MAX77751AEFG [MAXIM]
3.15A USB-C Autonomous Charger for 1-Cell Li Batteries;
| 型号： | MAX77751AEFG |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 3.15A USB-C Autonomous Charger for 1-Cell Li Batteries |
| 文件： | 总40页 (文件大小：1782K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
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MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
Benefits and Features
General Description
•
•
•
•
•
•
Up to 16V Protection
The MAX77751 is a standalone, 3.15A charger with
13.7V Maximum Input Operating Voltage
3.15A Maximum Charging Current
6A Discharge Current Protection
No Firmware or Communication Required
Integrated USB Detection
• CC Detection for USB Type-C
• BC1.2 Detection for Legacy SDP, DCP, and CDP
• Automatic Input Current Limit Configuration
• Input Voltage Regulation with Adaptive Input
Current Limit (AICL)
®
integrated USB Type-C CC detection and reverse
boost capability. The fast-charge current and top-off
current thresholds are easily configured with resistors.
The MAX77751 operates with an input voltage of 4.5V
to 13.7V and has a maximum input current limit of 3A.
The IC also implements the adaptive input current limit
(AICL) function that regulates the input voltage by
reducing input current, to prevent the voltage of a weak
adapter from collapsing or folding back.
The USB Type-C Configuration Channel (CC) detection
pins on the MAX77751 enable automatic USB Type C
power source detection and input current limit
configuration. To support a variety of legacy USB as well
as proprietary adapters, the IC also integrates BC1.2
detection using the D+ and D- pins. The IC runs the CC
detection and BC1.2 detection automatically without any
software as soon as the USB plug is inserted.
•
•
Reverse Boost Capability up to 5.1V, 1.5A
Pin Control of All Functions
• Resistor-Configurable Fast-Charge Current
• Resistor-Configurable Top-Off Current
• ENBST Pin to Enable and Disable Reverse Boost
• STAT Pin to Indicate Charging Status
• INOKB Pin to Indicate Input Power-OK (POK)
• ITOPOFF Pin to Disable Charge
The IC also offers Reverse-Boost capability up to 5.1V,
1.5A, which can be enabled with the ENBST pin. The
STAT pin indicates charging status, while the INOKB pin
indicates valid input voltage. Charging can be stopped
by pulling the ITOPOFF pin low.
•
•
Integrated Battery True-Disconnect FET
3mm x 3mm, 24 Lead FC2QFN Package
Ordering Information appears at end of data sheet.
The MAX77751 is equipped with a Smart Power
Selector™ and a battery true-disconnect FET to control
the charging and discharging of the battery or isolate the
battery in case of a fault. The MAX77751 is offered in
several variants to support Li-ion batteries with various
termination voltages from 4.1V to 4.5V. The IC comes in
a 3mm x 3mm, 0.4mm pitch 24-lead FC2QFN package
making it suitable for low-cost PCB assembly.
Applications
•
•
•
•
•
•
•
Mobile Point-of-Sale (mPOS) Terminals
Portable Medical Devices
Wireless Headphones
GPS Trackers
Charging Cradles for Wearable Devices
Power Banks
Mobile Routers
USB Type-C is a registered trademark of USB Implementers Forum.
Smart Power Selector is a trademark of Maxim Integrated Products, Inc.
19-100802; Rev 4; 11/20
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
Simplified Block Diagram
4.5V TO 13.7V/3A
BYP
CHGIN
10µF +
2.2µF
22µF
USB TYPE-C
CONNECTOR
DP
DN
BST
0.1µF
LX
CC2
CC1
MAX77751
0.47µH
V
SYS
SYS
PVL
SYS
2.2µF
2x10µF
3.15A
INOKB
STAT
PGND
ENBST
IFAST
BATT
10µF
2.2µF
V
DD
ITOPOFF
GND
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Maxim Integrated | 2
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
Absolute Maximum Ratings
CHGIN to GND................................................-0.3V to +16.0V
BYP, LX to PGND............................................-0.3V to +16.0V
BATT, SYS, INOKB, STAT, ENBST to GND .....-0.3V to +6.0V
BST to PVL......................................................-0.3V to +16.0V
BST to LX..........................................................-0.3V to +2.2V
DN, DP to GND .................................................-0.3V to +6.0V
CC1, CC2 to GND .............................................-0.3V to +6.0V
V
, PVL, IFAST, ITOPOFF to GND................ -0.2V to +2.2V
DD
V
, BYP Continuous Current .............................3.2A
CHGIN
RMS
RMS
RMS
LX, PGND Continuous Current ..................................3.5A
SYS, BATT Continuous Current.................................4.5A
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
24 FC2QFN
Package Code
F243A3F+1
21-100385
90-100128
Outline Number
Land Pattern Number
Thermal Resistance, Four-Layer Board:
Junction-to-Ambient (θ
)
31°C/W
7.5°C/W
JA
Junction-to-Case Thermal Resistance (θ
)
JC
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Maxim Integrated | 3
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ 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 | 4
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
Electrical Characteristics
(Limits are 100% tested at T = +25°C. Limits over the operating temperature range and relevant supply voltage range are guaranteed
A
by design and characterization.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
GENERAL ELECTRICAL CHARACTERISTICS
Battery Only Quiescent
Current
USB Type-C as UFP and BATT = SYS =
3.6V
I
30
50
µA
BATT_Q
SWITCHING MODE CHARGER
V
V
CHGIN_
UVLO
CHGIN_
OVLO
CHGIN Voltage Range
V
Operating voltage (Note 1)
V
V
CHGIN
CHGIN Overvoltage
Threshold
V
V
V
rising
falling
13.4
13.7
300
14
CHGIN_OVLO
CHGIN
CHGIN Overvoltage
Threshold Hysteresis
CHGIN to GND
Minimum Turn-On
Threshold Accuracy
CHGIN to SYS
V
CHGINH_OVL
O
mV
CHGIN
V
V
rising
rising
4.6
4.7
4.8
V
V
CHGIN_UVLO
CHGIN
CHGIN
V
+
V
+
V
+
SYS
SYS
0.20
SYS
Minimum Turn-On
Threshold
V
V
CHGIN2SYS
0.12
0.28
CHGIN Adaptive
Voltage Regulation
Threshold Accuracy
CHGIN Current Limit
Range
V
4.4
0.5
4.5
4.6
3.0
4
V
A
CHGIN_REG
Automatically configured after charger-
type detection.
CHGIN_ILIM
V
= 5.0V, Charger enabled, V
CHGIN
= V
SYS
= 4.5V, (No switching, battery
CHGIN Supply Current
I
2.7
mA
IN
BATT
charged)
Charger enabled, 500mA input current
423
460
500
setting, T = +25°C
A
VCHGIN Input Current
Limit
Charger enabled, 1500mA input current
setting, T = +25°C
A
Charger enabled, 3000mA input current
setting, T = +25°C
A
Time required for the charger input to
cause CHGIN capacitor to decay from
6.0V to 4.3V
I
1300
2600
1400
2800
1500
3000
mA
ms
INLIMIT
CHGIN Self-Discharge
Down to UVLO Time
t
100
INSD
CHGIN Input Self-
Discharge Resistance
CHGIN to BYP
Resistance
R
44
45
kΩ
INSD
R
Bidirectional
mΩ
CHGIN2BYP
LX High-Side
Resistance
R
60
60
20
mΩ
mΩ
mΩ
HS
LX Low-Side Resistance
R
LS
BATT to SYS Dropout
Resistance
R
BAT2SYS
Calculation estimates a 0.04Ω inductor
CHGIN to BATT
Dropout Resistance
resistance (R ).
L
R
165
mΩ
CHGIN2BAT
R
= R
+ R + R
HS L
CHGIN2BAT
+ R
CHGIN2BYP
BAT2SYS
LX = PGND or BYP, T = +25°C
LX Leakage Current
0.01
10
µA
A
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Maxim Integrated | 5
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
(Limits are 100% tested at T = +25°C. Limits over the operating temperature range and relevant supply voltage range are guaranteed
A
by design and characterization.)
