MP26124
24V Input, 2A, 600kHz,
4S Cell Switching Li-Ion Battery Charger
DESCRIPTION
FEATURES
The MP26124 is a monolithic, DC/DC, stepdown, switching charger for 4-series cell Li-ion
battery packs. The MP26124 has an integrated
high-side power MOSFET that can output a
charge current up to 2A and also has peakcurrent-mode control for fast loop response and
easy compensation.
The MP26124 uses a sense resistor to control a
programmable charge current and regulates the
charge current and charge voltage accurately
using two control loops.
The MP26124 has multiple fault condition
protections including cycle-by-cycle current
limiting and thermal shutdown. Other safety
features include battery temperature monitoring
and protection, charge status indication, and a
programmable timer to stop the charging cycle
when the timer expires.
Charge 4S Cell Li-Ion Battery Packs
Up to 24V Operation Voltage
Programmable Charging Current up to 2A
±0.75% VBATT Accuracy
0.2Ω Integrated Power MOSFET
Up to 90% Efficiency
Fixed 600kHz Frequency
Preconditioning for Fully Depleted Batteries
Charging Status Indicator
Input Supply Fault Indicator
Thermal Shutdown
Cycle-by-Cycle Over-Current Protection
(OCP)
Battery Temperature Monitor and Protection
Available in a QFN-16 (4mmx4mm)
Package
APPLICATIONS
The MP26124 requires a minimal number of
readily available external components and is
available in a QFN-16 (4mmx4mm) package.
Clean Robots
Drones
Chargers for 4S Cell Li-Ion Batteries
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.
TYPICAL APPLICATION
D1
VIN
C1
4.7μF
18V to 24V
VIN
C3
1μF
SW
VREF33
R1 R2
VCC
BST
CHGOK
MP26124
R3
10k
Ω
RNTC
10kΩ
BATT
SGND
COMPI
ONOFF
EN
COMPV
GND
TMR
R5
200m
Ω
D2
C2
10μF
4S
Battery
750
Ω
R42.5kΩ
C6
0.1μF
MP26124 Rev. 1.0
10/10/2017
RS1
10μH
CSP
ACOK
NTC
C7
0.1μF
L
C4
2.2nF
C5
4.7nF
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1
MP26124 –24V INPUT, 2A, 600kHz, 4S SWITCHING LI-ION BATTERY CHARGER
ORDERING INFORMATION
Part Number*
MP26124GR
Package
QFN-16 (4mmx4mm)
Top Marking
See Below
*For Tape & Reel, add suffix –Z (e.g. MP26124GR–Z)
TOP MARKING
MP: MPS prefix
Y: Year code
WW: Week code
M26124: Product code of MP26124GR
LLLLLL: Lot number
PACKAGE REFERENCE
QFN-16 (4mmx4mm)
MP26124 Rev. 1.0
10/10/2017
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2
MP26124 –24V INPUT, 2A, 600kHz, 4S SWITCHING LI-ION BATTERY CHARGER
ABSOLUTE MAXIMUM RATINGS (1)
Thermal Resistance (4)
Supply voltage (VCC, VIN) ..........................28V
VSW ................................... -0.3V to (VIN + 0.3V)
VBST .....................................................VSW + 6V
VCSP, VBATT ................................... -0.3V to +20V
VACOK, VCHGOK ............................... -0.3V to +28V
All other pins .................................. -0.3V to +6V
Continuous power dissipation (TA = 25°C) (2)
..................................................................2.7W
Junction temperature ............................... 150°C
Lead temperature .................................... 260°C
Storage temperature ................ -65°C to +150°C
QFN-16 (4mmx4mm) ............ 46 ....... 10 ... °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 board.
Supply voltage (VIN) ........................ 18V to 24V
Maximum junction temp. (TJ) ................... 125°C
MP26124 Rev. 1.0
10/10/2017
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3
MP26124 –24V INPUT, 2A, 600kHz, 4S SWITCHING LI-ION BATTERY CHARGER
ELECTRICAL CHARACTERISTICS
VIN = 24V, TA = 25°C, unless otherwise noted.
