MP2639A
The Future of Analog IC Technology
2-Cell Li-Ion or Li-Polymer Switching Charger
Compatible with 5V Input and Integrated,
Bidirectional Charge/Discharge with Cell Balance
DESCRIPTION
FEATURES
The MP2639A is a highly integrated, flexible,
switch-mode, battery-charging management
device for 2-cell series Li-ion and Li-polymer
batteries used in a wide range of portable
applications.
The MP2639A is able to charge a 2-cell battery
from a 5V adapter or USB input. The MP2639A
can work in three modes: charge mode,
discharge mode, and sleep mode.
In 2-cell applications, the 5V input charges the
2-cell battery via the MP2639A operating in
step-up mode. When the 5V input is absent, the
2-cell battery voltage is discharged to the 5V
output via the MP2639A working in step-down
mode.
For the charging function, the MP2639A detects
the battery voltage automatically and charges
the battery in three phases: trickle current,
constant current, and constant voltage. Other
features include charge termination and autorecharge.
To guarantee safe operation, the MP2639A
limits the die temperature to a preset value of
120°C. Other safety features include input overvoltage protection (OVP), battery over-voltage
protection (OVP), thermal shutdown, battery
temperature monitoring, and a programmable
timer to prevent prolonged charging of a dead
battery.
The MP2639A is available in a QFN-26
(4mmx4mm) package.
4.0V to 5.75V Input Voltage Range
Charge 2-Cell Batteries with 5V Input
USB-Compliant Charger
Integrates Input Current-Based and Input
Voltage-Based
Power
Management
Functions
Programmable Input Current and Input
Voltage Limit
Up to 2.5A Programmable Charge Current
for 2-Cell Applications
8.4V Charge Voltage with 0.5% Accuracy
Cell Balance with 200mA current
Up to 5.0A Programmable Discharge
Current
Negative Temperature Coefficient Pin for
Temperature Monitoring
No Load Shutdown and Push Button TurnOn in Discharge Mode
Programmable Timer Back-Up Protection
Discharge Mode Load Trace Compensation
Thermal Regulation and Thermal Shutdown
Internal Battery Reverse Leakage Blocking
Integrated Short-Circuit Protection (SCP) for
Both Charge and Discharge Mode
Four LED Battery Level and Status
Indicators
Available in a QFN-26 (4mmx4mm)
Package
APPLICATIONS
Power Station Applications
Power Bank Applications for Smart Phones,
Tablets, and Other Portable Devices
Mobile Internet Devices
All MPS parts are lead-free, halogen-free, and adhere to the RoHS
directive. For MPS green status, please visit the MPS website under
Quality Assurance. “MPS” and “The Future of Analog IC Technology” are
registered trademarks of Monolithic Power Systems, Inc.
MP2639A Rev. 1.01
www.MonolithicPower.com
12/23/2019
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© 2019 MPS. All Rights Reserved.
1
MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
TYPICAL APPLICATION
2-Cell Application – Charge Mode
R2
R1
FB Q1
VL
L1
SW
BST
LX QRB
5V Input
VH
VBATT
VL
CVH
Q2
MID
Battery
R3
ACOK
MID
NTC
CVL
VLIM
VNTC
PB
MODE
IB
VCC
MP2639A
OLIM
ILIM
LED1
ISET
LED2
TMR
LED3
LED4
CHGOK
CTMR RISET RILIM ROLIM CVCC
R4
PGND
AGND
2-Cell Application – Discharge Mode
R2
L1
R1
SW
FB Q1 BST
L
X QRB
5V Output
VH
VBATT
VL
CV
MID
H
Battery
Q2
MID
NTC
VNTC
PB
MOD
E
IB
LED
1
LED
2
LED
3
LED
4
CHGOK
MP2639A
ACOK
VLI
M
VCC
OLI
M
R3
CVL
ILIM
ISET
TMR
CTMR
AGND
RISET RIILIM ROLIM CVCC R4
PGND
Adapter
Term
BATT
Term
MODE
CHG/DSG
VL
VH
High
Low
DSG
CHG
Active
SW
Q1
Q2
Topology
Step-down
Step-up
MP2639A Rev. 1.01
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12/23/2019
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© 2019 MPS. All Rights Reserved.
2
MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
ORDERING INFORMATION
Part Number*
Package
Top Marking
MP2639AGR
QFN-26 (4mmx4mm)
See Below
* For Tape & Reel, add suffix –Z (e.g. MP2639AGR–Z)
TOP MARKING
MPS: MPS prefix
Y: Year code
WW: Week code
M2639A: Product code of MP2639AGR
LLLLLL: Lot number
PACKAGE REFERENCE
TOP VIEW
QFN-26 (4mmx4mm)
MP2639A Rev. 1.01
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12/23/2019
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3
MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
ABSOLUTE MAXIMUM RATINGS (1)
Thermal Resistance (4)
VH ................................................. -0.3V to +20V
SW..........................-0.3V (-2V for 50ns) to +20V
VL .................................................. -0.3V to +16V
MID ................................................ -0.3V to +12V
BST to SW ................................... -0.3V to +5.5V
All other pins to GND ................... -0.3V to +5.5V
Continuous power dissipation (TA = +25°C) (2)
................................................................... 2.97W
Junction temperature ................................ 150°C
Lead temperature (solder) ........................ 260°C
Storage temperature .................-65°C to +150°C
QFN-26 (4mmx4mm) ............. 42 ....... 9 .... °C/W
Recommended Operating Conditions (3)
θJA
θJC
NOTES:
1) Exceeding these ratings may damage the device.
2) The maximum allowable power dissipation is a function of the
maximum junction temperature TJ (MAX), the junction-toambient thermal resistance θJA, and the ambient temperature
TA. The maximum allowable continuous power dissipation at
any ambient temperature is calculated by PD (MAX) = (TJ
(MAX)-TA)/θJA. Exceeding the maximum allowable power
dissipation produces an excessive die temperature, causing
the regulator to go into thermal shutdown. Internal thermal
shutdown circuitry protects the device from permanent
damage.
3) The device is not guaranteed to function outside of its
operating conditions.
