EVALUATION KIT AVAILABLE
Click here to ask about the production status of specific part numbers.
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
General Description
Benefits and Features
The MAX20459 combines a 3A high-efficiency, automotive-grade, step-down converter, a USB Type-C DFP controller, and automatic BC1.2 DCP, Apple®, and Samsung® dedicated charger-detection circuitry. The device
also includes a USB load current-sense amplifier and configurable feedback-adjustment circuit designed to provide
automatic USB voltage compensation. The device limits
the USB load current using both a fixed internal peak-current threshold and a user-configurable external currentsense USB load threshold.
● One-Chip Type-C Solution Directly from Car Battery to
Portable Device
• USB Type-C-Compliant DFP Controller
• Integrated iPhone®/iPad®, Samsung® and BC1.2
DCP Charger Detection
• 4.5V to 28V Input (40V Load Dump), Synchronous
Buck Converter
• 5V to 7V, 3A Output Capability
• Standalone Device or I2C Configuration Options
and Fault Autorecovery
The MAX20459 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 application requirements. The fully synchronous DC-DC converter integrates
high-side and low-side MOSFETs along with an external
SYNC input/output, and can be configured for spreadspectrum operation. Additionally, thermal foldback is implemented to avoid excessive heating of the module while
charging at high ambient temperature.
● 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
The MAX20459 allows flexible configuration and advanced diagnostic options for both standalone and supervised applications. The device can operate as a true onechip solution that offers advanced fault autorecovery and
can be programmed using external programming resistors
and/or internal I2C registers.
The MAX20459 is available in a small 5mm x 5mm 32-pin
TQFN package and is designed to minimize required external components and layout area.
Applications
● Dedicated USB Charging Port (DCP)
• Host and Hub Module Dedicated Charging Ports
• Dedicated Charging Modules
● 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
• ±15kV Air/±8kV Contact ISO 10605 (330pF, 330Ω)*
• ±15kV Air/±8kV Contact ISO 10605 (330pF, 2kΩ)*
• ±15kV Air/±8kV Contact IEC 61000-4-2 (150pF,
330Ω)*
• Overtemperature Protection, Warning, and
Intelligent Current Foldback
• AEC-Q100 Qualified
• -40ºC to +125ºC Operating Temperature Range
*Tested in Typical Application Circuit as used on the
MAX20459 Evaluation Kit
Ordering Information appears at end of datasheet.
Apple is a registered trademark of Apple Inc.
Samsung is a registered trademark of Samsung Electronics
Co., Ltd.
19-100676; Rev 3; 5/21
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
Simplified Block Diagram
Charging
Module
VBAT
MAX20459ATJA
DC-DC +
USB Type-C
VBUS
HVD-
MCU
Charging
Module
VBAT
I²C/
Diag.
HVD+
Portable
Device
USB Type-C
Connector
Portable
Device
CC1/CC2
MAX20459ATJC
DC-DC +
USB Type-C
VBUS
HVDCONFIG
www.maximintegrated.com
USB Type-C
Connector
HVD+
CC1/CC2
Maxim Integrated | 2
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Typical Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Pin Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
MAX20459 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Functional Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
DCDC_ON Reset Behavior and Timing Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
ADC Timing Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
ATTACH Logic Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Cable Attach-Detach and SENSN Discharge Timing Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Detailed Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Detailed Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
USB Type-C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
VBUS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
External FET Gate Drive (G_DMOS Pin) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Legacy Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
USB Type-A-Only Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Power-Up and Enabling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
System Enable (HVEN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
DC-DC Enable (ENBUCK) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.3V Input (IN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Linear Regulator Output (BIAS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Power-On Sequencing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Step-Down DC-DC Regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Step-Down Regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Wide Input Voltage Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Maximum Duty-Cycle Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Output Voltage (SENSP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Soft-Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Reset Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Reset Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Switching Frequency Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
www.maximintegrated.com
Maxim Integrated | 3
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
TABLE OF CONTENTS (CONTINUED)
Switching Frequency Synchronization (SYNC Pin) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Forced-PWM Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Intelligent Skip-Mode Operation and Attach Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Spread-Spectrum Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Current Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Output Short-Circuit Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Thermal Overload Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Pre-Thermal Overload Warning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Automatic Thermal Foldback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
USB Current-Limit and Output-Voltage Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Current-Sense Amplifier (SENSP, SENSN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
USB DC Current Limit Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Voltage Feedback Adjustment Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Remote-Sense Feedback Adjustment (SHIELD Pin) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
High Voltage Modes Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Automatic Charge Detection with ESD and Short-Circuit Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
I2C, Control, and Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
I2C Configuration (CONFIG1 and I2C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Standalone Configuration (CONFIG1–CONFIG3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
I2C Diagnostics and Event Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Interrupt and Attach Output (INT(ATTACH)) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
I2C Output Voltage and Current Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
I2C Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Bit Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
STOP and START Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Early STOP Condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Clock Stretching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
I2C General Call Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
I2C Slave Addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Acknowledge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Write Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Read Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Fault Detection and Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Fault Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Fault Output Pin (FAULT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Summary Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Register Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Applications Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
www.maximintegrated.com
Maxim Integrated | 4
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
TABLE OF CONTENTS (CONTINUED)
DC-DC Switching Frequency Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
DC-DC Input Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
DC-DC Output Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
DC-DC Output Inductor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Layout Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Determining USB System Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
USB Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
USB Output Current Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
USB Voltage Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Selecting a Current-Sense Resistor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Example CONFIG Resistor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
USB Type-C Certification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
ESD Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
ESD Test Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Human Body Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
IEC 61000-4-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Typical Application Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
www.maximintegrated.com
Maxim Integrated | 5
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
LIST OF FIGURES
Figure 1. USB Type-C Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Figure 2. Remote Cable-Sense Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Figure 3. Charge Detection Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 4. I2C Timing Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Figure 5. START, STOP and REPEATED START Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Figure 6. Acknowledge Condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Figure 7. Data Format of I2C Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Figure 8. DC Voltage Adjustment Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Figure 9. Increase in SENSP vs. USB Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Figure 10. Human Body ESD Test Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Figure 11. IEC 61000-4-2 ESD Test Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Figure 12. Human Body Current Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Figure 13. IEC 61000-4-2 Current Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
www.maximintegrated.com
Maxim Integrated | 6
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
LIST OF TABLES
Table 1. Charge Detection Precedence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Table 2. DC-DC Converter Intelligent Skip Mode Truth Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table 3. Charge-Detection Mode Truth Table (I2C Variants) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Table 4. Charge-Detection Mode Truth Table (Standalone Variants) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Table 5. CONFIG1 Pin Table (I2C Variants) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Table 6. CONFIG1 Pin Table (Standalone Variants) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Table 7. CONFIG2 and CONFIG3 Pin Table (Standalone Variants) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Table 8. I2C Slave Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Table 9. Fault Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Table 10. Recommended Output Filters For ILOAD of 3A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
www.maximintegrated.com
Maxim Integrated | 7
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
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
BIAS to AGND .......................................................... -0.3V to +6V
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, DCP_MODE, FAULT, INT(ATTACH), SHIELD, CC1, CC2
to AGND ................................................................... -0.3V to +6V
HVDP, HVDM to AGND.......................................... -0.3V to +18V
G_DMOS to AGND................................................. -0.3V to +16V
LX Continuous RMS Current .................................................3.5A
Output Short-Circuit Duration......................................Continuous
Thermal Characteristics
Continuous Power Dissipation, Single-Layer Board (TA =
+70°C, 32-TQFN (derate 21.3mW/°C above +70°C)) .... mW to
1702.10mW
Continuous Power Dissipation, Multilayer 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.
Electrical Characteristics
(VSUPSW = 14V, VIN = 3.3V, VENBUCK = 3.3V, 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; VENBUCK
= 0V; VIN = 0V; off state
10
Supply Current - Buck
Off
ISUPSW
VHVEN = 14V; VENBUCK = 0V
1.1
www.maximintegrated.com
mA
Maxim Integrated | 8
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
Electrical Characteristics (continued)
(VSUPSW = 14V, VIN = 3.3V, VENBUCK = 3.3V, Temperature = TA = TJ = -40°C to +125°C, unless otherwise noted, actual typical values
may vary and are not guaranteed.)
