DC Output Inductor Selection
Three key inductor parameters must be considered when selecting an inductor: inductance value (L), inductor saturation
current (ISAT), and DC resistance (RDCR). To select the proper inductance value, the ratio of inductor peak-to-peak AC
current to DC average current (LIR) must be selected. A small LIR will reduce the RMS current in the output capacitor
and results in small output ripple voltage, but this requires a larger inductor. A good compromise between size and loss
is LIR = 0.35 (35%). Determine the inductor value using the equation below,
(
VSENSP × VSUPSW − VSENSP
)
L= V
SUPSW × fSW × ILOAD(MAX) × LIR
where VSUPSW and VSENSP are typical values (such that efficiency is optimum for nominal operating conditions). Ensure
the inductor ISAT is above the buck converter's cycle-by-cycle peak current limit.
Table 13. Recommended Output Filters For ILOAD of 3A
fSW (kHz)
LOUT (μH)
2200
1.5
22μF ceramic
RECOMMENDED COUT
488
8.2
3 x 22μF ceramic
488
8.2
22μF ceramic + low-ESR 68μF electrolytic (< 0.25Ω)
248
20
22μF ceramic + low-ESR 68μF electrolytic (< 0.25Ω)
Layout Considerations
Proper PCB layout is critical for robust system performance. See the MAX20461 EV kit datasheet for a recommended
layout. Minimize the current-loop area and the parasitics of the DC-DC conversion circuitry to reduce EMI. The input
di
capacitor placement should be prioritized because in a buck converter, the ceramic input capacitor has high dt . Place
the input capacitor, power inductor, and output capacitor as close as possible to the IC SUPSW and PGND pins. Shorter
traces should be prioritized over wider traces.
A low-impedance ground connection between the input and output capacitor is required (route through the ground pour
on the exposed pad). Connect the exposed pad to ground. Place multiple vias in the pad to connect to all other ground
layers for proper heat dissipation. Failure to do so can result in the IC repeatedly reaching thermal shutdown. Do not
use separate power and analog ground planes. Instead, use a single common ground and manage currents through
component placement. High-frequency return current flows through the path of least impedance (through the ground pour
directly underneath the corresponding traces).
USB traces must be routed as a 90Ω differential pair with an appropriate keep-out area. Avoid routing USB traces near
clocks and high-frequency switching nodes. The length of the routing should be minimized and avoid 90° turns, excessive
vias, and RF stubs.
Determining USB System Requirements
The nominal cable resistance (with tolerance) for both the USB power wire (BUS) and return GND should be determined
from the cable manufacturer. In addition, be sure to include the resistance from any inline or PCB connectors. Determine
the desired operating temperature range for the application, and consider the change in resistance over temperature.
A typical application presents a 200mΩ BUS resistance with a matching 200mΩ resistance in the ground path. In this
application, the voltage drop at the far end of the captive cable is 800mV when the load current is 2A. This voltage
drop requires the voltage-adjustment circuitry of the IC to increase the output voltage to comply with the USB and Apple
specifications.
USB Loads
MAX20461 is compatible with both USB-compliant and non-compliant loads. A compliant USB device is not allowed to
sink more than 30mA and must not present more than 10μF of capacitance when initially attached to the port. The device
then begins its HVD+/HVD- connection and enumeration process. After completion of the connect process, the device
can pull 100mA/150mA and must not present a capacitance greater than 10μF. This is considered the hot-inserted, USBcompliant load of 44Ω in parallel with 10μF.
www.maximintegrated.com
Maxim Integrated | 56
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
For non-compliant USB loads, the ICs can also support both a hot insertion and soft-start into a USB load of 2Ω in parallel
with 330μF.
USB Output Current Limit
The USB load current is monitored by an internal current-sense amplifier through the voltage created across RSENSE.
MAX20461 offers a digitally adjustable USB current-limit threshold. See SETUP_2 or Table 10 to select an appropriate
register or resistor value for the desired current limit.
Some systems require the need to supply up to 160% of ILOAD(MAX) for brief periods. It is possible to increase the
MAX20461 current limit beyond 3.04A (min) by decreasing RSENSE using this scaling factor:
3.04A
RSENSE = 33mΩ · 1.6 · I
.
LOAD(MAX)
USB Voltage Adjustment
Figure 9 shows a DC model of the voltage-correction function of MAX20461. Without voltage adjustment (VADJ = 0,
GAIN[4:0] = 0), the voltage seen by the device at the end of the cable will decrease linearly as load current increases.
