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MITSUMI
Protection of Lithium Ion Batteries (four cells in series) MM1294
Protection of Lithium Ion Batteries (four cells in series)
Monolithic IC MM1294
Outline
This IC provides protection for lithium ion batteries in the event of overcharging, overdischarging and
overcurrents. When anomalies occur during charging or at other times and excessive voltages are applied,
after a certain time has elapsed for each cell an external FET switch is turned off (overcharging detection); and
in order to prevent overdischarge of the battery during discharge, when the voltage of individual batteries falls
below a fixed voltage, an external FET switch is turned off (overdischarge detection), and the IC is put into
low-consumption current mode. When large currents flow due to a short-circuit or other cause, an external
MOS switch is turned off (overcurrent detection).
Package
SSOP-16
Features
1. Current consumption (overcharging) VCELL > VCELLU 170µA typ.
2. Current consumption (normal operation) V
CELL < VALM 35µA typ.
3. Current consumption (overdischarge) V
CELL < VCELLS 0.1µA max.
4. Overcharge detection voltage (
-
20 to +70°C) VCELL : L H 4.25V±50mV/CELL
5. Overcharge hystereis voltage V
CELL : H L VCELLU
-
200mV/CELL typ.
6. Overcharge sensing dead time C=0.1µF 1.0S typ.
7. Overcharge sensing operation voltage V
CELL : L H 4.10V±150mV/CELL
8. Overdischarge detection voltage V
CELL : H L 2.40V/CELL typ.
9. Overdischarge sensing dead time C=0.1µF 1.0S typ.
10.Overcurrent detection voltage 0.15V typ.
11.Overcharge and overdischarve voltages as well as the overcurrent detection voltage can be changed upon
request.
Applications
Lithium ion battery pack for notebook computers
4-Cell Protection ICs
Rank
Overcharge Overcharge
Overdischarge Overdischarge
Overcurrent At overcurrent Overcurrent
detection voltage hysteresis voltage detection voltage
resume voltage
detection voltage
detection
release conditions
A
4.35V±50mV
200mV typ. 2.35V typ. 3.05V typ.
150mV typ.
Pin 3 (DOHG pin) L H
Load release
300kΩ or more
B
4.25V±50mV
2.40V typ. 3.10V typ.
C
Same as rank A
200mV typ. Same as rank A Charging reset
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MITSUMI
Protection of Lithium Ion Batteries (four cells in series) MM1294
Block Diagram
Pin Assignment
SSOP-16
13 762458
16 13 1115 14 12910
1 OV 9 V1
2 CS 10
3 DCHG 11 V2
4 PF 12
5 CDC 13 V3
6 COL 14
7 COV 15 V4
8 GND 16 V
CC
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MITSUMI
Protection of Lithium Ion Batteries (four cells in series) MM1294
Pin Description
Absolute Maximun Ratings
(Ta=25°C)
Pin no.
Pin name
Input/
Function
output
1 OV Output
2 CS Input
3 DCHG Output
4 PF Output
5 CDC Input
Pin to set the dead time for overdischarge detection
By connecting a capacitor between the CDC pin and GND, a dead time can be set.
6 COL Input
7 COV Input
Pin to set the dead time for overcharge detection
By connecting a capacitor between the COV pin and GND, a dead time can be set.
8 GND Input Ground pin
9 V1 Input Pin for input of V1 cell high-side voltage and V2 cell low-side voltage
10 N.C
11 V2 Input Pin for input of V2 cell high-side voltage and V3 cell low-side voltage
12 N.C
13 V3 Input Pin for input of V3 cell high-side voltage and V4 cell low-side voltage
14 N.C
15 V4 Input Pin for input of V4 cell high-side voltage
16 V
CC Input
Power supply input pin
The same potential as the V4 pin should be input
Overcharge detection output pin
NPN transistor open collector output; normally high impedance, goes to L level on
overdischarge
Overcurrent detection pin
Monitors equivalent load current through source-drain voltage drop of discharge-controlling
FET, and at or above the overcurrent detection voltage sets the DCHG pin to "H" and turns
off the discharge-controlling FET. Following overcurrent detection, current is passed from
this pin, and if the load is decreased, the overcurrent mode is canceled. Through this action
there is a temporary consumption current (at the V
CC
pin) of approx. 1 mA on resumption of
discharge and detection of overdischarge. This function is disabled in overdischarge mode.
Pin driving the discharge-controlling FET (P-ch)
Normally "L"; on overdischarge set to "H"
Output pin for overdischarge detection signals
Overdischarge detection signal output pin
When the overdischarge detector detects overdischarge at the open collector output
of the NPN transistor, this pin is turned on. A delay is provided by setting a dead
time until discharge ends, so that by utilizing a reset or other signal from a CPU or
some other controlling device, the equipment can be put into standby mode.
Pin to set the dead time for overcurrent detection
By connecting a capacitor between the COL pin and GND, a dead time can be set.
If NC, protection is triggered in a short amount of time; the dead time should be
set according to the application.