PARAMETER
BST Leakage Current
BYP Leakage Current
SYMBOL
CONDITIONS
LX = PGND or BYP, T = +85°C
MIN
TYP
1
MAX
UNITS
µA
A
BST = PGND or 1.8V, T = +25°C
0.01
1
10
A
BST = PGND or 1.8V, T = +85°C
A
V
= 5V, V
= 0V, LX = 0V,
CHGIN
BYP
charger disabled, T = +25°C
0.01
1
10
10
A
µA
V
= 5V, V
= 0V, LX = 0V,
CHGIN
BYP
charger disabled, T = +85°C
A
V
SYS
= 0V, V
= 4.2V, charger
BATT
0.01
1
disabled, T = +25°C
A
SYS Leakage Current
µA
V
SYS
= 0V, V = 4.2V, charger
BATT
disabled, T = +85°C
A
Minimum ON Time
Minimum OFF Time
Buck Current Limit
t
75
75
ns
ns
A
ON-MIN
t
OFF-MIN
I
5.16
6.0
6.84
LIM
Reverse Boost
Non-switching: output forced 200mV
above its target regulation voltage
2000
5.1
µA
V
Quiescent Current
Reverse Boost BYP
Voltage in OTG Mode
CHGIN Output Current
Limit
V
4.94
5.26
BYP.OTG
I
CHGIN.OTG.LI
M
3.4V < V
BATT
< 4.5V, T = +25°C
1500
1725
mA
A
Discontinuous inductor current (i.e., skip
mode)
±150
±150
-0.3
Reverse Boost Output
Voltage Ripple
mV
Continuous inductor current
T
A
= +25°C, BATT regulation voltage
-0.9
-1
+0.3
+0.5
(See the Ordering Information table)
= 0°C to +85°C, BATT regulation
BATT Regulation
Voltage Accuracy
%
A
T
A
voltage (See the Ordering Information
table)
-0.3
Fast-Charge Current
Program Range
External resistor programmable
0.5
2850
1900
465
3.15
3150
2100
535
T
= +25°C, V
BATT
> V
,
,
,
A
SYSMIN
SYSMIN
SYSMIN
3000
2000
500
programmed for 3.0A
= +25°C, V > V
T
A
BATT
programmed for 2.0A
= +25°C, V > V
Fast-Charge Currents
I
mA
FC
T
A
BATT
programmed for 0.5A
Trickle Charge
Threshold
V
V
V
V
rising
rising
3.0
2.4
3.1
2.5
100
300
55
3.2
2.6
V
TRICKLE
BATT
Precharge Threshold
V
PRECHG
BATT
Prequalification
Threshold Hysteresis
V
PQ-H
Applies to both V
and V
TRICKLE PRECHG
mV
mA
mA
Trickle Charge Current
I
270
40
330
80
TRICKLE
Precharge Charge
Current
I
PRECHG
Charger Restart
Threshold
V
50
100
150
mV
RSTRT
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Maxim Integrated | 6
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
(Limits are 100% tested at T = +25°C. Limits over the operating temperature range and relevant supply voltage range are guaranteed
A
by design and characterization.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Charger Restart
Deglitch Time
Charger Enable
Threshold
10mV overdrive, 100ns rise time
130
ms
V
295.2
100
367.7
439.7
350
mV
mA
CHGR_EN
Top-Off Current
Program Range
Resistor programmable from 100mA to
350mA
I
TO
Gain
5
%
Top-Off Current
Accuracy
Offset
20
mA
Charge Termination
Deglitch Time
t
2mV overdrive, 100ns rise/fall time
30
ms
TERM
Charger Soft Start Time
t
1.5
70
ms
SS
I
= 10mA
mV
BATT
BATT to SYS Reverse
Regulation Voltage
V
BSREG
Load regulation during the reverse
regulation mode
1
mV/A
V
Minimum SYS Voltage
V
V
3.5
SYSMIN
Minimum SYS Voltage
Accuracy
-3
+3
%
SYSMIN
Applies to both low-battery precharge and
trickle modes
Prequalification Time
t
30
min
PQ
Fast-Charge Constant
Current Plus Fast-
Charge Constant
Voltage Time
t
6
hours
FC
Top-Off Time
t
30
s
TO
Timer Accuracy
-20
+20
%
Junction Temperature
Thermal Regulation
Loop Setpoint Program
Range
Junction temperature when charge
current is reduced
T
REG
130
°C
Thermal Regulation
Gain
AT
I
= 3.15A
FC
-157.5
6.0
mA/°C
A
JREG
BOVCR
BOVRC
Battery Overcurrent
Threshold
I
t
Battery Overcurrent
Debounce Time
Battery Overcurrent
Retry
6
ms
t
0.15
3 +
sec
OCP_RETRY
Battery Overcurrent
Protection Quiescent
Current
I
I
/
µA
BOVRC
BATT
18040
System Power-Up
Current
System Power-Up
Voltage
I
35
50
80
mA
V
SYSPU
V
V
SYS
rising, 100mV hysteresis
1.9
2.0
0.1
2.1
SYSPU
INOKB, STAT
Logic Input Leakage
Current
1
µA
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Maxim Integrated | 7
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
(Limits are 100% tested at T = +25°C. Limits over the operating temperature range and relevant supply voltage range are guaranteed
A
by design and characterization.)
PARAMETER
SYMBOL
CONDITIONS
= 5mA, T = +25°C
MIN
TYP
MAX
0.4
UNITS
Output Low Voltage
INOKB, STAT
I
V
SOURCE
A
V
V
= 5.5V, T = +25°C
-1
0
+1
Output High Leakage
INOKB, STAT
SYS
A
µA
= 5.5V, T = +85°C
0.1
SYS
A
ENBST
ENBST Logic Input Low
Threshold
V
0.4
60
V
V
IL
ENBST Logic Input High
Threshold
V
IH
1.4
ENBST Logic Input
Leakage Current
ENBST Pulldown
Resistor
ENBST = 5.5V (including current through
pulldown resistor)
I
24
µA
kΩ
ENBST
R
235
ENBST
CHARGER DETECTION
BC1.2 State Timeout
t
180
700
200
800
220
900
ms
ms
TMO
Data Contact Detect
Timeout
t
DCDtmo
Proprietary Charger
Debounce
t
5
7.5
35
50
10
39
55
71
ms
ms
ms
PRDeb
Primary-to-Secondary
Timer
t
27
45
57
PDSDWait
Charger Detection
Debounce
t
CDDeb
DP and DN pins. Threshold in percent of
VBUS64 Threshold
VBUS64 Hysteresis
VBUS47 Threshold
VBUS47 Hysteresis
VBUS31 Threshold
V
64
0.015
47
%
V
BUS64
V
BUS
voltage. 3V < V
< 5.5V
BUS
V
BUS64_H
DP and DN pins. Threshold in percent of
voltage. 3V < V < 5.5V
V
43.3
26
51.7
36
%
V
BUS47
V
BUS
BUS
0.015
31
DP and DN pins. Threshold in percent of
voltage. 3V < V < 5.5V
V
%
BUS31
WEAK
V
BUS
BUS
VBUS31 Hysteresis
IWEAK Current
0.015
0.1
V
I
0.01
14.25
7
0.5
24.8
13
µA
kΩ
µA
RDM_DWN Resistor
IDP_SRC Current
R
20
DM_DWN
I
/I
Accurate over 0V to 2.5V
Accurate over 0.15V to 3.6V
10
DP_SRC DCD
I
/I
DM_SINK DAT
SINK
IDM_SINK Current
45
80
125
1.9
µA
VLGC Threshold
V
LGC
1.62
1.7
V
V
V
V
VLGC Hysteresis
V
0.015
0.32
LGC_H
VDAT_REF Threshold
VDAT_REF Hysteresis
V
0.25
0.4
DAT_REF
V
0.015
DAT_REF_H
V
/V
DN_SRC SR
VDN_SRC Voltage
VDP_SRC Voltage
Accurate over I
Accurate over I
= 0 to 200µA
= 0 to 200µA
0.5
0.5
0.6
0.6
0.7
0.7
V
V
LOAD
LOAD
C06
V
/V
DP_SRC SR
C06
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Maxim Integrated | 8
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
(Limits are 100% tested at T = +25°C. Limits over the operating temperature range and relevant supply voltage range are guaranteed
A
by design and characterization.)
