MP2623
Stand-Alone, 2A, 1- or2-Cell
Switching LiFePO4 Battery Charger
The Future of Analog IC Technology
DESCRIPTION
FEATURES
The MP2623 is a monolithic, DC-DC, stepdown, switching charger for a 1-or-2-cell serial
LiFePO4 battery. It has an integrated high-side
power MOSFET that can output up to a 2A
charge current. It also has peak-current–mode
control for fast loop response and easy
compensation.
The MP2623 uses a sense resistor to control a
programmable charge current, and accurately
regulates the charge current and the charge
voltage using two control loops.
The MP2623 has multiple fault-condition
protections that include 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 halt charging after a set
time period.
Charges 1- and 2-Cell LiFePO4 Battery
Packs
Wide Operating-Input Range
Programmable Charging Current of up to 2A
±0.75% VBATT Accuracy
0.2Ω Integrated Power MOSFET
Up to 90% Efficiency
Fixed 1.1MHz Frequency
Preconditioning for Fully-Depleted Batteries
Charging Status Indicator
Input Supply Fault Indicator
Thermal Shutdown
Cycle-by-Cycle Over-Current Protection
Battery Temperature Monitor and Protection
APPLICATIONS
The MP2623 requires a minimal number of
readily-available external components.
Power Tools and Portable Equipment
Handheld Terminals
LiFePO4 Battery Chargers
All MPS parts are lead-free and adhere to the RoHS directive. For MPS green
status, please visit MPS website under Quality Assurance. “MPS” and “The
Future of Analog IC Technology” are Registered Trademarks of Monolithic
Power Systems, Inc.
The MP2623 is available in a 4mm×4mm 16-pin
QFN package.
TYPICAL APPLICATION
D1
VIN
5.5V to 24V
C1
4.7
CIN
10
L
VIN
SW
VREF33
C3
1
R1
R2
VCC
MP2623
BATT
CELLS
COMPI
10k
ON OFF
C2
GND
R5
750
R4
2.5k
TMR
C6
0.1
MP2623 Rev. 1.0
12/26/2013
1-2 Cell
LiFePO4
COMPV
NTC
RNTC
100 m
D2
CSP
ACOK
EN
C7
0.1
BST
22
CHGOK
R3
10k
RS1
4.7
C4
2.2nF
C5
2.2nF
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© 2013 MPS. All Rights Reserved.
1
MP2623 – 2A, 24V INPUT, 1.1MHz 1- OR 2-CELL SWITCHING LIFEPO4 BATTERY CHARGER
ORDERING INFORMATION
Part Number*
MP2623GR
Package
QFN16 (4×4mm)
Top Marking
MP2623
*For Tape & Reel, add suffix –Z (e.g. MP2623GR–Z)
PACKAGE REFERENCE
TOP VIEW
PIN 1 ID
VIN
SW
BST
TMR
16
15
14
13
VCC
1
12
GND
NTC
2
11
CSP
ACOK
3
10
BATT
CHGOK
4
9
COMPI
5
6
7
8
VREF33 EN CELLS COMPV
EXPOSED PAD
ON BACKSIDE
ABSOLUTE MAXIMUM RATINGS (1)
Thermal Resistance
Supply Voltage VCC, VIN ............................ 26V
VSW ..................................... -0.3V to (VIN + 0.3V)
VBST ...................................................... VSW + 6V
VCSP, VBATT, ...................................-0.3V to +18V
VACOK, VCHGOK, ..............................-0.3V to +26V
All Other Pins ..................................-0.3V to +6V
(2)
Continuous Power Dissipation
(TA = 25°C)
............................................................. 2.7W
Junction Temperature ...............................150°C
Lead Temperature ....................................260°C
Storage Temperature............... -65°C to +150°C
QFN16 (4x4mm) ..................... 46 ...... 10... °C/W
Recommended Operating Conditions
(3)
(4)
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 will cause excessive die
temperature, and the regulator will 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 ..............................5V to 24V
Operating Junction Temp. (TJ) -40°C to +125°C
MP2623 Rev. 1.0
12/26/2013
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2
MP2623 – 2A, 24V INPUT, 1.1MHz 1- OR 2-CELL SWITCHING LIFEPO4 BATTERY CHARGER
ELECTRICAL CHARACTERISTICS
VIN = 19V, TA = 25°C, CELLS=0V, unless otherwise noted.