4) Measured on JESD51-7, 4-layer PCB.
VL to GND .......................................... 4V to 5.5V
VH to GND ......................................... 6V to 8.7V
Operating junction temp. (TJ) ....-40°C to +125°C
MP2639A Rev. 1.01
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12/23/2019
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© 2019 MPS. All Rights Reserved.
4
MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
ELECTRICAL CHARACTERISTICS
VIN = VL = 5V, TA = 25°C, unless otherwise noted.
Parameter
DC/DC Parameter
LV side input over-voltage
threshold
LV side input over-voltage
threshold hysteresis
VCC LDO output
Symbol Condition
VLOVP
VCC
Input power good threshold
VUVLO
High-side NMOS on
resistance
Q1_ON
Low-side NMOS on resistance
Q2_ON
Reverse blocking NMOS on
resistance
QBR_ON
Min
VL rising until the switching
is off
MODE = high, VH = 7.6V
MODE = low, VH = 0V,
VL = 5V
VL rising
VL falling
TA = 25°C
TA = -40°C to +85°C
TA = 25°C
TA = -40°C to +85°C
TA = 25°C
TA = -40°C to +125°C
4.4
Typ
V
200
mV
4.5
3.9
3.6
19
19
24
24
10
10
Step-down mode
6
8
Peak current limit for low-side
NMOS
Step-up CC mode
Step-up TC mode
7
3
9
4
1300
Input quiescent current
IIN
Trickle charge threshold
Trickle charge threshold
hysteresis
Trickle input current
VBATT_TC
ICC
Termination charge current
IBF
Input voltage clamp reference
Input current limit
Termination charge voltage
V
29
36
15
10
mΩ
mΩ
A
V
VBATT falling
240
mV
794
2.2
2.5
38
1.18
400
720
2.56
300
992
2.46
10
150
1.2
449
817
2.71
1.22
500
900
3
mA
mA
A
%
mA
V
mA
mA
A
8.35
8.38
8.41
V
RISET = 215kΩ
RISET = 86.6kΩ
As the percentage of ICC
If 10% * ICC < 167mA
RILIM = 475kΩ
RILIM = 261kΩ
RILIM = 78.7kΩ
VBATT_FULL
1191
2.7
17.5
8.00
VBATT_OV
mΩ
A
A
kHz
2.5
Auto-recharge threshold
Battery over-voltage threshold
V
5.9
VIN_ClAMP
IIN_LMT
V
Battery float, charging is
enabled
VBATT rising
ITC
Constant fast charge current
4.6
4.5
FSW
Units
5.75
Peak current limit for high-side
NMOS
Operating frequency
Charging Operation
Max
As the percentage of
VBATT_FULL
101
103.3
mA
V
105
MP2639A Rev. 1.01
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5
MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
ELECTRICAL CHARACTERISTICS (continued)
VIN = VL = 5V, TA = 25°C, unless otherwise noted.
Parameter
Symbol Condition
Discharge Operation
Output voltage range
Feedback voltage
IOUT = 0A
Feedback input current
VFB = 1.2V
Output over-voltage threshold
Output over-voltage threshold
hysteresis
Shutdown current
Typ
Max
Units
1.2
5.5
1.22
V
V
300
nA
6.0
V
5.75
160
IOUT_LIMIT
Battery UV threshold
VBATTUV
Discharging is disabled
ROLIM = 86.6kΩ
ROLIM = 71.5kΩ
ROLIM = 44.2kΩ
Rising
Falling
2.2
2.77
4.49
2.46
2.98
4.83
6.28
5.75
mV
20
2.7
3.19
5.17
μA
A
V
V
-------------
ACOK, CHG output low
voltage
----------------
4.5
1.18
5.6
Programmable output current
limit
----------------
Min
-------------
ACOK, CHG leakage current
LED blinking frequency
EN, MODE input logic low
voltage
EN, MODE input high voltage
IB voltage output
Trickle charge time
Total current charge time
Sinking 1.5mA
400
mV
1
µA
Connected to 5V
CTMR = 0.1μF, ICHG = 1A
1
Hz
0.4
1.4
ICHG = 1A in charge mode
IDIS = 1A in discharge mode
CTMR = 0.1µF, stay in TC
mode, IL = 1A
CTMR = 0.1µF, IL = 1A
V
0.38
0.42
V
V
V
30
mins
5.4
hours
MP2639A Rev. 1.01
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12/23/2019
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6
MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
ELECTRICAL CHARACTERISTICS
(continued)
VIN = VL = 5V, TA = 25°C, unless otherwise noted.
Parameter
Protection
NTC low temp rising threshold
NTC low temp rising threshold
hysteresis
NTC cool temp rising
threshold
NTC cool temp rising
threshold hysteresis
NTC warm temp falling
threshold
NTC warm temp falling
threshold hysteresis
NTC hot temp falling threshold
NTC hot temp falling threshold
hysteresis
No load shutdown delay time
No load shutdown current
threshold
Threshold between long and
short touch
LED auto-off timer delay
Voltage-Based Fuel Gauge
Charge Mode
First level of battery voltage
threshold
Hysteresis
Second level of battery voltage
threshold
Hysteresis
Third level of battery voltage
threshold
Hysteresis
Symbol Condition
VCOLD
As percentage of VVNTC
Min
Typ
Max
Units
69.3
69.9
70.5
%
0.8
As percentage of VVNTC
VCOOL
As percentage of VVNTC
67.2
As percentage of VVNTC
VWARM
As percentage of VVNTC
As percentage of VVNTC
68.4
1.2
54.7
55.3
46.9
47.4
%
%
55.9
1.5
As percentage of VVNTC
VHOT
67.8
%
%
%
47.9
%
1.5
%
tNOLOAD
20
s
INOLOAD
50
mA
2.5
s
5
s
7.35
V
400
mV
7.75
V
400
mV
8.15
V
400
mV
As percentage of VVNTC
Battery voltage rising
Battery voltage rising
Battery voltage rising
MP2639A Rev. 1.01
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12/23/2019
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7
MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
ELECTRICAL CHARACTERISTICS (continued)
VIN = VL = 5V, TA = 25°C, unless otherwise noted.