PARAMETER
COMP2 Load Resistor
CC DETECTION
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
R
USB
Load Resistor on DP/DN
3
6.1
12
MΩ
CC Pin Voltage, in DFP
1.5A Mode
Measured at CC pins with 126kΩ load.
V
1.85
V
V
V
CC_PIN
IDFP1.5_CC enable and V
≥ 2.5V
AVL
CC Pin Clamp Voltage
V
60µA ≤ I
≤ 600µA
1.1
1.32
5.5
CC_CLAMP
CC_
CC Pin Clamp Voltage
(5.5V)
I
< 2mA
5.25
CC_
CC UFP Pulldown
Resistance
R
-10%
5.1K
+10%
Ω
PD_UFP
CC DFP 1.5A Current
Source
I
-8%
0.15
0.61
180
0.2
+8%
0.25
0.7
µA
V
DFP1.5_CC
CC RA RD Threshold
V
RA_RD0.5
CC UFP 0.5A RD
Threshold
V
0.66
V
UFP_RD0.5
CC UFP 0.5A RD
Hysteresis
V
0.015
1.23
0.15
V
V
UFP_RD0.5_H
CC UFP 1.5A RD
Threshold
V
1.16
1.31
UFP_RD1.5
CC UFP 1.5A RD
Hysteresis
V
V
UFP_RD1.5_H
Max time allowed from removal of voltage
clamp until 5.1kΩ resistor is attached
CC Pin Power Up Time
t
15
ms
ClampSwap
CC Detection Debounce
USB Type-C Debounce
t
100
10
119
15
200
20
ms
ms
CCDeb
t
PDDeb
USB Type-C Quick
Debounce
t
0.9
1
1.1
ms
QDeb
The CHGIN input must be less than V
to turn on.
and greater than both V
and V for the charger
CHGIN2SYS
Note 1:
CHGIN_OVLO
CHGIN_UVLO
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Maxim Integrated | 9
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
Typical Operating Characteristics
(V
= 5V, V
= 3.8V, T = +25°C, unless otherwise noted.)
BATT A
CHGIN
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Maxim Integrated | 10
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
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Maxim Integrated | 11
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
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Maxim Integrated | 12
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
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Maxim Integrated | 13
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
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Maxim Integrated | 14
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
Pin Configurations
FC2QFN
TOP VIEW
23
21
24
22
20
19
1
2
18
17
16
BST
PGND
PVL
INOKB
SYS
3
4
STAT
CC2
CC1
DP
MAX77751FEFG+T
SYS
15
14
13
BATT
5
6
BATT
7
8
9
10
11
12
(3mm x 3mm, 0.4mm PITCH)
Pin Descriptions
PIN
NAME
FUNCTION
Provides Drive to High-Side Internal nMOS. Connect a 100nF/6.3V bootstrap capacitor between this pin
and the LX node.
1
BST
Charger Input Valid, Active Low Logic Output Flag. Open-drain output indicates when valid voltage is
present at CHGIN.
2
3
INOKB
STAT
Open Drain Charge Status Indication Output. STAT toggles low and high impedance during charge.
STAT becomes low when top-off threshold is detected and in done state. STAT becomes high
impedance when charge faults occur.
4
5
6
7
8
9
CC2
CC1
DP
USB Type-C CC2 Connection
USB Type-C CC1 Connection
Common Positive Output 1. Connect to D+ on USB Type-C or micro USB connector.
Common Negative Output 1. Connect to D- on USB Type-C or micro USB connector.
Active High Logic Input. Enable/Disable the Reverse Boost Converter
Analog Ground. Short to ground plane.
DN
ENBST
GND
Output of On-Chip LDO Used to Power On-Chip, Low-Noise Circuits. Bypass with a 2.2µF/10V ceramic
capacitor to GND. Powering external loads from VDD is not recommended other than pullup resistors.
Top Off Current Setting Pin. Connect a resistor (RTOPOFF) from ITOPOFF to GND to program the top-
10
11
12
V
DD
ITOPOFF off current from 100mA to 350mA. Use 8.06kΩ for 100mA top-off current. The pin is also used to enable
or disable the charger. See the Application Information section.
Fast Charge Current Setting Pin. Connect a resistor (RIFAST) from IFAST to GND to program the fast
charge current. Use 24.9kΩ for 3.15A fast charge current. See the Application Information section.
IFAST
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Maxim Integrated | 15
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
Battery Power Connection. Connect to the positive terminal of a single-cell (or parallel cell) Li-ion battery.
Bypass BATT to PGND ground plane with a 10µF ceramic capacitor.
13, 14
15, 16
17
BATT
SYS
PVL
System Power Node. Bypass SYS to PGND with a 2x10µF/10V ceramic capacitor.
Output of On-Chip LDO, Noisy Rail Due to Bootstrap Operation. Bypass with a 2.2µF/10V ceramic
capacitor to PGND. Powering external loads from PVL is not recommended.
18, 19
PGND
Power Ground. Connect the return of the buck output capacitor close to these pins.
Switching Node. Connect an inductor between LX and SYS. When the buck converter is enabled, LX
switches between BYP and PGND to control the input current, battery current, battery voltage, and die
temperature.
20, 21
LX
System Power Connection. Output of OVP adapter input block and input to switching charger. Bypass
with 22µF/16V ceramic capacitor from BYP to PGND.
22
BYP
Charger Input. Up to 13.7V operating, 16VDC withstand input pin connected to an adapter or USB power
source. Connect a 2.2µF/16V ceramic capacitor from CHGIN to GND.
23, 24
CHGIN
Functional Diagram
SYS
1kΩ
INOKB
CHGIN
BYP
BST
10µF+
22µF
CHARGER INPUT SENSE
AND CONTROL
2
MAX77751
V
BUS
2.2µF
PVL
0.1µF
BIAS AND REF
V
DD
2.2µF
LX
2
2
2.2µF
DN
DP
SYS
CC2
PGND
SYS
BC1.2,
USB TYPE-C CC
DETECTION
CHARGER SW
CONTROL,
REVERSE BOOST
2x10µF/10V
CC1
2
10µF
SYS
1kΩ
BATT
2
ENBST
SWITCH
STAT
+
BATTERY
PACK
IFAST
24.9kΩ
ITOPOFF
24.3kΩ
GND
MCU
(OPTIONAL)
www.maximintegrated.com
Maxim Integrated | 16
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
Detailed Description
The MAX77751 is a highly integrated USB Type-C Charger with autonomous configuration. The MAX77751 can operate
at an input range from 4.5V to 13.7V to support a 5V, 9V, and 12V AC adapter and USB input. It is capable of supplying
a fast-charge current up to 3.15A and the maximum input current limit is 3.0A.
The MAX77751 can run BC1.2 and USB Type-C CC detection when USB input is plugged in and can configure the input
source to the maximum power option and the charger input current limit to maximum power.
The fast-charge current and top-off current threshold can be programmed with an external resistor. The input voltage
regulation feature with adaptive input current limit (AICL) allows charging to continue even with a weak adapter by
preventing it from collapsing or folding back.
The power path design provides system power even when the battery is fully discharged, and it supplements current from
the battery and CHGIN input automatically when the system demands higher current.
Reverse boost from the battery can be enabled by the ENBST pin to allow 5.1V/1.5A OTG to V
.
