EVALUATION KIT AVAILABLE
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MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger
with Integrated FETs for 2S/3S Li-Ion Batteries
General Description
Benefits and Features
The MAX77960/MAX77961 are high-performance wideinput 3A (MAX77960)/6A (MAX77961) buck-boost chargers with Smart Power Selector™ and operate as a reverse
buck converter without an additional inductor, allowing the
ICs to power USB on-the-go (OTG) accessories. The devices integrate low-loss power switches and provide high
efficiency, low heat, and fast battery charging in a small
solution size. The reverse buck has true load disconnect
and is protected by an adjustable output current limit. The
devices are highly flexible and programmable through I2C
configuration or autonomously through resistor configuration.
● 3.5V to 25.4V Input Operating Range, 30VDC
Withstand
● 97% Peak Efficiency for 2S Battery at
9VIN/7.4VOUT/1.5AOUT
● 97% Peak Efficiency for 3S Battery at
15VIN/12.6VOUT/2AOUT
● MAX77960
• 100mA to 3.15A Programmable Input Current Limit
• 100mA to 3A Programmable Constant Current
Charge
The battery charger includes the Smart Power Selector to
accommodate a wide range of battery sizes and system
loads. The Smart Power Selector allows the system to
start up smoothly when an input source is available even
when the battery is deeply discharged (dead battery) or
missing. For battery safety/authentication reasons, the ICs
can be configured to keep charging disabled, and allow
the DC-DC to switch and regulate the SYS voltage. The
system processor can later enable charging using I2C
commands as appropriate. Alternatively, the ICs can be
configured to automatically start charging.
Applications
● USB Type-C Powered Wide-Input Charging
Applications
● 2- and 3-Cell Battery-Powered Devices
● Smartphones, Tablets, and 2-in-1 Laptops
● Medical Devices, Health and Fitness Monitors
● Digital Still, Video, and Action Cameras
● Handheld Computers and Terminals
● Handheld Radios
● Power Tools
● Drones
● Battery Backup
● Wireless Speakers
● MAX77961
• 100mA to 6.3A Programmable Input Current Limit
• 100mA to 6A Programmable Constant Current
Charge
● Remote Differential Voltage Sensing
● 600kHz Switching Frequency
● System Instant On with Smart Power Selector Power
Path
● Charge Safety Timer
● Die Temperature Regulation with Thermal Foldback
Loop
● Input Power Management with Adaptive Input Current
Limit (AICL) and Input Voltage Regulation
● 10mΩ BATT to SYS Switch, Up to 10A Overcurrent
Threshold
● Reverse Buck Mode 5.1V/3A to Support USB OTG
● JEITA Compliant with NTC Thermistor Monitor
● I2C or Resistor Programmable
● 4mm x 4mm, 30-Lead FC2QFN
Ordering Information appears at end of data sheet.
Smart Power Selector is a trademark of Maxim Integrated Products, Inc.
19-100909; Rev 0; 9/20
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
LX2
BST2
LX1
BST1
Simplified Block Diagram
SYS
CHGIN
VBUS
VSYS
SYSA
Q1
CSINN
CSINP
VPVL
Q3
PGND
Q2
Q4
PVL
VAVL
AVL
QBAT
BATT
BIAS AND
REFERENCE
VAVL
OPTIONAL I2C
COMMUNICATION
JEITA
SCL
SCL
SDA
SDA
INTB
INTB
OTGEN
DISQBAT
STBY
STAT
I2C INTERFACE AND
INTERRUPT
THM
THM
BATSP
PK+
CHARGER AND OTG CONTROL
BATSN
OTGEN
PK2/3-CELL LI-ION BATTERY
DISQBAT
ISET
ITO
INLIM
VSET
STBY
STAT
OPTIONAL RESISTOR
PROGRAMMABILITY
CNFG
VPVL
INOKB
INOKB
MAX77960
MAX77961
www.maximintegrated.com
VBATT
GATE DRIVER
UVLO
OVLO
OCP
THERMAL SHDN
THERMAL MONITOR
GND
Maxim Integrated | 2
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
TABLE OF CONTENTS
General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Benefits and Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Simplified Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
30-Lead FC2QFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Typical Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Pin Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
MAX77960/MAX77961 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Detailed Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Charger Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Device Configuration Input (CNFG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
CHGIN Standby Input (STBY) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Battery to SYS QBAT Disable Input (DISQBAT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
QBAT and DC-DC Control—Configuration Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Thermistor Input (THM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Autonomous Charging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Charger Input Current Limit Setting Input (INLIM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Fast-Charge Current Setting Input (ISET) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Top-Off Current Setting Input (ITO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Charge Termination Voltage Setting Input (VSET) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Switch Mode Charger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Smart Power Selector (SPS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
CHGIN Regulation Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
SYS Regulation Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Power States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Powering Up with the Charger Disabled by Default . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Input Validation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Adaptive Input Current Limit (AICL) and Input Voltage Regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Input Self-Discharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
System Self-Discharge with No Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Charger States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
No Input Power or Charger Disabled Idle State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Precharge State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Trickle Charge State. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
www.maximintegrated.com
Maxim Integrated | 3
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
TABLE OF CONTENTS (CONTINUED)
Fast-Charge Constant Current State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Fast-Charge Constant Voltage State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Top-Off State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Done State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Timer Fault State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Watchdog Timer Suspend State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Thermal Shutdown State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Thermal Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Thermal Foldback. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
JEITA Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Thermal Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Factory Ship Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Minimum System Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Battery Differential Voltage Sense (BATSP, BATSN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Battery Overcurrent Alert . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Charger Interrupt Debounce Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Input Power-OK/OTG Power-OK Output (INOKB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Charge Status Output (STAT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Reverse Buck Mode (OTG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
OTG Enable (OTGEN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Analog Low-Noise Power Input (AVL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Low-Side Gate Driver Power Supply (PVL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
System Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Interrupt Output (INTB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
I2C Serial Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
System Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Bit Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
START and STOP Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Acknowledge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Slave Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Clock Stretching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
General Call Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Communication Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Communication Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Writing to a Single Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Writing to Sequential Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Writing Multiple Bytes using Register-Data Pairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Reading from a Single Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
www.maximintegrated.com
Maxim Integrated | 4
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
TABLE OF CONTENTS (CONTINUED)
Reading from Sequential Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
FUNC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Register Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Applications Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Inductor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
CHGIN Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
SYS Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Battery Insertion Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
PCB Layout Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Typical Application Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Wide-Input I2C Programmable Charger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Wide-Input I2C Programmable Charger with Charger Disabled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Wide-Input Autonomous Charger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
www.maximintegrated.com
Maxim Integrated | 5
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
LIST OF FIGURES
Figure 1. Li Battery Charge Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Figure 2. Charger State Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Figure 3. Charge Currents vs. Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Figure 4. JEITA Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Figure 5. B2SOVRC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Figure 6. Functional Logic Diagram for Communications Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Figure 7. I2C Bit Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Figure 8. I2C Start Stop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Figure 9. Writing to a Single Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Figure 10. Writing to Sequential Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Figure 11. Writing to Multiple Registers with “Multiple Byte Register-Data Pairs” Protocol . . . . . . . . . . . . . . . . . . . . . . 47
Figure 12. Reading from a Single Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Figure 13. Reading from Sequential Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Figure 14. Battery Insertion Protection with 2S Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Figure 15. Battery Insertion Protection with 3S Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Figure 16. PCB Layout Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
www.maximintegrated.com
Maxim Integrated | 6
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
LIST OF TABLES
Table 1. CNFG Program Options Lookup Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Table 2. QBAT and DC-DC Control Configuration Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Table 3. Trip Temperatures for Different Thermistors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Table 4. INLIM, ITO, ISET, and VSET Pin Connections for Autonomous Charging . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Table 5. INLIM Program Options Lookup Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Table 6. ISET Program Options Lookup Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table 7. ITO Program Options Lookup Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table 8. VSET Program Options Lookup Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Table 9. List of Charger Interrupt Debounce Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Table 10. Charge Status Indicator by STAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Table 11. Recommended Inductance for Combinations of Switching Frequency and Maximum Nominal CHGIN
Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Table 12. Suggested Inductors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Table 13. Suggested CHGIN Capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Table 14. Suggested SYS Capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
www.maximintegrated.com
Maxim Integrated | 7
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Absolute Maximum Ratings
CHGIN to GND .................................................... -0.3V to +30.0V
CSINP, CSINN to CHGIN ...................................... -0.3V to +0.3V
LX1 to PGND ....................................................... -0.3V to +30.0V
LX2 to PGND ....................................................... -0.3V to +16.0V
BST1 to PVL ........................................................ -0.3V to +30.0V
BST2 to PVL ........................................................ -0.3V to +16.0V
BST_ to LX ............................................................ -0.3V to +2.2V
SYS, SYSA to GND ............................................. -0.3V to +16.0V
BATT to GND ...................................................... -0.3V to +16.0V
SYS to BATT ....................................................... -0.3V to +16.0V
BATSP to GND .......................................... -0.3V to VBATT + 0.3V
BATSN, PGND to GND ......................................... -0.3V to +0.3V
PVL, AVL, ISET, VSET, INLIM, ITO, CNFG, THM to GND . -0.3V
to +2.2V
AVL to PVL ............................................................ -0.3V to +0.3V
DISQBAT, OTGEN, STBY, STAT, INOKB, INTB, SDA, SCL to
GND ....................................................................... -0.3V to +6.0V
CHGIN Continuous Current ........................................... 6.5ARMS
LX_, PGND Continuous Current .................................... 6.5ARMS
SYS, BATT Continuous Current .................................. 10.0ARMS
Continuous Power Dissipation (Multilayer Board) (TA = +70°C,
derate 40.37mW/°C above +70°C.) ...........................3229.71mW
Operating Temperature Range .............................-40°C to +85°C
Storage Temperature Range ..............................-65°C to +150°C
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
30-Lead FC2QFN
Package Code
F304A4F+1
Outline Number
21-100278
Land Pattern Number
90-100100
Thermal Resistance, Four-Layer Board:
Junction-to-Ambient (θJA)
24.77°C/W
Junction-to-Case Thermal Resistance (θJC)
1.67°C/W
www.maximintegrated.com
Maxim Integrated | 8
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages.
Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different
suffix character, but the drawing pertains to the package regardless of RoHS status.
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a
four-layer board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/
thermal-tutorial.
www.maximintegrated.com
Maxim Integrated | 9
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Electrical Characteristics
(VSYS = 7.6V, VBATT = 7.6V, VCHGIN = 9V, TA = -40°C to +85°C. TA = +25°C (typ). Limits are production tested at TA = +25°C. Limits
over the operating temperature range and relevant supply voltage range are guaranteed by design and characterization.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
25.4
V
26.7
V
GENERAL ELECTRICAL CHARACTERISTICS
CHGIN Voltage Range
CHGIN Overvoltage
Threshold
CHGIN Overvoltage
Delay
CHGIN Undervoltage
Threshold
CHGIN Quiescent
Current (ISYS = 0A)
VCHGIN
Operating voltage
3.5
VCHGIN_OVLO
VCHGIN rising, 365mV hysteresis
25.4
tD_CHGIN_OVL
VCHGIN rising, 100mV overdrive (Note 1)
10
μs
O
VCHGIN falling, 100mV overdrive (Note 1)
7
ms
VCHGIN_UVLO
ICHGIN
VCHGIN = 2.4V, the input is undervoltage
and RINSD is the only loading
0.075
VCHGIN = 9.0V, charger disabled
0.17
0.5
VCHGIN = 9.0V, charger enabled, VSYS =
VBATT = 8.7V (2S configuration), no
switching
2.7
4
FSHIP_MODE = 1 or DISQBAT = high,
VCHGIN = 0V, ISYS = 0A, VBATT = 13.5V
2.3
5.0
DISQBAT = low, I2C enabled, VCHGIN =
0V, ISYS = 0A, VBATT = 13.5V
100
200
VSYS = 7.6V, VBATT = 0V, charger
disabled, TA = +25°C
0.01
10
VSYS = 7.6V, VBATT = 0V, charger
disabled, TA = +85°C (Note 1)
10
VCHGIN = 9V, VBATT = 8.4V, QBAT is off,
battery overcurrent protection disabled,
charger is enabled but in its done mode,
TA = +25°C
57
VCHGIN = 9V, VBATT = 8.4V, QBAT is off,
battery overcurrent protection disabled,
charger is enabled but in its done mode,
TA = +85°C (Note 1)
57
Guaranteed by VSYSUVLO and
VSYSOVLO
SYSUVL
O rising
VSYSUVLO
VSYS falling, 530mV hysteresis
3.95
VSYS rising, 430mV hysteresis, 2S
battery
VSYS rising, 267mV hysteresis, 3S
battery
VSYSOVLO
VPVL
Thermal Shutdown
Threshold
TSHDN
TJ rising (Note 1)
V
mA
1
VSYS
PVL Output Voltage
www.maximintegrated.com
3.57
ISHDN
IBATTDN
SYS Overvoltage
Lockout Threshold
3.5
MODE[3:0] = 0x0 (DC-DC off), STBY = H
or STBY_EN = 1, VCHGIN = 5V
BATT Quiescent Current
(ISYS = 0A)
SYS Undervoltage
Lockout Threshold
3.43
ICHGIN_STBY
IBATT
SYS Operating Voltage
VCHGIN rising, 20% hysteresis
26.05
µA
65
SYSOVL
O rising
V
4.1
4.25
V
10.65
10.9
11.15
13.75
14.1
14.45
1.7
1.8
1.9
V
165
V
°C
Maxim Integrated | 10
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Electrical Characteristics (continued)
(VSYS = 7.6V, VBATT = 7.6V, VCHGIN = 9V, TA = -40°C to +85°C. TA = +25°C (typ). Limits are production tested at TA = +25°C. Limits
over the operating temperature range and relevant supply voltage range are guaranteed by design and characterization.)
