MP2623GR [MPS]
Stand-Alone, 2A, 1- or2-Cell Switching LiFePO4 Battery Charger;
| 型号： | MP2623GR |
| 厂家： | 
MONOLITHIC POWER SYSTEMS |
| 描述： | Stand-Alone, 2A, 1- or2-Cell Switching LiFePO4 Battery Charger 电池 |
| 文件： | 总16页 (文件大小：457K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
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, step-
down, 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.
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
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.
APPLICATIONS
Power Tools and Portable Equipment
Handheld Terminals
LiFePO4 Battery Chargers
The MP2623 requires a minimal number of
readily-available external components.
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
CIN
C1
4.7
10
L
RS1
VIN
SW
4.7
VREF33
C7
0.1
100 m
C3
D2
MP2623
1-2 Cell
LiFePO4
1
R1
R2
VCC
BST
C2
22
CHGOK
CSP
ACOK
BATT
R3
R5 750
10k
CELLS
COMPI
COMPV
TMR
NTC
EN
R4 2.5k
GND
RNTC
10k
ON
OFF
C6
0.1
C4
C5
2.2nF
2.2nF
MP2623 Rev. 1.0
3/16/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
1
MP2623 – 2A, 24V INPUT, 1.1MHz 1- OR 2-CELL SWITCHING LIFEPO4 BATTERY CHARGER
ORDERING INFORMATION
Part Number*
Package
Top Marking
MP2623GR
QFN16 (4×4mm)
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
NTC
1
2
3
4
12 GND
11
CSP
ACOK
CHGOK
10 BATT
9
COMPI
5
6
7
8
VREF33 EN CELLS COMPV
EXPOSED PAD
ON BACKSIDE
ABSOLUTE MAXIMUM RATINGS (1)
Supply Voltage VCC, VIN ............................ 26V
Thermal Resistance (4)
QFN16 (4x4mm).....................46...... 10... °C/W
θJA
θJC
V
V
V
SW..................................... -0.3V to (VIN + 0.3V)
BST ...................................................... VSW + 6V
CSP, VBATT, ...................................-0.3V to +18V
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-to-
ambient thermal resistance θJA, and the ambient temperature
TA. The maximum allowable continuous power dissipation at
VACOK, VCHGOK, ..............................-0.3V to +26V
All Other Pins..................................-0.3V to +6V
(2)
any
ambient
temperature
is
calculated
by
Continuous Power Dissipation
(TA = 25°C)
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.
............................................................. 2.7W
Junction Temperature...............................150°C
Lead Temperature ....................................260°C
Storage Temperature............... -65°C to +150°C
3) The device is not guaranteed to function outside of its
operating conditions.
4) Measured on JESD51-7 4-layer board.
Recommended Operating Conditions (3)
Supply Voltage VIN ..............................5V to 24V
Operating Junction Temp. (TJ) -40°C to +125°C
MP2623 Rev. 1.0
3/16/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
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
Min
Typ
3.6
7.2
1
Max
3.627
7.254
Units
CELLS=0V
VBATT
3.573
7.146
Battery-terminal voltage
V
CELLS=Float
CSP，BATT current
Switch-on resistance
Switch leakage
ICSP,IBATT Charging disabled
µA
Ω
RDS(ON)
0.2
0
1
μA
EN= 4V, VSW = 0V
CC(5)
4.1
2
A
A
Peak-current limit
TRICKLE
CC current
ICC
ITRICKLE
VTC
RS1=100mΩ
1.8
5%
2.0
2.2
A
Trickle-charge current
Trickle-charge voltage threshold
Trickle-charge hysteresis
Termination current threshold
10%
2.52
300
10%
ICC
V/cell
mV/cell
ICC
IBF
15%
230
CELLS=0V,
VBATT =3.2V
Oscillator frequency
fSW
1100
350
kHz
Fold-back frequency
Maximum duty cycle
VBATT =0V
kHz
%
90
Maximum current-sense voltage
(CSP to BATT)
Minimum ON time (5)
VSENSE
tON
170
200
100
3.3
mV
ns
V
Under-voltage lockout threshold,
rising
VIN
3.1
5
3.5
Under-voltage lockout threshold,
hysteresis
300
1000
mV
mA
min
Open-drain sink current
VDRAIN =0.3V
In trickle mode
CTMR=0.1μF
Dead battery indicator
30
Recharge threshold for VBATT
Recharge hysteresis
VRECHG
3.42
100
V/cell
mV
%of
VREF33
NTC low-temp rising threshold
NTC high-temp falling threshold
RNTC=NCP18X103, 0°C
70.5
27.5
73.5
29.5
180
76.5
31.5
R
NTC=NCP18X103,
%of
VREF33
50°C
VIN min. head-room (reverse
blocking)
VIN−VBATT
mV
MP2623 Rev. 1.0
3/16/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
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
Max
Units
0.4
V
EN input low voltage
EN input high voltage
1.8
V
4
EN
EN
=4V
=0V
μA
mA
EN input current
0.2
0.5
EN=4V
EN=4V,
Supply current (shutdown)
Supply current (quiescent)
Thermal shutdown (5)
VREF33 output voltage
VREF33 load regulation
Consider VREF33 pin
output current,
R3=10k,RNTC=10k
0.665
mA
2.0
mA
EN=0V, CELLS=0V
150
3.3
30
°C
V
ILOAD =0 to 10mA
mV
Notes:
5) Guaranteed by design.