BUS
Switching Mode Charger
Features
•
Complete Li-ion/Li-Polymer Switching Charger
• Prequalification, Constant Current, Constant Voltage Charging
• 55mA Precharge, 300mA Trickle Charge Current
• 500mA to 3.15A Resistor-Adjustable Fast-Charge Current
• 100mA to 350mA Resistor-Adjustable Charge Termination Threshold
• 4.1V to 4.5V Battery Regulation Voltage (see the Ordering Information section)
•
Smart Power Selector
• Optimally Distributes Power Between the Charge Adapter, System, and Battery
• When Powered by a Charge Adapter, the Main Battery Can Provide Supplemental Current to the System
• The Charge Adapter Can Support the System Without a Battery
• 20mΩ BATT to SYS Switch with up to 4.5A Continuous Discharge Capability
•
•
No External MOSFETs Required
4.5V to 13.7V Input Operating Voltage
• Reverse Leakage Protection Prevents the Battery Current Leaking to the Input
• Automatic Detection of USB Type-C and BC1.2 Adapters
• 500mA to 3A Automatic Input Current Limit Selection After USB Charger Type Detection
• Supports Non-USB Sources
•
•
•
•
6-Hour Charge Safety Timer
Die Temperature Monitor with Thermal Foldback Loop (130°C Threshold)
Input Voltage Regulation Allows Operation from High-Impedance Sources (AICL)
Short Circuit Protection
• BATT to SYS Overcurrent Threshold: 6A
• SYS Short-to-Ground
www.maximintegrated.com
Maxim Integrated | 17
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
V
/V
CHGIN
USB ADP
Q
CHGIN
BYP
CHGIN
BST
5.1V
UP TO +13.7V OPERATING
UP TO 3.0A INPUT CURRENT
(REVERSE BOOST MODE)
Q
HS
CHGIN INPUT CURRENT
LIMIT SWITCH
LX
BUCK/BOOST
CONTROLLER
Q
LS
PGND
SYS
Q
BAT
CHARGE AND
SMART POWER
MAX77751
PATH CONTROLLER
UP TO 3.0A
CHARGE CURRENT
BATT
+
Figure 1. Simplified Functional Diagram
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Maxim Integrated | 18
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
MAX77751
R
INSD
Q
CHGIN
V
BYP
CHGIN
BYP
BYP
V
/V
USB ADP
22µF
16V
0603
10µF
16V
0603
2.2µF
16V
0603
UP TO +13.7V OPERATING
UP TO 3.0A INPUT CURRENT
V
CHGIN
INPUT CONTROL
WATCHDOG
CHARGE
TIMER
BST
HS
0.1µF
6.3V
1.3MHz
0402
Q
BUCK CONTROLLER
0.47µH
LX
DRV_OUT
CHARGE CONTROLLER
Q
LS
REVERSE BOOST
CONTROLLER
PGND
JUNCTION
TEMPERATURE
SENSOR TEMP
SYS
SYS
T
J
V
SYS
2x10µF
10V
0603
Q
BAT
V
IBATT
BATT
BATT
10µF
10V
0603
UP TO 3.0A OF
CHARGE
CURRENT AND
UP TO 6A OF
DISCHARGE
CURRENT
BATT
GND
+
V
MBATT
Figure 2. Battery Charger Detailed Functional Diagram
Detailed Description
The MAX77751 includes a full-featured switch-mode charger for a one-cell lithium ion (Li+) or lithium polymer (Li-polymer)
battery. As shown in Figure 2, the current limit for the CHGIN input is automatically configured allowing the flexibility for
connection to either an AC-to-DC wall charger or a USB port.
The synchronous switch-mode DC-DC converter utilizes a high 1.3MHz switching frequency, which is ideal for portable
devices because it allows the use of small components while eliminating excessive heat generation. The DC-DC has both
a buck and a boost mode of operation. When charging the battery, the converter operates as a buck. The DC-DC buck
www.maximintegrated.com
Maxim Integrated | 19
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
operates from a 4.3V to 13.7V source and delivers up to 3.15A to the battery. The battery charge current is programmable
from 500mA to 3.15A with an external resistor.
As a boost converter, the DC-DC uses energy from the battery to boost the voltage at BYP. The boosted BYP voltage
supplies the power to CHGIN as USB OTG voltage, which is fixed to 5.1V.
Maxim’s Smart Power Selector architecture makes the best use of the limited adapter power and the battery power at all
times to supply up to the Buck Current Limit from the buck to the system (supplement mode also provides additional
current from the battery to the system up to B2SOVRC). Adapter power that is not used for the system goes to charging
the battery. All power switches for charging and switching the system load between the battery and adapter power are
included on chip—no external MOSFETs are required.
Maxim’s proprietary process technology allows for low-RDSON devices in a small solution size. The total dropout
resistance from adapter power input to the battery is 165mΩ (typ) assuming that the inductor has 0.04Ω of ESR. This
165mΩ typical dropout resistance allows for charging a battery up to 3.0A from a 5V supply. The resistance from the
BATT-to-SYS node is 20mΩ, allowing for low-power dissipation and long battery life.
A multitude of safety features ensures reliable charging. Features include a charge timer, junction thermal regulation,
over/undervoltage protection, and short circuit protection.
The BATT-to-SYS switch has overcurrent protection (see the Battery Overcurrent Protection section for more information).
Smart Power Selector
The Smart Power Selector (SPS) architecture is a network of internal switches and control loops that distributes energy
between CHGIN, BYP, SYS, and BATT.
Figure 1 shows a simplified arrangement for the smart power selector’s power steering switches. Figure 2 shows a more
detailed arrangement of the smart power selector switches and gives them the following names: Q
, Q , Q , and
CHGIN
HS LS
Q
BAT
.
Switch and Control Loop Descriptions
•
•
•
CHGIN Input Switch: Q
provides input overvoltage protection of +16V. The input switch is either completely on
CHGIN
or completely off. As shown in Figure 2, there are SPS control loops that monitor the current through the input switches
as well as the input voltage.
DC-DC Switches: Q
and Q are the DC-DC switches which can operate as a buck (step-down) or a boost (step-
HS
LS
up). When operating as a buck, energy is moved from BYP to SYS. When operating as a boost, energy is moved from
SYS to BYP. SPS control loops monitor the DC-DC switch current, the SYS voltage, and the BYP voltage.
Battery-to-System Switch: Q
controls the battery charging and discharging. Additionally, Q
allows the battery
BAT
BAT
to be isolated from the system (SYS). An SPS control loop monitors the Q
current.
BAT
SYS Regulation Voltage
•
When the DC-DC is enabled as a buck and the charger is enabled but in a non-charging state (i.e., Done, thermal
shutdown, or timer fault), V is regulated to V and Q is off.
SYS
BATTREG
BAT
•
When the DC-DC is enabled as a buck and is charging in trickle-charge, fast-charge, or top-off modes, V
is
SYS
regulated to V
and is charging in precharge mode (V
when the V
< V
< V
< V
. Additionally, when the DC-DC is enabled as a buck
SYSMIN
SYSMIN
PRECHG
BATT
), V
PRECHG
is regulated to V
. In these modes, the Q
BATTREG BAT
BATT
SYS
switch acts like a linear regulator and dissipates power [P = (V
- V
) × I
BATT
]. When V
BATT
> V
, then
SYSMIN
SYS
BATT
V
= V
I
× R
. In this mode, the Q
switch is closed.
SYS
BATT + BATT
BAT2SYS
BAT
For the above modes, if the combined SYS loading exceeds the input current limit, then V
and the battery provides supplemental current.
drops to V
– V
,
BSREG
SYS
BATT
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Maxim Integrated | 20
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
Input Validation
The charger input is compared with several voltage thresholds to determine if it is valid. A charger input must meet the
following three characteristics to be valid:
•
CHGIN must be above V
to be valid
CHGIN_UVLO
Once CHGIN is above the UVLO threshold, the information (together with LIN2SYS, as shown in Figure 3) is latched
and can only be reset when the charger is in the adaptive input current loop (AICL) and the input current is lower than
the IULO threshold of 60mA. Note that V
is lower than the UVLO falling threshold.