PARAMETER
SYMBOL
Thermal Shutdown
Hysteresis
CHGIN Self-Discharge
Resistance
RINSD
CONDITIONS
MIN
TYP
MAX
UNITS
(Note 1)
15
°C
VCHGIN = 3V
44
kΩ
BATT Self-Discharge
Resistance
RBATSD
VCHGIN = 9V, VSYS = VBATT = 5V
600
Ω
SYS Self-Discharge
Resistance
RSYSSD
VCHGIN = 9V, VSYS = VBATT = 5V
600
Ω
(Note 1)
300
ms
Self-Discharge Latch
Time
SWITCH MODE CHARGER / CHARGER
BATT Regulation
Voltage Range
VBATTREG
BATT Regulation
Voltage Accuracy
Programmable from 8.0V to 9.26V (2S
battery) and 12.0V to 13.05V (3S
battery), production tested at 8V, 8.38V,
8.8V and 9.26V only (2S battery) and
12V, 12.57V, 13.2V, and 13.89V only (3S
battery)
8.00
8.8V or 13.2V settings, TA = +25°C
-0.9
-0.3
+0.3
8.8V or 13.2V settings, TA = 0°C to
+85°C (Note 2)
-1
-0.3
+0.5
13.05
V
%
BATT Overvoltage
Lockout Threshold
VBATTOVLO
VBATT rising above VBATTREG, 2%
hysteresis
75
240
375
mV/cell
BATT Undervoltage
Lockout Threshold
VBATTUVLO
VBATT rising, 100mV hysteresis
2.0
2.5
3.0
V
MAX77960; 100mA to 3A; production
tested at 100mA, 200mA, 500mA,
1000mA, 1500mA, 2000mA, and 3000mA
settings
0.10
MAX77961; 100mA to 6A; production
tested at 100mA, 200mA, 500mA,
1000mA, 1500mA, 2000mA, 3000mA,
3500mA, and 3800mA settings
0.10
Fast-Charge Current
Program Range
www.maximintegrated.com
IFC
3
A
6
Maxim Integrated | 11
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Electrical Characteristics (continued)
(VSYS = 7.6V, VBATT = 7.6V, VCHGIN = 9V, TA = -40°C to +85°C. TA = +25°C (typ). Limits are production tested at TA = +25°C. Limits
over the operating temperature range and relevant supply voltage range are guaranteed by design and characterization.)
PARAMETER
SYMBOL
Fast-Charge Current
Accuracy
Fast-Charge Current
Accuracy (Over
Temperature)
CHGIN Adaptive
Voltage Regulation
Range
VCHGIN_REG
CHGIN Adaptive
Voltage Regulation
Accuracy
CHGIN Current Limit
Range
www.maximintegrated.com
CHGIN_ILIM
MIN
TYP
MAX
TA = +25°C, VBATT > VSYSMIN,
programmed for 100mA
CONDITIONS
80
100
120
TA = +25°C, VBATT > VSYSMIN,
programmed for 200mA
180
200
220
TA = +25°C, VBATT > VSYSMIN,
programmed for 500mA
481
500
519
TA = +25°C, VBATT > VSYSMIN,
programmed for 1000mA
962
1000
1038
TA = +25°C, VBATT > VSYSMIN,
programmed for 2000mA
1925
2000
2075
TA = +25°C, VBATT > VSYSMIN,
programmed for 3000mA
2887
3000
3113
MAX77961. TA = +25°C, VBATT >
VSYSMIN, programmed for 3500mA
3369
3500
3631
MAX77961. TA = +25°C, VBATT >
VSYSMIN, programmed for 3800mA
3657
3800
3943
UNITS
mA
-40°C < TA < +85°C, VBATT > VSYSMIN,
programmed for 200mA or less (Note 2)
-20
+20
mA
-40°C < TA < +85°C, VBATT > VSYSMIN,
programmed for greater than 200mA
(Note 2)
-5
+5
%
I2C programmable
4.025
19.05
V
4.55V setting
4.42
4.68
V
MAX77960; programmable; production
tested at 100mA, 150mA, 200mA,
500mA, 1000mA, 1500mA, and 3000mA
settings only
0.1
MAX77961; programmable; production
tested at 100mA, 150mA, 200mA,
500mA, 1000mA, 1500mA, 3000mA,
4000mA, and 6300mA settings only
0.1
4.55
3.15
A
6.3
Maxim Integrated | 12
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Electrical Characteristics (continued)
(VSYS = 7.6V, VBATT = 7.6V, VCHGIN = 9V, TA = -40°C to +85°C. TA = +25°C (typ). Limits are production tested at TA = +25°C. Limits
over the operating temperature range and relevant supply voltage range are guaranteed by design and characterization.)
PARAMETER
SYMBOL
CHGIN Current Limit
Accuracy
CHGIN Current Limit
Accuracy (Over
Temperature)
Precharge Voltage
Threshold
VPRECHG
Precharge Current
IPRECHG
Prequalification
Threshold Hysteresis
Minimum SYS Voltage
Accuracy
Trickle Charge Current
Top-Off Current
Program Range
Charge Termination
Deglitch Time
Charger Restart
Threshold Range
www.maximintegrated.com
VPQ-H
VSYSMIN
ITRICKLE
ITO
tTERM
VRSTRT
MIN
TYP
MAX
Charger enabled, 100mA input current
setting, TA = +25°C
CONDITIONS
88
98
108
Charger enabled, 200mA input current
setting, TA = +25°C
175
195
215
Charger enabled, 500mA input current
setting, TA = +25°C
475
488
500
Charger enabled, 1000mA input current
setting, TA = +25°C
950
975
1000
Charger enabled, 3000mA input current
setting, TA = +25°C
2850
2925
3000
MAX77961; charger enabled, 4000mA
input current setting, TA = +25°C
3800
3900
4000
MAX77961; charger enabled, 6300mA
input current setting, TA = +25°C
5985
6143
6300
Charger enabled, 200mA or less input
current setting, -40°C < TA < +85°C
(Note 2)
-22.5
Charger enabled, greater than 200mA
input current setting, -40°C < TA < +85°C
(Note 2)
-7.5
VBATT rising, voltage threshold per cell
2.4
2.5
2.6
V/Cell
35
50
65
mA
mA
+17.5
%
Applies to VPRECHG
+2.5
150
mV/Cell
Programmable from 5.535V to 6.970V
(2S battery) and 8.303V to 10.455V (3S
battery), VBATT = 5.6V (2S battery) or
8.4V (3S battery), tested at 3V/cell setting
-3
Default setting = enabled; ITRICKLE[1:0]
= 00
75
100
125
Default setting = enabled; ITRICKLE[1:0]
= 01 (Note 2)
150
200
250
Default setting = enabled; ITRICKLE[1:0]
= 10 (Note 2)
225
300
375
Default setting = enabled; ITRICKLE[1:0]
= 11
300
400
500
Programmable from 100mA to 600mA
100
+3
%
mA
2mV overdrive, 100ns rise/fall time (Note
1)
Program options for disabled, 100mV/
cell, 150mV/cell, and 200mV/cell with
CHG_RSTRT[1:0]
UNITS
600
160
100
mA
ms
200
mV/cell
Maxim Integrated | 13
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Electrical Characteristics (continued)
(VSYS = 7.6V, VBATT = 7.6V, VCHGIN = 9V, TA = -40°C to +85°C. TA = +25°C (typ). Limits are production tested at TA = +25°C. Limits
over the operating temperature range and relevant supply voltage range are guaranteed by design and characterization.)
PARAMETER
SYMBOL
Charger Restart
Deglitch Time
Charger State Change
Interrupt Deglitch Time
tSCIDG
CONDITIONS
MIN
TYP
MAX
UNITS
10mV overdrive, 100ns rise time (Note 1)
130
ms
Excludes transition to timer fault state,
watchdog timer state (Note 1)
30
ms
SWITCH MODE CHARGER / CHARGE TIMER
Prequalification Time
tPQ
Applies to both low-battery
prequalification and dead-battery
prequalification modes (Note 1)
30
min
Fast-Charge Constant
Current + Fast-Charge
Constant Voltage Time
tFC
Adjustable from 3hrs, 4hrs, 5hrs, 6hrs,
7hrs, 8hrs, 10hrs including a disable
setting; 3hrs default (Note 1)
3
hrs
Top-Off Time
tTO
Adjustable from 30s to 70min in 10min
steps (Note 1)
30
min
SWITCH MODE CHARGER / WATCHDOG TIMER
Watchdog Timer Period
tWD
(Note 3)
80
s
SWITCH MODE CHARGER / BUCK-BOOST
CHGIN OK to Start
Switching Delay
Buck-Boost Current
Limit
tSTART
HSILIM
Delay from INOKB H → L to LX_ start
switching (Note 1)
150
ms
MAX77960, VCHGIN = 9V, VSYS = VBATT
= 7.6V
4.3
5
5.7
MAX77961, VCHGIN = 9V, VSYS = VBATT
= 7.6V
8.6
10
11.4
A
SWITCH MODE CHARGER / BUCK-BOOST / SWITCH IMPEDANCE AND LEAKAGE CURRENT
LX1 High-Side
Resistance
RLX1_HS
VCHGIN = 9V, VSYS = VBATT = 7.6V
16.5
26
mΩ
LX1 Low-Side
Resistance
RLX1_LS
VCHGIN = 9V, VSYS = VBATT = 7.6V
17
30
mΩ
LX2 High-Side
Resistance
RLX2_HS
VCHGIN = 9V, VSYS = VBATT = 7.6V
9
18
mΩ
LX2 Low-Side
Resistance
RLX2_LS
VCHGIN = 9V, VSYS = VBATT = 7.6V
21
33
mΩ
LX1 = PGND or CHGIN, LX2 = PGND or
SYS, TA = +25°C
0.01
10
LX1 = PGND or CHGIN, LX2 = PGND or
SYS, TA = +85°C (Note 1)
1
LX_ Leakage Current
BST_ = 1.8V, TA = +25°C
BST_ Leakage Current
www.maximintegrated.com
0.01
BST_ = 1.8V, TA = +85°C (Note 1)
0.01
VCHGIN = 26.05V, VCSINP = VCSINN =
26.05V, TA = +25°C
µA
10
µA
VSYS = VSYSA = 8.4V, VBATT = 0V,
charger disabled, TA = +85°C (Note 1)
ICSINP, ICSINN
10
1
VSYS = VSYSA = 8.4V, VBATT = 0V,
charger disabled, TA = +25°C
SYS, SYSA Leakage
Current
CSINP, CSINN Leakage
Current
µA
1
-1
+1
µA
Maxim Integrated | 14
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Electrical Characteristics (continued)
(VSYS = 7.6V, VBATT = 7.6V, VCHGIN = 9V, TA = -40°C to +85°C. TA = +25°C (typ). Limits are production tested at TA = +25°C. Limits
over the operating temperature range and relevant supply voltage range are guaranteed by design and characterization.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
RBAT2SYS
10
17
mΩ
VBSREG
90
SWITCH MODE CHARGER / SMART POWER SELECTOR
BAT to SYS Dropout
Resistance
BATT to SYS Reverse
Regulation Voltage
mV
SWITCH MODE CHARGER / BATT TO SYS OVERCURRENT ALERT
Battery Overcurrent
Threshold Range
IBOVCR
Programmable from 3A to 10A. Option to
disable.
Battery Overcurrent
Debounce Time
tBOVRC
Response time for generating the
overcurrent interrupt (Note 3)
3
10
A
3.3
ms
130
°C
SWITCH MODE CHARGER / THERMAL FOLDBACK
Junction Temperature
Thermal Regulation
Loop Setpoint Program
Range
Thermal Regulation
Gain
TREG
Junction temperature when charge
current is reduced; programmable from
85°C to 130°C in 5°C steps; default value
is 115°C
ATJREG
The charge current is decreased 5% of
the fast-charge current setting for every
degree that the junction temperature
exceeds the thermal regulation
temperature. This slope ensures that the
full-scale current of 3A (MAX77960)/6A
(MAX77961) is reduced to 0A by the time
the junction temperature is 20°C above
the programmed loop set point. For lower
programmed charge currents such as
480mA, this slope is valid for charge
current reductions down to 80mA; below
100mA the slope becomes shallower but
the charge current still reduced to 0A if
the junction temperature is 20°C above
the programmed loop set point. (Note 1)
85
-5
%/°C
SWITCH MODE CHARGER / THERMISTOR MONITOR
THM Threshold, COLD
THM_COLD
VTHM/VAVL rising, 1% hysteresis
(thermistor temperature falling)
70.05
74.56
77.43
%
THM Threshold, COOL
THM_COOL
VTHM/VAVL rising, 1% hysteresis
(thermistor temperature falling)
56.37
60
62.31
%
THM Threshold, WARM
THM_WARM
VTHM/VAVL falling, 1% hysteresis
(thermistor temperature rising)
32.58
34.68
36.01
%
THM_HOT
VTHM/VAVL falling, 1% hysteresis
(thermistor temperature rising)
21.18
22.5
23.41
%
THM Threshold,
Disabled
VTHM/AVL falling, 1% hysteresis, THM
function is disabled below this voltage
4.67
5.9
7.01
%
THM Threshold, Battery
Removal Detection
VTHM/VAVL rising, 1% hysteresis, battery
removal
81.74
87
90.35
%
THM Threshold, HOT
www.maximintegrated.com
Maxim Integrated | 15
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Electrical Characteristics (continued)
(VSYS = 7.6V, VBATT = 7.6V, VCHGIN = 9V, TA = -40°C to +85°C. TA = +25°C (typ). Limits are production tested at TA = +25°C. Limits
over the operating temperature range and relevant supply voltage range are guaranteed by design and characterization.)
PARAMETER
SYMBOL
THM Input Leakage
Current
TYP
MAX
VTHM = GND or VAVL; TA = +25°C
CONDITIONS
MIN
0.1
1
VTHM = GND or VAVL; TA = +85°C (Note
1)
0.1
UNITS
µA
REVERSE BUCK
Buck Current Limit
HSILIM_REV
Reverse Buck
Quiescent Current
Minimum BATT Voltage
in OTG Mode
CHGIN Voltage in OTG
Mode
4.3
Not switching: output forced 200mV
above its target regulation voltage
VBATT.MIN.OT
G
VCHGIN.OTG
CHGIN Undervoltage
Threshold in OTG Mode
VCHGIN.OTG.U
CHGIN Overvoltage
Threshold in OTG Mode
VCHGIN.OTG.
CHGIN Output Current
Limit in OTG Mode
fSW = 600kHz
V
OV
ICHGIN.OTG.LI
M
CHGIN Output Voltage
Ripple in OTG Mode
5
5.7
1150
A
µA
VBATT = VSYS, SYS UVLO falling
threshold in OTG mode
5.96
6.14
6.32
V
VBATT = VBATT.MIN.OTG, OTGEN = high
4.94
5.1
5.26
V
VCHGIN falling, OTGEN = high
85
%
VCHGIN rising, OTGEN = high
110
%
VBATT = VBATT.MIN.OTG, TA = +25°C,
OTG_ILIM[2:0] = 0b000, OTGEN = high
500
550
VBATT = VBATT.MIN.OTG, TA = +25°C,
OTG_ILIM[2:0] = 0b001, OTGEN = high
900
990
VBATT = VBATT.MIN.OTG, TA = +25°C,
OTG_ILIM[2:0] = 0b011, OTGEN = high
1500
1650
VBATT = VBATT.MIN.OTG, TA = +25°C,
OTG_ILIM[2:0] = 0b111, OTGEN = high
3000
3300
Discontinuous inductor current (i.e., skip
mode), OTGEN = high (Note 1)
±150
Continuous inductor current, OTGEN =
high (Note 1)
±150
mA
mV
IO CHARACTERISTICS
RINLIM, RISET, RVSET,
RTO, RCNFG Resistor
Range
RPROG_
Output Low Voltage
INOKB, STAT
ISINK = 1mA, TA = +25°C
5.5V, TA = +25°C
Output High Leakage
INOKB, STAT
-1
5.5V, TA = +85°C (Note 1)
DISQBAT, OTGEN,
STBY Logic Input Low
Threshold
VIL
DISQBAT, OTGEN,
STBY Logic Input High
Threshold
VIH
www.maximintegrated.com
5.49
0
226
kΩ
0.4
V
+1
0.1
0.4
1.4
µA
V
V
Maxim Integrated | 16
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Electrical Characteristics (continued)
(VSYS = 7.6V, VBATT = 7.6V, VCHGIN = 9V, TA = -40°C to +85°C. TA = +25°C (typ). Limits are production tested at TA = +25°C. Limits
over the operating temperature range and relevant supply voltage range are guaranteed by design and characterization.)
