MITSUMI
Protection of Lithium Ion Batteries (two cells in series) MM1292
Protection of Lithium Ion Batteries (two cells in series)
Monolithic IC MM1292
Outline
This IC is for protecting a lithium ion battery from overcharging, excess discharging, and overcurrent. If
abnormalities occur during charging and excess voltage is applied, it has a function that turns off the external
FET switch when voltage is applied to each battery beyond a specified time (overcharging detection). It also
has a function that turns off the external FET switch when the voltage for each battery falls below a set
voltage, to prevent excess discharge when discharging the battery (discharging detection). At that time, the IC
is switched to low current consumption mode. Also, when there is a large current flow due to shorting or other
reasons, there is a function for turning off the external FET switch (overcurrent detection).
These functions comprise a protection circuit, with few external parts, for lithium ion batteries.
2-Cell Protection ICs
Model name
MM1302A
MM1292C
MM1292D
MM1302E
MM1302F
MM1302G
MM1292H
MM1292J
MM1292K
MM1292L
Overcharge protection
Detection voltage
Hysteresis
4.25±0.05V
10mV
4.25±0.05V
200mV
4.35±0.05V
200mV
4.10±0.05V
10mV
4.35±0.05V
10mV
4.215±35V
10mV
4.30±0.05V
220mV
4.25±0.05V
220mV
4.25±0.05V
220mV
4.25±0.05V
220mV
Overdischarge protection
Detection voltage
Hysteresis
2.3V±0.1V
700mV
2.4V±0.1V
600mV
2.4V±0.1V
600mV
2.4V±0.1V
600mV
None
2.3V±0.1V
700mV
2.05V±0.1V
950mV
2.4V±0.1V
600mV
2.4V±0.1V
600mV
2.2V±0.1V
800mV
Overcurrent
Detection voltage
220±20mV
150±15mV
150±15mV
150±15mV
None
220±20mV
170±15mV
150±15mV
150±15mV
100±10mV
Features
1. Current consumption (during overcharging)
2. Current consumption (normal)
3. Current consumption (during excess discharging)
4. Current consumption (during excess discharging)
5. Overcharge detection voltage (Ta=-20°C~+70°C)
6. Hysteresis voltage
7. Excess discharge detection voltage
8. Discharge resumption voltage
9. Overcurrent detection voltage
10.Reset after overcurrent detection
11.Operating limit voltage
V
CELL
=4.5V
V
CELL
=3.5V
V
CELL
=1.9V
V
CELL
=1.0V
80µA typ.
13µA typ.
0.5µA typ.
0.1µA max.
4.25V±50mV (detection for each cell)
200mV±60mV (detection for each cell)
2.4V±0.1V (detection for each cell)
3.0V±0.1V (detection for each cell)
150mV±15mV
load release
0.9V max.
Package
SOP-8C, SOP-8D(MM1292 F)
The box represents the rank resulting from the combination of protection functions.
*
MITSUMI
Protection of Lithium Ion Batteries (two cells in series) MM1292
Applications
1. Cellular phones
2. Movies
Pin Assignment
1
2
8
7
6
5
3
4
5
1
2
3
4
6
7
SOP-8C/SOP-8D
8
OC
GD
N.C
GND
TD
VL
CS
VH
Pin Description
Pin No.
Pin
Output
Function
Output pin for control of the charging control FET. When voltage detected between
VH-VL or VL-GND goes over overcharge detection voltage (VALM), the output PNP-
1
OC
Output
TR (open collector output) is switched ON, and charging is prohibited by activating
the element (NPN-TR, or N-ch FET) that switches the charging control FET to OFF.
This operation continues until the voltage falls below VALM.
Output pin for driving the discharge control FET. When voltage detected between VH-
2
GD
Output
VL and VL-GND goes over excess discharge voltage (VS), this pin goes H. When
voltage detected between VH-VL and VL-GND falls below VS and the voltage between
CS-GND is more than the voltage detected for an overcurrent (VCS), it goes L.
Input pin for discharge detection. When voltage between DS-GND during charge
3
DS
Input
detection exceeds discharge detection voltage (VDS), OC output is switched OFF
and charge control FET is switched ON.
4
GND
Input
Negative connection pin for the low side battery. It is also the GND pin for this IC.
(The IC's reference power supply pin.)
Over charge detection output non-induction time setting pin. The capacitor connected
5
TD
Input
between TD-GND is charged with constant current (ITC) during over charging. When
TC pin voltage exceeds the threshold value (VTC), OC output is switched ON.
6
VL
Input
Positive connection pin for the low side battery, and negative connection pin for the
high side battery.
Overcurrent detection pin during discharge, and charging detection pin during
power down. It detects discharge current using the source drain voltage (voltage
7
CS
Input
between CS-GND) of discharge control FET. Also, when the battery is charged with
a current whose CS-GND voltage after power down exceeds the start-up voltage
(VST), the bias current is drained to the interior circuit and operating status results.
8
VH
Input
Positive connection pin for the high side battery, and the IC's current input pin.