CHGIN_REG
•
•
CHGIN must be below its overvoltage lockout threshold (V
)
CHGIN_OVLO
CHGIN must be above the system voltage (V
)
CHGIN2SYS
INPUT IS NOT
OVERVOLTAGE
V
CHGIN
V
CHGIN_OVLOB
USB_CHGR_EN
S
R
Q
V
INPUT IS NOT
UNDERVOLTAGE
CHGIN_VLD
V
V
V
CHGINUVLO
LOW INPUT TO
SYS HEADROOM
LIN2SYS
CHGIN2SYS
ADAPTIVE INPUT
CURRENT LOOP
CHGIN_REG
I_IULO
INPUT CURRENT
LOW
I
CHGIN2BYP
Figure 3. CHGIN Valid Signal Generation Logic
If V
is greater than V
, the USB Type-C CC and BC1.2 detection process starts. After the MAX77751
CHGIN_UVLO
CHGIN
finishes USB detection, the switcher in the chip starts. The system can detect that a valid charger is present by the INOKB
output signal, which is issued when the switcher starts and the VCHGIN_VLD signal is valid, as shown in Figure 4.
Figure 4. INOKB Signal Generation Logic
Input Current Limit
After the charger-type detection is done, the MAX77751 automatically configures the input current limit to the highest
settings that the source can provide. If the input source is not a standard power source described by BC1.2 or USB Type-
C or is not a proprietary charger type that the MAX77751 can detect, the MAX77751 sets the input current limit to 3A.
www.maximintegrated.com
Maxim Integrated | 21
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
Input Voltage Regulation Loop
An input voltage regulation loop allows the charger to be well behaved when it is attached to a poor-quality charge source.
The loop improves performance with relatively high resistance charge sources that exist when long cables are used or
devices are charged with noncompliant USB hub configurations.
The input voltage regulation loop automatically reduces the input current limit in order to keep the input voltage at
V
V
. If the input current limit is reduced to I
, then the charger input is turned off.
(50mA typ) and the input voltage is below
CHGIN_REG
CHGIN_REG
CHGIN_REG_OFF
Input Self-Discharge
When the charge source is removed, the input voltage decays below the UVLO threshold in time (t
). The input self-
INSD
discharge is implemented with a 44kΩ resistor (R
) from the CHGIN input to ground.
INSD
Charger States
The MAX77751 utilizes several charging states to safely and quickly charge batteries, as shown in Figure 5 and Figure 6.
Figure 5 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: precharge ➔ trickle ➔fast-charge ➔top-off
➔done.
NOT TO SCALE, V
= 5.0V, I
= 0A, T = +25°C
SYS J
CHGIN
V
BATTREG
V
RSTRT
V
TRICKLE
V
PRECHG
0V
TIME
I
I
CHG SET
I
TRICKLE
I
TO
I
PRECHG
0A
TIME
CHARGER
ENABLED
Figure 5. Li+/Li-Poly Charge Profile
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Maxim Integrated | 22
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
INIT
INPUT IS VALID
INKOB = HI-Z OR STAT = HI-Z
ICHG = 0
CHG TIMER = 0
INPUT IS INVALID
BUCK
INKOB = LOW OR STAT = HI-Z
SWITCHER = BUCK MODE
QBAT = OFF UNLESS SUPPLEMENT
VITOPOFF > VCHGR_EN
AND TJ < TSHDN
VPRECHG VBATT
and PQEN = 0
(SOFT START)
PRECHARGE
INOKB = LOW AND
STAT = BLINK
CHG TIMER ꢀ tPQ
CHG TIMER SUSPEND
ICHG IPRRECHG
VPRECHG VBATT
(SOFT START)
VBATT < VPRECHG
(SOFT START)
CHG TIMER ꢀ tPQ
CHG TIMER SUSPEND
TRICKLE CHARGE
INOKB = LOW AND
STAT = BLINK
ICHG ITRICKLE
TIMER FAULT
INOKB = LOW AND STAT = HI-Z
VBATT < VTRICKLE
AND
VPRECHG VBATT
ICHG = 0
VTRICKLE VBATT
(SOFT START)
VBATT < VRECHG
(SOFT START)
VITOPOFF < VCHGR_EN
OR TJ > TSHDN
CHG TIMER SUSPEND
CHG TIMER ꢀ tFC
CHG TIMER SUSPEND
INPUT IS INVALID
CHG TIMER SUSPEND
FAST CHARGE (CC)
INOKB = LOW AND
STAT = BLINK
ICHG IFC
VBATTREG VBATT
I
< ICHG
FC
CHG TIMER ꢀ tFC
CHG TIMER SUSPEND
FAST CHARGE (CV)
INOKB = LOW AND
STAT = BLINK
ANY CHARGING STATE
ITO < ICHG IFC
ICHG ITO FOR tTERM
TOP OFF
INOKB = LOW AND
STAT = LOW
ICHG ITO
VBATT < (VBATTREG – VRSTRT
(NO SOFT START)
)
CHG TIMER ꢀ tTO
CHG TIMER SUSPEND
CHARGER STATE WHERE THE CHARGE IS DISABLED
(BATTERY CHARGE STOPPED)
CHARGER STATE WHERE THE CHARGE IS ENABLED
(BATTERY CHARGE ON-GOING)
DONE
INOKB = LOW AND
STAT = LOW
ICHG = 0
VBATT < VPQLB
CONDITION NEEDED TO TRANSITION BETWEEN TWO CHARGER STATES
CHG TIMER = 0
CHG TIMER
VBATT < (VBATTREG – VRSTRT
)
CHG TIMER RESUME
TRANSITION BETWEEN TWO CHARGER STATES
Figure 6. Charger State Diagram
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Maxim Integrated | 23
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
INIT State
From any state shown in Figure 6 except thermal shutdown, the INIT state is entered whenever the charger inputs that
CHGIN is invalid or the charger timer is suspended.
While in the INIT state, the charger current is 0mA, the charge timer is forced to 0, and the power to the system is provided
by the battery.
To exit the INIT state, the charger input must be valid.
Buck State
The chip has a state where battery charging is disabled while the charger input CHGIN is valid. The state is called buck
state. Entering or leaving buck state is controlled by the voltage of the ITOPOFF pin. If the voltage of this pin is pulled
down by an external device (i.e., MCU) under V
, the chip goes to the buck state from any state if CHGIN is
CHGR_EN
valid, as shown in Figure 6. In the buck state, charging is disabled, which means Q
is off, unless it is in supplement
BAT
mode. If the voltage of this pin is over V
, the chip gets out of the buck state and resumes charging. Note that
CHGR_EN
only when CHGIN is valid, charging can be enabled or disabled. Therefore, the external device (i.e., MCU) should check
using the INOKB signal if CHGIN is valid before trying to enable or disable charging.
Precharge State
As shown in Figure 6, the precharge state occurs when the battery voltage is less than V
. In the precharge state,
PRECHG
charge current into the battery is I
.
PRECHG
The following events cause the state machine to exit this state:
•
•
Battery voltage rises above V
, and the charger enters the next state in the charging cycle, trickle charge state.
PRECHG
If the battery charger remains in this state for longer than t , the charger state machine transitions to the timer fault
PQ
state.
The precharge state works with battery voltages down to 0V. The low 0V operation typically allows this battery charger to
recover batteries that have an “open” internal pack protector. Typically, an internal pack 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 state current flows into the 0V battery—this current raises the pack’s terminal voltage
to the voltage 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 state for longer than t
might be experiencing a problem.
PQ
Trickle Charge State
As shown in Figure 6, the trickle charge state occurs when V
> V
and V
< V
.
TRICKLE
BATT
PRECHG
BATT
When the MAX77751 is in the trickle charge state, the charge current in the battery is less than or equal to I
.
TRICKLE
The charge current might be less than I
for any of the following reasons:
TRICKLE
•
•
•
•
The charger input current is lower than the 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 main battery voltage rises above V
charge constant current state.
, the charger enters the next state in the charging cycle, fast-
TRICKLE
•
If the battery charger remains in this state for longer than t , the charger state machine transitions to the timer fault
PQ
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 state for longer than t
might be experiencing a problem.
PQ
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Maxim Integrated | 24
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
Fast-Charge Constant Current State
As shown in Figure 6, the fast-charge constant current (CC) state occurs when the battery voltage is greater than the
trickle threshold and less than the battery regulation threshold (V < V < V ).