To compensate for this, the output voltage of the buck converter should increase linearly with load current. The slope of
RSENSE
SENSP is called RCOMP such that VADJ = RCOMP · ILOAD and RCOMP = GAIN[4 : 0] · RLSB · 33mΩ (see Figure 10).
The RCOMP adjustment values available on MAX20461 are listed in the GAIN[4:0] register description and are based on
a 33mΩ sense resistor.
For VDUT = VNO _ LOAD; 0 ≤ ILOAD, RCOMP must equal the sum of the system resistances. Calculate the minimum
RCOMP for the system so that VDUT stays constant:
RCOMP _ SYS = RLR + RSENSE + RPCB + RCABLE _ VBUS + RCABLE _ GND
Where RCABLE_VBUS + RCABLE_GND is the round-trip resistance of the USB cable (including the effect from the cable
shield, if it conducts current), RLR is the buck converter’s load regulation expressed in mΩ (51mΩ typ.), and RPCB is
the resistance of any additional VBUS parasitics (the VBUS FET, PCB trace, ferrites, and the USB connectors). Find the
setting for GAIN[4:0] using the minimum RCOMP.
GAIN[4:0] = ceiling
(
RCOMP _ SYS
RLSB
33mΩ
·R
SENSE
)
The nominal DUT voltage can then be estimated at any load current by:
[ ]
RSENSE
VDUT = VNO _ LOAD + RLSB · GAIN 4 : 0 · 33mΩ · ILOAD − RCOMP _ SYS · ILOAD
RLR
RSENSE
RPCB
RCABLE
CABLE__VBUS
VADJ
+
-
+
-
+
VSENSP
-
ILOAD
+
VDUT
-
VNO
NO__LOAD
RCABLE
CABLE__GND
Figure 9. DC Voltage Adjustment Model
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Maxim Integrated | 57
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
6.8
GAIN[4:0]
31
VSUPSW = 14V
6.6
RSENSE = 33mΩ
6.4
24
VSENSP (V)
6.2
6
18
5.8
12
5.6
5.4
6
5.2
5
4.8
0
0
0.5
1
1.5
2
2.5
3
3.5
ILIM_SET = 3.14A (typ)
ILOAD (A)
Figure 10. Increase in SENSP vs. USB Current
Tuning of USB Data Lines
USB Hi-Speed mode requires careful PCB layout with 90Ω controlled differential impedance, with matched traces of
equal length and with no stubs or test points. MAX20461 includes high-bandwidth USB data switches (>1GHz). This
means data-line tuning is generally not required. However, all designs are recommended to include pads that would
allow LC components to be mounted on the data lines so that tuning can easily be performed later, if necessary. Tuning
components should be placed as close as possible to the IC data pins, on the same layer of the PCB as the IC. The
proper configuration of the tuning components is shown in Figure 11. Figure 12 shows the reference eye diagram used
in the test setup. Figure 13 shows the MAX20461 high-voltage eye diagram on the standard EVKIT with no tuning
components. Tuning inductors should be high-Q wire-wound inductors. Contact Maxim’s application team for assistance
with the tuning process for your specific application.
4.7nH
12nH
6pF
12nH
6pF
HVD-
D-
HVD+
D+
2pF
4.7nH
2pF
Figure 11. Tuning of Data Lines
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Maxim Integrated | 58
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
DIFFERENTIAL SIGNAL (V)
MAX20461
TIME (ns)
DIFFERENTIAL SIGNAL (V)
Figure 12. Near-Eye Diagram (with No Switch)
TIME (ns)
Figure 13. Untuned Near-Eye Diagram (with MAX20461)
USB Data Line Common-Mode Choke Placement
Most automotive applications use a USB-optimized common-mode choke to mitigate EMI signals from both leaving and
entering the module. Optimal placement for this EMI choke is at the module’s USB connector. This common-mode choke
does not replace the need for the tuning inductors previously mentioned.
ESD Protection
The high-voltage MAX20461 requires no external ESD protection. All Maxim devices incorporate ESD protection
structures to protect against electrostatic discharges encountered during handling and assembly. While competing
solutions can latch-up and require the power to be cycled after an ESD event, the MAX20461 continues to work without
latch-up. When used with the configuration shown in the Typical Application Circuit, the MAX20461 is characterized for
protection to the following limits:
●
●
●
●
●
●
±25kV ISO 10605 (330pF, 2kΩ) Air Gap
±8kV ISO 10605 (330pF, 2kΩ) Contact
±15kV IEC 61000-4-2 (150pF, 330Ω) Air Gap
±8kV IEC 61000-4-2 (150pF, 330Ω) Contact
±15kV ISO 10605 (330pF, 330Ω) Air Gap
±8kV ISO 10605 (330pF, 330Ω) Contact
Note: All application-level ESD testing is performed on the standard evaluation kit with 1m captive cable.