Parameters
Symbol Condition
Battery-terminal voltage
CSP，BATT current
Switch-on resistance
VBATT
CELLS=0V
CELLS=Float
Min
Typ
Max
Units
3.573
7.146
3.6
7.2
3.627
7.254
V
ICSP,IBATT Charging disabled
RDS(ON)
Switch leakage
CC current
CC
(5)
TRICKLE
ICC
Trickle-charge current
Trickle-charge voltage threshold
RS1=100mΩ
1.8
4.1
A
2
A
2.0
2.2
A
2.52
V/cell
300
mV/cell
fSW
5%
CELLS=0V,
VBATT =3.2V
VBATT =0V
10%
15%
170
VSENSE
tON
kHz
350
kHz
%
200
230
100
3.1
VIN
VDRAIN =0.3V
In trickle mode
CTMR=0.1μF
mV
ns
3.3
3.5
V
300
1000
mV
5
VRECHG
ICC
1100
90
Dead battery indicator
mA
30
min
3.42
100
V/cell
mV
%of
VREF33
%of
VREF33
NTC low-temp rising threshold
RNTC=NCP18X103, 0°C
70.5
73.5
76.5
NTC high-temp falling threshold
RNTC=NCP18X103,
50°C
27.5
29.5
31.5
VIN min. head-room (reverse
blocking)
VIN−VBATT
MP2623 Rev. 1.0
12/26/2013
μA
VTC
Oscillator frequency
Recharge threshold for VBATT
Recharge hysteresis
1
ICC
IBF
Under-voltage lockout threshold,
rising
Under-voltage lockout threshold,
hysteresis
Open-drain sink current
Ω
10%
Termination current threshold
Minimum ON time (5)
0.2
ITRICKLE
Trickle-charge hysteresis
Fold-back frequency
Maximum duty cycle
Maximum current-sense voltage
(CSP to BATT)
µA
0
EN = 4V, VSW = 0V
Peak-current limit
1
180
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mV
3
MP2623 – 2A, 24V INPUT, 1.1MHz 1- OR 2-CELL SWITCHING LIFEPO4 BATTERY CHARGER
ELECTRICAL CHARACTERISTICS (continued)
VIN = 19V, TA = 25°C, CELLS=0V, unless otherwise noted.
Parameters
Symbol Condition
Min
Typ
EN input low voltage
Supply current (shutdown)
Supply current (quiescent)
0.4
V
V
EN =4V
4
EN =0V
0.2
EN =4V
0.5
mA
0.665
mA
EN =4V,
Consider VREF33 pin
output current,
R3=10k,RNTC=10k
ILOAD =0 to 10mA
μA
2.0
EN =0V, CELLS=0V
(5)
Thermal shutdown
VREF33 output voltage
VREF33 load regulation
Units
1.8
EN input high voltage
EN input current
Max
150
3.3
30
mA
°C
V
mV
Notes:
5) Guaranteed by design.
MP2623 Rev. 1.0
12/26/2013
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4
MP2623 – 2A, 24V INPUT, 1.1MHz 1- OR 2-CELL SWITCHING LIFEPO4 BATTERY CHARGER
PIN FUNCTIONS
Pin #
Name
1
VCC
2
3
4
5
6
Description
IC Supply Voltage.
Thermistor Input. Connect a resistor from this pin to VREF33, and the thermistor from this
NTC
pin to ground.
Valid Input Supply Indicator. Open drain output. Add a pull-up resistor. Logic LOW indicates
ACOK the presence of a valid input supply.
Charging Status Indicator. Open drain output. Add a pull-up resistor. Logic LOW indicates
CHGOK normal charging. Logic HIGH indicates either a completed charge process or a faultsuspended process.
Internal Linear Regulator, 3.3V Reference Output. Bypass to GND with a 1μF ceramic
VREF33
capacitor.
On/Off Control Input.
EN
7
CELLS
8
COMPV
9
COMPI
10
BATT
11
CSP
12
GND
13
TMR
14
BST
15
SW
16
VIN
MP2623 Rev. 1.0
12/26/2013
Command Input. Indicates the number of LiFePO4 battery cells. Connect to VREF33 or float
for 2-cell operation. Ground for 1-cell operation.
V-LOOP Compensation. Decouple this pin with a capacitor and a resistor.