MP2623 Rev. 1.0
3/16/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
4
MP2623 – 2A, 24V INPUT, 1.1MHz 1- OR 2-CELL SWITCHING LIFEPO4 BATTERY CHARGER
PIN FUNCTIONS
Pin #
Name Description
1
VCC
IC Supply Voltage.
Thermistor Input. Connect a resistor from this pin to VREF33, and the thermistor from this
pin to ground.
2
3
NTC
Valid Input Supply Indicator. Open drain output. Add a pull-up resistor. Logic LOW indicates
the presence of a valid input supply.
ACOK
Charging Status Indicator. Open drain output. Add a pull-up resistor. Logic LOW indicates
normal charging. Logic HIGH indicates either a completed charge process or a fault-
suspended process.
4
CHGOK
VREF33
Internal Linear Regulator, 3.3V Reference Output. Bypass to GND with a 1μF ceramic
capacitor.
5
6
On/Off Control Input.
EN
Command Input. Indicates the number of LiFePO4 battery cells. Connect to VREF33 or float
for 2-cell operation. Ground for 1-cell operation.
7
CELLS
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.
8
COMPV
COMPI
BATT
9
10
Battery-Charge Current-Sense–Positive Input. Connect a resistor RS1 between CSP and
200mV
11
CSP
I
CHG
A
BATT. The full charge current is:
.
RS1
mΩ
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.
12
13
GND
TMR
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.
14
15
16
BST
SW
VIN
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.
MP2623 Rev. 1.0
3/16/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
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
2 Cells Battery Charge Curve
Battery Simulator
3.62
3.57
3.52
3.47
3.42
3.37
3.32
3.27
2.5
2.5
7.3
7.2
2.4
2
I
CHG
ICHG
2
2
VIN=24V
VIN=5V
7.1
7
1.6
1.2
1.5
1
1.5
6.9
V
BATT
1
6.8
6.7
6.6
6.5
VBATT
0.8
0.5
0
0.5
0
0.4
0
0
10
20
30
40
50
0
1
2
3
4
60
0
5
10
15
20
25
TIMES(MIN)
BATTERY VOLTAGE(V)
TIMES(MIN)
Breakdown Voltage
2 Cells Charge Current vs.
Battery Voltage
NTC Control Window
Battery Simulator
16
14
12
10
8
2.4
2
3
2.5
2
Low Temp Off
Low Temp On
1.6
1.2
0.8
0.4
0
1.5
1
High Temp On
High Temp Off
6
4
VIN=24
VIN=9V
0.5
0
2
0
0
1
2
3
4
5
6
7
8
0
10
20
30
40
8
12
16
20
24
28
BATTERY VOLTAGE(V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
Efficiency vs.