Parameters
Symbol
Terminal battery voltage
CSP, BATT current
Switch on resistance
VBATT
ICSP, IBATT
RDS(ON)
Switch leakage
Peak current limit
CC current
Condition
Min
Typ
Max
Units
16.67
16.93
Charging disabled
16.8
1
200
V
µA
mΩ
EN = 4V, VSW = 0V
0
1
μA
CC (5)
4.1
A
TRICKLE
2
A
ICC
RS1 = 100mΩ
1900
2100
2300
mA
Trickle charge current
ITRICKLE
10%
ICC
Trickle charge voltage
threshold
VTC
12.0
V
1400
mV
Trickle charge hysteresis
Termination current threshold
Oscillator frequency
Fold-back frequency
Maximum duty cycle
Maximum current sense
voltage (CSP to BATT)
Minimum on time (5)
IBF
fSW
5%
VBATT = 14V
VBATT = 0V
VSENSE
180
tON
Dead battery indicator
In trickle mode, CTMR = 0.1μF
MP26124 Rev. 1.0
10/10/2017
ICC
kHz
kHz
%
210
240
mV
100
VDRAIN = 0.3V
NTC low-temp rising threshold
NTC high-temp falling
threshold
VIN min head room (reverse
blocking)
15%
90
Under-voltage lockout
threshold rising
Under-voltage lockout
threshold hysteresis
Open-drain sink current
Recharge threshold at VBATT
Recharge hysteresis
10%
600
190
3.05
3.25
ns
3.45
300
mV
5
VRECHG
V
mA
30
min
16.0
400
V
mV
VTL
As a percentage of VREF33
64.2
65.2
66.2
%
VTH
As a percentage of VREF33
34
35
36
%
VIN - VBATT
250
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mV
4
MP26124 –24V INPUT, 2A, 600kHz, 4S SWITCHING LI-ION BATTERY CHARGER
ELECTRICAL CHARACTERISTICS (continued)
VIN = 24V, TA = 25°C, unless otherwise noted.
Parameters
Symbol
Condition
Min
Typ
EN input low voltage
0.4
V
V
EN = 4V
4
EN = 0V
0.2
EN = 4V
0.5
mA
0.665
mA
Supply current (shutdown)
EN = 4V, considering the
VREF33 output current,
R3 = 10kΩ, RNTC = 10kΩ
Supply current (quiescent)
EN = 0V
(5)
Thermal shutdown
VREF33 output voltage
VREF33 load regulation
Units
1.8
EN input high voltage
EN input current
Max
ILOAD = 0 to 10mA
μA
2.0
mA
150
3.3
°C
V
35
mV
NOTE:
5) Guaranteed by design.
MP26124 Rev. 1.0
10/10/2017
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5
MP26124 –24V INPUT, 2A, 600kHz, 4S SWITCHING LI-ION BATTERY CHARGER
TYPICAL PERFORMANCE CHARACTERISTICS
VIN = 18V, C1 = 4.7μF, C2 = 22μF, L = 10μH, RS1 = 200mΩ, real/simulation battery load, TA = 25°C,
unless otherwise noted.
4-Cell Charge Current vs. Battery
Voltage
Efficiency vs. ICHG
4 cells, VBATT = 16.4V
Battery simulator
100%
1
95%
0.8
EFFICIENCY
CHARGE CURRENT(A)
1.2
0.6
0.4
90%
85%
0.2
80%
0
0
5
10
15
0
20
0.2
0.4
0.6
0.8
1
ICHG(A)
BATTERY VOLTAGE(V)
Efficiency vs. VIN
NTC Control Window
4 cells, VBATT = 14.8V
2.5
96%
94%
VNTC(V)
Efficiency
2
92%
1.5
1
High Temp On
High Temp Off
0.5
Low Temp On
Low Temp Off
90%
18
20
22
0
24
18
VIN(V)
20
22
24
VIN(V)
Battery Leakage Current vs. VBATT
BATT Full Voltage vs. VIN
16.8
10
8
VBATT(V)
IBATT(μA)
16.7
6
4
2
16.6
16.5
0
0
4
8
12
VBATT(V)
MP26124 Rev. 1.0
10/10/2017
16
20
18
20
22
24
VIN(V)
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6
MP26124 –24V INPUT, 2A, 600kHz, 4S SWITCHING LI-ION BATTERY CHARGER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 18V, C1 = 4.7μF, C2 = 22μF, L = 10μH, RS1 = 200mΩ, real/simulation battery load, TA = 25°C,
unless otherwise noted.
Terminal Battery Voltage vs.