I-LOOP Compensation. Decouple this pin with a capacitor and a resistor.
Positive Battery Terminal.
Battery-Charge Current-Sense–Positive Input. Connect a resistor RS1 between CSP and
200mV
.
BATT. The full charge current is: ICHG A
RS1mΩ
Ground. Voltage reference for the regulated output voltage. Place this node outside of the
path of the switching diode (D2) to the input ground to prevent switching current spikes from
inducing voltage noise.
Set-Safe–Time Period. A 0.1µA current charges and discharges the external capacitor
decoupled to GND. The capacitor value programs the time period.
Bootstrap. Requires a charged capacitor to drive the power switch’s gate above the supply
voltage. Connect a capacitor between SW and BST pins to form a floating supply across the
power switch driver.
Switch Output.
Regulator Input Voltage. The MP2623 regulates a 5V-to-24V input to a voltage suitable for
charging either a 1- or 2-cell LiFePO4 battery. Requires capacitors to prevent large voltage
spikes from appearing at the input.
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5
MP2623 – 2A, 24V INPUT, 1.1MHz 1- OR 2-CELL SWITCHING LIFEPO4 BATTERY CHARGER
TYPICAL PERFORMANCE CHARACTERISTICS
VIN=5V/ 9V, C1=4.7μF, C2=22μF, L=4.7μH, RS1=100mΩ, Real/Simulation Battery Load, TA=25°C,
unless otherwise noted.
1 Cell Charge Current vs.
Battery Voltage
1 Cell Battery Charge Curve
1
3.37
0.5
3.32
3.27
0
10
20
30
40
TIMES(MIN)
CHARGE CURRENT(A)
VBATT
3.42
2
1.6
VIN=5V
1.2
0.8
0.4
0
50
VIN=24V
0
0
60
1
2
3
BATTERY VOLTAGE(V)
2 Cells Charge Current vs.
Battery Voltage
7
1.5
6.9
1
6.8
VBATT
6.7
0.5
6.6
6.5
4
2
7.1
CHARGE CURRENT(A)
1.5
3.47
ICHG
7.2
CHARGE CURRENT(A)
2
3.52
2.5
7.3
2.4
I CHG
3.57
BATTERY VOLTAGE(V)
Battery Simulator
2.5
BATTERY VOLTAGE(V)
3.62
2 Cells Battery Charge Curve
0
0
5
10
15
TIMES(MIN)
20
25
Breakdown Voltage
NTC Control Window
Battery Simulator
1.6
Low Temp On
2
1.2
0.8
1.5
High Temp On
1
VIN=24
0.4
High Temp Off
0.5
VIN=9V
1
2
3
4
5
6
7
0
8
Efficiency vs.
Battery Voltage
1 Cell, ICHG=2A
12
16
20
24
INPUT VOLTAGE (V)
70
60
VIN=5V
VIN=24V
50
40
30
80
70
60
8
6
4
2
28
VIN=9V
VIN=19V
50
VIN=24V
40
30
80
70
60
50
40
30
10
10
3.1
3.3
3.5
BATTERY VOLTAGE(V)
MP2623 Rev. 1.0
12/26/2013
3.7
0
500 1000 1500 2000 2500
CHARGE CURRENT(A)
40
90
VIN=5
20
2.9
30
1 Cell, VBATT=3.4V, ICHG=2A
20
2.7
20
Efficiency vs. VIN
10
2.5
10
INPUT VOLTAGE (V)
20
0
0
1 Cell, VBATT=3.6V
90
EFFICIENCY (%)
EFFICIENCY (%)
VIN=19V
10
Efficiency vs. ICHG
100
VIN=9V
80
12
0
8
EFFICIENCY (%)
0
BATTERY VOLTAGE(V)
90
14
Low Temp Off
2.5
INPUT CURRENT (mA)
2
0
16
3
VNTC(V)
CHARGE CURRENT(A)
2.4
0
0
5
10
15
20
INPUT VOLTAGE (V)
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25
6
MP2623 – 2A, 24V INPUT, 1.1MHz 1- OR 2-CELL SWITCHING LIFEPO4 BATTERY CHARGER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN=5V/ 9V, C1=4.7μF, C2=22μF, L=4.7μH, RS1=100mΩ, Real/Simulation Battery Load, TA=25°C,
unless otherwise noted.