Parameter
Symbol Condition
Discharge Mode
Fourth level of battery voltage
threshold
Hysteresis
Third level of battery voltage
threshold
Hysteresis
Second level of battery
voltage
Hysteresis
First level of battery voltage
Hysteresis
Cell Balancing
Discharge MOSFET on
resistance
Cell balance start voltage
Balance threshold
Balance threshold hysteresis
Min
Battery voltage falling
Max
Units
8
V
400
mV
7.6
V
400
mV
Battery voltage falling
7.2
V
Battery voltage falling
400
6
400
mV
V
mV
Battery voltage falling
HS
LS
VCBST
∆VCELL
Typ
3.4
6
6
3.5
65
30
(5)
Ω
3.6
V
mV
mV
NOTE:
5) Guaranteed by design.
MP2639A Rev. 1.01
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12/23/2019
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© 2019 MPS. All Rights Reserved.
8
MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = VL= 5V, VBATT = VH = 7.4V, CVL = CVH = 22µF, L1 = 2.2µH, CTMR = 0.1µF, R1 = 76.8kΩ, R2 =
24.3kΩ, R3 = 27.4kΩ, R4 = 10kΩ, battery simulator, unless otherwise noted.
MP2639A Rev. 1.01
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12/23/2019
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© 2019 MPS. All Rights Reserved.
9
MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = VL = 5V, VBATT = VH = 7.4V, CVL = CVH = 22µF, L1 = 2.2µH, CTMR = 0.1µF, R1 = 76.8kΩ, R2 =
24.3kΩ, R3 = 27.4kΩ, R4 = 10kΩ, battery simulator, unless otherwise noted.
Battery Charge
Curve
Auto-Recharge
LED Indication
during Charging
VBATT_FULL = 8.4V, RILIM = 0Ω,
RISET = 86.6kΩ
VBATT_FULL = 8.4V, RILIM = 0Ω,
RISET = 86.6kΩ
VBATT_FULL = 8.4V, RILIM = 0Ω,
RISET = 86.6kΩ, VBATT_OFFSET = 6V
CH2: VIN
2V/div.
CH2: VIN
2V/div.
CH1: LED1
CH3:
CH3:
CHGOK
2V/div.
CHGOK
2V/div.
CH2: LED2
2V/div.
CH1: VBATT
CH1: VBATT
CH3: LED3
2V/div.
2V/div.
2V/div.
CHR1: VBATT
CH4: IBATT
1A/div.
CH4: IBATT
1A/div.
500mV/div.
4s/div.
2V/div.
CH4:LED4
2V/div.
4s/div.
4s/div.
Battery Charge
Curve
TC Charge
Steady State
TC Charge Steady
State @ VH = VL - 1V
VBATT_FULL = 8.4V, RILIM = 73.2kΩ,
RISET = 86.6kΩ
VBATT = 5.0V, RILIM = 73.2kΩ,
RISET = 86.6kΩ
VBATT = 4.0V, RILIM = 73.2kΩ,
RISET = 86.6kΩ
CH1: VIN
CH3: VBATT
2V/div.
CH1: VSW
CH2: VBATT
2V/div.
CH1: VSW
2V/div.
CH3: VBATT
2V/div.
CH3:
CH2: IL
500mA/div.
CH2: IL
500mA/div.
CH4: IBATT
500mA/div.
CH4: IBATT
500mA/div.
2V/div.
CHGOK
1V/div.
CH4: IBATT
1A/div.
4s/div.
2V/div.
2µs/div.
CC Charge
Steady State
CV Charge
Steady State
VBATT = 6.6V, RILIM = 73.2kΩ,
RISET = 86.6kΩ
VBATT = 8.4V, RILIM = 73.2kΩ,
RISET = 86.6kΩ
CH3: VBATT
2V/div.
CH3: VBATT
2V/div.
CH1: VSW
5V/div.
CH2: IL
1A/div.
CH2: IL
1A/div.
CH4: IBATT
500mA/div.
CH4: IBATT
1A/div.
CH1: VSW
1µs/div.
5V/div.
1µs/div.
1µs/div.
MP2639A Rev. 1.01
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12/23/2019
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10
MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = VL = 5V, VBATT = VH = 7.4V, CVL = CVH = 22µF, L1 = 2.2µH, CTMR = 0.1µF, R1 = 76.8kΩ, R2 =
24.3kΩ, R3 = 27.4kΩ, R4 = 10kΩ, battery simulator, unless otherwise noted.
Power On,
TC Charge Mode
Power On,
CC Charge Mode
Power Off,
CC Charge Mode
VBATT = 4.0V, RILIM = 73.2kΩ,
RISET = 86.6kΩ
VBATT = 6.6V, RILIM = 73.2kΩ,
RISET = 86.6kΩ
VBATT = 6.6V, RILIM = 73.2kΩ,
RISET = 86.6kΩ
CH2: VBATT
2V/div.
CH2: VBATT
2V/div.
CH2: VBATT
2V/div.
CH1: VIN
2V/div.
CH1: VIN
2V/div.
CH1: VIN
2V/div.
CH4: IL
500mA/div.
CH4: IL
1A/div.
CH4: IL
1A/div.
CH3: VSW
2V/div.
CH3: VSW
5V/div.
CH3: VSW
5V/div.
2ms/div.
2ms/div.
Input Current Limit
40ms/div.
Input Voltage
Regulation
VIN = 5.0V, RILIM = 75kΩ,
RISET = 100kΩ
Mode On, CC Mode
VBATT = 6.6V, RILIM = 73.2kΩ,
RISET = 86.6kΩ
VIN = 5.0V/4A, VIN_REG = 4.49V
CH2: VBATT
2V/div.
CH1: VBATT
2V/div.
CH3: VBATT
CH1: VIN
2V/div.
CH4: IIN
1A/div.
CH1: VMODE
2V/div.
CH4: IIN
1A/div.
CH3: IBATT
CH2: VSW
1A/div.
5V/div.
CH3: IBATT
CH2: VIN
200mV/div.