PARAMETER
SYMBOL
DISQBAT, OTGEN,
STBY Logic Input
Leakage Current
DISQBAT, OTGEN,
STBY Pulldown Resistor
CONDITIONS
MIN
5.5V (including current through pulldown
resistor)
RDISQBAT
TYP
MAX
UNITS
5.5
10
µA
1000
1200
kΩ
0.3 x
VAVL
V
INTERFACE / I2C INTERFACE AND INTERRUPT
SCL, SDA Input Low
Level
SCL, SDA Input High
Level
0.7 x
VAVL
SCL, SDA Input
Hysteresis
V
0.05 x
VAVL
V
SCL, SDA Logic Input
Current
SDA = SCL = 5.5V
SCL, SDA Input
Capacitance
(Note 1)
SDA Output Low
Voltage
Sinking 20mA
0.4
V
Output Low Voltage
INTB
ISINK = 1mA
0.4
V
VINTB = 5.5V, TA = +25°C
Output High Leakage
INTB
-10
+10
10
-1
VINTB = 5.5V, TA = +85°C (Note 1)
0
µA
pF
+1
0.1
μA
INTERFACE / I2C COMPATIBLE INTERFACE TIMING FOR STANDARD, FAST, AND FAST-MODE PLUS
Clock Frequency
Hold Time (Repeated)
START Condition
fSCL
1000
kHz
tHD;STA
0.26
µs
CLK Low Period
tLOW
0.5
µs
CLK High Period
tHIGH
0.26
µs
Set-Up Time Repeated
START Condition
tSU;STA
0.26
µs
DATA Hold Time
tHD:DAT
0
µs
DATA Valid Time
tVD:DAT
0.45
µs
DATA Valid
Acknowledge Time
tVD:ACK
0.45
µs
DATA Set-Up time
tSU;DAT
50
ns
Set-Up Time for STOP
Condition
tSU;STO
0.26
µs
tBUF
0.5
µs
Bus-Free Time Between
STOP and START
www.maximintegrated.com
Maxim Integrated | 17
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Electrical Characteristics (continued)
(VSYS = 7.6V, VBATT = 7.6V, VCHGIN = 9V, TA = -40°C to +85°C. TA = +25°C (typ). Limits are production tested at TA = +25°C. Limits
over the operating temperature range and relevant supply voltage range are guaranteed by design and characterization.)
PARAMETER
SYMBOL
CONDITIONS
MIN
Pulse Width of Spikes
that Must be
Suppressed by the Input
Filter
TYP
MAX
50
UNITS
ns
INTERFACE / I2C COMPATIBLE INTERFACE TIMING FOR HS-MODE (CB = 100pF)
Clock Frequency
fSCL
3.4
MHz
Set-Up Time Repeated
START Condition
tSU;STA
160
ns
Hold Time (Repeated)
START Condition
tHD;STA
160
ns
CLK Low Period
tLOW
160
ns
CLK High Period
tHIGH
60
ns
DATA Set-Up Time
tSU;DAT
10
ns
DATA Hold Time
tHD:DAT
0
ns
Set-Up Time for STOP
Condition
tSU;STO
160
ns
Pulse Width of Spikes
that Must be
Suppressed by the Input
Filter
10
ns
INTERFACE / I2C COMPATIBLE INTERFACE TIMING FOR HS-MODE (CB = 400pF)
Clock Frequency
fSCL
1.7
MHz
Set-Up Time Repeated
START Condition
tSU;STA
160
ns
Hold Time (Repeated)
START Condition
tHD;STA
160
ns
tLOW
320
ns
CLK Low Period
CLK High Period
tHIGH
120
ns
DATA Set-Up time
tSU;DAT
10
ns
DATA Hold Time
tHD:DAT
0
ns
Set-Up Time for STOP
Condition
tSU;STO
160
ns
Pulse Width of Spikes
that Must be
Suppressed by the Input
Filter
10
ns
Note 1: Internal design target.
Note 2: Guaranteed by design. Not production tested.
Note 3: Guaranteed by design. Production tested through scan.
www.maximintegrated.com
Maxim Integrated | 18
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Typical Operating Characteristics
(CCHGIN = 10μF, CSYS = 2x47μF, L = 3.3μH (CMLE063T-3R3MS), TA = +25°C unless otherwise noted.)
www.maximintegrated.com
Maxim Integrated | 19
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Pin Configuration
MAX77960/MAX77961
BST1
1
CHGIN
2
CSINP
STBY
PVL
AVL
ITO
VSET
ISET
29
28
27
26
25
24
23
MAX77960
MAX
MAX77961
77961
22
CNFG
21
INLIM
20
GND
19
SYSA
18
INTB
17
INOKB
16
STAT
15
SDA
3
8
9
10
11
12
13
14
SCL
7
THM
6
BATT
SYS
BATSP
5
BATSN
LX2
BST2
4
DISQBAT
PGND
30
OTGEN
LX1
CSINN
TOP VIEW
30-LEAD FC2QFN
(4mm x 4mm)
www.maximintegrated.com
Maxim Integrated | 20
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Pin Description
PIN
NAME
FUNCTION
1
BST1
2
CHGIN
3
LX1
4
PGND
5
LX2
Inductor Connection Two. Connect an inductor between LX1 and LX2.
6
SYS
System Supply Output. Bypass SYS to PGND with two 47µF/25V ceramic capacitors.
7
OTGEN
Active-High Input. Connect the OTGEN pin to high enables the OTG function. When OTGEN pin is
pulled low, the OTG enable function is controlled by I2C. To pull the OTGEN pin low with a
pulldown resistor, the resistance must be lower than 44kΩ.
8
DISQBAT
Active-High Input. Connect high to disable the integrated QBAT FET between SYS and BATT.
Charging is disabled when DISQBAT connects to high. When DISQBAT is pulled low, QBAT FET
control is defined in the QBAT and DC-DC Control—Configuration Table. To pull the DISQBAT pin
low with a pulldown resistor, the resistance must be lower than 44kΩ.
9
BST2
10
BATSN
Battery Voltage Differential Sense Negative Input. Connect to the negative terminal of the battery
pack.
11
BATSP
Battery Voltage Differential Sense Positive Input. Connect to the positive terminal of the battery
pack.
12
BATT
Battery Power Connection. Connect to the positive terminal of the battery pack. Bypass BATT to
PGND with a 10μF/25V capacitor. All BATT pins must be connected together externally.
13
THM
Thermistor Input. Connect a negative temperature coefficient (NTC) thermistor from THM to GND.
Connect a resistor equal to the thermistor +25°C resistance from THM to AVL. JEITA-controlled
charging available with JEITA_EN = 1. Charging is suspended when the thermistor voltage is
outside of the hot and cold limits. Connect THM to GND to disable the thermistor temperature
sensor. Connect THM to AVL to emulate battery removal and prevent charging.
14
SCL
Serial Interface I2C Clock Input
15
SDA
Serial Interface I2C Data. Open-drain output.
High-Side Input MOSFET Driver Supply. Bypass BST1 to LX1 with a 0.22μF/6.3V capacitor.
Buck-Boost Charger Input. CHGIN is also the buck output when the charger is operating in the
reverse mode. Bypass with two 10μF/35V ceramic capacitors from CHGIN to PGND.
Inductor Connection One. Connect an inductor between LX1 and LX2.
Power Ground for Buck-Boost Low-Side MOSFETs
High-Side Output MOSFET Driver Supply. Bypass BST2 to LX2 with a 0.22μF/6.3V capacitor.
Charger Status Output. Active-low, open-drain output, connect to the pullup through a 10kΩ
resistor. Pulls low when the charging is in progress. Otherwise, STAT is high impedance.
16
STAT
17
INOKB
18
INTB
Active-Low Open-Drain Interrupt Output. Connect a pullup resistor to the pullup power source.
19
SYSA
SYS Voltage Sensing Input for SYS UVLO and OVLO Detection
20
GND
Analog Ground
21
INLIM
Charger Input Current Limit Setting Input. Connect a resistor (RINLIM) from INLIM to GND
programs the charger input current limit. Refer to Table 5.
22
CNFG
STAT toggles between low and high (when connected to a pullup rail) during charge. STAT
becomes low when top-off threshold is detected and charger enters the done state. STAT
becomes high (when connected to a pullup rail) when charge faults are detected.
Input Power-OK/OTG Power-OK Output. Active-low, open-drain output pulls low when the CHGIN
voltage is valid.
Device Configuration Input. Connect a resistor (RCNFG) from CNFG to GND to program the
following parameter, see Table 1.
● Number of battery cells in series connection (2S or 3S)
www.maximintegrated.com
Maxim Integrated | 21
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Pin Description (continued)
PIN
NAME
23
ISET
Fast-Charge Current Setting Input. Connect a resistor (RISET) from ISET to GND programs the
fast charge current. See Table 6.
24
VSET
Charge Termination Voltage Setting Input. Connect a resistor (RVSET) from VSET to GND
programs the charge termination voltage. See Table 8.
25
ITO
Top-Off Current Setting Input. Connect a resistor (RITO) from ITO to GND programs the top-off
current. See Table 7.
26
AVL
Analog Voltage Supply for On-Chip, Low-Noise Circuits. Bypass with a 4.7μF/6.3V ceramic
capacitor to GND and connect AVL to PVL with a 4.7Ω resistor.
PVL
Internal Bias Regulator High Current Output Bypass. Supports internal noisy and high current gate
drive loads. Bypass to GND with a minimum 4.7μF/6.3V ceramic capacitor, and connect AVL to
PVL with a 4.7Ω resistor. Powering external loads from PVL is not recommended, other than pullup
resistors.
27
FUNCTION
28
STBY
Active-High Input. Connect high to disable the DC-DC between CHGIN input and SYS output.
Battery supplies the system power if the QBAT is on. See Table 2. Connect low to control the DCDC with the power-path state machine. To pull the STBY pin low with a pulldown resistor, the
resistance must be lower than 44kΩ.
29
CSINP
Input Current-Sense Positive Input
30
CSINN
Input Current-Sense Negative Input
www.maximintegrated.com
Maxim Integrated | 22
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Detailed Description
Charger Configuration
The MAX77960/MAX77961 are highly flexible, highly integrated switch mode charger. Autonomous charging inputs
configure the charger without host I2C interface, see the Autonomous Charging section for more details. The MAX77960/
MAX77961 have an I2C interface that allows the host controller to program and monitor the charger. Charger
configuration registers, interrupt, interrupt mask, and status registers are described in the Register Map.
Device Configuration Input (CNFG)
The CNFG is the MAX77960/MAX77961's configuration input for the number of battery cells in series connection (2S or
3S).
Connect a resistor (RCNFG) from CNFG to GND to program. See Table 1.
Table 1. CNFG Program Options Lookup Table
PART NUMBER
MAX77960EFV06+
MAX77961EFV06+
SWITCHING FREQUENCY (MHz)
0.6
NUMBER OF
SERIES BATTERY
CELLS
RCNFG (Ω)
2
Tied to PVL or
86600
3
8660
CHGIN Standby Input (STBY)
The host can reduce the MAX77960/MAX77961's CHGIN supply current by driving STBY pin to high or setting STBY_EN
bit to 1. When STBY is pulled high or STBY_EN bit is set to 1, the DC-DC turns off. When STBY is pulled low and
STBY_EN bit is set to 0, the DC-DC is controlled by the power-path state machine. To pull the STBY pin low with a
pulldown resistor, the resistance must be lower than 44kΩ.
Battery to SYS QBAT Disable Input (DISQBAT)
The host can disable the QBAT switch by setting DISIBS bit to 1 or driving DISQBAT pin to high. Charging stops when
QBAT switch is disabled.
When DISQBAT is pulled low and DISIBS bit is set to 0, QBAT FET control is defined in Table 2. To pull the DISQBAT
pin low with a pulldown resistor, the resistance must be lower than 44kΩ.
www.maximintegrated.com
Maxim Integrated | 23
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
QBAT and DC-DC Control—Configuration Table
The QBAT control and the DC-DC control depend on both hardware pins (OTGEN, DISQBAT, and STBY) and their
associated I2C registers.
Table 2. QBAT and DC-DC Control Configuration Table
OTGEN (PIN) OR
MODE [3:0] = 0xA
(I2C)
DISQBAT (PIN)
OR DISIBS (I2C)
STBY (PIN) OR
STBY_EN (I2C)
0
0
0
Power-path state machine/internal logic
control
Power-path state
machine/internal logic
control
0
0
1
Enable
(SYS is powered from battery through
QBAT switch while DC-DC is disabled)
Disable
0
1
0
Disable
Power-path state
machine/internal logic
control
Disable
Power-path state
machine/internal logic
control
QBAT
0
1
1
Disable
(SYS is powered from battery through
QBAT body diode while DC-DC is
disabled)
1
x
x
Enable
DC-DC
Thermistor Input (THM)
The thermistor input can be utilized to achieve functions include charge suspension, JEITA-compliant charging and
battery removal detection. Thermistor monitoring feature can be disabled by connecting the THM pin to ground.
Charge Suspension
The THM input connects to an external negative temperature coefficient (NTC) thermistor to monitor battery or system
temperature. Charging stops when the thermistor temperature is out of range (T < TCOLD or T > THOT). The charge
timers are reset and the CHG_DTLS[3:0], CHG_OK register bits report the charging suspension status and CHG_I
interrupt bit is set. When the thermistor comes back into range (TCOLD < T < THOT), charging resumes and the charge
timer restarts.
JEITA-Compliant Charging
JEITA-compliant charging is available with JEITA_EN = 1. See the JEITA Compliance section for more details.