Battery Voltage
1 Cell, ICHG=2A
Efficiency vs. I
1 Cell, VBATT=3.6V
Efficiency vs. V
CHG
IN
1 Cell, VBATT=3.4V, ICHG=2A
90
80
70
60
50
40
30
20
10
0
90
80
70
60
50
40
30
20
10
0
100
90
VIN=9V
VIN=5
VIN=5V
VIN=19V
80
70
VIN=9V
VIN=19V
VIN=24V
60
50
40
30
20
10
VIN=24V
2.5 2.7 2.9 3.1 3.3 3.5 3.7
BATTERY VOLTAGE(V)
0
500 1000 1500 2000 2500
CHARGE CURRENT(A)
0
5
10
15
20
25
INPUT VOLTAGE (V)
MP2623 Rev. 1.0
3/16/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
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 Float Voltage vs. V
1 Cell
BATT Charge Full Voltage
vs. Temperature
BATT Charge Full Voltage
vs. Temperature
IN
V
=19V
IN
1 Cell
2 Cells
7.3
V
=19V
IN
3.65
3.6
3.65
3.6
7.2
7.1
7
3.55
3.5
3.55
3.5
6.9
3.45
3.45
6.8
80
0
5
10 15 20
25 30
-40 -20
0
20 40 60 80
-40 -20
0
20 40 60
o
o
INPUT VOLTAGE(V)
TEMPERATURE ( C)
TEMPERATURE ( C)
Constant Current Charge
vs. Temperature
VREF33 vs. Temperature
RDS_ON vs. Temperature
V
=19V
IN
1 Cell ICHG=500mA
0.35
0.3
3.5
3.4
3.3
3.2
3.1
3.0
500
490
480
470
460
450
0.25
0.2
0.15
0.1
-40 -20
0
20 40 60 80
o
-40 -20
0
20 40 60 80
o
-40 -20
0
20 40 60 80
o
TEMPERATURE( C)
TEMPERATURE ( C)
TEMPERATURE ( C)
MP2623 Rev. 1.0
3/16/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
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, V
=2V
BATT
1 Cell, V
=3.2V
BATT
1 Cell, V
=3.6V
BATT
V
V
IN
IN
2V/div.
V
2V/div.
IN
2V/div.
V
V
BATT
BATT
V
BATT
2V/div.
2V/div.
1V/div.
V
V
SW
V
SW
SW
2V/div.
2V/div.
2V/div.
I
CHG
1A/div.
I
CHG
I
CHG
1A/div.
1A/div.
400ns/div.
400ns/div.
Power On Waveform
Power Off Waveform
EN On Waveform
1 Cell, I
=2A,V
=3V
1 Cell, I
=2A,V
=3V
1 Cell, I
CHG
=2A,V =3V
BATT
CHG
BATT
CHG
BATT
V
EN
5V/div.
V
V
IN
IN
2V/div.
2V/div.
V
BATT
2V/div.
V
BATT
2V/div.
V
SW
V
SW
2V/div.
5V/div.
V
V
SW
BATT
1V/div.
2V/div.
I
CHG
I
I
2A/div.
CHG
CHG
2A/div.
1A/div.
4ms/div.
100ms/div.
EN Off Waveform
NTC Control
1 Cell, ICHG=2A, V
Battery Simulator
,
Timer Out
1 Cell, I
=2A,V
=3V
=2.5V,
1 Cell,I
CHG
=2A, V =3.5V,
BATT
CHG
BATT
BATT
C
=47pF, Battery Simulator
TIMER
V
V
NTC
EN
5V/div.
5V/div.
V
TMR
500mV/div.
V
BATT
V
BATT
2V/div.
2V/div.
V
V
SW
V
SW
SW
2V/div.
2V/div.
5V/div.
V
BATT
1V/div.
I
CHG
I
CHG
2A/div.
1A/div.
I
CHG
1A/div.
200ms/div.
MP2623 Rev. 1.0
3/16/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 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
1100kHz
OSC
BST
PRE_REGS
EN
Regulator
Current Limit
Comparator
M1
5 bit trim
S
Q
VREF
IREF
Drive
R
R
CTRL
SW
3 bit trim
PWM
Comparator
D2
Mini Refresh
L
LDO
Charge
Current Sense
VBATT
VREF33
CSP
x6
FB
cells
RS1
A2
GMI
GMV
BATT
NTC
COMP
0.12V
or 1.2V
1.2V
1- or 2- cell
LiFePO Battery
4
TC/CC
Charge Comparator
CTRL
FB
COMPI
0.83V
Max Trickle Time
Max Reflesh Time
Max Charge Time
TMR
Timer
Charge Control
Logic
FB
1.11V
COMPV
Recharge Comparator
VIN
0.12V
Charge
Current Sense
BF
Comparator
ACOK
BATT+300mV
GND
CELLS
ACOK
CHGOK
Figure 1: Functional Block Diagram
MP2623 Rev. 1.0
3/16/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
9
MP2623 – 2A, 24V INPUT, 1.1MHz 1- OR 2-CELL SWITCHING LIFEPO4 BATTERY CHARGER
(10% of the RS1-programmed constant-charge
current, ICC) until the battery voltage reaches VTC.
OPERATION
The MP2623 is a peak-current–mode controlled
switching charger for use with LiFePO4 batteries.
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.
At the beginning of each cycle, M1 is off and the
COMP voltage exceeds the output of the current-
sense 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.
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 constant-
voltage 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.