TRICKLE
BATT
BATTREG
In the fast-charge CC state, the current into the battery is less than or equal to I . The charge current can be less than
FC
I
for any of the following reasons:
FC
•
•
•
•
The charger input current is lower than the 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 battery voltage rises above V
constant voltage state.
, the charger enters the next state in the charging cycle, fast-charge
BATTREG
•
If the battery charger remains in this state for longer than t , the charger state machine transitions to the timer fault
FC
state.
The battery charger dissipates the most power in the fast-charge CC state. This power dissipation causes the internal die
temperature to rise. If the die temperature exceeds T
, I is reduced. See the Thermal Foldback section for more
REG FC
information.
Fast-Charge Constant Voltage State
As shown in Figure 6, the fast-charge constant voltage (CV) state occurs when the battery voltage rises to V
BATTREG
from the fast-charge CC state.
In the fast-charge CV state, the battery charger maintains V
across the battery, and the charge current is less
BATTREG
than or equal to I . As shown in Figure 5, the charger current decreases exponentially in this state as the battery
FC
becomes fully charged.
The smart power selector control circuitry might reduce the charge current lower than the battery can otherwise consume
for any of the following reasons:
•
•
•
•
The charger input current is lower than the 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 I for t
, the charger enters the next state in the charging cycle, top-off state.
TO
TERM
If the battery charger remains in this state for longer than t , the charger state machine transitions to the timer fault
FC
state.
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Maxim Integrated | 25
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
Top-Off State
As shown in Figure 6, the top-off state can only be entered from the fast-charge CV state when the charger current
decreases below I for t . In the top-off state, the battery charger tries to maintain V across the battery,
TO
TERM
BATTREG
and typically, the charge current is less than or equal to I
.
TO
The smart power selector control circuitry might reduce the charge current lower than the battery can otherwise consume
for any of the following reasons:
•
•
•
•
The charger input current is lower than the 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:
•
•
After being in this state for the top-off time (t ), the charger enters the next state in the charging cycle, done state.
TO
If V
< V
– V
, the charger goes back to the fast-charge CC state
RSTRT
BATT
BATTREG
Done State
As shown in Figure 6, the battery charger enters its done state after the charger has been in the top-off state for t
.
TO
The state machine exits this state if V
state
< V
– V
and the charger goes back to the fast-charge CC
RSTRT
BATT
BATTREG
In the done state, the charge current into the battery (I
) is 0A, and the charger presents a very low quiescent current
CHG
to the battery. If the system load presented to the battery is low (<<100μA), then a typical system can remain in the done
state for many days. If left in the done state long enough, the battery voltage decays below the restart threshold (V
)
RSTRT
and the charger state machine transitions back into the fast-charge CC state. There is no soft-start (di/dt limiting) during
the done state to fast-charge state transition.
Timer Fault State
The battery charger provides a charge timer to ensure safe charging. As shown in Figure 6, the charge timer prevents
the battery from charging indefinitely. The time that the charger is allowed to remain in each of its prequalification states
is t . The time that the charger is allowed to remain in the fast-charge CC and fast-charge CV states is t . Finally, the
PQ
FC
time that the charger is in the top-off state is t . Upon entering the timer fault state, STAT becomes Hi-Z.
TO
In the timer fault state, the charger is off. The charger input can be removed and re-inserted to exit the timer fault state
(see the “any state” bubble in the lower left of Figure 6).
Thermal Shutdown State
As shown in Figure 6, the thermal shutdown state occurs when the battery charger is in any state and the junction
temperature (T ) exceeds the device’s thermal shutdown threshold (TSHDN). When T is close to T , the charger
J
J
REG
folds back the charge current to 0A so that the charger is effectively off (see the Thermal Foldback section).
In the thermal shutdown state, the charger is off.
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Maxim Integrated | 26
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
Reverse Boost Mode
The DC-DC converter topology of the MAX77751 allows it to operate as a buck converter or as a reverse boost converter.
The modes of the DC-DC converter are controlled by ENBST. When ENBST = high, the DC-DC converter operates in
reverse boost mode allowing it to source current to BYP and CHGIN. It is commonly referred to as OTG mode or a source
role.
The current through the BYP to CHGIN switch is limited to 1.5A minimum. When the reverse boost mode is enabled, the
unipolar CHGIN transfer function measures current going out of CHGIN.
The BYP to CHGIN switch automatically tries to retry after 300ms if CHGIN loading exceeds the 1.5A current limit. If the
overload at CHGIN persists, then the CHGIN switch toggles ON and OFF with approximately 60ms ON and approximately
300ms OFF.
Battery Overcurrent Protection During System Power-Up
The battery overcurrent protection during system power-up feature limits the battery to system current to I
if V
SYS
SYSPU
is less than V
. This feature limits the surge current that typically flows from the battery to the device’s low-
SYSPU
impedance system to bypass capacitors during a system power-up. System power-up is anytime that energy from the
battery is supplied to SYS when V < V . This system power-up condition typically occurs when a battery is hot
SYS
SYSPU
inserted into an otherwise unpowered device.
When system power-up occurs due to hot-insertion into an otherwise unpowered device, a small delay is required for this
feature’s control circuits to activate. A current spike over I
might occur during this time.
SYSPU
Battery Overcurrent Protection Due to Fault
The MAX77751 protects itself, the battery, and the system from potential damage due to excessive battery discharge
current. Excessive battery discharge current can occur for several reasons such as exposure to moisture, a software
problem, an IC failure, a component failure, or a mechanical failure that causes a short circuit.
When the battery (BATT)-to-system (SYS) discharge current (I
) exceeds 6A for at least t
BATT
, then the MAX77751
BOVRC
disables the BATT-to-SYS discharge path (Q
switch) and turns off buck.
BAT
Under the OCP fault condition, when SYS is low (V
< V
) for t
, the MAX77751 restarts on its own
OCP_RETRY
SYS
SYSUP
and attempts to pull up SYS again. If the fault condition remains, the whole cycle repeats until this fault condition is
removed.
Thermal Foldback
Thermal foldback maximizes the battery charge current while regulating the MAX77751 junction temperature. As shown
in Figure 7, when the die temperature exceeds the REGTEMP (T
), a thermal limiting circuit reduces the battery
REG
charger’s target current by 5% of the fast charge current per 1°C (A
), which corresponds to 157.5mA/°C when the
TJREG
fast charge current is 3.15A. The target charge current reduction is achieved with an analog control loop (i.e., not a digital
reduction in the input current).
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Maxim Integrated | 27
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
DRAWN TO SCALE, V
= 5.0V, V
SYS
= 0A, CHGIN INPUT CURRENT LIMIT IS SET TO MAXIMUM
CHGIN
I
= 3.15A
FC
3.0A
A
= -5%/°C
TJREG
2.0A
1.0A
0.0A
T
+ 20°C
T
JREG
JREG
JUNCTION TEMPERATURE (°C)
Figure 7. Charge Currents vs. Junction Temperature
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Maxim Integrated | 28
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
V
DD
Internal Supply
V
is the 1.8V power for the MAX77751 charger’s analog circuit. V
is generated from the higher value between BATT
DD
DD
and CHGIN as the power input source and generates the internal power supply. V
has a bypass capacitance of 2.2µF.
DD
ENBST For Reverse Boost
ENBST is an input control signal for the reverse boost mode with an external logic signal. If ENBST is driven high, the
reverse boost is enabled and the BYP-to-CHGIN path is closed. ENBST has an internal 235kΩ pulldown resistor. When
ENBST sets to high, the MAX77751 disconnects Rd from the CC line and provides a 180μA current source.
USB BC1.2 Charger Detection
Features
•
•
•
D+/D- Charging Signature Detector
USB BC1.2 Compliant SDP, DCP, and CDP Detection
Proprietary Charger Types Detection
• Apple 500mA, 1A, 2A, 2.4A
• Samsung 2A
Description
The USB charger detection is USB BC1.2 compliant with the ability to automatically detect some common proprietary
charger types.