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Maxim Integrated | 59
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
ESD Test Conditions
ESD performance depends on a variety of conditions. Contact Maxim for test setup, test methodology, and test results.
Human Body Model
Figure 14 shows the Human Body Model, and Figure 16 shows the current waveform it generates when discharged
into a low impedance. This model consists of a 100pF capacitor charged to the ESD voltage of interest, which is then
discharged into the device through a 1.5kΩ resistor.
IEC 61000-4-2
The IEC 61000-4-2 standard covers ESD testing and performance of finished equipment. MAX20461 helps users design
equipment that meets Level 4 of IEC 61000-4-2. The main difference between tests done using the Human Body
Model and IEC 61000-4-2 is a higher peak current in IEC 61000-4-2. Because the series resistance is lower in the IEC
61000-4-2 ESD test model Figure 15, the ESD withstand-voltage measured to this standard is generally lower than that
measured using the Human Body Model. Figure 17 shows the current waveform for the 8kV, IEC 61000-4-2 Level 4 ESD
Contact Discharge test. The Air Gap Discharge test involves approaching the device with a charged probe. The Contact
Discharge method connects the probe to the device before the probe is energized.
RC
1MΩ
RD
1500Ω
CHARGE-CURRENT-LIMIT
RESISTOR
DISCHARGE
RESISTANCE
HIGHVOLTAGE
DC
SOURCE
CS
100pF
STORAGE
CAPACITOR
DEVICE
UNDER
TEST
Figure 14. Human Body ESD Test Model
RC
50MΩ to 100MΩ
CHARGE-CURRENT-LIMIT
RESISTOR
HIGHVOLTAGE
DC
SOURCE
CS
150pF
RD
330Ω
DISCHARGE
RESISTANCE
STORAGE
CAPACITOR
DEVICE
UNDER
TEST
Figure 15. IEC 61000-4-2 ESD Test Model
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Maxim Integrated | 60
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
IPEAK (AMPS)
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
Ir
100%
90%
36.8%
10%
0
0
TIME
tRL
tDL
Figure 16. Human Body Current Waveform
IPEAK (AMPS)
100%
90%
10%
t
tR = 0.7ns TO 1ns
30ns
60ns
Figure 17. IEC 61000-4-2 Current Waveform
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Maxim Integrated | 61
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Typical Application Circuits
Typical Application Circuit
4
4
+3.3V
USB I/O
VOLTAGE
+VDD
4
MAX20461
RX/TX
SBU2
TX1+
TX1RX1+
RX1TX2+
TX2RX2+
RX2-
1µF
USB3 MUX
A11
8
A10
A2
A3
B11
1Optional
4
4
SCL (CONFIG3)
SDA (CONFIG2)
4
1
RX1/TX1
AGND
INT (ATTACH)
FAULT
B2
A11
ENBUCK
4
4
24
CONFIG1
HVEN
RX2/TX2
A10
CC1
D-
BCMODE
RCONFIG1
DD+
D+
A5
2
B5
4
6
A7
B7
RX/TX
CC1
VCONN
SCL
16
SDA
12
INT
14
GPIO
18
25
GPIO
1kΩ
FROM ACC OR GPIO
17
13
GPIO
SYNC
IN/OUT
3
CC2
LOW
VOLTAGE
MCU OR
ASIC WITH
INTEGRATED
USB PHY
1Optional
+VCONN
1µF
HVD-
D-
10
D2Tuning
7
A6
100kΩ
15
2Tuning
HVD+
D+
9
D+
B6
28
31
30
29
19
RSENSE
33mΩ
0.1µF
VBUS
SHIELD
4
100kΩ
1kΩ
CC_POL (SHIELD)
B10
B3
1kΩ
3V3
SYNC
CC2
11
100kΩ
USB-C RECEPTACLE
SBU1
IN
22µF
1.5µH
20
21
22
VBMON
AGND
5
G_DMOS
BIAS
SENSN
32
2.2µF
SENSP
BST
LX
SUPSW
LX
SUPSW
PGND
PGND
26
VBAT
27
0.1µF
10µF
47µF
23
EP
3OPTIONAL
1DEPENDENT
2SEE
ON THE TYPE-C SOURCE VCONN AND USB3 DESIGN REQUIREMENTS.