CH4: IBATT
2A/div.
1A/div.
2s/div.
2V/div.
2s/div.
Mode Off, CC Mode
Mode On, CV Mode
VBATT = 6.6V, RILIM = 73.2kΩ,
RISET = 86.6kΩ
VBATT = 8.4V, RILIM = 73.2kΩ,
RISET = 86.6kΩ
CH3: VBATT
CH3: VBATT
2V/div.
2V/div.
CH1: VMODE
2V/div.
CH1: VMODE
2V/div.
CH2: VSW
CH2: VSW
2V/div.
5V/div.
CH4: IBATT
2A/div.
CH4: IBATT
1A/div.
400µs/div.
400µs/div.
MP2639A Rev. 1.01
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12/23/2019
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© 2019 MPS. All Rights Reserved.
11
MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = VL = 5V, VBATT = VH = 7.4V, CVL = CVH = 22µF, L1 = 2.2µH, CTMR = 0.1µF, R1 = 76.8kΩ, R2 =
24.3kΩ, R3 = 27.4kΩ, R4 = 10kΩ, battery simulator, unless otherwise noted.
NTC Protection,
TC Mode
NTC Protection,
CC Mode
NTC Protection,
CC Mode
VBATT = 5.6V, RILIM = 73.2kΩ,
RISET = 86.6kΩ
VBATT = 7.4V, RILIM = 73.2kΩ,
RISET = 86.6kΩ
VBATT = 8.15V, RILIM = 73.2kΩ,
RISET = 86.6kΩ
CH2: VBATT
2V/div.
CH2: VBATT
2V/div.
CH2: VBATT
2V/div.
CH1: VNTC
1V/div.
CH1: VNTC
1V/div.
CH1: VNTC
1V/div.
CH4: IBATT
CH4: IBATT
CH4: IBATT
200mA/div.
1A/div.
1A/div.
CH3: VSW
5V/div.
CH3: VSW
5V/div.
CH3: VSW
5V/div.
10ms/div.
10ms/div.
Timer Out Protection
10ms/div.
Recovery from
Timer Out
VBATT = 7.4V, RILIM = 73.2kΩ,
RISET = 86.6kΩ, CTMR = 220pF
Timer Period
VBATT = 7.4V, RILIM = 73.2kΩ,
RISET = 86.6kΩ, CTMR = 220pF
VBATT = 7.4V, RILIM = 73.2kΩ,
RISET = 86.6kΩ, CTMR = 220pF
CH1: VTMR
1V/div.
CH1: VTMR
1V/div.
CH1: VTMR
1V/div.
CH2: VBATT
2V/div.
CH2: VBATT
2V/div.
CH2: VBATT
2V/div.
CH3:
CH3:
CH3:
CHGOK
CHGOK
CHGOK
2V/div.
2V/div.
2V/div.
CH4: IBATT
1A/div.
CH4: IBATT
1A/div.
CH4: IBATT
1A/div.
100µs/div.
1ms/div.
4s/div.
Indication
@ BATT OVP
Indication
@ Charge Mode Off
Indication
@ NTC Fault
VBATT = 9.0V, RILIM = 73.2kΩ,
RISET = 86.6kΩ
VBATT = 7.4V, RILIM = 73.2kΩ,
RISET = 86.6kΩ
VBATT = 3.7V, RILIM = 14.7kΩ,
RISET = 49.9kΩ
CH1: VBATT
2V/div.
CH1: VMODE
2V/div.
CH1: VNTC
2V/div.
CH2: ACOK
2V/div.
CH2: ACOK
2V/div.
CH2: ACOK
2V/div.
CH3:
CH3:
CH3:
CHGOK
CHGOK
CHGOK
2V/div.
2V/div.
2V/div.
CH4: IBATT
1A/div.
CH4: IL
2A/div.
CH4: IL
2A/div.
1ms/div.
1ms/div.
MP2639A Rev. 1.01
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400ms/div.
12
MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = VL = 5V, VBATT = VH = 7.4V, CVL = CVH = 22µF, L1 = 2.2µH, CTMR = 0.1µF, R1 = 76.8kΩ, R2 =
24.3kΩ, R3 = 27.4kΩ, R4 = 10kΩ, battery simulator, unless otherwise noted.
Discharge Mode
Steady State
No Load Shutdown,
Discharge Mode
VBATT = 7.4V, ILOAD = 5A
VBATT = 7.4V, ILOAD = 0A
Weak Battery
Protection,
Discharge Mode
ILOAD = 1.5A, VBATT_OFFSET = 5V
CH1: VBATT
2V/div.
CH1: VBATT
2V/div.
CH1: VBATT
500mV/div.
CH2: VL
2V/div.
CH2: VL
2V/div.
CH2: VL
2V/div.
CH3: VSW
CH4: ILOAD
20mA/div.
CH4: ILOAD
1A/div.
CH3: VSW
CH3: VSW
5V/div.
5V/div.
CH4: IL
1A/div.
10V/div.
1µs/div.
4s/div.
4s/div.
Discharge Output
Current Limit
Load Transient,
Discharge Mode
Power Off by PB,
Discharge Mode
VBATT = 6.6V, ROLIM = 100kΩ
VBATT = 8.0V, load transient
from 0.5A to 2.5A
VBATT = 8.0V, ILOAD = 5A
CH1: VBATT
2V/div.
CH1: VBATT
2V/div.
CH3: VBATT
CH2: VL
2V/div.
CH2: VL
500mV/div.
CH1: VPB
2V/div.
CH3: VSW
CH3: VSW
10V/div.
5V/div.
CH2: VL
2V/div.
CH4: ILOAD
1A/div.
CH4: ILOAD
2A/div.
CH4: IL
2A/div.
2s/div.
2V/div.
400µs/div.
1s/div.
Short Protection,
Discharge Mode
Short Recovery,
Discharge Mode
LED Indication
Discharge Mode
VBATT = 8.0V, ILOAD = 5A,
VL short to GND
VBATT = 8.0V, ILOAD = 5A,
VL short to GND
VBATT_OFFSET = 5V
CH1: VBATT
2V/div.