CV charge
Threshold
Constant
Charge
Current
ICHG
VBATT
CC charge
Threshold
IBF
Trickle
Charge
Current
Trickle charge
CC charge
CV charge
Charge Full
Figure 2: Li-Ion Battery Charging Profile
Automatic Recharge
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.
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 trickle-
charge threshold, VTC (typically 2.52V/cell), the
charging cycle will start in trickle-charge mode
MP2623 Rev. 1.0
3/16/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
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:
CHGOK
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.
to the NTC pin, and connect the thermistor from
the NTC pin to GND. A resistor divider
determines the voltage on the NTC pin as a
function of the battery temperature. Charging
halts when the NTC voltage falls below the lower
NTC window threshold. Charging resumes when
the voltage is within the NTC window range.
ACOK and
. The ACOK pin goes low
Application with Power Selector
CHGOK
indicates charge status. Table 1
MP2623 is a stand-alone, switching charger.
Typically, VIN receives power from the adapter
input, VIN, through a diode that blocks the battery
voltage to VCC. For power selector application,
however, VIN powers the system and charges the
battery simultaneously so the user can start-up a
device with a drained battery when it is
connected to an adapter. Replace the diode from
the stand-alone switching charger circuit with a
MOSFET to improve system efficiency and
reduce voltage drop of the block device.
CHGOK
different charge conditions.
describes ACOK and
outputs under
Table 1―Charging Status Indication
Charger Status
ACOK
CHGOK
low
low
In charging
End of charge, NTC
fault, timer out, thermal
low
high
high
shutdown, EN disable
VIN–VBATT<0.3V.
VCC<UVLO,
high
An additional MOSFET between VIN and the
battery allows the battery to charge even in the
absence of an adapter or connection to an invalid
adapter. Figure 3 shows a typical application
circuit with power-path management. When the
adapter input is invalid or absent, the block diode
Timer Operation
MP2623 uses an internal timer to limit the charge
period during both the trickle charge and the total
charge cycle. The MP2623 terminates charging
once the charge time exceeds the time limit. A
good battery should fully recharge within the
allotted time period; otherwise the battery has a
fault. An external capacitor at the TMR pin
programs the time period.
is replaced by a MOSFET controlled by ACOK
signal.
The trickle mode charge time is:
CTMR
tTRICKLE _ TMR 30mins
0.1F
The total charge time is:
CTMR
tTOTAL _ TMR 3hours
0.1F
When time-out occurs, the charger is suspended.
Only refreshing the input power or EN signal can
restart the charge cycle.
Negative Thermal Coefficient (NTC)
Thermistor
The MP2623 has a built-in NTC-resistance
window comparator that allows the MP2623 to
sense the battery temperature through the
thermistor included in the battery pack. Connect
a resistor with an appropriate value from VREF33
MP2623 Rev. 1.0
3/16/2012
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11
MP2623 – 2A, 24V INPUT, 1.1MHz 1- OR 2-CELL SWITCHING LIFEPO4 BATTERY CHARGER
M1
VIN
VSYS
5V to 24V
C8
22
R6
M2
C1
4. 7
L
RS1
VIN
SW
4.7
VREF33
C7
0.1
100 m
C3
1
1- or 2- cell
LiFePO Battery
MP2623
R1
R2
VCC
BST
C2
22
D2
4
CHGOK
CSP
ACOK
CELLS
NTC
BATT
R3
10k
R5 750
COMPI
COMPV
TMR
R4 2.5k
GND
EN
RNTC
10k
ON
OFF
C6
0.1
C4
2.2nF
C5
2.2nF
Figure 3: MP2623 with Power Selector
MP2623 Rev. 1.0
3/16/2012
www.MonolithicPower.com
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12
MP2623 – 2A, 24V INPUT, 1.1MHz 1- OR 2-CELL SWITCHING LIFEPO4 BATTERY CHARGER
OPERATION FLOW CHART
Figure 4: Normal Charging Operation Flow Chart
MP2623 Rev. 1.0
3/16/2012
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© 2012 MPS. All Rights Reserved.
13
MP2623 – 2A, 24V INPUT, 1.1MHz 1- OR 2-CELL SWITCHING LIFEPO4 BATTERY CHARGER
OPERATION FLOW CHART (continued)
Figure 5: Fault-Protection Flow Chart
MP2623 Rev. 1.0
3/16/2012
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14
MP2623 – 2A, 24V INPUT, 1.1MHz 1- OR 2-CELL SWITCHING LIFEPO4 BATTERY CHARGER
APPLICATION INFORMATION
Setting the Charge Current
R6//RNTC _Hot
VTH_High
(5)
29.5%
R3 R6//RNTC _Hot VREF33
RS1 sets the MP2623 charge current (See
Typical Application). Determine the current with
the following equation:
According to equation (4) and equation (5), R3 =
9.63k and R6 = 505k.