Battery Removal Detection
Connecting THM to AVL emulates battery removal and prevents charging.
Disable Thermistor Monitoring
Connecting THM to GND disables the thermistor monitoring function, and JEITA-controlled charging is unavailable in
this configuration. The MAX77960/MAX77961 detect an always-connected battery when THM is grounded, and charging
starts automatically when a valid adapter is plugged in. In applications with removable batteries, do not connect THM
to GND because the MAX77960/MAX77961 cannot detect battery removal when THM is grounded. Instead, connecting
THM to the thermistor pin in the battery pack is recommended.
www.maximintegrated.com
Maxim Integrated | 24
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Since the thermistor monitoring circuit employs an external bias resistor from THM to AVL, the thermistor is not limited
only to 10kΩ (at +25ºC). Any resistance thermistor can be used as long as the value is equivalent to the thermistors
+25ºC resistance. For example, with a 10kΩ at RTB resistor, the charger enters a temperature suspend state when
the thermistor resistance falls below 3.97kΩ (too hot) or rises above 28.7kΩ (too cold). This corresponds to 0ºC to
+50ºC range when using a 10kΩ NTC thermistor with a beta of 3500. The general relation of thermistor resistance to
temperature is defined by the following equation:
RT = R25xe
{βx(
1
1
−
)}
T + 273 ° C 298 ° C
where:
RT = The resistance in Ω of the thermistor at temperature T in Celsius
R25 = The resistance in Ω of the thermistor at +25ºC
β = The material constant of the thermistor, which typically ranges from 3000k to 5000k
T = The temperature of the thermistor in °C
Some designs might prefer other thermistor temperature limits. Threshold adjustment can be accommodated by changing
RTB, connecting a resistor in series and/or in parallel with the thermistor, or using a thermistor with different β. For
example, a +45ºC hot threshold and 0°C cold threshold can be realized by using a thermistor with a β to 4250 and
connecting 120kΩ in parallel. Since the thermistor resistance near 0ºC is much higher than it is near +50ºC, a large
parallel resistance lowers the cold threshold, while only slightly lowering the hot threshold. Conversely, a small series
resistance raises the cold threshold, while only slightly raising the hot threshold. Raising RTB raises both the hot and cold
threshold, while lowering RTB lowers both thresholds.
Since AVL is active whenever a valid input power is connected at DC, thermistor bias current flows at all times, even
when charging is disabled. When using a 10kΩ thermistor and a 10kΩ pullup to ADCREF, this results in an additional
250μA load. This load can be reduced to 25μA by instead using a 100kΩ thermistor and 100kΩ pullup resistor.
Table 3. Trip Temperatures for Different Thermistors
THERMISTOR
TRIP TEMPERATURES
R25 (Ω)
β
RTB (Ω)
R15 (Ω)
R45 (Ω)
TCOLD (˚C)
TCOOL (˚C)
TWARM (˚C)
THOT (˚C)
10000
3380
10000
14826
4900
-0.8
+14.7
+42.6
+61.4
10000
3940
10000
15826
4354
+2.6
+16.1
+40.0
+55.7
47000
4050
47000
75342
19993
+3.2
+16.4
+39.6
+54.8
100000
4250
100000
164083
40781
+4.1
+16.8
+38.8
+53.2
Autonomous Charging
The MAX77960/MAX77961 support autonomous charging without I2C. In applications without I2C serial communication,
use the following pins to configure the MAX77960/MAX77961 charger:
CNFG, INLIM, ITO, ISET, VSET, OTGEN, DISQBAT, STBY.
The INLIM, ITO, ISET, and VSET pins are used to program the charger's input current limit, top-off current, constant
charging current, and termination voltage.
Connect a valid resistor from each of these pins to ground to program the charger. See the Pin Description for details.
Connect all four pins (INLIM, ITO, ISET, VSET) to PVL to use the default values for the associated charger registers.
For autonomous charging, it is considered an abnormal condition if some of these pins (INLIM, ITO, ISET, VSET) connect
to a valid resistor, but others do not (for example open or connects to PVL or connects to a resistor that is out of range).
When this happens, the MAX77960/MAX77961 allow the DC-DC to switch and regulate the SYS voltage, but disable
charging for safety reasons. The STAT pin reports no charge.
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Maxim Integrated | 25
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Table 4. INLIM, ITO, ISET, and VSET Pin Connections for Autonomous Charging
INLIM PIN
ITO PIN
ISET PIN
VSET PIN
AUTONOMOUS CHARGING
Valid resistor
Valid resistor
Valid resistor
Valid resistor
Normal, charger configuration is programmed by resistors
Tied to PVL
Tied to PVL
Tied to PVL
Tied to PVL
Normal, charger configuration uses default values
All other connections
Abnormal, no charging
Charger Input Current Limit Setting Input (INLIM)
When a valid charge source is applied to CHGIN, the MAX77960/MAX77961 limit the current drawn from the charge
source to the value programmed with INLIM pin.
The default charger input current limit is programmed with the resistance from INLIM to GND. See Table 5.
If I2C is used in the application, the CHGIN input current limit can also be reprogrammed with CHGIN_ILIM[6:0] register
bits after the devices power up. Connect INLIM pin to PVL to use I2C default settings.
Table 5. INLIM Program Options Lookup Table
RINLIM (Ω)
MAX77960
CHGIN INPUT CURRENT LIMIT (mA)
DEFAULT VALUE OF CHGIN_ILIM[6:0]
MAX77961
CHGIN INPUT CURRENT LIMIT (mA)
DEFAULT VALUE OF CHGIN_ILIM[6:0]
Tied to PVL
500
500
226000
100
100
178000
200
200
140000
300
300
110000
400
400
86600
500
500
69800
1000
1000
54900
1500
1500
39200
2000
2000
22600
2500
2500
17800
3000
3000
14000
N/A
3500
11000
N/A
4000
8660
N/A
4500
6980
N/A
5000
5490
N/A
6000
Fast-Charge Current Setting Input (ISET)
When a valid input source is present, the battery charger attempts to charge the battery with a fast-charge current
programmed with ISET pin.
The default fast-charge current is programmed with the resistance from ISET to GND. See Table 6.
If I2C is used in the application, the fast-charge current can also be reprogrammed with CHGCC[5:0] register bits after
the devices power up. Connect ISET pin to PVL to use I2C default settings.
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Maxim Integrated | 26
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Table 6. ISET Program Options Lookup Table
RISET (Ω)
MAX77960
FAST-CHARGE CURRENT SELECTION (mA)
DEFAULT VALUE OF CHGCC[5:0]
MAX77961
FAST-CHARGE CURRENT SELECTION (mA)
DEFAULT VALUE OF CHGCC[5:0]
Tied to PVL
450
450
226000
100
100
178000
200
200
140000
300
300
110000
400
400
86600
500
500
69800
1000
1000
54900
1500
1500
39200
2000
2000
22600
2500
2500
17800
3000
3000
14000
N/A
3500
11000
N/A
4000
8660
N/A
4500
6980
N/A
5000
5490
N/A
6000
Top-Off Current Setting Input (ITO)
When the battery charger is in the top-off state, the top-off charge current is programmed by ITO pin.
The default top-off charge current is programmed with the resistance from ITO to GND. See Table 7.
If I2C is used in the application, the top-off current can also be reprogrammed with TO_ITH[2:0] register bits after the
device powers up. Connect ITO pin to PVL to use I2C default settings.
Table 7. ITO Program Options Lookup Table
RITO (Ω)
TOP-OFF CURRENT THRESHOLD (mA)
DEFAULT VALUE OF TO_ITH[2:0]
Tied to PVL
100
226000
100
178000
200
140000
300
110000
400
86600
500
69800
600
Charge Termination Voltage Setting Input (VSET)
The default charge termination voltage is programmed with the resistance from VSET to GND. See Table 8.
If I2C is used in the application, the charge termination voltage can also be reprogrammed with CHG_CV_PRM[5:0]
register bits after the device powers up. Connect the VSET pin to PVL to use I2C default settings.
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Maxim Integrated | 27
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Table 8. VSET Program Options Lookup Table
RVSET (Ω)
CHARGE TERMINATION VOLTAGE SETTING - 2S (V)
DEFAULT VALUE OF CHG_CV_PRM[5:0]
CHARGE TERMINATION VOLTAGE SETTING - 3S (V)
DEFAULT VALUE OF CHG_CV_PRM[5:0]
Tied to PVL
8.0
12.0
226000
8.0
12.0
178000
8.1
12.15
140000
8.2
12.3
110000
8.3
12.45
86600
8.4
12.6
69800
8.5
12.75
54900
8.6
12.9
39200
8.7
13.05
22600
8.8
N/A
17800
8.9
N/A
14000
9.0
N/A
11000
9.1
N/A
8660
9.2
N/A
6980
9.26
N/A
5490
9.26
N/A
Switch Mode Charger
The MAX77960/MAX77961 feature a switch mode buck-boost charger for a two-cell or three-cell lithium ion (Li+) or
lithium polymer (Li-polymer) battery. The charger operates from a wide input range from 3.5V to 25.4V, ideal for USB-C
charging applications. The charger input current limit is programmable from 100mA to 3.15A (MAX77960)/100mA to 6.3A
(MAX77961), which is flexible to operate from either an AC-to-DC wall charger or a USB-C adapter.
The MAX77960/MAX77961 offer a high level of integration and do not require any external MOSFETs to operate, which
significantly reduces the solution size. They operate with a fixed switching frequency of 600kHz. The battery charging
current is programmable from 100mA to 3A (MAX77960)/100mA to 6A (MAX77961) to accommodate small or large
capacity batteries.
When the input source is not available, the MAX77960/MAX77961 can be enabled in a reverse buck mode, delivering
energy from the battery to the input, CHGIN, commonly known as USB on-the-go (OTG). In OTG mode, the regulated
CHGIN voltage is 5.1V with programmable current limit up to 3A.
Maxim’s Smart Power Selector architecture makes the best use of the limited adapter power and the battery power to
power the system. Adapter power that is not used for the system charges the battery. When system load exceeds the
input limit, battery provides additional current to the system up to the BAT to SYS overcurrent threshold, programmable
with B2SOVRC[3:0] I2C register bits. All power switches for charging and switching the system load between battery and
adapter power are integrated on chip—no external MOSFETs required.
Maxim’s proprietary process technology allows for low-RDSON devices in a small solution size. The resistance between
BAT to SYS is 10mΩ (typ), allowing low power dissipation and long battery life.
A multitude of safety features ensure reliable charging. Features include charge timers, watchdog, junction thermal
regulation, and over-/undervoltage protection.
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Maxim Integrated | 28
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Smart Power Selector (SPS)
The smart power selector (SPS) architecture includes a network of internal switches and control loops that efficiently
distributes energy between an external power source (CHGIN), the battery (BAT) and the system (SYS). This architecture
allows power path operation with system instant on with a dead battery.
The Simplified Block Diagram shows the smart power selector switches and gives them the following names: Q1, Q2, Q3,
Q4 and QBAT.
Power Switches and Current Sense Resistor Descriptions
● CHGIN Current-Sense Resistor: As shown in the Simplified Block Diagram, the CHGIN current is monitored with the
input current sensing resistor, RS1, connected between CSINP and CSINN pins.
● DC-DC Switches: Q1, Q2, Q3, and Q4 are the DC-DC switches that can operate as a buck (step down) or a boost
(step up), depending on the external power source and battery voltage conditions.
● Battery-to-System Switch: QBAT is used to control battery charging and discharging operations.
I2C Configuration Register Bits
● MODE[3:0] configures the Smart Power Selector mode to be Charging, OTG or DC-DC mode respectively. See
MODE[3:0] register bits in the Register Map for details.
● VCHGIN_REG[4:0] sets the CHGIN regulation voltage, when the MAX77960/MAX77961 operate in forward mode
(CHGIN has a valid power source). See the CHGIN Regulation Voltage section for details.
● MINVSYS[2:0] sets the minimum system regulation voltage. See the SYS Regulation Voltage section for details.
● B2SOVRC[3:0] sets the battery to system discharge overcurrent protection threshold.
Energy Distribution Priority
● With a valid external power source at CHGIN:
• The external power source is the primary source of energy.
• The battery is the secondary source of energy.
• Energy delivery to SYS has the highest priority.
• Any remaining energy from the power source that is not required by the system is available to the battery charger.
● With no valid external power source at CHGIN:
• The battery is the primary source of energy.
• When OTG mode is enabled, energy delivery to SYS has the highest priority.
• Any remaining energy from the battery that is not required by the system is available to power the CHGIN.
CHGIN Regulation Voltage
● In forward mode (when CHGIN is powered from a valid external source), CHGIN voltage is regulated to
VCHGIN_REG[4:0] when a high impedance or current limited source is applied. VCHGIN might experience significant
voltage droop from the high-impedance source when the MAX77960/MAX77961 extract high power from the source.
Regulating VCHGIN allows the MAX77960/MAX77961 to extract the most power from the power source. See the
Adaptive Input Current Limit (AICL) and Input Voltage Regulation section for more detail.
● In reverse mode (OTG), CHGIN voltage is regulated to 5.1V with programmable current limit up to 3A
(OTG_ILIM[2:0]).
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Maxim Integrated | 29
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
SYS Regulation Voltage
With a valid external power source at CHGIN:
● When the DC-DC is disabled (MODE[3:0] = 0x00 or STBY_EN = 0b1 or STBY pin = high), the QBAT switch is fully on
and VSYS = VBATT - IBATT x RBAT2SYS.
● When the DC-DC is enabled and the charger is disabled (MODE[3:0] = 0x04), VSYS is regulated to VBATTREG
(CHG_CV_PRM) and QBAT is off.
● When the DC-DC is enabled and the charger is enabled (MODE[3:0] = 0x05), but in a noncharging state such as
Done, Thermistor Suspend, Watchdog Suspend, or Timer Fault, VSYS is regulated to VBATTREG (CHG_CV_PRM)
and QBAT is off.
● When the DC-DC is enabled and the charger is enabled (MODE[3:0] = 0x05) and in a valid charging state such as
Precharge or Trickle Charge (VBATT < VSYSMIN - 500mV), VSYS is regulated to VSYSMIN. The charger operates as
a linear regulator, and the power dissipation can be calculated with P = (VSYSMIN - VBATT) x IBATT.
● When the DC-DC is enabled and the charger is enabled (MODE[3:0] = 0x05) and in a valid charging state such as
Fast Charge (CC or CV) or Top-Off (VBATT > VSYSMIN - 500mV), the QBAT switch is fully on, and VSYS = VBATT +
IBATT x RBAT2SYS.