BATT Charge Full Voltage
vs. Temperature
1 Cell
3.65
BATTERY VOLTAGE(V)
CHARGE FULL VOLTAGE(V)
3.65
3.6
3.55
3.5
3.45
0
10
5
15
20
25
1 Cell VIN=19V
3.6
3.55
3.5
3.45
-40
30
BATT Charge Full Voltage
vs. Temperature
2 Cells VIN=19V
7.3
BATTERY VOLTAGE(V)
BATT Float Voltage vs. VIN
-20
0
20
40
60
0.3
3.4
0.25
0.2
0.15
60
TEMPERATURE(oC)
MP2623 Rev. 1.0
12/26/2013
80
3.3
3.2
3.0
-40
-20
0
20
40
60
80
1 Cell ICHG=500mA
500
3.1
40
-20
Constant Current Charge
vs. Temperature
CHARGE CURRENT (mA)
3.5
VREF33 (V)
0.35
20
6.9
TEMPERATURE (oC)
VIN=19V
0
7
6.8
-40
80
VREF33 vs. Temperature
RDS_ON vs. Temperature
-20
7.1
TEMPERATURE (oC)
INPUT VOLTAGE(V)
0.1
-40
7.2
0
20
40
60
TEMPERATURE (oC)
80
490
480
470
460
450
-40
-20
0
20
40
60
80
TEMPERATURE (oC)
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7
MP2623 – 2A, 24V INPUT, 1.1MHz 1- OR 2-CELL SWITCHING LIFEPO4 BATTERY CHARGER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN=5V/ 9V, C1=4.7μF, C2=22μF, L=4.7μH, RS1=100mΩ, Real/Simulation Battery Load, TA=25°C,
unless otherwise noted.
Steady State Waveform
Steady State Waveform
Steady State Waveform
1 Cell, VBATT=2V
1 Cell, VBATT=3.2V
1 Cell, VBATT=3.6V
VIN
2V/div.
VBATT
1V/div.
VSW
2V/div.
ICHG
1A/div.
VIN
2V/div.
VBATT
2V/div.
VIN
2V/div.
VSW
2V/div.
VSW
2V/div.
ICHG
1A/div.
VBATT
2V/div.
ICHG
1A/div.
400ns/div.
400ns/div.
Power On Waveform
Power Off Waveform
EN On Waveform
1 Cell, ICHG=2A,VBATT=3V
1 Cell, ICHG=2A,VBATT=3V
1 Cell, ICHG=2A,VBATT=3V
VEN
5V/div.
VIN
2V/div.
VIN
2V/div.
VBATT
2V/div.
VBATT
2V/div.
VSW
2V/div.
VSW
2V/div.
VBATT
1V/div.
ICHG
2A/div.
ICHG
1A/div.
4ms/div.
NTC Control,
1 Cell, ICHG=2A, VBATT=2.5V,
Battery Simulator
1 Cell, ICHG=2A,VBATT=3V
VBATT
2V/div.
VSW
5V/div.
ICHG
2A/div.
MP2623 Rev. 1.0
12/26/2013
ICHG
2A/div.
100ms/div.
EN Off Waveform
VEN
5V/div.
VSW
5V/div.
Timer Out
1 Cell,ICHG=2A, VBATT=3.5V,
CTIMER=47pF, Battery Simulator
VNTC
5V/div.
VTMR
500mV/div.
VBATT
2V/div.
VSW
2V/div.
ICHG
1A/div.
VSW
2V/div.
VBATT
1V/div.
ICHG
1A/div.
200ms/div.
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© 2013 MPS. All Rights Reserved.
8
MP2623 – 2A, 24V INPUT, 1.1MHz 1- OR 2-CELL SWITCHING LIFEPO4 BATTERY CHARGER
FUNCTIONAL BLOCK DIAGRAM
VIN
VCC
Current Sense
A1
PRE_REGS
EN
BST
1100kHz
OSC
Regulator
Current Limit
Comparator
5 bit trim
VREF
M1
S
Q
Drive
R
IREF
CTRL
R
3 bit trim
SW
PWM
Comparator
D2
Mini Refresh
L
LDO
Charge
Current Sense
VBATT
VREF33
CSP
x6
FB
cells
NTC
A2
GMI
GMV
0.12V
or 1.2V
COMP
1.2V
FB
Max Reflesh Time
Max Charge Time
FB
Charge Control
Logic
1.11V
Recharge Comparator
0.12V
Charge
Current Sense
CELLS
COMPI
0.83V
Max Trickle Time
Timer
1- or 2- cell
LiFePO4 Battery
TC/CC
Charge Comparator
CTRL
TMR
RS1
BATT
COMPV
VIN
BF
Comparator
ACOK
ACOK
CHGOK
BATT+300mV
GND
Figure 1: Functional Block Diagram
MP2623 Rev. 1.0
12/26/2013
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© 2013 MPS. All Rights Reserved.