CH1: VBATT
2V/div.
CHR1: VBATT
CH2: VL
2V/div.
CH2: VL
2V/div.
CH4:LED4
2V/div.
CH3: VSW
CH3: VSW
10V/div.
10V/div.
CH3: LED3
2V/div.
CH4: IL
5A/div.
CH4: IL
5A/div.
CH2: LED2
2V/div.
500mV/div.
CH1: LED1
2V/div.
400µs/div.
4ms/div
MP2639A Rev. 1.01
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2s/div.
13
MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
PIN FUNCTIONS
Pin #
Name
Type
Description
1
2
3
4
5
6
VL
LX
VH
SW
PGND
BST
Power
Power
Power
Power
Power
Power
Low-voltage terminal. Attach a 5V input to VL.
Connection node between the induction and internal block switch.
High-voltage terminal. Attach a 2-cell battery to VH.
Switching node.
Power ground. Connect the exposed pad and GND to the same ground plane.
Bootstrap. Connect a 100 - 500nF BST capacitor between the BST and SW node.
-----
Push button input. Connect a push button from PB to AGND pulled up internally by
-----
-----
7
PB
I
8
MODE
I
9
10
VCC
I/O
AGND
I/O
11
TMR
I
12
MID
I
13
LED1
O
14
LED2
O
15
LED3
O
16
LED4
O
17
18
FB
VLIM
I
I
19
VNTC
O
20
NTC
I
a resistor. When PB is pushed for less than 2.5s, the discharge function is enabled
-----
and latched when MODE is high. If discharging is enabled, push PB for more than
2.5s to disable the discharge. Otherwise, discharging remains, and LED1-4 are
enabled for 5s.
Charge or discharge mode selection. Pull MODE to low logic to make the
MP2639A work in charge mode. Pull MODE to logic high to make the MP2639A
work in discharge mode.
Internal circuit power supply. Bypass VCC to AGND with a 1μF ceramic
capacitor. VCC cannot float or carry an external load higher than 50mA.
Analog ground.
Oscillator period timer. Connect a timing capacitor between TMR and AGND to
set the oscillator period. Short TMR to AGND to disable the timer function.
Middle point of the 2-cell battery. MID is used to detect the voltage of each cell in
a 2-cell application. Connect MID to GND if it is not being used.
Fuel gauge indication. LED1 works with LED2, LED3, and LED4 to achieve the
voltage-based fuel gauge.
Fuel gauge indication. LED2 works with LED1, LED3, and LED4 to achieve the
voltage-based fuel gauge.
Fuel gauge indication. LED3 works with LED1, LED2, and LED4 to achieve the
voltage-based fuel gauge.
Fuel gauge indication. LED4 works with LED1, LED2, and LED3 to achieve the
voltage-based fuel gauge.
Voltage feedback input in discharge mode.
Input voltage limit setting in charge mode.
Pull-up bias voltage of both the NTC resistive dividers. VNTC is connected to
VCC by an internal switch, which is turned on only in charge mode. Do not connect
any capacitors to VNTC.
Negative temperature coefficient (NTC) thermistor.
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MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
PIN FUNCTIONS (continued)
Pin #
Name
Type
Description
Current output for the battery current monitor. IB is proportional to the real
battery current. Connect an R-C filter from IB to AGND.
Discharge output current limit setting. Connect an external resistor from OLIM to
AGND to program the system current.
Charge current set. Connect an external resistor from ISET to AGND to program
the charge current.
Input current limit setting in charge mode.
21
IB
O
22
OLIM
I
23
ISET
I
24
ILIM
I
25
----------------
O
Valid input supply indicator. ACOK is an open-drain output. ACOK is pulled low
when the input voltage is recognized as a good source.
O
Charging completion indicator. CHG at logic low indicates charge mode. CHG
becomes an open drain once the charging has completed or is suspended.
----------------
26
ACOK
-------------
CHG
----------------
-------------
MP2639A Rev. 1.01
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-------------
15
MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
BLOCK DIAGRAM
Figure 1: Block Diagram for 2-Cell Charge Mode
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MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
BLOCK DIAGRAM
(continued)
Figure 2: Block Diagram for 2-Cell Discharge Mode
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MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
FLOW CHART
Figure 3: Input Power Start-Up Flow Chart
MP2639A Rev. 1.01
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MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
FLOW CHART (continued)
ENCHG is OK
TC Phase (Linear Down Mode)
QRB softly trun on,
Set Q1 on signal,
Q2 remains off
VH > VL-1.0V?
No
QRB works as a current source
Set Q1 on signal,
Q2 remains off
Yes
QRB works as a current
source
Start 2.8μs BST refresh
100ns each cycle
TC Phase (SW Down TC Mode)
No
No
VH > VL-1.0V?
Yes
VH>VL-114mV?
Yes
COMP>V(ITC)?
Yes
Fully turn on QRB
Turn off the Q1
TC Phase (SW Mode)
VH>VL+400mV?
No
Boost works in
Non-sync mode
FSW=280kHz
Yes
FSW increases to 1.3MHz
Control the input current to
implement TC charge
Figure 4: Three-Phase Trickle Charge
MP2639A Rev. 1.01
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MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
OPERATION
The MP2639A is a highly integrated, switchmode battery charger with a sophisticated
control strategy to charge 2-cell series Lithiumion or Lithium-polymer batteries from a 5V
adapter or USB input.
The sense gain can be programmed by the
external resistor (RIB) connected from IB to
GND. For example, for a 40kΩ RIB, a 0.3V IB
value represents a 1A battery current.
CHARGE MODE
Input Power Start-Up
As shown in Figure 3, once VCC exceeds the
UVLO threshold, the MP2639A qualifies both
the LV side and HV side voltage according to
the MODE status.
MODE Control
When MODE is low, the MP2639A works in
charging mode to charge a 2-cell series battery
from 5V. The MP2639A operates in step-up
mode at this time, and Q2 works as the active
switch, while Q1 works as the synchronous
switch.
In charging mode, VL is the input power
terminal. Once VOVLO > VLV > VUVLO and no fault
occurs, the MP2639A is ready for charging.