PARAMETER
SYMBOL
CONDITIONS
Supply Current - Skip
Mode
ISUPSW
VHVEN = 14V; buck switching; no load
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
MIN
28
4.5
4.7
50
150
3.0
3.3
VSUPSW rising
3.9
SUPSW Undervoltage
Lockout Hysteresis
IN Input Current
VIN_OVLO
3
VIN rising
3.8
3.6
VHVEN_R
HVEN Falling Threshold
VHVEN_F
0.6
VHVEN
tHVEN_R
2.5
HVEN Delay Falling
tHVEN_F
5
V
V
V
4.3
V
10
µA
2.4
V
0.4
V
0.2
HVEN Delay Rising
HVEN Input Leakage
1.5
V
V
3.6
4
V
mA
4.42
IIN
HVEN Rising Threshold
HVEN Hysteresis
mA
5.25
0.2
VIN
UNITS
mA
0.2
SUPSW Undervoltage
Lockout
IN Overvoltage Lockout
MAX
1.8
BIAS Undervoltage
Lockout Hysteresis
IN Voltage Range
TYP
V
15
μs
25
μs
10
µA
10
13.0
V
100
250
kΩ
12
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 / Current Level Characteristics
CC DFP Default 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 state
160
ms
HVD+, HVD- Pins
Protection Trip
Threshold
www.maximintegrated.com
VOV_D
3.65
3.85
4.1
V
Maxim Integrated | 9
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
Electrical Characteristics (continued)
(VSUPSW = 14V, VIN = 3.3V, VENBUCK = 3.3V, Temperature = TA = TJ = -40°C to +125°C, unless otherwise noted, actual typical values
may vary and are not guaranteed.)
PARAMETER
SYMBOL
CONDITIONS
On-Resistance of
HVD+/HVD- short
RSHORT
VHVDP = 1V, IHVDM = 500μA
HVD+/HVD- OnLeakage Current
IHVD_ON
VHVD± = 3.6V or 0V
HVD+/HVD- OffLeakage Current
IHVD_OFF
VHVD+ = 18V or VHVD- = 18V, VD± = 0V
MIN
TYP
MAX
UNITS
90
180
Ω
7
µA
150
µA
-7
Current-Sense Amplifier (SENSP, SENSN) and Analog Inputs (VBMON)
10mV < VSENSP - VSENSN < 110mV,
GAIN[4:0] = 0b11111
Gain
Cable Compensation
LSB
Overcurrent Threshold
RLSB
ILIM_SET
SENSN / VBMON
Discharge Current
ISENSN_DIS
Startup Wait Time
tBUCK_WAIT
SENSN / VBMON
Discharge Time
Forced Buck Off-Time
tDIS_POR
19.4
V/V
18
mΩ
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
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
www.maximintegrated.com
16
tB,OV_SENSN
From overvoltage condition to FAULT
asserted
3
ms
6
µs
Maxim Integrated | 10
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
Electrical Characteristics (continued)
(VSUPSW = 14V, VIN = 3.3V, VENBUCK = 3.3V, Temperature = TA = TJ = -40°C to +125°C, unless otherwise noted, actual typical values
may vary and are not guaranteed.)
PARAMETER
SYMBOL
SENSN Discharge
Threshold Falling
CONDITIONS
VSENSN Falling
MIN
TYP
MAX
UNITS
0.47
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, DCP_MODE)
Input Leakage Current
VPIN = 5.5V, 0V
Logic-High
VIH
Logic-Low
VIL
-5
+5
1.6
µA
V
0.5
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
Cycles
SYNC Input Clock
Acquisition time
tSYNC
(Note 3)
1
High-Side Switch OnResistance
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
LX Current-Limit
Threshold
Skip Mode Peak-Current
Threshold
MAX20459ATJA, MAX20459ATJC
5
MAX20459ATJM, MAX20459ATJZ
6
ISKIP_TH
Negative Current Limit
mA
A
1
A
1.2
A
Soft-Start Ramp Time
tSS
8
ms
LX Rise Time
tLXR
(Note 3)
3
ns
LX Fall Time
tLXF
(Note 3)
4
ns
www.maximintegrated.com
Maxim Integrated | 11
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
Electrical Characteristics (continued)
(VSUPSW = 14V, VIN = 3.3V, VENBUCK = 3.3V, Temperature = TA = TJ = -40°C to +125°C, unless otherwise noted, actual typical values
may vary and are not guaranteed.)
PARAMETER
SYMBOL
CONDITIONS
MIN
BST Refresh Algorithm
Low-Side Minimum OnTime
TYP
MAX
60
UNITS
ns
FAULT, INT (ATTACH), SYNC Outputs
Output-High Leakage
Current
FAULT, INT(ATTACH) = 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
Configuration Resistors Converter
CONFIG1-3 Current
Leakage
VCONFIG = 0V to 4V
Minimum Window
Amplitude
-4
±5
µA
4
%
ADC
Resolution
ADC Gain Error
Offset Error
Offset_ADC
8
Bits
±2
LSBs
±1
LSB
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
130
°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
START Condition Hold
Time
tHD:STA
0.6
µs
www.maximintegrated.com
400
kHz
Maxim Integrated | 12
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
Electrical Characteristics (continued)
(VSUPSW = 14V, VIN = 3.3V, VENBUCK = 3.3V, Temperature = TA = TJ = -40°C to +125°C, unless otherwise noted, actual typical values
may vary and are not guaranteed.)
PARAMETER
STOP Condition Hold
Time
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
tSU:STO
0.6
µs
Clock-Low Period
tLOW
1.3
µs
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)
ESD Protection Level
VESD
ISO 10605 Air Gap (330pF, 330Ω)
±15
ISO 10605 Air Gap (330pF, 2kΩ)
±15
ISO 10605 Contact (330pF, 330Ω)
±8
ISO 10605 Contact (330pF, 2kΩ)
±8
IEC 61000-4-2 Air Gap (150pF, 330Ω)
±15
IEC 61000-4-2 Contact (150pF, 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: Guaranteed by design and bench characterization; not production tested.
www.maximintegrated.com
Maxim Integrated | 13
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
Typical Operating Characteristics
EFFICIENCY (%)
(TA = +25°C, unless otherwise noted.)
www.maximintegrated.com
Maxim Integrated | 14
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
www.maximintegrated.com
Maxim Integrated | 15
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
, TA = +25° C
www.maximintegrated.com
Maxim Integrated | 16
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
Pin Configuration
PGND
PGND
LX
LX
BST
ENBUCK
DCP_MODE
TOP VIEW
CONFIG1
MAX20459
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
MAX20459
10 AGND
+
3
4
5
6
7
CC1
AGND
CC2
AGND
HVDM
HVDP
AGND
8
SHIELD
2
AGND
9
1
TQFN
5mm x 5mm
Pin Description
PIN
NAME
1, 3, 5, 9, 10
AGND
FUNCTION
2
CC1
Type-C Configuration Channel (CC).
4
CC2
Type-C Configuration Channel (CC).
6
HVDM
High-Voltage-Protected USB D- Interface. Connect HVD- to the downstream USB connector D- pin
for charge detection.
7
HVDP
High-Voltage-Protected USB D+ Interface. Connect HVD+ to the downstream USB connector D+
pin for charge detection.
8
SHIELD
Analog Ground.
Optional Remote-Feedback Input. Tie to AGND if not used.
Logic Enable Input. Connect to 3.3V. If no 3.3V rail is available in the system, use a 1kΩ/2kΩ
resistor-divider from BIAS to generate 3.3V on IN. See Typical Application Circuits.
11
IN
IN is also used for clamping during overvoltage events on HVD+ or HVD-. Connect a 1μF ceramic
capacitor from IN to GND.
www.maximintegrated.com
Maxim Integrated | 17
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
Pin Description (continued)
PIN
NAME
FUNCTION
Interrupt/Attach.
12
INT
(ATTACH)
On the I²C variants, functions as an active-low interrupt pin.
On the standalone variants, functions as an active-low attach indicator.
Connect a 100kΩ pullup resistor to IN. Tie to AGND if not used.
13
SYNC
Switching Frequency Input/Output for Synchronization with Other Supplies. Configure Sync as an
input and tie to AGND if not used. See Applications Information section.
14
FAULT
Active-Low, Open-Drain, Fault Indicator Output. Connect a 100kΩ pullup resistor to IN. Tie to
AGND if not used.
SCL/Configuration 3.
15
SCL
(CONFIG3)
For the I²C variants, this serves as the SCL pin.
For the standalone variants, this serves as CONFIG3 pin. Connect a resistor to AGND to configure
thermal foldback, gain, current limit, and USB type-C source current.
SDA/Configuration 2.
16
SDA
(CONFIG2)
For the I²C variants, this serves as the SDA pin.
For the standalone variants, this serves as the CONFIG2 pin. Connect a resistor to AGND to
configure cable compensation.
17
DCP_MODE
18
ENBUCK
DCP Mode Select. Tie low for Apple 2.4A mode, tie high for Apple 1A mode.
DC-DC Enable Input. Drive high/low to enable/disable the buck converter. Connect to BIAS for
always-on operation.
19
BST
20, 21
LX
22, 23
PGND
24
CONFIG1
25
HVEN
Active-High System Enable Pin. HVEN is battery-voltage tolerant. Connect to SUPSW for alwayson operation.
26, 27
SUPSW
Internal High-Side Switch Supply Input. SUPSW provides power to the internal buck converter and
LDO. Connect a 100nF and 10μF ceramic capacitor in parallel with a 47μF electrolytic capacitor
from SUPSW to PGND. See DC-DC Input Capacitor Selection.