MITSUMI
Protection of Lithium Ion Batteries (two cells in series) MM1292
Block Diagram
Note 1. 45µA max. (current consumption during operation of overcharge detection section) flows to input
protection resistor R1.
Note 2. 0.3µA max. (when cells are balanced) flows to input protection resistor R2. When the cells are not
balanced, the current increases to wards correction.
tOP
Operating
interval
t1
tST
waiting interval
Data intake
prohibition interval
Data intake prohibition interval
t2
30µA
Current
consumption
5µA
tOP
tST
Current
consumption
Average
current
Time
Timing for setting non-induction time
V
CELL
>4.25V
Data processing V
CELL
<4.25V
section
Reset
Non-induction
time
Overcharging
identification
VH
GC
VCS (battery-)
MITSUMI
Protection of Lithium Ion Batteries (two cells in series) MM1292
Timing Chart
V
ALM
V
ALM
V
ALM
VS
V
ALM
V
ALM
VS
Discharging
state
AND process
OR
processing
VH
VS
VL
VS
Discharging
GD
prohibited
Start-up signal
generation timing
operation starts
operation stop
Overcharging
detection output
Hold untill t (N+1)
Overcharging identification
Data latch
TD
OC
unsettled (High impedance)
Charging prohibited,
constant
current output
(source current)
unsettled
Current
consumption
Absolute Maximum Ratings
Item
Storage temperature
Operating temperature
Power supply voltage
OC pin applied voltage
CS pin applied voltage
Allowable power dissipation
Symbol
T
STG
T
OPR
V
OC
max.
V
OVOUT
V
DCOUT
Pd
Rating
-40~+125
-20~+70
-0.3~18
-10~V
H
-0.6~V
H
300
Units
°C
°C
V
V
V
mA
MITSUMI
Protection of Lithium Ion Batteries (two cells in series) MM1292
Electrical Characteristics
Item
Current consumption 1
Current consumption 2
Current consumption 3
Current consumption 4
VL pin input voltage
Overcurrent detection voltage
Hysteresis voltage
Overcharge detection voltage
Discharge resumption voltage
Starting voltage
GD pin output voltage H
GD pin output voltage L
OC pin output current
Overcurrent detection voltage
Reset by overcurrent
Overcurrent detection delay 1
Overcurrent detection delay 2
Excess discharge detection delay
TC pin charge current
TC pin threshold value
Non-induction time for overcharge
Operating limit voltage
(unless otherwise specified, Ta=25°C)
Symbol
I
VH
1
I
VH
2
I
VH
3
I
VH
4
I
VL
V
ALM
V
AL
V
S
V
DF
V
ST
V
GDH
V
GDL
I
OCH
V
CS
T
OC
1
T
OC
2
T
OD
I
TC
1
V
TC
T
OC
V
OPL
Measurement Conditions
Min. Typ. Max. Units
V
CELL
=4.5V, R
OC
=270kΩ
80
100
µA
V
CELL
=3.5V (normal)
13.0 20.0 µA
V
CELL
=1.9V (During excess discharge)
0.5
0.8
µA
V
CELL
=1.0V (During excess discharge)
0.1
µA
V
H
=V
L
-0.3
0
0.3
µA
Ta=-20°C~70°C
4.20 4.25 4.30
V
V
AL
=V
ALMH
-V
ALML
140 200 260 mV
2.30 2.40 2.50
V
Discharge resumed through voltage rise 2.90 3.00 3.10
V
Voltage applied between GND-CS pins -0.6 -0.5
V
V
CELL
=3.5V, I
L
=10µA
VH-0.3 VH-0.2
V
V
CELL
=3.5V, I
L
=10µA, V
CS
=1V
0.2
0.3
V
V
CELL
=4.5V
20
150
µA
135 150 165 mV
load release
10
20
mS
between CS-GND pins > 0.8V
30
100
µS
10
20
mS
30
50
80
nA
V
CELL
=4.5V, V
TC
=0 5V
3.65 3.90 4.15
V
V
OC
=L H
C
TC
=0.012µF
0.5
1.0
1.5
S
0.9
V
Note 1. For current consumption, it is assumed that high side cell voltage and low side cell voltage are
identical. When the cell voltages differ, it is set by the higher voltage.
2. GD pin are high impedance when the current consumption is below the operating limit voltage.
3. When the circuit configuration calls for discharge resumption through charging, the discharge
resumption voltage is 2.4V typ.
Description of Operation
[Outline]
This IC is used for protecting lithium ion batteries (two cell series connection type). Overcharge detection,
excess discharge detection, and overcurrent detection are built into each circuit. It controls the FET for
discharge control and charge control (external N-MOS FET). There are four major operating modes.
1. Overcharge mode
When the voltage between Vh-VI and VI-GND exceeds the overcharge voltage (V
ALM
).
2. Normal mode
When the voltage between Vh-VI and VI-GND exceeds the excess discharge voltage (V
S
) and is less
than the over charge voltage (V
ALM
).
3. Excess discharge mode
When the voltage between Vh-VI and VI-GND is less than the excess discharge voltage (V
S
).
4. Overcurrent mode
When the voltage between CS-GND is less than the overcurrent voltage (V
CS
).
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