Temperature
Charge Current vs. Temperature
RS1 = 100mΩ, BATT = 14V
2300.0
2100.0
16.8
I_CC (mA)
Terminal VBATT (V)
16.85
16.75
1900.0
1700.0
16.7
1500.0
-50
0
50
100
TEMPERATURE (°C)
-50
VCC Leakage Current @ 28V vs.
Temperature
VIN Leakage Current @ 28V vs.
Temperature
BATT = 20V
410
400
200
I_VCC_Leakage (μA)
I_VIN_Leakage (μA)
250
150
100
50
0
390
380
370
360
350
340
-50
0
50
100
TEMPERATURE (°C)
-50
IBATT Leakage @ 20V vs. Temperature
0
50
100
TEMPERATURE (°C)
RDS(ON) vs. Temperature
300
0.02
250
0.015
RDS_ON (mΩ)
I_BATT_Leakage (μA)
0
50
100
TEMPERATURE (°C)
0.01
0.005
200
150
100
50
0
-50
MP26124 Rev. 1.0
10/10/2017
0
50
100
TEMPERATURE (°C)
0
-50
0
50
100
TEMPERATURE (°C)
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7
MP26124 –24V INPUT, 2A, 600kHz, 4S SWITCHING LI-ION BATTERY CHARGER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 18V, C1 = 4.7μF, C2 = 22μF, L = 10μH, RS1 = 200mΩ, real/simulation battery load, TA = 25°C,
unless otherwise noted.
Steady State
Steady State
Trickle charge, 4 cells, VBATT = 10V
CC charge, 4 cells, VBATT = 14.4V
CH1: VIN
5V/div.
CH1: VIN
5V/div.
CH2: VBATT
5V/div.
CH2: VBATT
5V/div.
CH4: IL
500mA/div.
CH4: IL
500mA/div.
CH3: VSW
CH3: VSW
10V/div.
10V/div.
1µs/div.
1µs/div.
Steady State
Power On
CV charge, 4 cells, VBATT = 16.6V
4 cells, ICHG = 1A, VBATT = 13.2V
CH1: VIN
5V/div.
CH2: VBATT
5V/div.
CH2: VBATT
5V/div.
CH1: VIN
5V/div.
CH4: IL
500mA/div.
CH4: IBATT
500mA/div.
CH3: VSW
CH3: VSW
10V/div.
10V/div.
1µs/div.
4ms/div.
Power Off
EN On
4 cells, ICHG = 1A, VBATT = 13.2V
4 cells, ICHG = 1A, VBATT = 13.2V
CH1: VIN
5V/div.
CH1: VEN
2V/div.
CH2: VBATT
5V/div.
CH2: VBATT
5V/div.
CH4: IBATT
500mA/div.
CH4: IBATT
500mA/div.
CH3: VSW
CH3: VSW
10V/div.
10V/div.
10ms/div.
MP26124 Rev. 1.0
10/10/2017
10ms/div.
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8
MP26124 –24V INPUT, 2A, 600kHz, 4S SWITCHING LI-ION BATTERY CHARGER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 18V, C1 = 4.7μF, C2 = 22μF, L = 10μH, RS1 = 200mΩ, real/simulation battery load, TA = 25°C,
unless otherwise noted.
EN Off
NTC Control
4 cells, ICHG = 1A, VBATT = 13.2V
4 cells, ICHG = 1A, VBATT = 13.2V
CH1: VEN
2V/div.
CH2: VBATT
5V/div.
CH2: VBATT
5V/div.
CH1: VNTC
1V/div.
CH4: IBATT
500mA/div.
CH4: IBATT
500mA/div.
CH3: VSW
10V/div.
CH3: VSW
20V/div.
10ms/div.
200ms/div.
Timer Out
4 cells, ICHG = 1A, VBATT = 13.2V
CH1: VTMR
1V/div.
CH2: VBATT
5V/div.
CH3: VSW
20V/div.
CH4: IBATT
500mA/div.
400µs/div.
MP26124 Rev. 1.0
10/10/2017
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9
MP26124 –24V INPUT, 2A, 600kHz, 4S SWITCHING LI-ION BATTERY CHARGER
PIN FUNCTIONS
Pin #
Name
1
VCC
2
NTC
3
ACOK
4
CHGOK
5
VREF33
6
EN
7
SGND
8
9
10
COMPV
COMPI
BATT
11
CSP
12
GND
13
TMR
14
BST
15
SW
16
VIN
Description
IC supply voltage.