When MODE is high, the MP2639A is
configured to discharge mode. Once discharge
mode is enabled, the MP2639A operates in
reverse to achieve a 5V output from a 2-cell
battery via step-down mode (see Table 1).
As shown in Figure 4, depending on VH, the
MP2639A operates in three different tricklecurrent charge modes: linear down mode,
switch down mode, and switch TC mode (see
Table 2).
Table 1: Operation MODE Table
1. Linear Down Mode: When VH < VL - 1V,
the QRB MOSFET works linearly to charge
the battery with the trickle charge current. At
this time, the pulse-width modulation (PWM)
block delivers the Q2 off signal and Q1 on
signal. The BST refresh block is still
disabled, so the Q1 MOSFET cannot be on.
When VH > VL - 1V, a 2.8μs BST refresh
window launches. In this window, the lowside Q2 MOSFET is turned on for 100ns
each cycle (1.3MHz). Whenever Q1 is set to
be on for 270μs, the 2.8μs BST refresh
window is launched again.
Adapter
Term
BATT
Term
MODE
CHG/DIS
VL
VH
High
Low
DSG
CHG
Active
SW
Q1
Q2
Topology
Step-down
Step-up
Internal Power Supply
The VCC output is used to power the internal
circuit and the MOSFET driver. This output is
supplied by the higher terminal voltage value of
VL or VH. After VL is set, the internal reference
voltage is set up during charge mode. In
discharge mode, VH is always higher than the
output voltage, so VCC is always comes from
VH when VH is higher than the under-voltage
lockout (UVLO).
Connect an external capacitor from VCC to
AGND. The VCC output current limit is 50mA.
Figure 3 shows the MODE selection and power
start-up flow chart in each mode.
Battery Current Monitor
The MP2639A has an IB pin to represent the
real battery current in both charge and
discharge mode. The current flowing out from
IB is proportional to the real battery current. An
external, precise, sense resistor can convert the
current signal to a voltage signal. Calculate the
IB voltage with Equation (1):
VIB
3 IBATT
RIB
400k
2. Switch Down Mode: When VH > VL 114mV, QRB is fully on, Q1 is turned off, Q2
is switching, and FSW is lowered to 280kHz.
3. Switch TC Mode: When VH > VL + 400mV,
QRB remains fully on, Q1 is turned off, Q2 is
switching, and FSW recovers to 1.3MHz.
(1)
MP2639A Rev. 1.01
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MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
Table 2: Operation Mode
VBATT Rising, Quit Linear
Down Mode
(enter switch down mode)
VBATT Falling, Enter Linear
Down Mode
(quit switch down mode)
VBATT Rising, Quit Switch
Down Mode
(enter normal switch mode)
VBATT Falling, Enter Switch
Down Mode
(quit normal switch mode)
VH > VL - 114mV
VH < VL - 342mV
VH > VL + 400mV
VH < VL + 114mV
Battery Charge Profile
The MP2639A provides three main charging
phases: trickle-current, constant-current charge,
and constant-voltage charge (see Figure 5).
VBATT_FULL
Battery Voltage
ICC
Charge Current
VBATT_LOW
ITC
IBF
Trickle charge
3. Phase 3 (constant-voltage charge): When
the battery voltage rises to the charge-full
voltage (VBATT_FULL), the charge current
begins to taper off. The charge cycle is
considered complete when the CV loop is
dominated, and the charge current reaches
the battery-full termination threshold. A
500μs force charge time is designed for
each charge cycle. After the 500μs force
charge time expires, the charge full signal is
allowed to assert.
CC Fast Charge Constant Voltage Charge
Charge Full
Figure 5: Battery Charge Profile
1. Phase 1 (trickle-current charge): When the
battery voltage is lower than VBATT_LOW, the
MP2639A applies a safe trickle-charge
current (ITC) to the deeply depleted battery
until the battery voltage reaches trickle
charge to the fast charge threshold
(VBATT_LOW). If VBATT_LOW is not reached
before the trickle-charge timer expires, the
charge
cycle
is
ceased,
and
a
corresponding timeout fault signal is
asserted. See the Safety Timer section on
page 21 for more detail.
2. Phase 2 (constant-current charge): When
the battery voltage exceeds VBATT_LOW, the
MP2639A stops the trickle-current charge
phase and enters constant-current charge
(fast charge) phase with a soft start. The
fast charge current can be programmed via
ISET.
If IBF is not reached before the safety charge
timer expires, the charge cycle is ceased,
and the corresponding timeout fault signal is
asserted. See the Safety Timer section for
more detail.
A new charge cycle starts when the following
conditions are valid:
The input power is re-plugged.
MODE is toggled from high to low.
No thermistor fault at NTC.
No safety timer fault.
No battery over-voltage.
Automatic Recharge
When the battery is fully charged and the
charging is terminated, the battery may be
discharged for system consumption or selfdischarge. The MP2639A starts a new charging
cycle automatically without requiring a manual
restart of a charging cycle.
Charge Current Setting
ISET is used to program the charge current.
The setting formula is shown in Equation (2):
ICHG
640(k)
(A)
3 RISET
(2)
Battery Over-Voltage Protection (OVP)
The MP2639A is designed with a built-in battery
over-voltage limit of 103.3% of VBATT_FULL. When
a battery over-voltage event occurs, the
MP2639A suspends the charging immediately.
Non-Sync Mode
When the input current at the VL side is lower
than 330mA, the MP2639A turns off Q1 and
switches to non-sync operation.
MP2639A Rev. 1.01
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MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
Safety Timer
The MP2639A uses an internal timer to
terminate the charging. The timer remains
active during the charging process. An external
capacitor between TMR and AGND programs
the charge cycle duration. An internal current
source charges and discharges the external
capacitor alternatively. When the voltage across
CTMR is lower than 0.7V, the internal current
source charges CTMR. Once the voltage
exceeds 1.5V, the internal current source
begins to discharge CTMR. As a result, the
voltage across CTMR oscillates between 0.7V
and 1.5V periodically, like a triangle wave.