Item Symbol Ratings Units
Storage temperature T
STG
-
40~+125 °C
Operating temperature T
OPR
-
20~+70 °C
Charge voltage VV4 max. 24 V
Power supply voltage V
CC max. 24 V
Voltage applied to OV pin V
OV max. 24 V
Allowable loss Pd 300 mW
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MITSUMI
Protection of Lithium Ion Batteries (four cells in series) MM1294
Recommended Operating Conditions
Electrical Characteristics
(Except where noted otherwise, Ta=25°C, VCC=20V, VCELL=V4=V3=V2=V1)
Item Symbol Ratings Units
Operating temperature T
OPR
-
20~+70 °C
Operating voltage V
OPR +2~+24 V
Item Symbol Measurement conditions Min. Typ. Max. Units
Consumption current (V
CC pin) 1 ICC1VCELL=4.4V 170 340 µA
Consumption current (V
CC pin) 2 ICC2VCELL=3.5V 35 70 µA
Consumption current (V
CC pin) 3 ICC3VCELL=2.2V 0.1 µA
Consumption current (V4 pin) 1 IV
41VCELL=4.4V 15 30 µA
Consumption current (V4 pin) 2 IV
42VCELL=3.5V 5 10 µA
Consumption current (V4 pin) 3 IV
43VCELL=2.2V 2 4 µA
V3 pin input current 1 IV
3 VCELL=3.5V ±300 nA
V3 pin input current 2 IV
3AVCELL=4.4V
-
0.6-0.3 0 µA
V2 pin input current 1 IV
2 VCELL=3.5V ±300 nA
V2 pin input current 2 IV
2AVCELL=4.4V
-
0.6-0.3 0 µA
V1 pin input current 1 IV
1 VCELL=3.5V ±300 nA
V1 pin input current 2 IV
1AVCELL=4.4V
-
0.6-0.3 0 µA
Overcharge detection voltage V
CELLU Ta=
-
20~+70°C, VCELL : 3.7V 4.5V 4.20 4.25 4.30 V
Overcharge detection release voltage
VCELL0VCELL : 4.5V 3.7V
V
CELL
UV
CELL
UV
CELL
U
-
260mV-200mV-140mV
V
Overcharge sensing dead time t
OV COV=0.1µF 0.5 1.0 1.5 S
Overcharge sensing operation voltage
VALM VCELL : 3.5V 4.4V 3.95 4.10 4.25 V
Overdischarge sensing hysteresis voltage
VALM VCELL : 4.4V 3.5V 130 230 330 mV
Overdischarge detection voltage V
CELLSVCELL : 3.5V 2.0V 2.30 2.40 2.50 V
Discharge resume voltage V
CELLDVCELL : 2.0V 3.5V 2.95 3.10 3.25 V
Overdischarge sensing hysteresis voltage
VCSDVCELLD-VCELLS 490 700 910 mV
Overdischarge sensing dead time
tCDC1CCDC=0.1µF 0.5 1.0 1.5 S
Overdischarge reset dead time t
CDC2CCDC=0.1µF, VCS=VCC+0.3V 7 mS
Overcurrent detection voltage V
OC VCC
-
VCS, DCHG 0.135 0.150 0.165 V
Overcurrent sensing dead time t
COL1CCOL=0.001µF, DCHG 51015mS
Overcurrent reset dead time t
COL2CCOL=0.001µF, DCHG 51015mS
Overcurrent sensing delay time t
COL3CCOL=0, DCHG 150 µS
Overcurrent reset delay time t
COL4CCOL=0, DCHG 150 µS
Overcurrent protection release
Open-load condition 300 kΩ
DCHG pin source current ISODCH
V
CELL
< V
CELL
S, SW1 : A, V
DCHG=VCC
-
1.8V
20 µA
DCHG pin sync current I
SIDCH
V
CELL
> VC
ELL
S, SW1 : A, V
DCHG
=0.8V
20 µA
DCHG pin output voltage H V
THDCHVCC
-
VDCHG, ISO=20µA, SW1 : B 1.8 V
DCHG pin output voltage L V
THDCLVDCHG
-
GND, ISI=-20µA, SW1 : B 0.8 V
OV pin sync current I
SIOV VOV=0.4V, Ta=
-
20~+70°C 0.2 mA
PF pin sync current I
SIPF VPF=0.4V, Ta=
-
20~+70°C 10 µA
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MITSUMI
Protection of Lithium Ion Batteries (four cells in series) MM1294
Timing Chart
Overcharge state
Sensing dead zone
tOV
Normal state
Overcharge detection voltage
Cell voltage
COV pin
Pin OV
(pulled up)
Charging off
Overcharge detection cancel voltage
Cell voltage
CDC pin
DCHG pin
Pin PF
Discharge off
Reset dead zone
Overdischarge state Normal state
tCDC1tCDC2
Discharge resume voltage
(pulled up)
Overdischarge detection voltage
Sensing dead zone
Overcharge
Overdischarge
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MITSUMI
Protection of Lithium Ion Batteries (four cells in series) MM1294
Application circuits
Characteristics
Capacitance C (F)
1
100m
10m
1m
100P 1000P 0.01µ 0.1µ
Dead time t (s)
Overcharge, overdischarge sensing dead
Note : The above characteristics are representative and are not guaranteed.
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