28
VBMON
USB VBUS Monitor Pin
29
SENSP
DC-DC Converter Feedback Input and Current-Sense Amplifier Positive Input. Place the DC-DC
bulk capacitance on this net. Connect to the positive terminal of the current-sense resistor
(RSENSE) and the main output of the converter. Used for internal voltage regulation loop.
30
SENSN
Current-Sense Amplifier Negative Input. Connect to the negative terminal of the current-sense
resistor (RSENSE).
31
G_DMOS
32
BIAS
EP
EP
www.maximintegrated.com
High-Side Driver Supply. Connect a 0.1μF capacitor from BST to LX.
Inductor Connection Pin. Connect an inductor from LX to the DC-DC converter output (SENSP).
Power Ground.
Configuration 1. Connect a resistor to AGND to configure spread spectrum, sync direction, and
switching frequency (standalone) or I2C address.
Gate-Drive Output. Optionally connect to the gate of an external n-channel FET. Otherwise,
terminate with a 2.7MΩ resistor or a 10pF capacitor to AGND.
5V Linear-Regulator Output. Connect a 2.2µF ceramic capacitor from BIAS to GND. BIAS powers
the internal circuitry.
Exposed Pad. Connect EP to multiple GND planes with 3 x 3 via grid (minimum).
Maxim Integrated | 18
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
Functional Diagrams
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 | 19
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
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 | 20
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
ATTACH Logic Diagram
SOFT START DONE
CC_ATTACH
LDO
SWITCHOVER
CC_ENB
500ms
ASSERTION
DELAY
DCDC ENABLE
CURRENT SENSE
ATTACH CRITERIA
CC_ENB
0
ENABLE FPWM
1ms
ASSERTION
DELAY
1
BC_ATTACH
USB2 DATA-LINE
ATTACH CRITERIA
INT
1
INT (ATTACH)
PIN
0
STANDALONE
Cable Attach-Detach and SENSN Discharge Timing Diagram
PASSENGER PHONE [RD] & PASSENGER POWERED CABLE [RA]
DCDC_ON low for ≥ 2s
DCDC_ON
VBIAS
CC1
0
VBIAS
CC2
RD
ATTACH
PASSENGER PHONE [RD] & PASSENGER UN-POWERED CABLE
DCDC_ON low for ≥ 2s
RD
DETACH
RD
DETACH
RD
ATTACH
CC2 DRIVEN
CC2 DRIVEN
RA
ATTACH
CC2 UNUSED
0
SENSN
G_DMOS
SENSN
DISCHARGE
tCCDEBOUNCE
RA ATTACH Region
www.maximintegrated.com
11ms
DEBOUNCE
tCCDEBOUNCE
tDIS_DET
11ms
DEBOUNCE
tDIS_DET
Maxim Integrated | 21
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
Detailed Block Diagram
CC2
CC1
USB TYPE-C DFP
VBMON
MAX20459
iPhone/iPad, BC1.2 DCP
AND SSG AUTO
CHARGER DETECTION
HVDM
HVDP
G_DMOS
CHARGE PUMP
SENSN MON
SENSN
CURRENT SENSE AMP
SENSP
7.46V
BST
REMOTE
CABLE
SENSE
SUPSW
HS_CS
3.5A FPWM
BUCK
CONVERTER
LS_CS
www.maximintegrated.com
SCL (CONFIG3)
UV
4.37V
DISCH
I/O CONTROL
AND
DIAGNOSTICS
DCP_MODE
FAULT
INT (ATTACH)
0.5V
ENBUCK
USB
OVERCURRENT
THRESHOLD
ADC
TEMP
MONITOR
HVEN
SHIELD
OSC
PGND
SDA (CONFIG2)
2V
FEEDBACK
ADJUSTMENT
LX
CONFIG1
OV
SHORT
BIAS
LDO
BIAS
IN
SYNC
AGND
Maxim Integrated | 22
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
Detailed Description
The MAX20459 combines a 5V/3A automotive-grade step-down converter and a USB Type-C host charger emulator. The
MAX20459ATJA & MAX20459ATJM variants are configured through I2C, while the MAX20459ATJC & MAX20459ATJZ
variants are configured using resistors connected to the CONFIG1, CONFIG2, and CONFIG3 pins. This device family is
designed for high-power USB ports in automotive dedicated charging applications.
The MAX20459 HVD+ and HVD- pins are protected from shorts up to 18V, and include internal ESD protection
circuitry.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, USB-IF BC1.2 DCP mode, Apple 1A and 2.4A DCP modes, Samsung
DCP, and China YD/T1591-2009.
The high-efficiency step-down DC-DC converter operates with an input voltage up to 28V and is protected from loaddump transients up to 40V. The DC-DC converter can be programmed for or synced to switching frequencies from
310kHz to 2.2MHz. The converter can deliver 3A of continuous current at an ambient temperature of 125°C.
The MAX20459 features a high-side current-sense amplifier and a programmable feedback-adjustment circuit designed
to provide automatic USB voltage adjustment to compensate for voltage drops. The precision current-sense internal
circuitry allows for an accurate DC output current limit, which 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 Type-C connector has a small form factor, is reversible, and bi-directional
(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, but also device attachment.
A Type-C implementation supports, but does not require, BC1.2. It is also desirable to implement BC1.2 detection on
HVDP/HVDM in addition to CC detection. This ensures the highest possible charge current when a legacy adapter is
used. Table 1 shows the USB-IF mandated precedence of power negotiation, see USB Type-C 2.0 for details.
MAX20459 provides an integrated Type-C 5V solution tailored to the automotive market. The device integrates all control
and power circuitry necessary to provide a 5V/3A Downstream Facing Port (DFP) with high conversion efficiency and low
thermal footprint, additionally providing BC1.2 charge detection to maintain compatibility and enable fast charging.
Table 1. Charge Detection Precedence
PRECEDENCE
Highest
Lowest
MODE OF OPERATION
NOMINAL VOLTAGE
MAXIMUM CURRENT
USB Type-C @ 3A Advertisement
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
www.maximintegrated.com
Maxim Integrated | 23
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
BIAS
RP
RP
CC1_RP_EN
CC2_RP_EN
CC1
CC1_VRA_RD
CC1_VOPEN
CC2
CC2_VRA_RD
CC1_RP_EN
CC2_VOPEN
CC2_RP_EN
5.5V CLAMPS
RP
VRA_RD
Type C
Control Logic
VOPEN
VRA_RD
VOPEN
VBMON
G_DMOS
VSAFE0V
BUCK CONTROL
CC_CUR_SRC[1:0]
ENBUCK
DCDC_ON
EN_DCDC
RP ENABLE
CC_ENB
FAULT RETRY TIMER EXPIRED
STARTUP/DISCHARGE TIMER EXPIRED
ALLOW DCDC
DCDC_ON RETRY TIMER EXPIRED
Figure 1. USB Type-C Block Diagram
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 turn the VBUS source off so that a near-zero voltage is present at the receptacle pin.
To achieve this, MAX20459 disables the external FET gate drive and turns off the buck converter when in a detached
state, reducing quiescent current. The MAX20459 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)
MAX20459 includes a gate drive for an optional external FET that can be used to isolate the bulk capacitance when VBUS
is not being sourced. A 2017 ECN from USB-IF increased the capacitance for source-only ports between VBUS and GND
when VBUS is not being sourced from 10µF to 3000µF, effectively removing the need for an isolation FET. Therefore, the
www.maximintegrated.com
Maxim Integrated | 24
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
external FET on MAX20459 is optional.
If not used, terminate G_DMOS with a 2.7MΩ resistor to ground or a 10pF capacitor to ground. If used, connect the
G_DMOS pin to the gate of the external FET. If VBUS short-to-battery is required with the external FET, 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 inter-operability with Type-A/Type-B devices by defining requirements for legacy
adapters. As a DFP, relevant adapters will 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, MAX20459 will detect a Type-C attachment whenever the adapter is
connected, regardless of whether a portable device is connected. The portable device will see the DFP as a BC1.2 port
(when configured as such).
USB Type-A-Only Operation
The following configurations allow using MAX20459 as a Type-A charger:
● On the I2C variants, CC_ENB can be set to 1 to bypass the Type-C state machine and allow only Type-A operation.
● On the standalone variants, connect one of the CC pins to a 5.1kΩ resistor to ground and the other to a 100kΩ resistor
to ground.
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 logiclow 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 variants assert 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 and a device attachment has occurred. This ensures that a portable
device cannot attach before the IC registers are correctly set for the application.
DC-DC Enable (ENBUCK)
The buck regulator on the MAX20459 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 DCDC_EN, determines if the
buck converter can be enabled by the Type-C control logic. On standalone variants, DCDC_EN 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. ENBUCK can be directly connected to the BIAS or IN pin for applications that do not require GPIO
control of the DC-DC converter enable.