There are two counter limits for the trickle
charge and total charge processes: 45056 for
trickle charge and 3407872 for CC and CV
charge. Once the counter reaches the
corresponding limit, the timer expires, and the
charging is suspended (see Figure 6).
Figure 6: Voltage Profile of TMR
In trickle-charge mode, the input trickle-charge
current is fixed at 300mA. The trickle-charge
time (τTC_TMR) is set using Equation (3):
TRICKLE_ TMR 33.7mins
CTMR (F)
0.1F
(3)
In CC and CV mode, the internal IOSC is
proportional to the reference of the inductor
current and is independent of the input current.
The total charge time (τTOTAL_TMR) is set using
Equation (4):
TOTAL _ TMR 6.05Hours
CTMR (F)
1A
0.1F
IL (A) 0.08
(4)
In the event of an NTC hot and cold fault, the
charging timer should be suspended. Once the
NTC fault is removed, the timer continues
counting from the value before an NTC fault.
Negative Temperature Coefficient (NTC)
Thermistor
“Thermistor” is the generic name given to
thermally sensitive resistors. A negative
temperature coefficient thermistor is called a
thermistor, typically. Depending on the
manufacturing method and the structure, there
are many shapes and characteristics available
for various purposes. The thermistor resistance
values, unless otherwise specified, are
classified at a standard temperature of 25°C.
The resistance of a temperature is solely a
function of its absolute temperature.
The relationship between the resistance and
the absolute temperature of a thermistor is
shown in Equation (5):
R1 R2 e
1 1
T1 T2
(5)
Where R1 is the resistance at absolute
temperature T1, R2 is the resistance at
absolute temperature T2, and β is a constant
that depends on the material of the thermistor.
The
MP2639A
monitors
the
battery’s
temperature continuously by measuring the
voltage at NTC during charge mode. This
voltage is determined by the resistor divider,
whose ratio is produced by different resistances
of the NTC thermistor under different ambient
temperatures of the battery.
The MP2639A sets a pre-determined upper and
lower bound of the range internally. If the
voltage at NTC goes out of this range, then the
temperature is outside of the safe operating
limit. At this time, charging stops unless the
operating temperature returns to the safe range.
To satisfy the JEITA requirement, the MP2639A
monitors four temperature thresholds: the cold
battery threshold (TNTC < 0°C), the cool battery
threshold (0°C < TNTC < 10°C), the warm battery
threshold (45°C < TNTC < 60°C), and the hot
battery threshold (TNTC > 60°C). For a given
NTC thermistor, these temperatures correspond
to VCOLD, VCOOL, VWARM, and VHOT. When VNTC <
VHOT or VNTC > VCOLD, charging and the timers
are suspended. When VHOT < VNTC < VWARM, the
charge-full voltage (VBATT_FULL) is reduced by
140mV from the programmable threshold.
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MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
When VCOOL < VNTC < VCOLD, the charging
current is reduced to half of the programmed
charge current (see Figure 7).
Note: VNTC is the ratio of the voltage at NTC pin
and the voltage at VNTC pin.
Maximum Charge Current 1C
0.5C
Maximum Charge Voltage : 4.25V
(4.2V Typical)
4.15V Maximum
Input Voltage-Based and Input CurrentBased Power Management
To meet the USB maximum current limit
specification and avoid overloading the adapter,
the MP2639A features both input current- and
input voltage-based power management by
monitoring the input current and input voltage
continuously. The total input current limit can be
programmed to prevent the input source from
overloading. When the input current reaches its
limit, the charge current tapers off to keep the
input current from increasing further. The input
current limit can be calculated with Equation (6):
IILIM
4.10V Maximum
Cold
Cool
T1
T2
(0DegC) (10DegC)
Normal
Warm
Hot
T3
T4
T5
(45DegC) (50 DegC) (60DegC)
Figure 7: JEITA-Compatible NTC Window
VNTC Output
VNTC is an input pin used to pull up both the
internal and external resistor dividers to the
same point (see Figure 8). VNTC is connected
to VCC via an internal switch. In charging mode,
the switch is turned on, and VNTC is connected
to VCC. In discharge mode, the switch is off,
and VNTC is bridged off from VCC.
(6)
If the preset input current limit is higher than the
rating at the adapter, the back-up input voltagebased power management also works to
prevent the input source from being overloaded.
When the input voltage falls below the input
voltage limit due to an overload, the charge
current is reduced to keep the input voltage
from dropping further.
The input voltage clamp threshold can be
programmed by VLIM. The internal reference of
the input voltage loop is 1.2V, so the input
voltage clamp limit can be calculated with
Equation (7):
VIN _ REG 1.2V
Charge/
Discharge?
R3 R4
R4
(7)
Indication
The MP2639A integrates indicators for the
conditions shown in Table 3.
VNTC
VCC
640(k)
(A)
3 RILIM
C old
Table 3: Indication in Difference Cases
C ool
NTC
N TC C ontrol
Block
Warm
H ot
Charging State
In Charging
Charging
complete, sleep
mode, charge
Mode is
disable, battery
low
OVP
AGND
Mode is
high
ACOK
Low
CHGOK
Low
Low
High
NTC fault, timer
fault,
Low
Blinking
at fixed
1Hz
Discharging
High
High
Figure 8: NTC Protection Circuit
MP2639A Rev. 1.01
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MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
-----
DISCHARGE MODE
Discharge Control
When MODE is configured high, discharge
mode is enabled. However, discharging can
only be enabled or disabled when the push
----button pin (PB ) is configured properly.
-----
A short push is defined as PB being pulled low
----for less than 2.5s. A long push is defined as PB
being pulled low for longer than 2.5s.
In the MP2639A, discharging is enabled only
when MODE is high and a short push is
detected. Discharging is disabled once MODE
is pulled low or a long push is detected.
Figure 9 shows the steps below.
1) Before t0, MODE is high, and discharging
has already been enabled. PBDIS is the
enable signal of the discharging. If PBDIS is
high, discharging is enabled. If PBDIS is low,
discharging is disabled.
2) During t0, PB is pulled low, and the 2.5s
----timer is reset. PB is released to high before
the 2.5s timer expires, so a short push is
detected. PBDIS remains high, and
discharging continues.