200mV
Simplifying, select R3=10k and R6 no connect to
approximate the estimate.
ICHG
A
(1)
RS1
mΩ
Selecting the Inductor
Use 1µH-to-10µH inductor for most
applications. Calculate the inductance value from
the following equation.
a
VREF33
Low Temp Threshold
VOUT (V VOUT
)
R3
IN
VTH_Low
L
(2)
NTC
V IL fOSC
IN
Where ΔIL is the inductor ripple current. Choose
ΔIL to be approximately 30% of the maximum
charge current, 2A. VOUT is the 1- or 2-cell battery
voltage.
RNTC
R6
High Temp Threshold
VTH_High
The maximum inductor peak current is:
Figure 6: NTC function block
Selecting the Input Capacitor
IL
2
IL(MAX) ICHG
(3)
The input capacitor reduces the surge current
drawn from the input and the switching noise
from the device. Chose an input capacitor with an
impedance at the switching frequency less than
the input source impedance to prevent a high-
frequency switching current. Use ceramic
capacitors with X5R or X7R dielectrics with low
ESR and small temperature coefficients. A 4.7µF
capacitor is sufficient for most applications.
Under light-load conditions (below 100mA), use a
larger inductor value to improve efficiency.
Select an inductor with a DC resistance of less
than 200mꢀ to optimize efficiency.
NTC Function
Figure 6 shows that the low temperature
threshold and high-temperature threshold are
preset internally to 73.5%·VREF33 and
29.5%·VREF33, respectively, using a resistor
divider. For a given NTC thermistor, we can
select appropriate R3 and R6 resistors to set the
NTC window.
Selecting the Output Capacitor
The output capacitor limits output voltage ripple
and ensures regulator-loop stability. The output
capacitor impedance should be low at the
switching frequency. Use ceramic capacitors with
X5R or X7R dielectrics.
For the thermistor (NCP18XH103) noted in the
electrical characteristic previous,
PC Board Layout
At 0°C, RNTC_Cold = 27.445k;
At 50°C, RNTC_Hot = 4.1601k.
Connect the high frequency and high current
paths (GND, IN, and SW) to the device with
short, wide, and direct traces. Place the input
capacitor as close as possible to the IN and GND
pins. Place the external feedback resistors next
to the FB pin. Keep the switching node SW short
and away from the feedback network.
Assuming that the NTC window is between 0°C
and 50°C, we can derive the following equations:
R6//RNTC _ Cold
VTH_Low
(4)
73.5%
R3 R6//RNTC _ Cold VREF33
MP2623 Rev. 1.0
3/16/2012
www.MonolithicPower.com
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© 2012 MPS. All Rights Reserved.
15
MP2623 – 2A, 24V INPUT, 1.1MHz 1- OR 2-CELL SWITCHING LIFEPO4 BATTERY CHARGER
PACKAGE INFORMATION
QFN16 (4 x 4mm)
3.90
4.10
2.15
2.45
0.50
0.70
PIN 1 ID
SEE DETAIL A
13
16
PIN 1 ID
MARKING
0.25
12
1
4
0.35
2.15
2.45
3.90
4.10
0.65
BSC
PIN 1 ID
INDEX AREA
9
8
5
TOP VIEW
BOTTOM VIEW
PIN 1 ID OPTION A
0.45x45º TYP.
PIN 1 ID OPTION B
R0.25 TYP.
0.80
1.00
0.20 REF
0.00
0.05
DETAIL A
SIDE VIEW
3.80
2.30
NOTE:
1) ALL DIMENSIONS ARE IN MILLIMETERS.
2) EXPOSED PADDLE SIZE DOES NOT INCLUDE MOLD FLASH.
3) LEAD COPLANARITY SHALL BE0.10 MILLIMETER MAX.
4) JEDEC REFERENCE IS MO-220, VARIATION VGGC.
5) DRAWING IS NOT TO SCALE.
1.00
0.35
0.65
RECOMMENDED LAND PATTERN
NOTICE: The information in this document is subject to change without notice. Please contact MPS for current specifications.
Users should warrant and guarantee that third party Intellectual Property rights are not infringed upon when integrating MPS
products into any application. MPS will not assume any legal responsibility for any said applications.
MP2623 Rev. 1.0
3/16/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
16
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