3.3V Input (IN)
IN is used as a clamping voltage to protect the internal DCP circuitry pins during an ESD or overvoltage event on the
HVD+ and HVD- pins. Bypass IN with a 1µF ceramic capacitor, place it close to the IN pin. For applications without a
3.3V rail available, provide the required voltage on IN by using a voltage divider from BIAS. Recommended values for
the resistor divider are 1kΩ and 2kΩ, see Typical Application Circuits.
Linear Regulator Output (BIAS)
BIAS is the output of a 5V linear regulator that powers the internal logic, control circuitry, and DC-DC drivers. 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 the device enters lowshutdown-current mode. Bypass BIAS to GND with a 2.2µF ceramic capacitor as close to the pin as possible.
Power-On Sequencing
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.
www.maximintegrated.com
Maxim Integrated | 25
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
Step-Down DC-DC Regulator
Step-Down Regulator
The MAX20459 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 features a cycle-bycycle current limit, and intelligent transition from skip mode to forced-PWM mode which makes the devices 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 crank 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 MAX20459 has a maximum duty cycle of 98% (typ). The IC monitors the on-time (time for which the high-side FET
is on) in both PWM and skip modes for every switching cycle. Once the on-time 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 the efficiency of the design. The
input voltage at which the device enters 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 connected to SENSP that is used to set the output voltage of
the DC-DC converter. The network nominally sets the no-load DC-DC converter output voltage to 5.15V.
Soft-Start
When the DC-DC converter is enabled, the regulator initiates soft-start by gradually ramping up the output voltage from
0V to 5.15V in approximately 8ms. This soft-start feature reduces inrush current during startup and is guaranteed into
compliant USB loads. See USB Loads.
Reset Behavior
The MAX20459 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 1 for reset timer details.
Reset Criteria
The MAX20459 DC-DC converter will automatically reset for all undervoltage, overvoltage, overcurrent and
overtemperature fault conditions. See Table 9 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 prevents 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
www.maximintegrated.com
Maxim Integrated | 26
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
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 MAX20459 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 MAX20459 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 2. 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.
Table 2. DC-DC Converter Intelligent Skip Mode Truth Table
CC_ENB
SYNC
PIN
SYNC_
DIR BIT
DATA SWITCH CHARGE
DETECTION MODE
DCP 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
1A / 2.4A Auto DCP
Modes
0
0
Intelligent Skip Mode: No
Device Attached
1
1
0
1A / 2.4A Auto DCP
Modes
1
x
Forced-PWM Mode:
Device Attached
1
1
0
1A / 2.4A Auto DCP
Modes
x
1
Forced-PWM Mode:
Device Attached
Spread-Spectrum Option
Spread-spectrum operation is offered to improve the EMI performance of the MAX20459. Spread-spectrum operation
is enabled by the SS_EN bit of the SETUP_0 register, which is pre-loaded 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
www.maximintegrated.com
Maxim Integrated | 27
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
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 MAX20459 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 and 3A, depending on the application requirements, and protects the system in the event of
a fault. Upon exceeding either the LX peak or user-programmable current thresholds, the high-side FET is immediately
turned off and current-limit algorithms are initiated. In some cases, the designer may want to increase the load to 160%,
refer to Selecting a Current-Sense Resistor for details.
On the I²C variants, 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. If the USB current limit is detected for 16ms, and the output voltage falls
below the reset threshold (4.38V typ.) but stays above the 2.0V threshold, the FAULT pin asserts, the VBUS_ILIM bit of
the IRQ_1 register is set, and the DC-DC converter resets (if ILIM_ITRIP = 0). Conversely, if ILIM_ITRIP = 1, the DC-DC
converter will not reset, and it will keep acting as a current source.
On the standalone variants, if the USB current limit is detected for 16ms, and the output voltage falls below the reset
threshold (4.38V typ.) but stays above the 2.0V threshold, the FAULT pin asserts, the DC-DC converter will not reset and
will keep acting as a current source.
On all variants, the DC-DC converter immediately resets if the output voltage droops to less than 2.0V and either
the external current threshold is exceeded, or the internal LX peak-current threshold is exceeded for four consecutive
switching cycles.
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 shutdown until the fault
condition resolves and 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 will shut down, allowing it to 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 Layout Considerations for more information.
Pre-Thermal Overload Warning
The MAX20459 I2C variants feature 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
The MAX20459 implements a thermal foldback feature that, when enabled, reduces the Type-C current limit and
advertisement. On the standalone variants, when a thermal warning occurs, the output current limit and the RP current
advertisement are reduced to the setting immediately below what was set by the CONFIG3 resistor (i.e. Type-C RP from
3.0A to 1.5A and ILIM from 3.04A to 2.60A). When the die temperature drops below the thermal-warning threshold, the
RP advertisement and current-limit threshold will return to their original settings based on the value of the CONFIG3
resistor. Note that CONFIGx resistor values are only read at POR.
On the I2C variants, when a thermal warning occurs, the RP current advertisement is reduced to the setting immediately
below what was set by the CC_SRC_CUR[1:0] register (ie. Type-C RP from 3.0A to 1.5A) and the current limit changes
www.maximintegrated.com
Maxim Integrated | 28
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
to 1.62A (min). When the die temperature drops below the thermal-warning threshold, the RP advertisement and currentlimit threshold will return to their original settings based on the values of CC_SRC_CUR[1:0] and ILIM[2:0] registers,
respectively.
Note that Type-C allows for dynamic RP changes in the Attached.SRC state without re-initializing detection. MAX20459
thermal foldback does not force BUS to reset or change the BC1.2 mode. Alternative thermal foldback algorithms are
available and can be done in system software. Contact Maxim Applications for support.
USB Current-Limit and Output-Voltage Adjustment
Current-Sense Amplifier (SENSP, SENSN)
MAX20459 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 Selecting a Current-Sense Resistor for
details.
USB DC Current Limit Configuration
The MAX20459 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.
The standalone variants allow selection of a subset of the eight available current-limit options by reading the CONFIG3
resistor. See Table 7 and the Applications Information section for more information.
In some cases, the designer may want to increase the load to 160%, refer to Selecting a Current-Sense Resistor for
details.
Voltage Feedback Adjustment Configuration
The MAX20459 compensates voltage drop for up to 474mΩ of total series resistance on the VBUS and GND path
(RSENSE = 33mΩ). Voltage gain is configured by selecting suitable resistors connected to CONFIG2 and CONFIG3 on
the standalone variants, or by changing the GAIN[4:0] register on the I2C variants.
In some cases, the designer may want to increase the load to 160%, refer to Selecting a Current-Sense Resistor for
details.
Remote-Sense Feedback Adjustment (SHIELD Pin)
The remote-sense feature (available by custom order only) gives 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 without
changing the GAIN[4:0] setting.
The user must compensate for the voltage drop due to the sense resistor, the load-line behavior of the buck, and any
difference between the VBUS and GND conductors. Contact Maxim Applications for support and ordering instructions.
www.maximintegrated.com
Maxim Integrated | 29
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
+ VDUT -
CAPTIVE
USB CABLE
REGULATED FOR
ILOAD and RCABLE
MAX20459
RVBUS
HVBUS
DM
HVD-
PORTABLE
DEVICE
HVD+
DP
AGND
RGND
SHEILD
USB SHEILD OR
SENSE WIRE
GAIN[4:0] =
Cannot connect to IC GND
Figure 2. Remote Cable-Sense Diagram
High Voltage Modes Configuration
I2C variants of MAX20459 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 Maxim
Applications for support.
Automatic Charge Detection with ESD and Short-Circuit Protection
To maintain compatibility with non-Type-C devices, MAX20459 includes automatic dedicated charger-detection circuitry
on the USB 2.0 data D+/D- lines. The device is compatible with Apple iPhone (1A), iPad (2.4A), BC1.2 DCP, and legacy
Samsung charge-detection methods. See Table 3 for the I2C variants and Table 4 for the standalone variants.
The MAX20459 does not require an external ESD array, and protects the HVD+ and HVD- pins up to ±15kV Air
Gap/±8kV Contact Discharge with the 150pF/330Ω IEC 61000-4-2 model, as well as protecting up to ±15kV Air Gap/±8kV
Contact Discharge with the 330pF/2kΩ or 330pF/330Ω ISO 10605 model. See ESD Protection for additional information.
Additionally, the HVD+ and HVD- short-circuit protection features include protection for short to +5V BUS and protection
for short to +18V car battery.