Thermistor input. Connect a resistor from NTC to VREF33. Connect the thermistor
from NTC to ground.
Valid input supply indicator. ACOK is an open-drain output. Add a pull-up resistor to
ACOK . Logic low indicates the presence of a valid input supply.
Charging status indicator. CHGOK is an open-drain output. Add a pull-up resistor to
MP26124 Rev. 1.0
10/10/2017
CHGOK . Logic low indicates normal charging. Logic high indicates either a completed
charge process or suspended process due to a fault.
Internal linear regulator, 3.3V reference output. Bypass VREF33 to GND with a 1μF
ceramic capacitor.
On/off control input.
Definition. Connect SGND to the GND plane.
V-LOOP compensation. Decouple COMPV with a capacitor and a resistor.
I-LOOP compensation. Decouple COMPI with a capacitor and a resistor.
Positive battery terminal.
Battery charge current sense positive input. Connect a resistor (RS1) between CSP
200mV
and BATT. The full charge current is: ICHG A
.
RS1mΩ
Ground. GND is the voltage reference for the regulated output voltage. This node
should be placed outside of the switching diode (D2) to the input ground path to prevent
switching current spikes from inducing voltage noise into the part.
Safe timer period. A 0.1µA current charges and discharges the external capacitor
decoupled to GND. The capacitor value programs the timer period.
Bootstrap. A charged capacitor is required to drive the power switch’s gate above the
supply voltage. Connect a capacitor between SW and BST to form a floating supply
across the power switch driver.
Switch output.
Input voltage. The MP26124 regulates an up to 24V input to a voltage suitable for
charging a 4-series Li-ion battery pack. Capacitors are required to prevent large voltage
spikes from appearing at the input.
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10
MP26124 –24V INPUT, 2A, 600kHz, 4S SWITCHING LI-ION BATTERY CHARGER
BLOCK DIAGRAM
VIN
Current Sense
A1
PRE_REGS
EN
600kHz
OSC
BST
Regulator
Current Limit
Comparator
5 bit trim
M1
S
VREF
Q
Drive
R
CTRL
R
3 bit trim
SW
PWM
Comparator
IREF
Mini Refresh
L
VCC
LDO
Charge
Current Sense
VBATT
VREF33
CSP
x6
FB
NTC
BATT
0.12V
or 1.2V
COMP
1.2V
FB
Max Reflesh Time
Max Charge Time
FB
Charge Control
Logic
4V
Recharge Comparator
0.12V
Charge
Current Sense
SGND
COMPI
2.8V
Max Trickle Time
Timer
4 cells
battery
TC/CC
Charge Comparator
CTRL
TMR
RS1
A2
GMI
GMV
COMPV
VIN
BF
Comparator
ACOK
BATT+300mV
GND
ACOK
CHGOK
Figure 1: Functional Block Diagram
MP26124 Rev. 1.0
10/10/2017
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11
MP26124 –24V INPUT, 2A, 600kHz, 4S SWITCHING LI-ION BATTERY CHARGER
OPERATION
The MP26124 is a peak-current modecontrolled switching charger for use with Li-ion
batteries.
At the beginning of a cycle, the MOSFET (M1)
is off, and the COMP voltage is higher than the
output of the current sense amplifier (A1). The
pulse-width modulation (PWM) comparator’s
output is low, and the rising edge of the 600kHz
CLK signal sets the RS flip-flop, which turns on
M1, connecting SW and the inductor to the
input supply.
As the inductor current increases, the output of
A1 increases. When this signal exceeds the
COMP voltage, the RS flip-flop resets and turns
M1 off. The external switching diode (D2) then
conducts the inductor current.
The MP26124 uses COMP to select the smaller
value of GMI and GMV to implement either
current loop control or voltage loop control.
Current loop control occurs when the battery
voltage is low, which results in the saturation of
the GMV output. GMI compares the charge
current (as a voltage sensed through RS1)
against the reference voltage to regulate the
charge current to a constant value. When the
battery voltage charges up to the reference
voltage, the output of GMV goes low and
initiates voltage loop control to control the duty
cycle to regulate the output voltage.
If the charge stays in trickle-charging mode until
the time-out condition is triggered, charging
terminates until the input power or EN signal
refreshes. Otherwise, GMI regulates the charge
current to the level set by RS1. The charger
operates at constant-current (CC) charging
mode. The duty cycle of the switcher is
determined by the COMPI voltage, which is
regulated by the amplifier GMI.