The Charger Detection State Machine follows USB BC1.2 requirements and detects SDP, CDP, and DCP types. In
addition to the USB BC1.2 State Machine, the IC also detects a limited number of proprietary charger types (Apple and
Samsung). The IC automatically sets the CHGIN input current limit based on the charger type detection results. If charger
type detection results are an unknown charger type or D+/D- are found as open, the input current limits are set to 3A max.
Table 1. USB BC1.2 Detected Charger Type
INPUT CURRENT LIMIT
CHARGER DETECTED
500mA
1.5A
1.5A
SDP
CDP
DCP
Table 2. Detected Proprietary Charger Type
INPUT CURRENT LIMIT
CHARGER DETECTED
500mA
1A
Apple
Apple
2A
Apple
2.4A
2A
3A
Apple
Samsung
All others
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Maxim Integrated | 29
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
USB Type-C CC Detection
Features
•
•
USB Type-C Sink Support
CC Source Detection
• Automatic Set of the Input Current Limit According to Source Capability
•
Source Role Support by ENBST Pin
CC Description
The MAX77751 is sink compliant to the USB Type-C Rev 1.2 specifications. The USB Type-C functions are
controlled by a logic state machine which follows the USB Type-C requirements. The MAX77751 sets the CHGIN
input current limit based on the current advertised on the CC wires. The source role is enabled by the ENBST pin.
When the source role is enabled, Rd is removed, and a 180μA current source is connected.
Detecting Connected Source
When a source is detected, the USB Type-C state machine auto detects the active CC line. The state machine also
automatically detects the source advertised current (500mA, 1.5A, and 3.0A). Upon detection of a change in the
advertised current, the MAX77751 automatically sets the input current limit.
D+/D- Detection in CC Detection
The MAX77751 executes D+/D- detection and CC detection in parallel and takes the higher of the two input current limit
values determined by D+/D- detection and by CC detection. No connection in the D+ and D- lines is considered as an
unknown adapter, and therefore the final input current limit is always 3A, regardless of the CC detection result.
Non-USB Type-C Connector Cases
Some target systems could have other types of connectors such as Micro-B and barrel connectors other than USB Type-
C connectors. Since the Micro-B connector does not have CC1 and CC2 pins and the barrel connector does not have
CC1, CC2, D+ and D- pins, the recommended connections described in the following sections can be used in the target
system.
Micro-B Connector
In the case of a Micro-B connector, CC1 and CC2 can be floated as shown in Figure 8. When CC1 and CC2 are floating,
the MAX77751 determines the input current limit solely based on D+/D- detection such as BC1.2 and some proprietary
TA detection.
USB MICRO-B
CONNECTOR
V
BUS
CHGIN
CC1
CC2
DP
MAX77751
D+
D-
DN
Figure 8. USB Signal Connections for a Micro-B Connector
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Maxim Integrated | 30
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
Barrel Connectors
When a barrel connector is used in the application, there is no connection to determine the input current limit. Resistors
can be connected to mimic BC1.2 detection and/or CC detection to configure the desired input current limit. If the capacity
of the power source is 500mA, the MAX77751 can set the input current limit to 500mA by configuring resistors on DP/DN
for BC1.2 SDP (Figure 9). R1 and R2 should have the same resistance with the recommended value of 20kΩ. Meanwhile,
if the capacity of the power source is 1.5A, the MAX77751 can set the input current limit to 1.5A by connecting a resistor
for BC1.2 DCP as shown in Figure 10. The recommended value of resistor R is 200Ω.
BARREL
CONNECTOR
V
BUS
CHGIN
CC1
CC2
DP
MAX77751
R
1
DN
R
2
Figure 9. Connections for a Barrel Connector (500mA Power Source)
BARREL
CONNECTOR
V
BUS
CHGIN
CC1
CC2
DP
MAX77751
R
DN
Figure 10. Connections for a Barrel Connector (1.5A Power Source)
Enable Source Role
ENBST = high enables the MAX77751's source role. The MAX77751 disconnects Rd from the CC line and connects an
180μA current source to advertise the 5V/1.5A power source. The MAX77751 enables the reverse boost and supply
5.1V/1.5A through the CHGIN pin.
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Maxim Integrated | 31
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
Applications Information
Fast-Charge Current Setting
When a valid input source is present, the battery charger attempts to charge the battery with a fast-charge current
determined by the resistance from I to GND. Table 3 shows the resistance values which correspond to the target
FAST
I
values.
FAST
Table 3. Fast-Charge Current Settings
RESISTANCE (kΩ)
I
(mA)
FAST
3150
24.9
22.6
20.5
18.7
16.9
15.4
14
3000
2800
2500
2400
2200
2000
1800
1500
1400
1200
1000
800
12.4
11
9.53
8.2
6.65
5.23
3.6
600
2.4
500
Top-Off Current Setting
The top-off charging current is programmed by an external resistor connected from ITOPOFF to GND (RTOPOFF).
Table 4 shows the resistance values which correspond to the target ITOPOFF values.
Table 4. Top-Off Current Settings
RTOPOFF (kΩ)
ITOPOFF (mA)
24.3
19.6
16.5
13.3
10.2
8.06
350
300
250
200
150
100
D+/D- Multiplexing
The USB D+/D- lines, which are used for BC1.2 and proprietary adapter detection, can be used for data communication.
If an MCU handles this communication in the target system, the D+/D- lines can be connected to the MAX77751 and the
MCU, as shown in Figure 11. The switchers are required for each D+ and D- lines to guarantee high impedance state for
the MCU connections to avoid incorrect adapter detection. It is recommended to connect the MAX77751’s INOKB to the
MCU in this configuration so that the MAX77751 can signal that detection is complete to the MCU. When the MCU
receives a valid INOKB signal, it can switch the D+/D- lines from the MAX77751 to the MCU for data communication.
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Maxim Integrated | 32
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
USB TYPE-C
CONNECTOR
CHGIN
CC1
V
BUS
CC1
CC2
D+
CC2
MAX77751
DP
D-
DN
INOKB
GPIO
GPIO
MCU
D+
D-
Figure 11. D+/D- Connections in a Reference System
Capacitor Selection
All capacitors should be X5R dielectric or better. Be aware that multi-layer ceramic capacitors have large voltage
coefficients. Before selecting capacitors, check for sufficient voltage rating and derated capacitance at the max operating
voltage condition. Table 5 shows the capacitors to select after considering the derating and operating voltage.
Table 5. Capacitor Selections
PIN
TYPE
2.2µF/16V
CHGIN Capacitor
BYP Capacitor
SYS Capacitor
BATT Capacitor
VDD Capacitor
PVL Capacitor
BST Capacitor
10µF + 22µF/16V
2x10µF/10V
10µF/10V
2.2µF/10V
2.2µF/10V
100nF/6.3V
Thermal Considerations
If the system that includes the MAX77751 can read the battery temperature, the temperature can be controlled by
adjusting the battery current through enabling switching and disabling charging. As described in the Buck State section,
charging is disabled by pulling the ITOPOFF pin low. Figure 12 shows a recommended system diagram where the MCU
has an ADC to sense the temperature, a GPIO output connected to ITOPOFF to enable or disable charging, and a GPIO
input connected to INOKB to check the presence of a valid charger. Note that the GPIO output should be an open-drain
type. In this system configuration, if the MCU judges the temperature is too high, the MCU should pull the GPIO output
low to disable charging. It is important to check if a valid charger is present through the INOKB signal before disabling
charging. Pulling ITOPOFF low when the INOKB signal is high (i.e., inactive) could affect the TOPOFF current sensing.
Meanwhile, if the temperature goes back to normal, the MCU should make the GPIO be high impedance state to enable
charging.