Table 3. Charge-Detection Mode Truth Table (I2C Variants)
PART NUMBER
MAX20459ATJA,
MAX20459ATJM
DEVICE INPUTS
SB SWITCHES
CHARGE-DETECTION MODE
HVEN
CD[1]
CD[0]
DCP_MODE
0
X
X
X
0
Off
1
1
0
0
1
Auto-DCP/Apple 2.4A (DCP)
1
1
1
0
1
1
1
X
1
1
Auto-DCP/Apple 1A (DCP)
Table 4. Charge-Detection Mode Truth Table (Standalone Variants)
PART NUMBER
MAX20459ATJC,
MAX20459ATJZ
www.maximintegrated.com
DEVICE INPUTS
SB SWITCHES
CHARGE-DETECTION MODE
X
0
Off
1
0
1
Auto-DCP/Apple 2.4A (DCP)
1
1
1
Auto-DCP/Apple 1A (DCP)
HVEN
DCP_MODE
0
Maxim Integrated | 30
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
MAX20459
SB
HVDP
ESD
Protection
SB
HVDM
iPhone/iPad
and DCP/SSG
AUTO CHARGER
DETECTION
DCP_MODE
HVEN
HVDP/HVDM OV
IN OV
CONTROL
LOGIC
ATTACH
FAULT/IRQ
SB
ESD
Protection
Figure 3. Charge Detection Block Diagram
I2C, Control, and Diagnostics
I2C Configuration (CONFIG1 and I2C)
The MAX20459 I2C variants allow basic device configuration through a resistor placed between the CONFIG1 pin and
GND. 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 the I2C variants, CONFIG1 sets the startup value of the DC-DC spread spectrum enable bit SS_EN and the SYNC
direction-control bit SYNC_DIR. CONFIG1 also sets the two LSBs of the I2C slave address. The configuration table for
the I2C variants is shown in Table 5.
In some cases, the designer may want to increase the load to 160%, refer to Selecting a Current-Sense Resistor for
details.
Table 5. CONFIG1 Pin Table (I2C Variants)
RESISTANCE (typ, Ω)
STEP
SS_EN
SYNC_DIR
I2C_ADDR LSBs
Short to GND
0
1 (ON)
1 (IN)
0b00
619
1
1 (ON)
1 (IN)
0b01
976
2
1 (ON)
1 (IN)
0b10
1370
3
1 (ON)
1 (IN)
0b11
1820
4
1 (ON)
0 (OUT)
0b00
2370
5
1 (ON)
0 (OUT)
0b01
3090
6
1 (ON)
0 (OUT)
0b10
3920
7
1 (ON)
0 (OUT)
0b11
4990
8
0 (OFF)
1 (IN)
0b00
6340
9
0 (OFF)
1 (IN)
0b01
8250
10
0 (OFF)
1 (IN)
0b10
11000
11
0 (OFF)
1 (IN)
0b11
15400
12
0 (OFF)
0 (OUT)
0b00
www.maximintegrated.com
Maxim Integrated | 31
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
Table 5. CONFIG1 Pin Table (I2C Variants) (continued)
RESISTANCE (typ, Ω)
STEP
SS_EN
SYNC_DIR
I2C_ADDR LSBs
23700
13
0 (OFF)
0 (OUT)
0b01
44200
14
0 (OFF)
0 (OUT)
0b10
Short to BIAS
(or R > 71.5kΩ)
15
0 (OFF)
0 (OUT)
0b11
Standalone Configuration (CONFIG1–CONFIG3)
The MAX20459 standalone variants allow full device configuration from three resistors placed among the three CONFIG
pins and AGND. CONFIG1 sets the internal oscillator switching frequency, the SYNC pin direction, and enables the DCDC spread-spectrum mode. CONFIG2 sets the 4 LSBs of the voltage adjustment gain (GAIN[3:0]). CONFIG3 sets the
USB DC current limit and sets the MSB of voltage-adjustment gain (GAIN[4]). See Table 6 and Table 7 for CONFIG
options. See the GAIN[4:0] register description for lookup values. See the Applications Information section for setting
selection and Ordering Information for variant part number information.
Table 6. CONFIG1 Pin Table (Standalone Variants)
RESISTANCE (typ, Ω)
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
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 7. CONFIG2 and CONFIG3 Pin Table (Standalone Variants)
RESISTANCE (typ, Ω)
STEP
GAIN[3:0]
THM_FLDBK_EN
GAIN[4]
CONFIG2
CURRENT LIMIT
(A, min)
TYPE-C MODE
(A)
CONFIG3
Short to GND
0
0b0000
1 (ON)
0
0.55
0.5
619
1
0b0001
1 (ON)
0
1.62
1.5
976
2
0b0010
1 (ON)
0
2.60
1.5
1370
3
0b0011
1 (ON)
0
3.04
3.0
1820
4
0b0100
1 (ON)
1
0.55
0.5
2370
5
0b0101
1 (ON)
1
1.62
1.5
3090
6
0b0110
1 (ON)
1
2.60
1.5
3920
7
0b0111
1 (ON)
1
3.04
3.0
www.maximintegrated.com
Maxim Integrated | 32
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
Table 7. CONFIG2 and CONFIG3 Pin Table (Standalone Variants) (continued)
RESISTANCE (typ, Ω)
STEP
GAIN[3:0]
THM_FLDBK_EN
GAIN[4]
CURRENT LIMIT
(A, min)
TYPE-C MODE
(A)
4990
8
0b1000
0 (OFF)
0
0.55
0.5
6340
9
0b1001
0 (OFF)
0
1.62
1.5
8250
10
0b1010
0 (OFF)
0
2.60
1.5
11000
11
0b1011
0 (OFF)
0
3.04
3.0
15400
12
0b1100
0 (OFF)
1
0.55
0.5
23700
13
0b1101
0 (OFF)
1
1.62
1.5
44200
14
0b1110
0 (OFF)
1
2.60
1.5
Short to BIAS
(or R > 71.5kΩ)
15
0b1111
0 (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 will 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 overcurrent 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 MAX20459 INT(ATTACH) pin functions as an interrupt (INT) for the I2C variants. The INT pin will assert 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 attach/detach, and for USB voltage/
current ADC conversion completion. The INT pin will only assert while a masked IRQ bit is asserted, which means that
its behavior is also dependent on the IRQ_AUTOCLR bit.
The standalone MAX20459 variants feature an open-drain, active-low, ATTACH output that serves as the attachdetection pin. 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.
I2C Output Voltage and Current Measurement
The MAX20459 I2C variants allow measurement of the instantaneous SENSN voltage and DC output current using
an integrated ADC. To initiate a measurement, set the ADC_REQ bit of the ADC_REQUEST register. The ADC_REQ
bit will be 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
will persist 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 by:
19.8V
VSENSN = 256 · ADC_USBV (Volts)
The measured SENSE voltage has a range of 0 to 116mV. Convert the sample to a current by:
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).
www.maximintegrated.com
Maxim Integrated | 33
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
I2C Interface
The MAX20459 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 MAX20459 and the master at clock rates up to 400kHz. The master,
typically a microcontroller, generates SCL and initiates data transfer on the bus. Figure 4 shows the 2-wire interface
timing diagram.
A master device communicates to the MAX20459 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 MAX20459 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 MAX20459 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
tSP
tHD,DAT
tHD,DAT
tSU,STO
SCL
tHIGH
tHD,STA
tR
tF
START CONDITION
REPEATED START
CONDITION
STOP
CONDITION
START
CONDITION
Figure 4. 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
SCL pulse. Changes in SDA while SCL is high are control signals (see STOP and START Conditions). 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 5). A START (S)
condition from the master signals the beginning of a transmission to the MAX20459. 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 5. START, STOP and REPEATED START Conditions
www.maximintegrated.com
Maxim Integrated | 34
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
Early STOP Condition
The MAX20459 recognizes a STOP condition at any point during data transmission except if 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 MAX20459 does not use any form of clock stretching to
hold down the clock line.
I2C General Call Address
The MAX20459 does not implement the I2C specification general call address. If the MAX20459 sees the general call
address (0b0000_0000), it will 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 devices 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 devices after the START condition.
Table 8. 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 ninth bit that the device uses to handshake receipt of each data byte (Figure
6). The device pulls down SDA during the master-generated ninth 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
of an unsuccessful data transfer, the bus master can reattempt communication.
Not Acknowledge (nA)
S
Acknowledge (A)
SDA
tSU:DAT
SCL
1
2
8
tHD:DAT
9
Figure 6. Acknowledge Condition
Write Data Format
A write to the device includes transmission of the following:
●
●
●
●
●
START condition
Slave address with the write bit set to 0,
1 byte of data to register address
1 byte of data to the command register
STOP condition.
www.maximintegrated.com
Maxim Integrated | 35
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
Read Data Format
A read from the device includes transmission of the following:
●
●
●
●
●
●
●
START condition
Slave address with the write bit set to 0
1 byte of data to register address
Restart condition
Slave address with read bit set to 1
1 byte of data to the command register
STOP condition
Figure 7 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 7. Data Format of I2C Interface
Fault Detection and Diagnostics
Fault Detection
The MAX20459 features advanced device-protection features with automatic fault handing and recovery. Table 9
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.
