MITSUMI
Protection of Lithium Ion Batteries (two cells in series) MM1292
Protection of Lithium Ion Batteries (two cells in series)
Monolithic IC MM1292
Outline
2-Cell Protection ICs
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.
Model name
Overcharge protection
Overdischarge protection
Overcurrent
Detection voltage
Hysteresis
Detection voltage
Hysteresis
Detection voltage
MM1302A
4.250.05V
10mV
2.3V0.1V
700mV
22020mV
MM1292C
4.250.05V
200mV
2.4V0.1V
600mV
15015mV
MM1292D
4.350.05V
200mV
2.4V0.1V
600mV
15015mV
MM1302E
4.100.05V
10mV
2.4V0.1V
600mV
15015mV
MM1302F
4.350.05V
10mV
None
None
MM1302G
4.21535V
10mV
2.3V0.1V
700mV
22020mV
MM1292H
4.300.05V
220mV
2.05V0.1V
950mV
17015mV
MM1292J
4.250.05V
220mV
2.4V0.1V
600mV
15015mV
MM1292K
4.250.05V
220mV
2.4V0.1V
600mV
15015mV
MM1292L
4.250.05V
220mV
2.2V0.1V
800mV
10010mV
Features
1. Current consumption (during overcharging)
V
CELL
=4.5V
80A typ.
2. Current consumption (normal)
V
CELL
=3.5V
13A typ.
3. Current consumption (during excess discharging)
V
CELL
=1.9V
0.5A typ.
4. Current consumption (during excess discharging)
V
CELL
=1.0V
0.1A max.
5. Overcharge detection voltage (Ta=-20C~+70C)
4.25V50mV (detection for each cell)
6. Hysteresis voltage
200mV60mV (detection for each cell)
7. Excess discharge detection voltage
2.4V0.1V (detection for each cell)
8. Discharge resumption voltage
3.0V0.1V (detection for each cell)
9. Overcurrent detection voltage
150mV15mV
10.Reset after overcurrent detection
load release
11.Operating limit voltage
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
Pin Assignment
1
4
3
2
8
5
6
7
SOP-8C/SOP-8D
1
OC
2
GD
3
N.C
4
GND
5
TD
6
VL
7
CS
8
VH
Pin Description
Pin No.
Pin
Output
Function
1
OC
Output
2
GD
Output
3
DS
Input
4
GND
Input
5
TD
Input
6
VL
Input
7
CS
Input
8
VH
Input
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-
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-
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
detection exceeds discharge detection voltage (VDS), OC output is switched OFF
and charge control FET is switched ON.
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
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.
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
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.
Positive connection pin for the high side battery, and the IC's current input pin.
Applications
1. Cellular phones
2. Movies
MITSUMI
Protection of Lithium Ion Batteries (two cells in series) MM1292
Block Diagram
Note 1. 45A max. (current consumption during operation of overcharge detection section) flows to input
protection resistor R1.
Note 2. 0.3A max. (when cells are balanced) flows to input protection resistor R2. When the cells are not
balanced, the current increases to wards correction.
Data intake
prohibition interval
Data intake prohibition interval
t2
t1
t OP
t ST
Operating
interval
waiting interval
t OP
t ST
Time
Average
current
30
A
5
A
Current
consumption
Current
consumption
Timing for setting non-induction time
V
CELL
>4.25V
V
CELL
<4.25V
Data processing
section
Non-induction
time
Overcharging
identification
Reset
VH
GC
VCS (battery-)
MITSUMI
Protection of Lithium Ion Batteries (two cells in series) MM1292
Timing Chart
OC
TD
Overcharging identification
Data latch
Hold untill t (N+1)
Overcharging
detection output
operation starts
Start-up signal
generation timing
AND process
Discharging
state
GD
VL
VH
VS
VS
VS
V
ALM
V
ALM
V
ALM
V
ALM
V
ALM
operation stop
Discharging
prohibited
VS
unsettled (High impedance)
Current
consumption
OR
processing
Charging prohibited,
constant
current output
(source current) unsettled
Absolute Maximum Ratings
Item
Symbol
Rating
Units
Storage temperature
T
STG
-40~+125
C
Operating temperature
T
OPR
-20~+70
C
Power supply voltage
V
OC
max.
-0.3~18
V
OC pin applied voltage
V
OVOUT
-10~V
H
V
CS pin applied voltage
V
DCOUT
-0.6~V
H
V
Allowable power dissipation
Pd
300
mA
MITSUMI
Protection of Lithium Ion Batteries (two cells in series) MM1292
Electrical Characteristics
(unless otherwise specified, Ta=25C)
Item
Symbol
Measurement Conditions
Min. Typ. Max. Units
Current consumption 1
I
VH
1
V
CELL
=4.5V, R
OC
=270k
80
100
A
Current consumption 2
I
VH
2
V
CELL
=3.5V (normal)
13.0
20.0
A
Current consumption 3
I
VH
3
V
CELL
=1.9V (During excess discharge)
0.5
0.8
A
Current consumption 4
I
VH
4
V
CELL
=1.0V (During excess discharge)
0.1
A
VL pin input voltage
I
VL
V
H
=V
L
-0.3
0
0.3
A
Overcurrent detection voltage
V
ALM
Ta=-20C~70C
4.20
4.25
4.30
V
Hysteresis voltage
V
AL
V
AL
=V
ALMH
-V
ALML
140
200
260
mV
Overcharge detection voltage
V
S
2.30
2.40
2.50
V
Discharge resumption voltage
V
DF
Discharge resumed through voltage rise
2.90
3.00
3.10
V
Starting voltage
V
ST
Voltage applied between GND-CS pins
-0.6
-0.5
V
GD pin output voltage H
V
GDH
V
CELL
=3.5V, I
L
=10A
VH-0.3 VH-0.2
V
GD pin output voltage L
V
GDL
V
CELL
=3.5V, I
L
=10A, V
CS
=1V
0.2
0.3
V
OC pin output current
I
OCH
V
CELL
=4.5V
20
150
A
Overcurrent detection voltage
V
CS
135
150
165
mV
Reset by overcurrent
load release
Overcurrent detection delay 1
T
OC
1
10
20
mS
Overcurrent detection delay 2
T
OC
2
between CS-GND pins > 0.8V
30
100
S
Excess discharge detection delay
T
OD
10
20
mS
TC pin charge current
I
TC
1
30
50
80
nA
TC pin threshold value
V
TC
V
CELL
=4.5V, V
TC
=0 5V
V
OC
=L H
3.65
3.90
4.15
V
Non-induction time for overcharge
T
OC
C
TC
=0.012F
0.5
1.0
1.5
S
Operating limit voltage
V
OPL
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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