● In all the modes described above when the power demand on SYS exceeds the input source power limit, the battery
automatically provides supplemental power to the system. If the QBAT switch is initially off when VSYS drops to VBATT
- VBSREG, the QBAT switch turns on, and VSYS is regulated to VBATT - VBSREG.
Without a valid external power source at CHGIN, including with OTG mode (MODE[3:0] = 0x0A):
● The QBAT switch is fully on, and VSYS = VBATT - IBATT x RBAT2SYS.
Power States
The MAX77960/MAX77961 transition between power states as input/battery and load conditions dictate.
The MAX77960/MAX77961 provide four (4) power states and one (1) no power state. Under power limited conditions,
the power path feature maintains SYS and USB-OTG loads at the expense of battery charge current. In addition, the
battery supplements the input power when needed. See the Smart Power Selector (SPS) section for more details. As
shown, transitions between power states are initiated by detection/removal of valid power sources, OTG events, and
undervoltage conditions.
1. NO INPUT POWER, MODE[3:0] = undefined: No input adapter or battery is detected. The charger and system are off.
Battery is disconnected.
2. BATTERY-ONLY, MODE[3:0] = any mode: CHGIN is invalid or outside the input voltage operating range. Battery is
connected to power the SYS load (QBAT = on).
3. NO CHARGE - DC-DC in FORWARD mode, MODE[3:0] = 0x04: CHGIN input is valid, DC-DC supplies power to SYS.
DC-DC operates from a valid input. Battery is disconnected (QBAT = off) when SYS load is less than the power that DCDC can supply.
4. CHARGE - DC-DC in FORWARD mode, MODE[3:0] = 0x05: CHGIN input is valid, DC-DC supplies power to SYS and
charges the battery with IBATT. DC-DC operates from a valid input.
5. OTG - DC-DC in REVERSE mode (OTG), MODE[3:0] = 0x0A: OTG is active. Battery is connected to support SYS and
OTG loads (QBAT = on), and charger operates in REVERSE buck mode.
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Maxim Integrated | 30
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Powering Up with the Charger Disabled by Default
The MAX77960/MAX77961's default power state is CHARGE - DC-DC in FORWARD mode, MODE[3:0] = 0x05. For
battery authentication/safety purposes, the MAX77960/MAX77961 can be configured to keep charging disabled while
allowing the DC-DC to switch and regulate the SYS voltage when power is applied to CHGIN. To implement this and
enable the charger when appropriate:
● Connect at least one of the INLIM, ITO, ISET or VSET pins to a valid resistor while tying the others (at least one) to
PVL. CHG_DTLS = 0x05 and CHG_OK = 0.
● The system processor can configure the charger through the I2C interface.
● The system processor enables charging by setting COMM_MODE to 1 (default is 0).
See Wide-Input I2C Programmable Charger with Charger Disabled for a pin connection example. Pin INLIM is connected
to a valid resistor while ITO, ISET and VSET tie to PVL. The default input current limit is programmed by RINLIM, while
default top-off current, constant charging current, and termination voltage use their default value. The system processor
can re-program all four settings through the I2C interface if needed.
Input Validation
The charger input is compared with several voltage thresholds to determine if it is valid. A charger input must meet the
following characteristics to be valid:
● CHGIN must be above VCHGIN_UVLO to be valid. Once CHGIN is above UVLO threshold, the information is latched
and can only be reset when charger is in adaptive input current loop (AICL) and input current is lower than IULO
threshold of 30mA.
● CHGIN must be below its overvoltage lockout threshold (VCHGIN_OVLO).
The devices generate a CHGIN_I interrupt (maskable with CHGIN_M bit) when the CHGIN status changes. Read the
CHGIN input status with CHGIN_OK and CHGIN_DTLS[1:0] register bits.
Adaptive Input Current Limit (AICL) and Input Voltage Regulation
The MAX77960/MAX77961 feature input power management to extract maximum input power while avoiding input
source overload. The adaptive input current limit (AICL) and the input voltage regulation (CHGIN_REG) features allow
the charger to extract more energy from relatively high resistance charge sources with long cables, noncompliant USB
hubs or current limited adapters. In addition, the input power management allows the MAX77960/MAX77961 to perform
well with adapters that have poor transient load responses.
With a high-resistance source, the charger input voltage drops substantially when it draws large current from the source.
The charger's input voltage regulation loop automatically reduces the current drawn from the input to regulate the input
voltage at VCHGIN_REG. If the input current is reduced to ICHGIN_REG_OFF (50mA typ) and the input voltage is still below
VCHGIN_REG, the charger input turns off. VCHGIN_REG is programmable with VCHGIN_REG[4:0] register bits.
With a current limited source, if the MAX77960/MAX77961’s input current limit is programmed above the current limit of
the adapter, the charger input voltage starts to drop when the input current drawn exceeds the source current limit. The
charger's input voltage regulation loop allows the MAX77960/MAX77961 to reduce its input current and operate at the
current limit of the adapter.
When operating with the input voltage regulation loop active, an AICL_I interrupt is generated, AICL_OK sets to 0. The
device prioritize system energy delivery over battery charging. See the Smart Power Selector (SPS) section for more
details.
To extract most input power from a current limited charge source, monitor the AICL_OK status while decreasing the
CHGIN_ILIM[6:0] register setting. Setting the CHGIN_ILIM[6:0] to a reduced to a value below the current limit of the
adapter causes the input voltage to rise. Although the CHGIN_ILIM[6:0] is lowered, more power can be extracted from
the adapter when the input voltage rises.
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Maxim Integrated | 31
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Input Self-Discharge
To ensure that a rapid removal and reinsertion of a charge source always results in a charger input interrupt, the charger
input presents loading to the input capacitor to ensure that when the charge source is removed, the input voltage decays
below the UVLO threshold in a reasonable time (tINSD). The input self-discharge is implemented by with a 44kΩ resistor
(RINSD) from CHGIN input to ground.
System Self-Discharge with No Power
To ensure a timely, complete, repeatable, and reliable reset behavior when the system has no power, the MAX77960/
MAX77961 actively discharge the BATT and SYS nodes when the adapter is missing, the battery is removed and VSYS
is less than VSYSUVLO. The BATT and SYS discharge resistors are both 600Ω.
Charger States
DONE
CHG_DTLS[3:0] = 0b0100
TOP-OFF
CHG_DTLS[3:0] = 0b0011
RESTART
FAST CHARGE (CV)
CHG_DTLS[3:0] = 0b0010
DONE
CHG_DTLS[3:0] = 0b0100
TOP-OFF
CHG_DTLS[3:0] = 0b0011
FAST CHARGE (CV)
CHG_DTLS[3:0] = 0b0010
FAST CHARGE (CC)
CHG_DTLS[3:0] = 0b0001
TRICKLE CHARGE
CHG_DTLS[3:0] = 0b0000
STATES
PRECHARGE
CHG_DTLS[3:0] = 0b0000
The MAX77960/MAX77961 utilize several charging states to safely and quickly charge batteries as shown in Figure 1 and
Figure 2. Figure 1 shows an exaggerated view of a Li+/Li-Poly battery progressing through the following charge states
when there is no system load and the die and battery are close to room temperature: Prequalification → Fast-charge →
Top-off → Done.
BATTERY
VOLTAGE
VBATTREG
VRSTRT
VSYSMIN - 500mV
VPRECHG
0V
TIME
BATTERY CHARGE CURRENT
ICHG ≤ ISET
ITRICKLE
IPRECHG
ITO
0A
CHARGER
ENABLED
TIME
NOT TO SCALE, VCHGIN = 5.0V, ISYS = 0A, TJ = +25°C
Figure 1. Li Battery Charge Profile
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Maxim Integrated | 32
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
IDLE (POR)
CHG_DTLS = 0x8
CHG_OK = 1
ICHG = 0
CHG TIMER = 0
WD TIMER = 0
MODE[3:0] PROGRAMS THE CHARGER ON AND
CHG_EN = 1 AND CONV_RDY = 1
VPRECHG ≤ VBATT
AND PQEN = 0
(SOFT-START)
TJ < TSHDN
(RESET O-TYPE
REGISTERS)
THERMAL SHUTDOWN
CHG_DTLS = 0xA
CHG_OK = 0
ICHG = 0
VBATT < VPRECHG
(SOFT-START)
TJ ≥ TSHDN
VBATT < VSYSMIN - 500mV
WATCHDOG SUSPEND
CHG_DTLS = 0xB
CHG_OK = 0
ICHG = 0
VPRECHG ≤ VBATT
AND PQEN = 1
(SOFT-START)
CHG TIMER ≥ tPQ
CHG TIMER SUSPEND
WD TIMER SUSPEND
TRICKLE CHARGE
CHG_DTLS = 0x0
CHG_OK = 1
ICHG ≤ ITRICKLE
CHG TIMER = 0 IF CHG_DTLS
TRANSITIONS FROM 0x01
WDTCLR = 1
OR WDTEN = 0
TJ ≥ TSHDN
CHG TIMER SUSPEND
WD TIMER SUSPEND
CHG TIMER ≥ tPQ
CHG TIMER SUSPEND
WD TIMER SUSPEND
PRECHARGE
CHG_DTLS = 0x0
CHG_OK = 1
ICHG ≤ IPRECHG
AND VPRECHG ≤ VBATT
AND PQEN = 1
VSYSMIN - 500mV ≤ VBATT
(SOFT-START)
OR PQEN = 0
TIMER FAULT
CHG_DTLS = 0x6
CHG_OK = 0
ICHG = 0
VBATT < VPRECHG
(SOFT-START)
MODE[3:0] PROGRAMS THE
CHARGER OFF OR CHG_EN = 0 OR
CONV_RDY = 0
CHG TIMER SUSPEND
WD TIMER SUSPEND
WDTEN = 1
AND WD TIMER > tWD
CHG TIMER SUSPEND
WD TIMER SUSPEND
VBATTREG ≤ VBATT
IFC < ICHG
ANY STATE
FAST CHARGE (CV)
CHG_DTLS = 0x2
CHG_OK = 1
ITO < ICHG ≤ IFC
CHG_EN
INTERNAL SIGNAL TO ENABLE CHARGER; REFER TO TRUTH TABLE
CONV_RDY
CONV_RDY = 1 WHEN ADC CONVERSION COMPLETES AND CHARGER TARGET
THRESHOLDS ARE SET, EITHER BASED ON PIN OR I2C
OUTPUT VOLTAGE LOOP IN CONTROL AND ICHG
TOP OFF
CHG_DTLS = 0x3
CHG_OK = 1
ICHG ≤ ITO
CHG TIMER = 0 IF CHG_DTLS
TRANSITIONS FROM
0x02
CHARGER STATE WHERE CHARGE IS ENABLED (BATTERY CHARGE
ON-GOING)
CHG TIMER = 0
CHG TIMER ≥ tFC
CHG TIMER SUSPEND
WD TIMER SUSPEND
≤ ITO FOR tTERM
CHARGER STATE WHERE CHARGE IS DISABLED (BATTERY CHARGE
STOPPED)
VBATT < VPQLB
CHG TIMER ≥ tFC
CHG TIMER SUSPEND
WD TIMER SUSPEND
FAST CHARGE (CC)
CHG_DTLS = 0x1
CHG_OK = 1
ICHG ≤ IFC
CHG TIMER = 0 IF CHG_DTLS
TRANSITIONS FROM
0x00 OR 0x03 OR 0x04
CONDITION NEEDED TO TRANSITION BETWEEN 2 CHARGER STATES
CHG TIMER AND WD TIMER STATE STATUS
TRANSITION BETWEEN 2 CHARGER STATES
VBATT < (VBATTREG - VRSTRT)
OR ICHG > ITO
(NO SOFT-START)
CHG TIMER ≥ tTO
CHG TIMER SUSPEND
WD TIMER SUSPEND
DONE
CHG_DTLS = 0x4
CHG_OK = 0
ICHG = 0
CHG TIMER = 0
WD TIMER = 0
VBATT < (VBATTREG - VRSTRT)
(NO SOFT-START)
CHG TIMER RESUME
WD TIMER RESUME
Figure 2. Charger State Diagram
No Input Power or Charger Disabled Idle State
From any state shown in Figure 2 except thermal shutdown, the no input power or charger disabled state is entered
whenever the charger is programmed to be off or the charger input CHGIN is invalid. After being in this state for tSCIDG,
CHG_DTLS is set to 0x08 and CHG_OK is set to 1. A CHG_I interrupt is generated if CHG_OK was 0 previously.
While in the no input power or charger disabled state, the charger current is 0mA, the watchdog and charge timers are
forced to 0, and the power to the system is provided by either the battery or the adapter. When both battery and adapter
power are available, the adapter provides primary power to the system and the battery contributes supplemental energy
to the system if necessary.
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Maxim Integrated | 33
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
To exit the no input power or charger disabled state, the charger input must be valid and the charger must be enabled.
Precharge State
As shown in Figure 2, the charger enters the precharge state when the battery voltage is less than VPRECHG. After being
in this state for tSCIDG, a CHG_I interrupt is generated if CHG_OK was 0 previously, CHG_OK is set to 1 and CHG_DTLS
is set to 0x00. In the precharge state, charge current into the battery is IPRECHG.
The following events cause the state machine to exit this state:
● Battery voltage rises above VPRECHG and the charger enters the next state in the charging cycle: Trickle Charge.
● If the battery charger remains in this state for longer than tPQ, the charger state machine transitions to the Timer Fault
state.
● If the watchdog timer is not serviced, the charger state machine transitions to the “Watchdog Suspend” state.
Note that the precharge state works with battery voltages down to 0V. The 0V operation typically allows this battery
charger to recover batteries that have an open internal pack protector. Typically, a battery pack's internal protection circuit
opens if the battery has seen an overcurrent, undervoltage, or overvoltage. When a battery with an open internal pack
protector is used with this charger, the precharge mode current flows into the 0V battery; this current raises the pack’s
terminal voltage to the level where the internal pack protection switch closes.
Note that a normal battery typically stays in the precharge state for several minutes or less. Therefore a battery that stays
in the precharge for longer than tPQ might be experiencing a problem.
Trickle Charge State
As shown in Figure 2, the charger state machine is in trickle charge state when VPRECHG< VBATT < VSYSMIN - 500mV.
After being in this state for tSCIDG, a CHG_I interrupt is generated if CHG_OK was 0 previously, CHG_OK is set to 1 and
CHG_DTLS = 0x00.
With PQEN = 1 (default) and the MAX77960/MAX77961 are in the trickle charge state, the current in the battery is less
than or equal to ITRICKLE. When PQEN = 0, the charger skips trickle charge state and transitions directly to fast charge
state and the battery charging current is less than or equal to IFC.
Charge current may be less than ITRICKLE/IFC for any of the following reasons:
●
●
●
●
The charger input is in input current limit.