Fault Output Pin (FAULT)
The MAX20459 features an open-drain, active-low FAULT output. The MAX20459 is designed to eliminate false FAULT
reporting by using an internal deglitch and fault-blanking timer. This ensures that FAULT is not falsely asserted during
normal operation such as starting into heavy capacitive loads. The FAULT pin is designed such that it can be tied directly
to the fault input of a microcontroller or used to enable an LED.
www.maximintegrated.com
Maxim Integrated | 36
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
Table 9. Fault Conditions
IRQ REGISTER
BITS
(I2C ONLY)
DEBOUNCE
PRIOR TO
ACTION
ACTION TAKEN
Thermal
Shutdown
THM_SHD
Immediate
Assert FAULT pin, shut down DC-DC converter, disconnect charge-detection
circuitry, and disable RP. When fault resolves and RETRY_TMR expires,
release FAULT pin, enable RP and DC-DC converter.
Thermal
Warning/
Foldback
THM_WARN
20 ms
EVENT
IN Overvoltage
IN_OV
Immediate
Assert FAULT pin and associated IRQ bit, shut down DC-DC converter,
disconnect charge-detection circuitry, disable RP, and reset BC1.2. When
fault resolves and RETRY_TMR expires, release FAULT pin, reconnect
charge detection circuitry, enable RP and DC-DC converter.
Assert FAULT pin, shut down DC-DC converter, disconnect charge-detection
circuitry, disable RP, and reset BC1.2. When fault resolves and RETRY_TMR
expires, release FAULT pin, reconnect charge detection circuitry, enable RP
and DC-DC converter.
HVDP/HVDM
Overvoltage
DATA_OV
Immediate
USB DC
Overcurrent
VBUS_ILIM
16 ms
USB DC
Overcurrent
and SENSN <
4.38V
If enabled, initiate thermal-foldback algorithm by reducing the type-C RP by
one step and current limit. When fault resolves and RETRY_TMR expires,
return to original current-advertisement and current-limit settings.
Assert FAULT pin after overcurrent condition persists for 16ms. When fault
resolves and RETRY_TMR expires, release FAULT pin.
Standalone variants or I²C variants with ILIM_ITRIP = 1:
Assert FAULT pin after overcurrent and undervoltage condition persists for
16ms. When fault resolves and RETRY_TMR expires, release FAULT pin.
VBUS_ILIM_UV
16 ms
VBUS_UV
16 ms
Assert FAULT pin after undervoltage condition persists for 16ms. When fault
resolves and RETRY_TMR expires, release FAULT pin.
USB DC
Overcurrent
and SENSN <
2V
VBUS_SHT_GND
Immediate
Assert FAULT pin, shut down DC-DC converter, disconnect charge-detection
circuitry, and disable RP. When RETRY_TMR expires after shutdown,
release FAULT pin, reconnect charge detection circuitry, enable RP and DCDC converter.
LX Overcurrent
for Four
Consecutive
Cycles and
SENSN < 2V
VBUS_SHT_GND
Immediate
Assert FAULT pin, shut down DC-DC converter, disconnect charge detection
circuitry, and disable RP. When RETRY_TMR expires after shutdown,
release FAULT pin, reconnect charge detection circuitry, enable RP and DCDC converter.
Assert FAULT pin and associated IRQ bit, shut down DC-DC converter,
disconnect charge detection circuitry, and disable RP. When fault resolves
and RETRY_TMR expires, release FAULT pin, reconnect charge detection
circuitry, enable RP and DC-DC converter.
SENSN <
4.38V
SENSN
Overvoltage
VBUS_OV
Immediate
VBUS PreOvervoltage
VBUS_PRE_OV
16 ms
www.maximintegrated.com
I²C variants and ILIM_ITRIP = 0:
Assert FAULT pin, shut down DC-DC converter, and disable RP after
overcurrent and undervoltage condition persists for 16ms. When
RETRY_TMR expires after shutdown, release FAULT pin, enable RP and
DC-DC converter.
Assert FAULT pin and associated IRQ bit after overvoltage condition persists
for 16ms. After overvoltage no longer exists and RETRY_TMR expires,
release FAULT pin.
Maxim Integrated | 37
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
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
–
RETRY_TMR[1:0]
CD[1:0]
–
ILIM[2:0]
CC_ENB
–
–
–
–
–
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_THM
_WARN
EN_IN_
OV
EN_DAT
A_OV
–
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
–
THM_W
ARN
IN_OV
DATA_O
V
–
0x0D
STATUS_0[7:0]
–
–
–
CC_ATT
ACH
BC_ATT
ACH
VBMON
_SAFE
–
VBUS_S
TAT
0x0E
STATUS_1[7:0]
–
–
0x10
ADC_0[7:0]
0x11
ADC_1[7:0]
ADC_USBV[7:0]
0x12
ADC_2[7:0]
ADC_TEMP[7:0]
CC_PIN_STATE[1:0
]
CC_SRC_CUR[1:0]
CC_STATE[3:0]
ADC_USBI[7:0]
Register Details
SETUP_0 (0x0)
www.maximintegrated.com
Maxim Integrated | 38
MAX20459
BIT
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
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
BITS
4
3
2
DESCRIPTION
1
0
SYNC_DIR
SS_EN
Write, Read
Write, Read
DECODE
THM_FLDBK
_EN
6
Lowers the type-C advertised current
capability and the output current limit when
Thermal Warning is tripped.
EN_DCDC
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
VOUT
4:2
0 = Disable Thermal Foldback
1 = Enable Thermal Foldback
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
www.maximintegrated.com
DESCRIPTION
DC/DC Convertor Switching-Frequency
Selection.
Initial value set by CONFIG1 resistor.
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 | 39
MAX20459
BITFIELD
GAIN
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
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
–
–
–
0b1
–
0b111
Access
Type
–
–
–
Write, Read
–
Write, Read
BITFIELD
ILIM_ITRIP
ILIM
BITS
4
2:0
www.maximintegrated.com
DESCRIPTION
2
1
0
DECODE
Determines the buck's retry behavior under
USB DC current-limit conditions
0 = VBUS_ILIM_UV fault enabled, VBUS_ILIM
fault disabled
1 = VBUS_ILIM_UV fault disabled, VBUS_ILIM
fault enabled
USB DC current-limit threshold. RSENSE =
33mΩ.
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
Maxim Integrated | 40
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
SETUP_3 (0x3)
BIT
7
6
Field
RETRY_TMR[1:0]
Reset
0b00
Access
Type
BITFIELD
RETRY_TM
R
CD
CC_ENB
CC_SRC_C
UR
5
4
CD[1:0]
Write, Read
Write, Read
BITS
3
2
CC_ENB
–
CC_SRC_CUR[1:0]
0b0
–
0b01
Write, Read
–
Write, Read
DESCRIPTION
1
0
DECODE
7:6
Determines the length of the RETRY timer
after a fault condition
0b00 = 2.0s
0b01= 1.0s
0b10 = 0.5s
0b11= 16ms
5:4
BC1.2 Charge-Detection Configuration
Selection.
This register is preloaded at startup with 0b10
when DCP_MODE = 0 and with 0b11 when
DCP_MODE = 1.
0b00 = Reserved
0b01 = Reserved
0b10 = Auto-DCP/Apple 2.4A
0b11 = Auto-DCP/Apple 1.0A
Disable Type-C Detection
0 = Type-C Enabled
1 = Type-C Disabled (for Type-A operation only)
Type-C DFP Source Pullup Current
Advertisement (RP).
0b00 = 0.5A
0b01 = 1.5A
0b10 = 3.0A
0b11 = 0.5A
3
1:0
SETUP_4 (0x4)
BIT
7
6
5
4
3
2
1
0
Field
–
–
–
–
–
–
–
CONFIGUR
ED
Reset
–
–
–
–
–
–
–
0b0
Access
Type
–
–
–
–
–
–
–
Write, Read
BITFIELD
CONFIGURE
D
BITS
DESCRIPTION
0
I2C Configuration Complete Indicator.
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.
DECODE
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
www.maximintegrated.com
Maxim Integrated | 41
MAX20459
BITFIELD
ADC_REQ
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
BITS
DESCRIPTION
DECODE
0
ADC V/I Sample Request.
When a 1 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
Field
–
–
–
–
–
–
CC_FORCE
_ERR
CC_SRC_R
ST
Reset
–
–
–
–
–
–
0b0
0b0
Access
Type
–
–
–
–
–
–
Write, Read
Write, Read
BITFIELD
CC_FORCE_
ERR
CC_SRC_RS
T
BITS
DESCRIPTION
1
Type-C Force Error Request.
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.
DECODE
0 = No change to current operating state
1 = Force transition to Error Recovery state
0
Type-C Force Source Reset Request.
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 0.