-----
3) During t1, PB is pulled low again, and the
----2.5s timer is reset. PB remains low until the
2.5s timer expires, so a long push is
detected. PBDIS is pulled low, and
discharging ceased. Then PBDIS rises high
----once PB goes high.
4) At the moment of t2, another long push is
detected. Discharging is still disabled.
5) At the moment of t3, a short push is
detected, and PDBIS remains high.
Discharging is enabled.
Figure 9: Push Button Detection Profile
MP2639A Rev. 1.01
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MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
-----
Since the MP2639A is in sleep mode, if PB is
pulled down to AGND for less than 2.5s (short
push), the IC enters discharge mode, and the
LEDs display the battery capacity. After 5s, the
LED pins switch to open drain automatically to
minimize the battery quiescent current. For the
LED to display the battery capacity, short push
----PB .
No-Load Automatic Shutdown
In discharge mode, the MP2639A monitors the
discharge current continuously. When the
discharge current (IBATT) is lower than 50mA,
discharging can be shut down after 20s
automatically (see Figure 10).
EN DSG
No
Output Over-Current Limit (OCL)
The MP2639A features an output over-current
limit (OCL), which can be programmed by the
resistor connected from OLIM to AGND. When
the output current flowing out from the VL node
exceeds the output over-current limit, the
MP2639A regulates the duty cycle to maintain
the output current at this limit, so the output
voltage drops accordingly. The output current
limit can be set using Equation (8):
IOLIM
640(k)
(A)
3 ROLIM
(8)
Output Short-Circuit Protection (SCP)
The MP2639A monitors the VL voltage
continuously. If VL drops below 3.9V, an event
of the output short circuit is detected. The
MP2639A works in hiccup mode with 1.2ms
intervals, and the peak current limit of the highside switch is cut by half (see Figure 11).
SS Done?
Yes
Reset 20s Timer
No
IBATT < 50mA?
Yes
No
20s timer expires?
Yes
No Load
Shutdown
Figure 10: No-Load Shutdown Detection
Output Over-Voltage Protection (OVP)
The MP2639A has an internal, output, overvoltage protection (OVP). If the voltage at the
VL node is higher than 5.75V, and an external,
abnormal voltage is added or FB is pulled to
GND falsely, then the MP2639A disables the
discharge and turns off the QRB MOSFET.
When the output voltage returns to a safe level,
the MP2639A restarts the discharging.
Figure 11: Output Short-Circuit Protection
MP2639A Rev. 1.01
www.MonolithicPower.com
12/23/2019
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2019 MPS. All Rights Reserved.
25
MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
Over-Discharge Control
The MP2639A has a battery over-discharge
control scheme to avoid over-discharging.
During discharging, the MP2639A shuts down
automatically when the battery voltage declines
to 5.75V, and the MP2639A recovers to
discharge when the battery voltage is over
6.28V.
Battery Cell Balance and Protection
The MP2639A provides battery cell balance
and protection for 2-cell applications. The
MP2639A senses the voltage across each cell.
If the two cell voltages are too different, the
balance function begins, and the internal
discharge circuit is turned on to decrease the
charge current of the cell with the higher
voltage. If the voltage across one of the cells
exceeds the battery OVP threshold, the
charging stops. If the two cell voltages are still
too different, the cell with the higher voltage
discharges to balance until the two cell voltages
match or the part recovers from OVP (120mV
lower than the OVP threshold) and recharges.
The MP2639A integrates the balance MOSFET
and control circuit (see Figure 12).
VH
1. The balance block is only active when a
valid power source is present and charging
is enabled.(6)
2. At least one of the cell voltages is higher
than the balance starting voltage (typical
3.5V).
3. The voltage difference between the cells is
higher than the balance threshold (65mV).
NOTE:
6) The balance block is valid only while the charge function is
applied. If both the charge and discharge functions are
enabled, disable the balance block by connecting MID to
GND.
The MP2639A detects the cell with the lower
voltage (VCMIN) and checks the voltage
difference between each cell. If the differential
voltage is higher than the balance threshold
(65mV), the related balance MOSFET is turned
on, and the charge current of the cell with the
higher voltage is decreased.
The balancing action is suppressed if the higher
cell voltage is less than the cell-balance start
voltage (VCBST) or the cell-voltage measurement
is active.
In each balance cycle, the cell voltage
measures for about 200µs and balances for
about 200ms. Cell measurements are frozen
when the balance is ongoing.
The cell balance flow chart is shown in Figure
13.
MID
Balance &
Protection
Start
No
Any Cell > VCBST?
PGND
Yes
Figure 12: Block Diagram of the Battery Balance
Find the Cell with minimum
voltage (VCMIN)
The balance current (less than 200mA)
depends on the external resistor from MID to
the middle of the 2-cell battery. If a larger
balance current is needed, then refer to the
external balance circuit in Figure 18.
VCELL-VCMIN > 65mV
The
balancing
algorithm
will
enable
automatically when the following conditions are
true:
Related Balance
MOSFET is on
No
Any
Yes
Figure 13: Flow Chart of the Battery Balance
MP2639A Rev. 1.01
www.MonolithicPower.com
12/23/2019
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2019 MPS. All Rights Reserved.
26
MP2639A – SWITCH-MODE BATTERY CHARGER W/ BIDIRECTIONAL OPERATION
Voltage-Based Fuel Gauge
The MP2639A integrates four comparators and
an open-drain circuit to indicate the fuel gauge
via four LEDs during both charge and discharge
mode (see Figure 14). The MP2639A compares
the battery voltage with four voltage references
to reveal the capacity of the battery, with four
options of 25%, 50%, 75%, and 100%.
VH_fb or VL_fb
LED1
Vref4
LED2
Bias Voltage
Vref3
LED3
Vref2
LED4
The indication plan is shown in Table 4.
Vref1
Figure 14: Block Diagram of Fuel Gauge
Table 4: Voltage-Based Fuel Gauge Indication
-------------
2-Cell Charge
LED1
LED2
LED3
LED4
Done
8.4V
On
On
On
On
On
On
8.2V
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