The charger input voltage is low.
The charger is in thermal foldback.
The system load is consuming adapter current. Note that the system load always gets priority over the battery charge
current.
Typical systems operate with PQEN = 1. When operating with PQEN = 0, the system’s software usually sets IFC to a low
value such as 200mA and then monitors the battery voltage. When the battery exceeds a relatively low voltage such as
6V, then the system’s software usually increases IFC.
The following events cause the state machine to exit this state:
● When the battery voltage rises above VSYSMIN - 500mV or the PQEN bit is cleared, the charger enters the next state
in the charging cycle: Fast Charge (CC).
● If the battery charger remains in this state for longer than tPQ, the charger state machine transitions to the Timer Fault
state.
● If the watchdog timer is not serviced, the charger state machine transitions to the Watchdog Suspend state.
Note that a normal battery typically stays in the trickle charge state for several minutes or less. Therefore, a battery that
stays in trickle charge for longer than tPQ might be experiencing a problem.
Fast-Charge Constant Current State
As shown in Figure 2, the charger enters the fast-charge constant current (CC) state when VSYSMIN - 500mV (typ) <
VBATT < VBATTREG. After being in the fast-charge CC state for tSCIDG, a CHG_I interrupt is generated if CHG_OK was
0 previously, CHG_OK is set to 1 and CHG_DTLS = 0x01.
www.maximintegrated.com
Maxim Integrated | 34
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
In the fast-charge CC state, the battery charging current is less than or equal to IFC. Charge current can be less than IFC
for any of the following reasons:
●
●
●
●
The charger input is in input current limit.
The charger input voltage is low.
The charger is in thermal foldback.
The system load is consuming adapter current. Note that the system load always gets priority over the battery
charging current.
The following events cause the state machine to exit this state:
● When the battery voltage rises above VBATTREG, the charger enters the next state in the charging cycle: Fast Charge
(CV).
● If the battery charger remains in this state for longer than tFC, the charger state machine transitions to the Timer Fault
state.
● If the watchdog timer is not serviced, the charger state machine transitions to the Watchdog Suspend state.
The battery charger dissipates the most power in the fast-charge constant current state, which causes the die
temperature to rise. If the die temperature exceeds TREG, the thermal foldback loop is engaged and IFC is reduced. See
the Thermal Foldback section for more information.
Fast-Charge Constant Voltage State
As shown in Figure 2, the charger enters the fast-charge constant voltage (CV) state when the battery voltage rises
to VBATTREG from the fast-charge CC state. After being in the fast-charge CV state for tSCIDG, a CHG_I interrupt is
generated if CHG_OK was 0 previously, CHG_OK is set to 1 and CHG_DTLS = 0x02.
In the fast-charge CV state, the battery charger maintains VBATTREG across the battery and the charge current is less
than or equal to IFC. As shown in Figure 1, charger current decreases exponentially in this state as the battery becomes
fully charged.
The smart power selector control circuitry can reduce the charge current for any of the following reasons:
●
●
●
●
The charger input is in input current limit.
The charger input voltage is low.
The charger is in thermal foldback.
The system load is consuming adapter current. Note that the system load always gets priority over the battery charge
current.
The following events cause the state machine to exit this state:
● When the charger current is below ITO for tTERM, the charger enters the Top-Off State.
● If the battery charger remains in this state for longer than tFC, the charger state machine transitions to the Timer Fault
State.
● If the watchdog timer is not serviced, the charger state machine transitions to the Watchdog Timer Suspend State.
Top-Off State
As shown in Figure 2, the top-off state can only be entered from the fast-charge CV state when the charger current
decreases below ITO for tTERM. After being in the top-off state for tSCIDG, a CHG_I interrupt is generated if CHG_OK was
0 previously, CHG_OK is set to 1, and CHG_DTLS = 0x03. In the top-off state the battery charger maintains VBATTREG
across the battery and typically the charge current is less than or equal to ITO.
The smart power selector control circuitry can reduce the charge current for any of the following reasons:
●
●
●
●
The charger input is in input current limit.
The charger input voltage is low.
The charger is in thermal foldback.
The system load is consuming adapter current. Note that the system load always gets priority over the battery charge
current.
www.maximintegrated.com
Maxim Integrated | 35
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
The following events cause the state machine to exit this state:
● After being in this state for the top-off time (tTO), the charger enters the Done State.
● If VBATT < VBATTREG - VRSTRT, the charger goes back to the Fast-Charge Constant Current State.
● If the watchdog timer is not serviced, the charger state machine transitions to the Watchdog Timer Suspend State.
Done State
As shown in Figure 2, the battery charger enters its done state after the charger has been in the top-off state for tTO.
After being in this state for tSCIDG, a CHG_I interrupt is generated only if CHG_OK was 0 previously, CHG_OK is set to
0 and CHG_DTLS = 0x04.
The following events cause the state machine to exit this state:
● If VBATT < VBATTREG - VRSTRT, the charger goes back to the Fast-Charge Constant Current State.
● If the watchdog timer is not serviced, the charger state machine transitions to the Watchdog Timer Suspend State.
In the done state, the battery charging current (ICHG) is 0A and the charger presents a very low load (IMBDN) to the
battery. If the system load presented to the battery is low ( VBATTREG - VRSTRT
and TJ < TSHDN
0x05: Charger is off because at least one pin of
INLIM, ITO, ISET, or VSET has valid resistance
while others don't (invalid resistance, open or tied
to PVL). Configure charger with I2C, then set
COMM_MODE to 1 enables charging.
CHG_OK = 0
0x06: Charger is in timer fault mode
CHG_OK = 0 and if BAT_DTLS = 0b001 then
VBATT < VSYSMIN - 500mV or VBATT < VPRECHG
and TJ < TSHDN
0x07: Charger is suspended because QBAT is
disabled (DISQBAT = high or DISIBS = 1)
CHG_OK = 0
0x08: Charger is off, charger input invalid and/or
charger is disabled
CHG_OK = 1
0x09: Reserved
0x0A: Charger is off and the junction temperature
is > TSHDN
CHG_OK = 0
0x0B: Charger is off because the watchdog timer
expired
CHG_OK = 0
0x0C: Charger is suspended or charge current or
voltage is reduced based on JEITA control. This
condition is also reported in THM_DTLS.
CHG_OK = 0
0x0D: Charger is suspended because battery
removal is detected on THM pin. This condition is
also reported in THM_DTLS.
CHG_OK = 0
0x0E: Reserved
0x0F: Reserved
Maxim Integrated | 57
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
CHG_DETAILS_02 (0x15)
BIT
7
6
5
4
3
2
1
0
Field
SPR
THM_DTLS[2:0]
APP_MOD
E_DTLS
Reset
0x0
0x2
0x0
0x0
0x0
Read Only
Read Only
Read Only
Read Only
Read Only
Access
Type
BITFIELD
SPR
BITS
7
THM_DTLS
6:4
APP_MODE
_DTLS
3
FSW_DTLS
NUM_CELL_
DTLS
2:1
0
FSW_DTLS[1:0]
NUM_CELL
_DTLS
DESCRIPTION
DECODE
Spare bit
Thermistor Status.
This is also reported in the CHG_DTLS as
0x0C.
0b000: Low temperature and charging suspended
(COLD)
0b001: Low temperature charging (cool)
0b010: Normal temperature charging (normal)
0b011: High temperature charging (warm)
0b100: High temperature and charging suspended
(hot)
0b101: Battery removal detected on THM pin
0b110: Thermistor monitoring is disabled
0b111: Reserved
Application Mode Status
0b0: Device is configured to operate as a
standalone DC-DC converter.
0b1: Device is configured to operate as a charger.
Programmed Switching Frequency Details
0b00: 600kHz
0b01: Reserved
0b10: Reserved
0b11: Reserved
Number of Serially Connected Battery Cells
Details
0b0: Device is configured to support a 2-cell
battery.
0b1: Device is configured to support a 3-cell
battery.
CHG_CNFG_00 (0x16)
Charger configuration 0
BIT
7
6
5
4
Field
COMM_MO
DE
DISIBS
STBY_EN
WDTEN
MODE[3:0]
Reset
0x0
0x0
0x0
0x0
0x5
Write, Read
Write, Read
Write, Read
Write, Read
Write, Read
Access
Type
www.maximintegrated.com
3
2
1
0
Maxim Integrated | 58
MAX77960/MAX77961
BITFIELD
BITS
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
DESCRIPTION
DECODE
0b0: Autonomous Mode
CHGIN_ILIM, CHGCC, CHG_CV_PRM, and
TO_ITH registers are programmed by external
resistors on INLIM, ISET, VSET and ITO pins.
COMM_MOD
E
7
I2C Mode Enable
Writing 0 to COMM_MODE is ignored.
0b1: I2C Mode Enabled
CHGIN_ILIM, CHGCC, CHG_CV_PRM and
TO_ITH registers are programmed by I2C.
Writing 1 to COMM_MODE is allowed.
Writting COMM_MODE=1 clears any charger
suspension due to invalid resistance detected on
INLIM, ISET, VSET, and ITO pins. Charger starts
with I2C programmed settings in CHGIN_ILIM,
CHGCC, CHG_CV_PRM, and TO_ITH registers.
DISIBS
STBY_EN
6
5
BATT to SYS FET Disable Control
Read back value of DISIBS register bit
reflects the actual DISIBS command or
DISQBAT PIN state.
CHGIN Standby Enable
Read back value of the STBY_EN register bit
reflects the actual CHGIN standby setting.
0b0: BATT to SYS FET is controlled by the power
path state machine.
0b1: BATT to SYS FET is forced off.
0b0: DC-DC is controlled by the power path state
machine.
0b1: Force DC-DC off. Device goes to CHGIN low
quiescent current standby.
Watchdog Timer Enable.
WDTEN
4
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While enabled, the system controller must
reset the watchdog timer within the timer
period (tWD) for the charger to operate
normally. Reset the watchdog timer by
programming WDTCLR = 0x01.
0b0: Watchdog timer disabled
0b1: Watchdog timer enabled
Maxim Integrated | 59
MAX77960/MAX77961
BITFIELD
MODE
BITS
3:0
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
DESCRIPTION
DECODE
Smart Power Selector Configuration.
Read back value of the MODE register
reflects the actual smart power selector
configuration.
0x0: Charger = off, OTG = off, DC-DC = off. When
the QBAT switch is on (DISQBAT = low and
DISIBS = 0), the battery powers the system.
0x1: Same as 0b0000
0x2: Same as 0b0000
0x3: Same as 0b0000
0x4: Charger = off, OTG = off, DC-DC = on. When
there is a valid input, the DC-DC converter
regulates the system voltage to be the maximum of
(VSYSMIN and VBATT + 4%).
0x5: Charger = on,OTG = off, DC-DC = on. When
there is a valid input, the battery is charging. VSYS
is the larger of VSYSMIN and ~VBATT + IBATT x
RBAT2SYS.
0x6: Same as 0b0101
0x7: Same as 0b0101
0x8: RSVD
0x9: RSVD
0xA: Charger = off, OTG = on, DC-DC = off. The
QBAT switch is on to allow the battery to support
the system, the charger's DC-DC operates in
reverse mode as a buck converter. The OTG
output, CHGIN, can source current up to
ICHGIN.OTG.LIM. The CHGIN target voltage is
VCHGIN.OTG.
0xB: RSVD
0xC: RSVD
0xD: RSVD
0xE: RSVD
0xF: RSVD
CHG_CNFG_01 (0x17)
Charger configuration 1
BIT
7
6
Field
PQEN
LPM
CHG_RSTRT[1:0]
STAT_EN
FCHGTIME[2:0]
Reset
0x1
0x0
0x1
0x1
0x1
Write, Read
Write, Read
Write, Read
Write, Read
Write, Read
Access
Type
BITFIELD
BITS
5
4
DESCRIPTION
3
2
1
0
DECODE
PQEN
7
Low-Battery Prequalification Mode Enable
0b0: Low-Battery Prequalification mode is
disabled.
0b1: Low-Battery Prequalification mode is enabled.
LPM
6
Low Power Mode control
0b0: QBAT charge pump runs in Normal mode.
0b1: QBAT charge pump is in Low Power Mode.
Charger Restart Threshold
0b00: 100mV/cell below the value programmed by
CHG_CV_PRM
0b01: 150mV/cell below the value programmed by
CHG_CV_PRM
10: 200mV/cell below the value programmed by
CHG_CV_PRM
11: Disabled
CHG_RSTR
T
5:4
www.maximintegrated.com
Maxim Integrated | 60
MAX77960/MAX77961
BITFIELD
STAT_EN
FCHGTIME
BITS
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
DESCRIPTION
3
2:0
DECODE
Charge Indicator Output Enable
0b0: Disable STAT output
0b1: Enable STAT output
Fast-Charge Timer setting (tFC, hrs)
0b000: Disable
0b001: 3
0b010: 4
0b011: 5
0b100: 6
0b101: 7
0b110: 8
0b111: 10
CHG_CNFG_02 (0x18)
Charger configuration 2
BIT
7
6
5
4
3
2
Field
SPR[1:0]
CHGCC[5:0]
Reset
0x0
0x7
Write, Read
Write, Read
Access
Type
BITFIELD
SPR
BITS
7:6
www.maximintegrated.com
DESCRIPTION
1
0
DECODE
Spare Bit
Maxim Integrated | 61
MAX77960/MAX77961
BITFIELD
CHGCC
BITS
5:0
www.maximintegrated.com
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
DESCRIPTION
Fast-Charge Current Selection (mA). When
the charger is enabled, the charge current
limit is set by these bits.
Read back value of the CHGCC register
reflects the actual fast charge current
programmed in the charger.
The thermal foldback loop can reduce the
battery charger’s target current by ATJREG.