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
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
7
BITFIELD
BITS
IRQ_AUTOC
LR
7
IRQ Autoclear
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
EN_CC_ATT
ACH_EV
2
Type-C ATTACH EVENT Interrupt Enable
0 = Not included in Interrupt
1 = Included in Interrupt
www.maximintegrated.com
DESCRIPTION
DECODE
Maxim Integrated | 42
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
BITFIELD
BITS
DESCRIPTION
DECODE
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
–
0b0
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_THM_
WARN
EN_IN_OV
EN_DATA_
OV
–
Field
–
–
EN_VBUS_
PREBIAS
Reset
–
–
0b0
–
0b0
0b0
0b0
–
Access
Type
–
–
Write, Read
–
Write, Read
Write, Read
Write, Read
–
BITFIELD
BITS
DESCRIPTION
DECODE
EN_VBUS_P
REBIAS
5
VBUS_PREBIAS Interrupt Enable
0 = Not included in Interrupt
1 = Included in Interrupt
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
www.maximintegrated.com
Maxim Integrated | 43
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
BITFIELD
BITS
EN_DATA_O
V
1
DESCRIPTION
DECODE
0 = Not included in Interrupt
1 = Included in Interrupt
DATA_OV 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
6
5
4
3
2
1
0
Field
UNCONFIG
URED
–
CC_STATE
_EV
CC_ATTAC
H_IRQ
BC_ATTAC
H_IRQ
CC_ATTAC
H_EV
BC_ATTAC
H_EV
ADC_DON
E
Reset
0b0
–
0b0
0b0
0b0
0b0
0b0
0b0
Read Only
–
Read
Clears All
Read
Clears All
Read
Clears All
Read
Clears All
Read
Clears All
Read
Clears All
Access
Type
BITFIELD
7
BITS
DESCRIPTION
DECODE
UNCONFIGU
RED
7
I2C Unconfigured Indicator Bit
0 = Device is fully configured (CONFIGURED
written to 1)
1 = Device is not fully configured (CONFIGURED
has not been written to 1)
CC_STATE_
EV
5
Type-C State Change Indicator.
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
CC_ATTACH
_IRQ
4
Type-C ATTACH Indicator.
This bit indicates a Type-C device attach is
observed on 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
BC_ATTACH
_IRQ
3
BC1.2 ATTACH Indicator.
This bit indicates a BC1.2 device attach is
observed on the HVDP/HVDM pins.
0 = No device attached
1 = Device attached
2
Type-C ATTACH Event Detected.
This bit indicates a Type-C device attach was
initiated and/or terminated as observed on
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.
Clear on read. Not affected by
IRQ_AUTOCLR.
0 = No attach or detach event detected since last
read
1 = New attach and/or detach event detected
BC_ATTACH
_EV
1
BC1.2 ATTACH Event Detected.
This bit indicates a BC1.2 device attach was
initiated and/or terminated as observed on
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.
Clear on read. Not affected by
IRQ_AUTOCLR.
0 = No attach or detach event detected since last
read
1 = New attach and/or detach event detected
ADC_DONE
0
ADC Meaurement Complete Indicator.
Clear on read.
0 = No new data available since last read
1 = New data available
CC_ATTACH
_EV
www.maximintegrated.com
Maxim Integrated | 44
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
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
4
3
2
1
0
Field
–
VBUS_PRE
_OV
VBUS_ILIM
_UV
VBUS_ILIM
VBUS_OV
VBUS_UV
VBUS_SHT
_GND
THM_SHD
Reset
–
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
Access
Type
BITFIELD
BITS
DESCRIPTION
DECODE
6
VBUS Pre-Overvoltage Fault Detected.
Asserts if overvoltage exists on VBMON
when Type-C is enabled and no Type-C
device is attached.
Clear on read if condition is resolved.
0 = No event
1 = Event detected
VBUS_ILIM_
UV
5
VBUS Current Limit and SENSN UV Fault
Detected.
Disabled when ILIM_ITRIP = 1. Clear on read
if condition is resolved.
0 = No event
1 = Event detected
VBUS_ILIM
4
VBUS Current-Limit Condition Detected.
Disabled when ILIM_ITRIP = 0. Clear on read
if condition is resolved.
0 = No event
1 = Event detected
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
0
Overtemperature Fault Detected.
Asserts when the die temperature exceeds
165°C (typ). Clear on read if condition is
resolved.
0 = No event
1 = Event detected
VBUS_PRE_
OV
THM_SHD
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
–
THM_WAR
N
IN_OV
DATA_OV
–
Field
–
–
VBUS_PRE
BIAS
Reset
–
–
0b0
–
0b0
0b0
0b0
–
Access
Type
–
–
Read
Clears All
–
Read
Clears All
Read
Clears All
Read
Clears All
–
BITFIELD
VBUS_PREB
IAS
BITS
DESCRIPTION
5
VBUS Pre-Bias.
Asserts if Type-C is enabled and VBMON >
VSAFE0V when no Type-C device is attached.
www.maximintegrated.com
DECODE
0 = No event
1 = Event detected
Maxim Integrated | 45
MAX20459
BITFIELD
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
BITS
DESCRIPTION
DECODE
THM_WARN
3
Thermal Warning Condition Detected.
Asserts when the temperature has reached
130°C (typ).
If thermal foldback is enabled, the type-C
current advertisement and current limit will be
lowered while this bit is asserted.
Clear on read if condition is resolved.
0 = No event
1 = Event detected
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
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
–
VBUS_STA
T
Field
–
–
–
CC_ATTAC
H
Reset
–
–
–
0b0
0b0
0b0
–
0b0
Access
Type
–
–
–
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 on 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 on the HVDP/HVDM pins. More details
can be read in the STATUS_1 register.
0 = No device currently attached
1 = Device currently attached
VBMON_SA
FE
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
VBUS_STAT
0
Type-C VBUS Status Indicator
0 – VBUS not applied to receptacle
1 – VBUS applied to receptacle (Attached.SRC)
BC_ATTACH
DESCRIPTION
DECODE
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]
Reset
–
–
0b00
Access
Type
–
–
Read Only
BITFIELD
CC_PIN_ST
ATE
BITS
5:4
www.maximintegrated.com
5
4
DESCRIPTION
Type-C Active CC Pin/Orientation Indicator
3
2
1
0
CC_STATE[3:0]
Read Only
DECODE
0b00 = No Attach
0b01 = RD detected on CC1
0b10 = RD detected on CC2
0b11 = Not used
Maxim Integrated | 46
MAX20459
BITFIELD
CC_STATE
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
BITS
3:0
DESCRIPTION
DECODE
Type-C Functional Status/State Indicator
0b0000 = Disabled
0b0010 = Error Recovery
0b0011 = Unattached.SRC
0b0110 = AttachWait.SRC
0b1000 = Attached.SRC (CC2)
0b1100 = Attached.SRC (CC1)
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 Output Current ADC Measurement
Result
ILOAD = ((116mV/256) x 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) x 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 x ADC_TEMP - 270 (°C)
Maxim Integrated | 47
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
Applications Information
DC-DC Switching Frequency Selection
The switching frequency (fSW) for MAX20459 is programmable through 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 10. 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 | 48
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
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, VSENSP, and IOUT are typical values (such that efficiency is optimum for nominal operating conditions).
Ensure that the indutor ISAT is above the buck converter's cycle-by-cycle peak current limit.
Table 10. Recommended Output Filters For ILOAD of 3A
fSW (kHz)
LOUT (μH)
RECOMMENDED COUT
2200
1.5
22μF ceramic OR
10μF ceramic + low-ESR 22μF electrolytic (< 0.8Ω)
488
8.2
3 x 22μF ceramic OR
22μF ceramic + low-ESR 68μF electrolytic (< 0.25Ω)
310
12
22μF ceramic + low-ESR 68μF electrolytic (< 0.25Ω)
Layout Considerations
Proper PCB layout is critical for robust system performance. See the MAX20459 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 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 may result in the IC repeatedly reaching thermal shutdown). Do not
use separate power and analog ground planes; 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).
Determining USB System Requirements
In a Dedicated USB Charging Port (DCP) application, the user port is generally located in a front-facing configuration on
the DCP or HUB module. To avoid VBUS voltage drop at the user port when current increases due to trace, connector,
and output ferrite resistance, MAX20459 implement voltage-adjustment circuitry that increases the buck's output-voltage
regulation point linearly with the output current. The voltage-adjustment gain can be set using either external resistors
or I2C depending on the variant. The gain setting must be calculated to take into account all series element and voltage
drops in the charging path, including ground return. See the USB Voltage Adjustment section for calculating the optimum
gain setting for your application. User cable can be of different length and type, and therefore should not be included in
the calculations.
USB Loads
MAX20459 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.
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.
www.maximintegrated.com
Maxim Integrated | 49
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
USB Output Current Limit
The USB load current is monitored by an internal current-sense amplifier through the voltage created across RSENSE.
MAX20459 offers an adjustable USB current-limit threshold. See SETUP_2 or Table 7 to select an appropriate register
or resistor value for the desired current limit.