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Maxim Integrated | 33
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
INOKB
VCC
GPIO
(INPUT)
MCU
MAX77751
ADC
GPIO
(OPEN DRAIN
OUTPUT)
ITOPOFF
THERMISTOR
RTOPOFF
Figure 12. System Configuration for Temperature Management
If the system does not have an MCU which can get the INOKB signal from the MAX77751 and provide the enable or
disable signal to ITOPOFF of the MAX77751, the circuit depicted in Figure 13 can provide the same function which the
MCU does in Figure 12. The Hot and Cold Temperature Detection portion of the circuit detects if the temperature is
greater than the hot threshold or less than the cold threshold. If the temperature is hot or cold, it provides the disable
signal (Active High) to the INOKB Control portion of the circuit, which can control the disable signal according to the
INOKB status. If INOKB is high (i.e., the charger input is not valid), the disable signal from the temperature detection part
is blocked. If INOKB is low (i.e., the charger input is valid), the disable signal passes through the INOKB Control part and
reach the ITOPOFF pin of the MAX77751. If the output of the temperature detection part is high (i.e., the disable signal)
when INOKB is low, ITOPOFF is pulled low, and battery charging through the MAX77751 is disabled.
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Maxim Integrated | 34
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
V
SYS
VSYS
470Ω
INOKB
100KΩ
VSYS
100KΩ
MAX9027
MAX9027
MAX77751
ITOPOFF
100KΩ
RT = 100KΩ
AT +25°C
1MΩ
RTOPOFF
INOKB CONTROL
HOT AND COLD TEMPERATURE DETECTION
Figure 13. System Configuration for Temperature Management
www.maximintegrated.com
Maxim Integrated | 35
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
Non-USB Type Power Source
In an application where the power source is not USB, all the USB related pins such as CC1, CC2, DP, and DN should be
left not connected (NC). In this case, the input current to the MAX77751 is limited to 3A.
Recommended PCB Layout and Routing
Place all bypass capacitors for CHGIN, BYP, SYS, V , and BATT as close as possible to the IC. Connect the battery to
DD
BATT as close as possible to the IC to provide accurate battery voltage sensing. Provide a large copper ground plane to
allow the PGND pad to sink heat away from the device. Use wide and short traces for high current connections such as
CHGIN, BYP, SYS, and BATT to minimize voltage drops. The MAX77751 has two kinds of ground pins: PGND and GND.
Carefully connect PGND because it is a switching node ground of the Charger Buck. It should be tied to ground of the
SYS and BYP capacitors and connected to the ground plane directly without sharing other ground. The GND can be
connected to the ground plane.
Figure 14 is a recommended placement and layout guide.
Figure 14. Recommended Placement and Layout
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Maxim Integrated | 36
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
Inductor Selection
The MAX77751's control scheme requires an external inductor from 0.47μH to 1μH for proper operation.
Table 6. Recommended Inductors
INDUCTANCE
I
I
DCR(TYP)
SIZE (L x W x T)
(mm)
SAT(TYP) RMS(TYP)
MANUFACTURER
PART NUMBER
(μH)
(A)
5.5
6
(A)
4.5
4.5
5
(mΩ)
SEMCO
SEMCO
SEMCO
CYNTEC
CIGT252008LMR47MNE
CIGT252010LMR47MNE
CIGT201610EHR47MNE
HTGH25201T-R47MSR-68
0.47
0.47
0.47
0.47
24
24
2.5 x 2.0 x 0.8
2.5 x 2.0 x 1.0
2.0 x 1.6 x 1.0
2.5 x 2.0 x 1.0
5.9
6.6
18
5.6
16.5
Charger Status Outputs
Input Status (INOKB)
INOKB is an open-drain and active low output that indicates the input status. If a valid input source is inserted and the
buck converter starts switching, INOKB pulls low. When the reverse boost is enabled, INOKB pulls low to indicate 5V
output from CHGIN.
INOKB can be used as a logic output for the system processor by adding a 200kΩ pullup resistor to the system IO voltage.
INOKB can also be used as an LED indicator driver by adding a current limit resistor and an LED to SYS.
Charging Status Output (STAT)
STAT is an open-drain and active low output that indicates charge status. Table 7 shows the STAT status changes.
Table 7. STAT Output Per Charging Status
CHARGING STATUS
STAT
LOGIC STATE
CHARGE STATUS LED
No input
High impedance
High
Off
Trickle, precharge, fast
charge
Repeat low and high impedance
with 1Hz, 50% duty cycle
After an external diode and a
capacitor rectifier, high
Blinking with 1Hz, 50% duty
cycle.
Top-off and done
Faults
Low
Low
High
Solid on
Off
High impedance
STAT can be used as a logic output for the system processor by adding a 200kΩ pullup resistor to the system IO voltage
and a rectifier (a diode and a capacitor).
STAT also can be used as an LED indicator driver by adding a current limit resistor and an LED to SYS.
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Maxim Integrated | 37
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
Typical Application Circuit
Figure 15 illustrates a typical charger application using the MAX77751. Although there are connections between the MCU
and the MAX77751, USB detection and battery charging occur automatically without MCU intervention. In the application,
the MCU performs two functions: controls the D+/D- switch (MAX4906) and enables or disables battery charging. For the
latter function, the MCU can be replaced by the circuit shown in Figure 13. ENBST can also be implemented in different
ways and is typically expected to be a switch or button of the target device.
USB TYPE-C
CONNECTOR
4.5V TO 13.7V/3A
23
22
1
CHGIN
V
BUS
BYP
BST
24
4
2.2µF
10µF + 22µF
CHGIN
CC2
CC2
CC1
5
CC1
MAX4906
0.1µF
20
21
6
7
LX
LX
DP
DN
D+
D-
0.47µH
15
16
V
SYS
SYS
SYS
MAX77751
SYS
2 x 10µF
17
PVL
2.2µF
18
19
1kΩ
1kΩ
PGND
PGND
3
2
STAT
INOKB
IFAST
BATTERY PACK
12
11
24.9kΩ
3.15A
10µF
13
14
BATT
BATT
ITOPOFF
24.3kΩ
GPIO
(OPEN DRAIN
OUTPUT)
GPIO D- D+
10
9
V
DD
2.2µF
8
MCU
ENBST
ENBST
GND
Figure 15. Typical Charger Application
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Maxim Integrated | 38
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
Ordering Information
BATTERY TERMINATION
PART NUMBER
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
VOLTAGE (V)
24 FC2QFN
4.10
MAX77751AEFG+
MAX77751AEFG+T
MAX77751BEFG+
MAX77751BEFG+T
MAX77751CEFG+
MAX77751CEFG+T
MAX77751DEFG+
MAX77751DEFG+T
MAX77751FEFG+
MAX77751FEFG+T
MAX77751GEFG+
MAX77751GEFG+T
MAX77751HEFG+
MAX77751HEFG+T
MAX77751JEFG+
MAX77751JEFG+T
(3mm x 3mm)
24 FC2QFN
4.10
(3mm x 3mm)
24 FC2QFN
4.15
(3mm x 3mm)
24 FC2QFN
4.15
(3mm x 3mm)
24 FC2QFN
4.20
(3mm x 3mm)
24 FC2QFN
4.20
(3mm x 3mm)
24 FC2QFN
4.30
(3mm x 3mm)
24 FC2QFN
4.30
(3mm x 3mm)
24 FC2QFN
4.35
(3mm x 3mm)
24 FC2QFN
4.35
(3mm x 3mm)
24 FC2QFN
4.40
(3mm x 3mm)
24 FC2QFN
4.40
(3mm x 3mm)
24 FC2QFN
4.45
(3mm x 3mm)
24 FC2QFN
4.45
(3mm x 3mm)
24 FC2QFN
4.50
(3mm x 3mm)
24 FC2QFN
4.50
(3mm x 3mm)
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
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Maxim Integrated | 39
MAX77751
3.15A USB-C Autonomous Charger
for 1-Cell Li+ Batteries
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
CHANGED
DESCRIPTION
0
1
2
6/20
7/20
9/20
Initial release
—
Updated the Ordering Information table
Updated the Ordering Information table
37
37
Updated Functional Diagram, Input Current Limit section, Figure 6, Thermal
Shutdown State section, Reverse Boost Mode section, USB BC1.2 Charger
Detection section, Table 1, Table 2, Table 5, and Figure 15; added D+/D- Detection
in CC Detection, Non-USB Type-C Connector Cases, Micro-B Connector, and
Barrel Connectors sections
16, 21, 23,
26, 27,
29–31, 33,
38
3
4
10/20
11/20
Updated the Ordering Information table
39
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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