When the battery voltage reaches the constantvoltage mode threshold, GMV regulates COMP
and the duty cycle for constant voltage (CV)
mode. When the charge current drops to the
battery-full threshold (IBF, typical 10% CC), the
battery is defined as fully charged. The charger
stops charging, and CHGOK goes high to
indicate the charge-full condition. If the total
charge time exceeds the timer period, the
charging terminates immediately and resumes
when either the input power or EN signal can
restart the charger.
Figure 2 shows the typical charge profile of the
MP26124.
CV charge
Threshold
Constant
Charge
Current
ICHG
VBATT
CC charge
Threshold
Trickle charge
The MP26124 has an internal linear regulator
(VREF33) to power the internal circuitry.
VREF33 can also power external circuitry as
long as the load does not exceed the maximum
current (30mA). Connect a 1μF bypass
capacitor from VREF33 to GND to ensure
stability.
Charge Cycle (Mode Change: Trickle CC
CV)
At the start of a charging cycle, the MP26124
monitors VBATT. If VBATT is lower than the tricklecharge threshold (VTC, typically 3.0V/cell), the
charging cycle starts in trickle-charge mode
(10% of the RS1 programmed constant-charge
current, ICC) until the battery voltage reaches
VTC.
MP26124 Rev. 1.0
10/10/2017
IBF
CC charge
CV charge
Trickle
Charge
Current
Charge Full
Figure 2: Li-Ion Battery Charge Profile
Automatic Recharge
After the battery has completely recharged, the
charger disables all blocks except for the
battery voltage monitor to limit the leakage
current. If the battery voltage falls below
4.0V/cell, the MP26124 begins recharging with
a soft start. The timer then resets to avoid
timer-related charging disruptions.
Charger Status Indication
The MP26124 has two open-drain status
outputs: ACOK and CHGOK . ACOK goes low
when the IC supply voltage (VCC) exceeds the
under-voltage lockout (UVLO) threshold and the
regulated voltage (VIN) is 300mV higher than
VBATT to ensure that the regulator can operate
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12
MP26124 –24V INPUT, 2A, 600kHz, 4S SWITCHING LI-ION BATTERY CHARGER
normally. CHGOK indicates the charge status.
Table 1 describes the ACOK and CHGOK
outputs under different charge conditions.
Table 1: Charging Status Indication
ACOK
CHGOK
Charger Status
low
low
low
high
In charging
End of charge, NTC
fault, timer out, thermal
high
high
shutdown, EN disable
VIN - VBATT < 0.3V
VCC < UVLO
Timer Operation
The MP26124 uses the internal timer to limit the
charge period during trickle charge and total
charge cycle. Once the charge time exceeds
the time limit, the MP26124 terminates charging.
A good battery should recharge completely
within the allotted time period. Otherwise, the
battery has a fault. An external capacitor at
TMR programs the time period.
When time-out occurs, charging is suspended.
The charge cycle can be restarted by refreshing
the input power or EN signal or auto-recharge
(VBATT falls through 4V/cell).
Negative
Thermal
Coefficient
(NTC)
Thermistor
The MP26124 has a built-in NTC resistance
window comparator that allows the MP26124 to
sense the battery temperature through the
thermistor included in the battery pack. Connect
a resistor with an appropriate value from
VREF33 to NTC, and connect the thermistor
from NTC to GND. A resistor divider determines
the voltage on NTC as a function of the battery
temperature. Charging stops when the NTC
voltage exits the NTC window range. Charging
resumes when the voltage is within the NTC
window range.
The trickle mode charge time can be calculated
with Equation (1):
TTRICKLE _ TMR 30mins
CTMR
0.1F
(1)
The total charge time can be calculated with
Equation (2):
TTOTAL _ TMR 3hours
MP26124 Rev. 1.0
10/10/2017
CTMR
0.1F
(2)
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13
MP26124 –24V INPUT, 2A, 600kHz, 4S SWITCHING LI-ION BATTERY CHARGER
OPERATION FLOW CHART
POR
VUVLOVBATT+0.3V?
SYS powered by
BATT
No
Yes
ACOK is low
No
Charging
EN?
Yes
VBATT_TC = 12V
VBATT_FULL=16.8V
VBATT_RECHG=16V
Normal Operation
Charger “On”,
CHGOK is low
Charge Mode?
VBATT>=VBATT_FULL
VBATT_TC
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