DECODE
0x00: 100
0x01: 150
0x02: 200
0x03: 250
0x04: 300
0x05: 350
0x06: 400
0x07: 450
0x08: 500
0x09: 600
0x0A: 700
0x0B: 800
0x0C: 900
0x0D: 1000
0x0E: 1100
0x0F: 1200
0x10: 1300
0x11: 1400
0x12: 1500
0x13: 1600
0x14: 1700
0x15: 1800
0x16: 1900
0x17: 2000
0x18: 2100
0x19: 2200
0x1A: 2300
0x1B: 2400
0x1C: 2500
0x1D: 2600
0x1E: 2700
0x1F: 2800
0x20: 2900
0x21: 3000
0x22: 3100
0x23: 3200
0x24: 3300
0x25: 3400
0x26: 3500
0x27: 3600
0x28: 3700
0x29: 3800
0x2A: 3900
0x2B: 4000
0x2C: 4100
0x2D: 4200
0x2E: 4300
0x2F: 4400
0x30: 4500
0x31: 4600
0x32: 4700
0x33: 4800
0x34: 4900
0x35: 5000
0x36: 5100
0x37: 5200
0x38: 5300
Maxim Integrated | 62
MAX77960/MAX77961
BITFIELD
BITS
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
DESCRIPTION
DECODE
0x39: 5400
0x3A: 5500
0x3B: 5600
0x3C: 5700
0x3D: 5800
0x3E: 5900
0x3F: 6000
CHG_CNFG_03 (0x19)
Charger configuration 3
BIT
7
6
Field
SYS_TRAC
K_DIS
B2SOVRC_
DTC
TO_TIME[2:0]
TO_ITH[2:0]
Reset
0x1
0x0
0x3
0x0
Write, Read
Write, Read
Write, Read
Write, Read
Access
Type
BITFIELD
SYS_TRACK
_DIS
B2SOVRC_D
TC
TO_TIME
TO_ITH
BITS
5
4
3
2
DESCRIPTION
1
0
DECODE
7
SYS Tracking Disable Control
0x0: SYS tracking is enabled. SYS is regulated to
MAX of (VBATT + 4%, VSYSMIN). This is also valid
in Charge Done state.
0x1: SYS tracking is disabled. SYS is regulated to
VCHG_CV_PRM.
6
Battery to SYS Overcurrent Debounce Time
Control.
While under OVRC condition, after tOCP
switcher (and therfore charge) is disabled.
0x0: tOCP = 6ms
0x1: tOCP = 100ms
5:3
Top-Off Timer Setting (min)
0b000: 30s
0b001: 10
0b010: 20
0b011: 30
0b100: 40
0b101: 50
0b110: 60
0b111: 70
2:0
Top-Off Current Threshold (mA). The charger
transitions from its fast-charge constant
voltage mode to its top-off mode when the
charger current decays to the value
programmed by this register. This transition
generates a CHG_I interrupt and causes the
CHG_DTLS register to report top-off mode.
This transition also starts the top-off time as
programmed by TO_TIME.
Read back value of the TO_ITH register
reflects the actual top-off current programmed
in the charger.
0b000: 100
0b001: 200
0b010: 300
0b011: 400
0b100: 500
0b101: 600
0b110: 600
0b111: 600
CHG_CNFG_04 (0x1A)
Charger configuration 4
www.maximintegrated.com
Maxim Integrated | 63
MAX77960/MAX77961
BIT
7
6
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
5
4
3
2
Field
SPR[1:0]
CHG_CV_PRM[5:0]
Reset
0x0
0x00
Write, Read
Write, Read
Access
Type
BITFIELD
SPR
BITS
7:6
www.maximintegrated.com
DESCRIPTION
1
0
DECODE
Spare Bit
Maxim Integrated | 64
MAX77960/MAX77961
BITFIELD
CHG_CV_P
RM
BITS
5:0
www.maximintegrated.com
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
DESCRIPTION
Charge Termination Voltage Setting (V).
Read back value of the CHG_CV_PRM
register reflects the actual charge termination
voltage programmed in the charger when
JEITA_EN = 0.
When JEITA_EN = 1, charge termination
voltage is controlled by VCHGCV_COOL and
VCHGCV_WARM register settings.
DECODE
2 Cell Battery
0x00: 8.000
0x01: 8.020
0x02: 8.040
0x03: 8.060
0x04: 8.080
0x05: 8.100
0x06: 8.120
0x07: 8.140
0x08: 8.160
0x09: 8.180
0x0A: 8.200
0x0B: 8.220
0x0C: 8.240
0x0D: 8.260
0x0E: 8.280
0x0F: 8.300
0x10: 8.320
0x11: 8.340
0x12: 8.360
0x13: 8.380
0x14: 8.400
0x15: 8.420
0x16: 8.440
0x17: 8.460
0x18: 8.480
0x19: 8.500
0x1A: 8.520
0x1B: 8.540
0x1C: 8.560
0x1D: 8.580
0x1E: 8.600
0x1F: 8.620
0x20: 8.640
0x21: 8.660
0x22: 8.680
0x23: 8.700
0x24: 8.720
0x25: 8.740
0x26: 8.760
0x27: 8.780
0x28: 8.800
0x29: 8.820
0x2A: 8.840
0x2B: 8.860
0x2C: 8.880
0x2D: 8.900
0x2E: 8.920
0x2F: 8.940
0x30: 8.960
0x31: 8.980
0x32: 9.000
0x33: 9.020
0x34: 9.040
0x35: 9.060
0x36: 9.080
0x37: 9.100
Maxim Integrated | 65
MAX77960/MAX77961
BITFIELD
BITS
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
DESCRIPTION
DECODE
0x38: 9.120
0x39: 9.140
0x3A: 9.160
0x3B: 9.180
0x3C: 9.200
0x3D: 9.220
0x3E: 9.240
0x3F: 9.260
3 Cell Battery
0x00: 12.000
0x01: 12.030
0x02: 12.060
0x03: 12.090
0x04: 12.120
0x05: 12.150
0x06: 12.180
0x07: 12.210
0x08: 12.240
0x09: 12.270
0x0A: 12.300
0x0B: 12.330
0x0C: 12.360
0x0D: 12.390
0x0E: 12.420
0x0F: 12.450
0x10: 12.480
0x11: 12.510
0x12: 12.540
0x13: 12.570
0x14: 12.600
0x15: 12.630
0x16: 12.660
0x17: 12.690
0x18: 12.720
0x19: 12.750
0x1A: 12.780
0x1B: 12.810
0x1C: 12.840
0x1D: 12.870
0x1E: 12.900
0x1F: 12.930
0x20: 12.960
0x21: 12.990
0x22: 13.020
0x23: 13.050
CHG_CNFG_05 (0x1B)
Charger configuration 5
BIT
7
6
5
4
3
2
1
Field
RESERVED[1:0]
ITRICKLE[1:0]
B2SOVRC[3:0]
Reset
0x1
0x0
0x4
Write, Read
Write, Read
Write, Read
Access
Type
www.maximintegrated.com
0
Maxim Integrated | 66
MAX77960/MAX77961
BITFIELD
RESERVED
ITRICKLE
B2SOVRC
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
BITS
7:6
5:4
3:0
DESCRIPTION
DECODE
Reserved
Trickle Charge Current Selection (mA)
0b00: 100
0b01: 200
0b10: 300
0b11: 400
BATT to SYS Overcurrent Threshold (A)
0x00: Disable
0x01: 3.000
0x02: 3.500
0x03: 4.000
0x04: 4.500
0x05: 5.000
0x06: 5.500
0x07: 6.000
0x08: 6.500
0x09: 7.000
0x0A: 7.500
0x0B: 8.000
0x0C: 8.500
0x0D: 9.000
0x0E: 9.500
0x0F: 10.000
CHG_CNFG_06 (0x1C)
Charger configuration 6
BIT
7
6
5
4
3
2
1
0
Field
SPR7
RESERVED[1:0]
SPR4
CHGPROT[1:0]
WDTCLR[1:0]
Reset
0x0
0x0
0x0
0x0
0x0
Write, Read
Write, Read
Write, Read
Write, Read
Write, Read
Access
Type
BITFIELD
SPR7
RESERVED
SPR4
BITS
DESCRIPTION
7
Spare bit
6:5
Reserved
4
Spare bit
DECODE
Charger Settings Protection Bit.
CHGPROT
WDTCLR
3:2
1:0
Writing 11 to these bits unlocks the write
capability for the registers that are Protected
with CHGPROT. Writing any value besides
11 locks the protected registers.
Watchdog Timer Clear Bit.
Writing 01 to these bits clears the watchdog
timer when the watchdog timer is enabled.
0b00: Write capability locked
0b01: Write capability locked
0b10: Write capability locked
0b11: Write capability unlocked
0b00: the watchdog timer is not cleared
0b01: the watchdog timer is cleared
0b10: the watchdog timer is not cleared
0b11: the watchdog timer is not cleared
CHG_CNFG_07 (0x1D)
Charger configuration 7
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Maxim Integrated | 67
MAX77960/MAX77961
BIT
7
6
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
5
4
3
2
1
0
Field
JEITA_EN
REGTEMP[3:0]
VCHGCV_
COOL
ICHGCC_C
OOL
FSHIP_MO
DE
Reset
0x0
0x6
0x0
0x1
0x0
Write, Read
Write, Read
Write, Read
Write, Read
Write, Read
Access
Type
BITFIELD
JEITA_EN
REGTEMP
BITS
7
6:3
DESCRIPTION
DECODE
JEITA Enable
0b0: JEITA disabled.
Fast-charge current and charge termination
voltage do not change based on thermistor
temperature.
0b1: JEITA enabled.
Fast-charge current and charge termination
voltage change based on thermistor temperature.
Junction Temperature Thermal Regulation
(ºC).
The charger's target current limit starts to
foldback and the TREG bit is set if the
junction temperature is greater than the
REGTEMP setpoint.
0x0: 85
0x1: 90
0x2: 95
0x3: 100
0x4: 105
0x5: 110
0x6: 115
0x7: 120
0x8: 125
0x9: 130
0b0: Battery termination voltage is set by
CHG_CV_PRM.
0b1: Battery termination voltage is set by
(CHG_CV_PRM - 180mV/cell).
VCHGCV_C
OOL
2
JEITA-Controlled Battery Termination Voltage
When Thermistor Temperature is Between
TCOLD and TCOOL
ICHGCC_CO
OL
1
JEITA-Controlled Battery Fast-Charge
Current When Thermistor Temperature is
Between TCOLD and TCOOL
0b0: Battery fast-charge current is set by CHGCC
0b1: Battery fast-charge current is reduced to 50%
of CHGCC
FSHIP_MOD
E
0
Factory Ship Mode Enable
0b0: Disable factory ship mode
0b1: Enable factory ship mode
CHG_CNFG_08 (0x1E)
Charger configuration 8
BIT
7
6
5
4
3
Field
RESERVED
CHGIN_ILIM[6:0]
Reset
0x1
0x0B
Write, Read
Write, Read
Access
Type
BITFIELD
RESERVED
BITS
7
www.maximintegrated.com
DESCRIPTION
2
1
0
DECODE
Reserved
Maxim Integrated | 68
MAX77960/MAX77961
BITFIELD
CHGIN_ILIM
BITS
6:0
www.maximintegrated.com
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
DESCRIPTION
CHGIN Input Current Limit (mA).
Read back value of the CHGIN_ILIM register
reflect the actual input current limit
programmed in the charger.
DECODE
0x00: 100
0x01: 100
0x02: 100
0x03: 100
0x04: 150
0x05: 200
0x06: 250
0x07: 300
0x08: 350
0x09: 400
0x0A: 450
0x0B: 500
0x0C: 550
0x0D: 600
0x0E: 650
0x0F: 700
0x10: 750
0x11: 800
0x12: 850
0x13: 900
0x14: 950
0x15: 1000
0x16: 1050
0x17: 1100
0x18: 1150
0x19: 1200
0x1A: 1250
0x1B: 1300
0x1C: 1350
0x1D: 1400
0x1E: 1450
0x1F: 1500
0x20: 1550
0x21: 1600
0x22: 1650
0x23: 1700
0x24: 1750
0x25: 1800
0x26: 1850
0x27: 1900
0x28: 1950
0x29: 2000
0x2A: 2050
0x2B: 2100
0x2C: 2150
0x2D: 2200
0x2E: 2250
0x2F: 2300
0x30: 2350
0x31: 2400
0x32: 2450
0x33: 2500
0x34: 2550
0x35: 2600
0x36: 2650
0x37: 2700
0x38: 2750
Maxim Integrated | 69
MAX77960/MAX77961
BITFIELD
BITS
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
DESCRIPTION
DECODE
0x39: 2800
0x3A: 2850
0x3B: 2900
0x3C: 2950
0x3D: 3000
0x3E: 3050
0x3F: 3100
0x40: 3150
0x41: 3200
0x42: 3250
0x43: 3300
0x44: 3350
0x45: 3400
0x46: 3450
0x47: 3500
0x48: 3550
0x49: 3600
0x4A: 3650
0x4B: 3700
0x4C: 3750
0x4D: 3800
0x4E: 3850
0x4F: 3900
0x50: 3950
0x51: 4000
0x52: 4050
0x53: 4100
0x54: 4150
0x55: 4200
0x56: 4250
0x57: 4300
0x58: 4350
0x59: 4400
0x5A: 4450
0x5B: 4500
0x5C: 4550
0x5D: 4600
0x5E: 4650
0x5F: 4700
0x60: 4750
0x61: 4800
0x62: 4850
0x63: 4900
0x64: 4950
0x65: 5000
0x66: 5050
0x67: 5100
0x68: 5150
0x69: 5200
0x6A: 5250
0x6B: 5300
0x6C: 5350
0x6D: 5400
0x6E: 5450
0x6F: 5500
0x70: 5550
0x71: 5600
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Maxim Integrated | 70
MAX77960/MAX77961
BITFIELD
BITS
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
DESCRIPTION
DECODE
0x72: 5650
0x73: 5700
0x74: 5750
0x75: 5800
0x76: 5850
0x77: 5900
0x78: 5950
0x79: 6000
0x7A: 6050
0x7B: 6100
0x7C: 6150
0x7D: 6200
0x7E: 6250
0x7F: 6300
CHG_CNFG_09 (0x1F)
Charger configuration 9
BIT
7
6
5
4
3
2
1
Field
INLIM_CLK[1:0]
OTG_ILIM[2:0]
MINVSYS[2:0]
Reset
0x2
0x3
0x3
Write, Read
Write, Read
Write, Read
Access
Type
BITFIELD
INLIM_CLK
OTG_ILIM
MINVSYS
BITS
7:6
5:3
2:0
www.maximintegrated.com
DESCRIPTION
0
DECODE
Input Current Limit Soft-Start Period (μs)
Between Consecutive Increments of 25mA
0b00: 8
0b01: 256
0b10: 1024
0b11: 4096
OTG Mode Current Limit Setting (mA)
0b000: 500
0b001: 900
0b010: 1200
0b011: 1500
0b100: 2000
0b101: 2250
0b110: 2500
0b111: 3000
Minimum System Regulation Voltage (V)
2 Cell Battery
0b000: 5.535
0b001: 5.740
0b010: 5.945
0b011: 6.150
0b100: 6.355
0b101: 6.560
0b110: 6.765
0b111: 6.970
3 Cell Battery
0b000: 8.303
0b001: 8.610
0b010: 8.918
0b011: 9.225
0b100: 9.533
0b101: 9.840
0b110: 10.148
0b111: 10.455
Maxim Integrated | 71
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
CHG_CNFG_10 (0x20)
Charger configuration 10
BIT
7
6
5
4
3
2
1
0
Field
SPR[1:0]
VCHGIN_REG[4:0]
DISKIP
Reset
0x0
0x04
0x0
Write, Read
Write, Read
Write, Read
Access
Type
BITFIELD
SPR
VCHGIN_RE
G
DISKIP
BITS
7:6
5:1
0
www.maximintegrated.com
DESCRIPTION
DECODE
Spare Bit
CHGIN Voltage Regulation Threshold (V)
0x00: 4.025
0x01: 4.200
0x02: 4.375
0x03: 4.550
0x04: 4.725
0x05: 4.900
0x06: 5.425
0x07: 5.950
0x08: 6.475
0x09: 7.000
0x0A: 7.525
0x0B: 8.050
0x0C: 8.575
0x0D: 9.100
0x0E: 9.625
0x0F: 10.150
0x10: 10.675
0x11: 10.950
0x12: 11.550
0x13: 12.150
0x14: 12.750
0x15: 13.350
0x16: 13.950
0x17: 14.550
0x18: 15.150
0x19: 15.750
0x1A: 16.350
0x1B: 16.950
0x1C: 17.550
0x1D: 18.150
0x1E: 18.750
0x1F: 19.050
Charger Skip Mode Disable
0b0: Autoskip mode
0b1: Disable skip mode
Maxim Integrated | 72
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Applications Information
Inductor Selection
Buck-boost allows a range of inductance for different combinations of switching frequency and maximum nominal CHGIN
voltage. See Table 11 for recommendations. The lower the inductor DCR is, the higher the buck-boost efficiency is. The
user needs to weigh the trade-offs between inductor size and DCR value and choose a suitable inductor for the buckboost. See Table 12 for inductor recommendations.