“TUNING OF USB DATA LINES” FOR MORE INFORMATION.
EXTERNAL ISOLATION FET.
3OPTIONAL
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Maxim Integrated | 62
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Ordering Information
PART NUMBER
TEMP
RANGE
PINPACKAGE
STARTUP MODE
(BCMODE PIN = 0)
I 2C
MAX20461ATJA/V+
Yes
MAX20461ATJD/V+
No
MAX20461AATJA/V+
MAX20461AATJD/V+
-40ºC to
+125ºC
32 TQFNEP
SDP Mode
VCONN
Yes
2.4 Amp
Yes
No
MAX20461AATJM/V+*
Yes
MAX20461AATJP/V+
No
NOMINAL OUTPUT CURRENT
FOR APPLE R30+
SPECIFICATIONS
No
3.0 Amp
/V Denotes Automotive Qualified Parts
+ Denotes a lead(Pb)-free/RoHS-compliant package.
* Future product – contact factory for availability.
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Maxim Integrated | 63
MAX20461
Automotive High-Current Step-Down Converter
with USB-C Protection/Host Charger
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
CHANGED
0
7/18
Initial release
1
8/18
Updated General Description, Simplified Block Diagram, Absolute Maximum
Ratings, Package Information, TOCs 4, 7–10, 13, 17, 18, 25, Pin Configuration, Pin
Description, Figure 1, CC Attachment and VBUS Discharge diagram, Detailed
Description, USB Type-C, VCONN, Figure 2, VBUS, External FET Gate Drive
(G_DMOS Pin), System Enable (HVEN), Linear Regulator Output (BIAS), Maximum
Duty-Cycle Operation, Reset Behavior, Output Short-Circuit Protection, Figure 3,
USB Host Adapter Emulator, I2C Configuration (CONFIG1 and I2C), I2C
Diagnostics and Event Handling, Interrupt and Attach Output (INT(ATTACH)), Fault
Output Pin (FAULT), Table 11, Register Map, SETUP_3 (0x3), SETUP_4 (0x04),
CC_REQUEST (0x06), IRQ_MASK_0 (0x07), IRQ_0 (0xA), STATUS_0 (0xD),
STATUS_1 (0xE), DC-DC Input Capacitor Selection, DC-DC Output Capacitor
Selection, USB Voltage Adjustment, Tuning of USB Data Lines, Figure 9, Figure 10,
Typical Application Circuit, and Ordering Information.
1, 21, 23, 25, 26,
27, 29–31, 33,
35, 38–41, 44,
45, 46, 48, 49,
52, 53, 55, 57,
60, 61
2
4/20
Updated General Description, Benefits and Features, Absolute Maximum Ratings,
Package Information, Electrical Characteristics, Typical Operating Characteristics,
Functional Diagrams, Detailed Description, Register Details, and Applications
Information.
1, 6, 7, 9, 10, 12,
14, 15, 19, 21,
27–30, 38, 41,
44, 51, 57
3
6/20
Added MAX20461A. Updated Benefits and Features, Simplified Block Diagram,
Absolute Maximum Ratings, Electrical Characteristics, Pin Configuration, Pin
Description, DCP Reset Behavior and Timing Diagram, ENBUCK Reset Behavior
and Timing Diagram, ATTACH Logic Diagram, CC Attachment and VBUS
Discharge, Detailed Block Diagram, CC Pulldown Response, VCONN, External FET
Gate Drive (G_DMOS Pin), Power-On Sequencing, Switching Frequency
Configuration, Switching Frequency Synchronization (SYNC Pin), CONFIG2 and
CONFIG3 Pin Table (Standalone Variants), Fault Conditions, SYNC_DIR bit, SS_EN
bit, CD bit, Ordering Information.
1–63
4
12/20
Updated USB Type-C functionality to meet latest specifications (search for
tDIS_DET). Improved SYNC pin logic for multi-port applications (search for SYNC).
Expanded design methods for overcurrent flexibility (search for ILOAD(MAX)).
1–65
5
5/21
Added MAX20461AATJM and MAX20461AATJP. Updated Electrical
Characteristics, ToCs 26-27, USB On-The-Go and Dual-Role Applications, Data
Switch Mode Truth Table, Typical Application Circuit and Ordering Information.
DESCRIPTION
—
13, 17, 35, 36,
37, 63, 64, 65
For pricing, delivery, and ordering information, please visit Maxim Integrated’s online storefront at https://www.maximintegrated.com/en/storefront/storefront.html.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent
licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max
limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
© 2021 Maxim Integrated Products, Inc.
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