9
MP2623 – 2A, 24V INPUT, 1.1MHz 1- OR 2-CELL SWITCHING LIFEPO4 BATTERY CHARGER
OPERATION
The MP2623 is a peak-current–mode controlled
switching charger for use with LiFePO4 batteries.
(10% of the RS1-programmed constant-charge
current, ICC) until the battery voltage reaches VTC.
At the beginning of each cycle, M1 is off and the
COMP voltage exceeds the output of the currentsense amplifier (A1). The PWM comparator’s
output is low, and the rising edge of the 1.1MHz
CLK signal sets the RS flip-flop that turns on M1;
this connects the SW pin and the inductor to the
input supply.
If the charge stays in the trickle-charge mode
until the time-out condition triggers, charging
terminates and will not resume until either the
input power or the EN signal refreshes.
Otherwise, GMI regulates the charge current to
the level set by RS1. The charger operates in
constant-current–charging mode. The COMPI
voltage—regulated by GMI—determines the
switching duty cycle.
A1 senses and amplifies the inductor current:
The PWM comparator then compares the sum of
this signal and the ramp compensator signal
against the COMP signal. When the sum of the
A1 output and the ramp compensator exceeds
the COMP voltage, the RS flip-flop resets and
turns M1 off. The external switching diode (D2)
then conducts the inductor current. If the sum of
the A1 output and the ramp compensator does
not exceed the COMP voltage, then the falling
edge of the CLK resets the flip-flop.
When the battery voltage triggers constantvoltage mode, GMV regulates the COMP pin and
the duty cycle. When the charge current drops to
the battery-full threshold, IBF (typically 10% ICC),
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, charging
terminates at once and will resume when either
the input power or EN signal can restart the
charger.
The MP2623 uses COMP to select the smaller
value of GMI and GMV to implement either
current-loop control or voltage-loop control.
Current-loop control triggers when the battery
voltage goes low, which results in the GMV
output saturating. The 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.
Figure 2 shows the typical charge profile of the
MP2623.
The MP2623 has an internal linear regulator—
VREF33—to power internal circuitry. It 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.
Automatic Recharge
After the battery completely recharges, the
charger removes all the blocks besides the
battery voltage monitor to reduce the leakage
current from the input or the battery. If the battery
voltage drops below 3.42V/Cell, the circuit will
automatically recharge the battery using soft-start.
The timer will then restart to avoid triggering a
false fault.
Charge Cycle (Mode change: Trickle CC
CV)
At the start of a charging cycle, the MP2623
monitors VBATT. If VBATT is lower than the tricklecharge threshold, VTC (typically 2.52V/cell), the
charging cycle will start in trickle-charge mode
MP2623 Rev. 1.0
12/26/2013
CV charge
Threshold
Constant
Charge
Current
ICHG
VBATT
CC charge
Threshold
Trickle charge
I BF
CC charge
CV charge
Trickle
Charge
Current
Charge Full
Figure 2: Li-Ion Battery Charging Profile
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10
MP2623 – 2A, 24V INPUT, 1.1MHz 1- OR 2-CELL SWITCHING LIFEPO4 BATTERY CHARGER
Charger Status Indication
MP2623 has two open-drain status outputs:
ACOK and CHGOK . The ACOK pin goes low
when the IC supply voltage (VCC) exceeds the
under-voltage lockout threshold and the
regulated voltage VIN is 300mV higher than VBATT
to make sure the regulator can operate normally.
CHGOK
indicates
charge
status.
Table
1
describes ACOK and CHGOK outputs under
different charge conditions.
Table 1―Charging Status Indication
ACOK
CHGOK
low
low
low
high
high
high
Charger Status
In charging
End of charge, NTC
fault, timer out, thermal
shutdown, EN disable
VIN–VBATT
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