Table 11. Recommended Inductance for Combinations of Switching Frequency and
Maximum Nominal CHGIN Voltage
SWITCHING FREQUENCY
(kHz)
MAXIMUM NOMINAL CHGIN VOLTAGE
(V)
RECOMMENDED NOMINAL INDUCTANCE
(µH)
15 or lower
600
2.2, 3.3
Higher than 15
3.3
Table 12. Suggested Inductors
ROOT
PART
NUMBER
MAX77960
MAX77961
MFGR.
SERIES
NOMINAL
INDUCTANCE
(µH)
TYPICAL DC
RESISTANCE
(mΩ)
CURRENT
RATING (A)
-30% (ΔL/L)
CURRENT
RATING (A)
ΔT = +40°C
RISE
DIMENSIONS
LxWxH
(mm)
Coilcraft
XAL4020-222ME
2.2
35.2
5.6
5.5
4.0 x 4.0 x 2.1
Coilcraft
XAL4030-332ME
3.3
26.0
5.5
6.6
4.0 x 4.0 x 3.1
Cyntec
CMLE063T2R2-063
2.2
11.0
14.0
10.0
6.95 x 6.6 x
2.8
Pulse
PA5007.332NLT
3.3
16.3
15.0
10.0
7.8 x 7.6 x 2.9
CHGIN Capacitor Selection
The CHGIN capacitor, CCHGIN, reduces the current peaks drawn from the input power source and reduces switching
noise in the device. In OTG mode, it also reduces the output voltage ripple and ensures regulation loop stability.
The impedance of CCHGIN at the switching frequency should be kept very low. Ceramic capacitors with X5R or X7R
dielectrics are highly recommended due to their small size, low ESR, and small temperature coefficients. For most
applications, a 10μF capacitor is sufficient. See Table 13 for CHGIN capacitor recommendations.
Table 13. Suggested CHGIN Capacitors
MFGR.
SERIES
NOMINAL
CAPACITANCE
(µF)
RATED
VOLTAGE (V)
TEMPERATURE
CHARACTERISTICS
CASE
SIZE (in)
DIMENSIONS
LxWxH
(mm)
Murata
GRM32ER7YA106KA12
10
35
X7R
1210
3.2 x 2.5 x 2.5
Murata
GRM21BR6YA106ME43
10
35
X5R
0805
2.0 x 1.25 x
1.25
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Maxim Integrated | 73
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
SYS Capacitor Selection
The SYS capacitor, CSYS, is required to keep the output voltage ripple small and to ensure regulation loop stability. The
CSYS must have low impedance at the switching frequency. Ceramic capacitors with X5R or X7R dielectric are highly
recommended due to their small size, low ESR, and small temperature coefficients. For stable operation, buck-boost
requires 40μF of minimum effective output capacitance. Considering the DC bias characteristic of ceramic capacitors,
2 x 47μF (1210) or 3 x 47μF (1206) or 7 x 22μF (0805) capacitors are recommended for 2-cell applications, and 3 x
47μF (1210) or 4 x 47μF (1206) capacitors are recommended for 3-cell applications. See Table 14 for SYS capacitor
recommendations.
Table 14. Suggested SYS Capacitors
MFGR.
SERIES
NOMINAL
CAPACITANCE
(µF)
RATED
VOLTAGE (V)
TEMPERATURE
CHARACTERISTICS
CASE
SIZE (in)
DIMENSIONS
LxWxH
(mm)
Taiyo
Yuden
EMK325ABJ476MM8P
47
16
X5R
1210
3.2 x 2.5 x 2.5
Murata
GRM31CR61C476ME44
47
16
X5R
1206
3.2 x 1.6 x 1.6
Murata
GRM21BR61C226ME44
22
16
X5R
0805
2.0 x 1.25 x
1.25
Battery Insertion Protection
When the battery hot inserts into the MAX77960/MAX77961, it creates high inrush current flowing through the body diode
of QBAT FET. The inrush current peaks at tens of amperes and lasts for less than a few hundreds of microseconds. Such
current can possibly damage the QBAT FET. For IC protection, the following battery insertion protection is required on
the board:
● For system designs with a 2S battery, include an external 3A Schottky diode from BATT to SYS. The Schottky diode
has low forward voltage drop when conducting high current in the forward direction. It diverts the inrush current from
BATT to SYS at battery insertion. The inrush current flowing through the QBAT FET is greatly reduced and therefore
the IC is protected. See Figure 14.
● For system designs with a 3S battery, the inrush current is higher than a 2S battery due to higher battery voltage. In
addition to the 3A Schottky diode from BATT to SYS, it is required to include an inrush protection circuit. The inrush
protection circuit consists of an FET and RC network. See Figure 15 for a complete solution. At battery hot insertion,
VGS of the FET is slowly charged by the RC network. The FET gradually turns on and limits the inrush current. For
FET selection, check the current and voltage rating of the FET to guarantee that it satisfies the system specification.
www.maximintegrated.com
Maxim Integrated | 74
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
MAX77960
MAX77961
PGND
SYS
QBAT
BATT
PACK+
HOT INSERTION
3A SCHOTTKY
DIODE
2S BATTERY
PACK-
Figure 14. Battery Insertion Protection with 2S Battery
www.maximintegrated.com
Maxim Integrated | 75
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
MAX77960
MAX77961
PGND
SYS
QBAT
BATT
PACK+
3A SCHOTTKY
DIODE
470K
INRUSH
PROTECTION
CIRCUIT
HOT INSERTION
3S BATTERY
1K
0.047µF
910K
PACK-
Figure 15. Battery Insertion Protection with 3S Battery
www.maximintegrated.com
Maxim Integrated | 76
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
PCB Layout Guidelines
Careful circuit board layout is critical to achieve low switching power losses and clean, stable operation. Figure 16 shows
a PCB layout example.
When designing the PCB, follow these guidelines:
1. Place the CHGIN capacitor (CCHGIN) and SYS capacitors (CSYS) immediately next to the CHGIN pin and SYS pin
of the IC, respectively. Since the IC operates at a high switching frequency, this placement is critical for minimizing
parasitic inductance within the input and output current loops which can cause high voltage spikes and can damage
the internal switching MOSFETs.
2. Place the inductor next to the LX pins and make the traces between the LX pins and the inductor short and wide to
minimize PCB trace impedance. Excessive PCB impedance reduces converter efficiency. When routing LX traces
on a separate layer, make sure to include enough vias to minimize trace impedance. Routing LX traces on multiple
layers is recommended to further reduce trace impedance. Furthermore, do not make LX traces take up an excessive
amount of area. The voltage on this node switches very quickly and additional area creates more radiated emissions.
3. Route LX nodes to their corresponding bootstrap capacitors (CBST) as short as possible. Prioritize CBST placement
to reduce trace length to the IC.
4. Route CSINP and CSINN traces as symmetrical as possible. Having the same trace parasitics improves accuracy of
the differential CHGIN current sensing.
5. Place the PVL capacitor (CPVL) immediately next to the PVL pin. Proximity to the IC provides a stable supply for the
internal circuitry.
6. Place the BATT capacitor (CBATT) and SYSA capacitor (CSYSA) immediately next to the BATT pin and SYSA pin of
the IC, respectively.
7. Keep the power traces and load connections short and wide. This is essential for high converter efficiency.
8. Do not neglect ceramic capacitor DC voltage derating. Choose capacitor values and case sizes carefully. See the
SYS Capacitor Selection section and refer to Tutorial 5527 for more information.
www.maximintegrated.com
Maxim Integrated | 77
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
CSINP
CSINN
RCSINN
0402
CCSINP
0402
CCSINN
0402
RCSINP
0402
CDIFF
0402
CPVL
0402
RSENSE
1206
BST1
CHGIN
CBST1
0402
RAVL
0402
AVL
PVL
CCHGIN
1210
LX1
CSYSA
0402
GND
SYSA
LX2
CSYS
1210
PGND
CSYS
1210
L (2.2uH)
6.95 x 6.6mm
CAVL
0402
VBUS
CBST2
0402
BST2
SYS
CBATT
0805
BATT
Figure 16. PCB Layout Example
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Maxim Integrated | 78
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Typical Application Circuits
Wide-Input I2C Programmable Charger
MAX77960
MAX77961
10mΩ
1206
3.5V TO 25.4V
VBUS
10µF
35V
1210
CHGIN
LX1
CSINN
CSINP
VPVL
4.7µF
6.3V
0402
PVL
4.7Ω
VAVL 0402
AVL
2.2µH
8A ISAT
LX2
SCL
SDA
SDA
INTB
INTB
SYS
47µF
16V
1210
BATT
INOKB
200kΩ
0402
VSYS
3A IF
VBATT
10µF
16V
0805
VAVL
200kΩ
0402
STAT
47µF
16V
1210
PGND
INOKB
VPVL
0.22µF
6.3V
0402
BST2
SYSA
4.7µF
6.3V
0402
SCL
0.22µF
6.3V
0402
BST1
THM
PK+
THM
BATSP
10kΩ
GND
STAT
OTGEN
DISQBAT
STBY
www.maximintegrated.com
OTGEN
DISQBAT
STBY
BATSN
ISET
ITO
INLIM
VSET
VPVL
INRUSH
PROTECTION
CIRCUIT
(FOR 3S BATTERY)
PK2/3-CELL LI-ION
BATTERY
CNFG
Maxim Integrated | 79
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Typical Application Circuits (continued)
Wide-Input I2C Programmable Charger with Charger Disabled
MAX77960
MAX77961
10mΩ
1206
3.5V TO 25.4V
VBUS
10µF
35V
1210
CHGIN
LX1
CSINN
CSINP
VPVL
4.7µF
6.3V
0402
PVL
4.7Ω
VAVL 0402
AVL
2.2µH
8A ISAT
LX2
SCL
SDA
SDA
INTB
INTB
SYS
47µF
16V
1210
BATT
INOKB
200kΩ
0402
VSYS
3A IF
VBATT
10µF
16V
0805
VAVL
200kΩ
0402
STAT
47µF
16V
1210
PGND
INOKB
VPVL
0.22µF
6.3V
0402
BST2
SYSA
4.7µF
6.3V
0402
SCL
0.22µF
6.3V
0402
BST1
THM
PK+
THM
BATSP
10kΩ
GND
STAT
BATSN
OTGEN
DISQBAT
STBY
www.maximintegrated.com
OTGEN
DISQBAT
STBY
ISET
ITO
INLIM
VSET
CNFG
VPVL
INRUSH
PROTECTION
CIRCUIT
(FOR 3S BATTERY)
PK2/3-CELL LI-ION
BATTERY
Maxim Integrated | 80
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Typical Application Circuits (continued)
Wide-Input Autonomous Charger
MAX77960
MAX77961
10mΩ
1206
3.5V TO 25.4V
VBUS
10µF
35V
1210
CHGIN
LX1
CSINN
CSINP
VPVL
4.7µF
6.3V
0402
PVL
4.7Ω
VAVL 0402
AVL
2.2µH
8A ISAT
LX2
0.22µF
6.3V
0402
BST2
SYS
47µF
16V
1210
SYSA
4.7µF
6.3V
0402
SCL
SDA
INTB
BATT
INOKB
200kΩ
0402
VSYS
3A IF
VBATT
10µF
16V
0805
VAVL
200kΩ
0402
STAT
47µF
16V
1210
PGND
INOKB
VPVL
0.22µF
6.3V
0402
BST1
THM
PK+
THM
BATSP
10kΩ
GND
STAT
OTGEN
DISQBAT
STBY
www.maximintegrated.com
OTGEN
DISQBAT
STBY
BATSN
ISET
ITO
INLIM
VSET
CNFG
INRUSH
PROTECTION
CIRCUIT
(FOR 3S BATTERY)
PK2/3-CELL LI-ION
BATTERY
Maxim Integrated | 81
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Ordering Information
PART NUMBER
TEMP
RANGE
PIN-PACKAGE
SWITCHING
FREQUENCY
AUTONOMOUS
OPERATION SUPPORTED
MAXIMUM
CHARGING
CURRENT
MAX77960EFV06+
-40°C to
+85°C
4mm x 4mm,
30-Lead FC2QFN
600kHz
Yes
3A
MAX77960EFV06+T
-40°C to
+85°C
4mm x 4mm,
30-Lead FC2QFN
600kHz
Yes
3A
MAX77961EFV06+
-40°C to
+85°C
4mm x 4mm,
30-Lead FC2QFN
600kHz
Yes
6A
MAX77961EFV06+T
-40°C to
+85°C
4mm x 4mm,
30-Lead FC2QFN
600kHz
Yes
6A
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
www.maximintegrated.com
Maxim Integrated | 82
MAX77960/MAX77961
25VIN 3A/6AOUT USB-C Buck-Boost Charger with
Integrated FETs for 2S/3S Li-Ion Batteries
Revision History
REVISION
NUMBER
REVISION
DATE
0
9/20
DESCRIPTION
Initial release
PAGES
CHANGED
—
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.
© 2020 Maxim Integrated Products, Inc.
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