USB Voltage Adjustment
Figure 8 shows a DC model of the voltage-correction function of MAX20459. 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
RSENSE
of SENSP is called RCOMP such that VADJ = RCOMP · ILOAD and RCOMP = GAIN[4 : 0] · RLSB · 33mΩ (see Figure 9).
The RCOMP adjustment values available on MAX20459 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 8. DC Voltage Adjustment Model
www.maximintegrated.com
Maxim Integrated | 50
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
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
ILOAD (A)
2.5
3
3.5
ILIM_SET = 3.14A (typ)
Figure 9. Increase in SENSP vs. USB Current
Selecting a Current-Sense Resistor
The external current-sense resistor (RSENSE) is critical for accurate current-limit, voltage-adjustment, attach-detection,
and ADC measurement. Select a resistor with high precision and low temperature variation (ppm). It is highly
recommended that designs use a resistor with an exact value of 33mΩ. Since the current limit and voltage adjustment
are selected digitally (there are a discrete number of levels), changing this value also changes the possible current-limit
thresholds, the voltage-adjustment compensation and the attach threshold. The specifications in the register and resistor
tables will need to be scaled accordingly.
Some systems require the need to supply up to 160% of ILOAD(MAX) for brief periods. It is possible to increase the
MAX20459 current limit beyond 3.04A (min) by decreasing RSENSE using this scaling factor:
3.04A
RSENSE = 33mΩ · 1.6 · I
.
LOAD(MAX)
Example CONFIG Resistor Selection
With RPCB = 20mΩ, RSENSE = 33mΩ, and RLR = 51mΩ, the total system resistance is RCOMP_SYS = 20 + 33 + 51 =
104mΩ. The desired GAIN[4:0] register setting is then ceiling(104/18) = 6 = 0b00110, which sets the adjustment level
to 108mΩ. To set GAIN[4:0] using the CONFIG resistors, the appropriate step must be selected for both CONFIG2 and
CONFIG3. The MSB of the GAIN register (GAIN[4]) is selected by CONFIG3. In this example, GAIN[4] = 0b0. If it is a 3A
application with automatic thermal foldback, then CONFIG3 should be set to Step 3, which is set with a 1370Ω resistor
on the CONFIG3 pin.
From the previous calculation, GAIN[3:0] = 0b0110. This corresponds to Step 6 and a CONFIG2 resistor of 3090Ω.
CONFIG1 sets the remaining parameters. For example, to run the buck using the internal clock switching at 488kHz with
spread spectrum enabled, CONFIG1 should be set to Step 1 (619Ω).
USB Type-C Certification
Industry specifications at times make changes. If a change prevents the use of non-BC 1.2 protocols, this application
change should be considered. Consider using a 0Ω resistor between USB Type-C D+/- and open MAX20459 HVD+/-.
www.maximintegrated.com
Maxim Integrated | 51
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
ESD Protection
The high-voltage MAX20459 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 MAX20459 continues to work without
latch-up. When used with the configuration shown in the Typical Application Circuit, the MAX20459 is characterized for
protection to the following limits:
●
●
●
●
●
●
±15kV ISO 10605 (330pF, 330Ω) Air Gap
±15kV ISO 10605 (330pF, 2kΩ) Air Gap
±8kV ISO 10605 (330pF, 330Ω) Contact
±8kV ISO 10605 (330pF, 2kΩ) Contact
±15kV IEC 61000-4-2 (150pF, 330Ω) Air Gap
±8kV IEC 61000-4-2 (150pF, 330Ω) Contact
Note: All application-level ESD testing is performed on the standard evaluation kit.
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 10 shows the Human Body Model, and Figure 12 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. MAX20459 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 11, the ESD withstand-voltage measured to this standard is generally lower than that
measured using the Human Body Model. Figure 13 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.
HIGHVOLTAGE
DC
SOURCE
RC
1MΩ
RD
1500Ω
CHARGE-CURRENT-LIMIT
RESISTOR
DISCHARGE
RESISTANCE
CS
100pF
STORAGE
CAPACITOR
DEVICE
UNDER
TEST
Figure 10. Human Body ESD Test Model
www.maximintegrated.com
Maxim Integrated | 52
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
RC
50Ω to 100Ω
RD
330Ω
CHARGE-CURRENT-LIMIT
RESISTOR
DISCHARGE
RESISTANCE
HIGHVOLTAGE
DC
SOURCE
CS
DEVICE
UNDER
TEST
STORAGE
150pF
CAPACITOR
Figure 11. IEC 61000-4-2 ESD Test Model
IPEAK (AMPS)
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
Ir
100%
90%
36.8%
10%
0
0
TIME
tRL
tDL
Figure 12. Human Body Current Waveform
IPEAK (AMPS)
100%
90%
10%
t
tR = 0.7ns TO 1ns
30ns
60ns
Figure 13. IEC 61000-4-2 Current Waveform
www.maximintegrated.com
Maxim Integrated | 53
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
Typical Application Circuits
Type-C 5V/3A
Standalone DCP
24
ATTACH
CONFIG1
FAULT
16
CONFIG2
HVD-
15
Select
Select
CONFIG3
HVD+
12
USB-C Receptacle
Optional
Diagnostic
14
A7
B7
6
7
Legacy BC1.2, Apple 2.4A, Samsung 1.2V, Short-to-Battery 18V
A6
Select
B6
Integrated Automotive High-ESD
17
SPREAD SPECTRUM
SYNC DIRECTION
FSW
GAIN[3..0]
THM FOLDBACK
GAIN[4]
ILIMIT
CC SRC CURRENT
2.2µF
CC1
CC2
1kΩ
2kΩ
DCP_MODE
18
ENBUCK
32
BIAS
11
G_DMOS
VBMON
IN
SENSN
26, 27
VBAT
10µF
50V
47µF
50V
BST
SUPSW
Type-C DFP 1.5A/3.0A
B5
A8
B8
28
30
A3
29
A2
19
B10
0.1µF
50V
Short-to-Battery 18V
0.1µF
25
13
To DC-DC External
Clock Input/Output
(for two ports)
LX
1.5µH
20, 21
RSENSE
33mΩ
B11
A4
HVEN
B4
0.1µF
22µF
SYNC
AGND
EP
PGND
D+
CC1
CC2
22, 23
SBU1
SBU2
TX1-
TX2-
TX1+
TX2+
RX1-
RX2-
RX1+
RX2+
B3
B2
A10
A11
VBUS
A9
B9
1, 3, 5, 8, 9, 10
DD+
31
2.7MΩ
SENSP
4.5V to 28V Input, 40V Load Dump
4
MAX20459ATJC
1µF
A5
2
D-
PGND
VBUS
GND
VBUS
GND
VBUS
GND
VBUS
GND
A1
B1
A12
B12
SHIELD
Ordering Information
PART NUMBER
TEMP RANGE
PIN-PACKAGE
MAX20459ATJA/V+
MAX20459ATJC/V+
MAX20459ATJM/V+*
I 2C
Yes
-40ºC to +125ºC
32 TQFN-EP
MAX20459ATJZ/V+
No
Yes
No
NOMINAL OUTPUT CURRENT FOR APPLE R30+
SPECIFICATIONS
2.4 Amp
3.0 Amp
/V Denotes Automotive Qualified Parts
+ Denotes a lead(Pb)-free/RoHS-compliant package.
* Future product – contact factory for availability.
www.maximintegrated.com
Maxim Integrated | 54
MAX20459
Automotive High-Current Step-Down Converter
with USB-C Dedicated Charging Port
Revision History
REVISION
NUMBER
REVISION
DATE
0
11/19
Initial release
1
6/20
Updated Benefits and Features, Thermal Resistance, Absolute Maximum Ratings,
Package Information, Electrical Characteristics, ToCs 16, 18-19, 21-22,
SCL(Config3) Pin Description, ENBUCK Reset Behavior and Timing Diagram,
Attach Logic Diagram, CC Attachment and VBUS Discharge, Maximum Duty-Cycle
Operation, Switching Frequency Synchronization (SYNC Pin), Spread-Spectrum
Option, Voltage Feedback Adjustment Configuration, Remote-Sense Feedback
Adjustment (SHIELD Pin), Table 8, SETUP_0 (0x0), SETUP_3 (0x3), IRQ_2 (0xC).
1, 8-9, 11, 15-16,
18-19, 21, 26-29,
37, 40, 42, 47
2
1/21
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 - 57
5/21
Added MAX20459ATJM and MAX20459ATJZ. Updated Electrical Characteristics,
ToCs 24-25, Pin Description, Detailed Description, DC-DC Enable (ENBUCK),
Charge-Detection Mode Truth Table, Typical Application Circuit and Ordering
Information.
12, 16, 18, 23,
30, 56, 57
3
PAGES
CHANGED
DESCRIPTION
—
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.
工商网监
湘ICP备2023018690号
