MITSUMI
Protection of Lithium-Ion Batteries (one cell) MM1421
Protection of Lithium-Ion Batteries (one cell)
Monolithic IC MM1421
Outline
This is a smaller, high-precision version of the conventional MM1301 series of lithium ion battery protection
ICs. Precision of 25mV at 0 ~ 50C is guaranteed. Also, MM1421 charging reset is overdischarge reset pin 2
voltage, and MM1491 overdischarge reset pin 2 voltage is set at 3.0 ~ 3.9V.
Features
1. Overcharge detection voltage accuracy (0C to 50C)
V
CEL
25mV
2. Overcharge detection dead time
C
TD
=0.01F 100ms
3. Consumption current (V
CEL
=0.01V)
10.0A typ.
4. Consumption current (V
CEL
=3.6V)
0.1A typ.
5. Overdischarge reset
Load open: 50M
typ. load between both ends of
battery pack
Package
SOT-26A
Applications
IC for protection of single-cell lithium-ion batteries.
MITSUMI
Pin Assignment
1
2
3
6
5
4
SOT-26A
1
VM
2
V
CC
3
TD
4
CO
5
GND
6
DO
Model
Package
SOT-26A
AN
4.2000.025
C
200100
2.30.1
charging reset
20026
MM1421
JN
4.2500.025
C
200100
2.30.1
charging reset
20026
LN
4.3500.025
C
200100
2.40.1
charging reset
20026
NN
4.2750.025
C
200100
2.30.1
charging reset
12026
Overcharge
detection
voltage (V)
Overcharge
detection voltage
temperature
conditions
Overcharge
detection
hysteresis
voltage (mV)
Overdischarge
detection
voltage (V)
Overdischarge
reset
voltage (V)
Overcurrent
detection
voltage (mV)
1-Cell Protection ICs
Temperature conditions A: Ta=-25 ~ 75C, B: Ta=-20 ~ 70C, C: Ta=0 ~ 50C,
D: Ta=0 ~ 40C, E: Ta=-20 ~ 25C
*
We are continuing to develop the series for the future.
*
Overcharge, overdischarge voltages and overcurrent detection voltage can be changed to customize the
ICs.
MITSUMI
Protection of Lithium-Ion Batteries (one cell) MM1421
Block Diagram
Note 1 : Overdischarge voltage
Note 2 : Overcharge voltage
Pin Description
Pin No. Pin Name
Function
1
V
M
Overcurrent detection input pin. Detects discharge current by connection to charging control
FET source pin.
Discharge current = (voltage between V
M
and GND) / (FET 2 ON resistance)
2
V
CC
Positive power supply pin.
3
TD
Overcharge detection dead time setting pin.
4
CO
Charging control FET (N-ch) gate connection pin. An external resistor is required between
gate and source. Turns off charging control FET (N-ch) for overcharge mode (during
charging) and overdischarge mode. Also, overcharge mode (during discharge) turns
charging control FET (N-ch) ON, and suppresses FET power consumption.
5
GND
Negative power supply pin. Also, negative input pin for battery connected between V
CC
and
GND.
6
DO
Discharge control FET (N-ch) gate connection pin. Turns gate OFF for overdischarge
mode and overcurrent mode. Turns gate ON for overcharge mode and normal mode.
(1) Overcharge mode:
Battery voltage > overcharge detection voltage
(2) Normal mode:
Overdischarge detection voltage < battery voltage <overcharge detection voltage
Discharge current < overcurrent detection level
(3) Overdischarge mode: Overdischarge detection voltage > battery voltage
(4) Overcurrent mode:
Discharge current > overcurrent detection level, voltage between V
M
and GND =
discharge current FET ON resistance
(discharge/charge control FET)
MITSUMI
Protection of Lithium-Ion Batteries (one cell) MM1421
MITSUMI
Pin Assignment
Pin No. Pin name
Equivalent circuit diagram
Pin No. Pin name
Equivalent circuit diagram
1
V
M
5
GND
6
DO
2
V
CC
4
CO
3
TD
Absolute Maximum Ratings
(Ta=25C)
Item
Symbol
Ratings
Unit
Storage temparature
T
STG
-40~+125 C
Operating temparature
T
OPR
-20~+70
C
Supply voltage
V
CC
max.
-0.3~+18
V
CO pin voltage
V
CO
max.
V
CC
-28~V
CC
V
V
M
pin voltage
V
VM
max.
Allowable loss
Pd
200
mW
Recommended Operating Conditions
Item
Symbol
Ratings
Unit
Operating temparature
T
OPR
-20~+70 C
Power supply voltage
V
OP
+1.8~+10
V
MITSUMI
Protection of Lithium-Ion Batteries (one cell) MM1421
MITSUMI
Electrical Characteristics
(Except where noted otherwise, Ta=25C, V
CC
=3.6V)
Item
Symbol
Measurement conditions
Min. Typ. Max. Unit
Consumption current 1
I
CC1
V
CC
= 3.6V: Set state
10.0
14.0
A
(condition: SET)
between CO-GND: 910k
connected
Consumption current 2
I
CC2
V
CC
= 3.6V: IC alone
6.0
10.0
A
(condition: IC only)
between CO-GND: 910k
not connected
Consumption current 3
I
CC3
V
CC
=3.6V: Discharge FET OFF state
0.4
1.2
A
(FET: OFF on SET)
between CO-BG: 910k
not connected
Consumption current 4
I
CC4
V
CC
=1.9V: Discharge FET OFF state
0.1
1.0
A
(FET: OFF on SET)
between CO-GND: 910k
not connected
Consumption current 5
I
CC5
V
CC
=4.5V between CO-BG: 910k
connected
35
60
A
(condition: SET)
Overcharge detection voltage
V
ALM
Ta=0~50C V
CC
: L H
4.175 4.200 4.225
V
Overcharge hysterisis voltage
V
ALM
V
CC
: H L
100
200
300
mV
Overdischarge detection voltage
V
OD
V
CC
: H L
2.20
2.30
2.40
V
Release overdischarge voltage
V
ODF
Charging reset
Overcurrent detection level
V
VMD
V
VM
: L H
174
200
226
mV
Release overcurrent level
V
VMDF
V
VM
: H L
130
mV
Release overcurrent level
I
CSL
Load condition
50
M
Short detection voltage
V
VMSHT
1.3
V
Overdischarge detection dead time
t
OD
7.0
10.0
15.0
ms
Overcurrent detection dead time
t
CS
V
M
: 0V 0.5V
7.0
10.0
15.0
ms
Short detection delay time
t
VMSHT
V
M
: 0V 2V
0.02
0.20
ms
Overcharge detection dead time
t
ALM
C
TD
=0.01F
50
100
150
ms
DO pin output voltage
V
GDH
V
CC
-0.3 V
CC
-0.1 V
CC
V
DO pin source current 1
I
DOH1
V
DO
=V
CC
-1.0V
-100
-30
A
DO pin source current 2
I
DOH2
V
DO
=V
CC
-0.3V
-0.40 0.07
A
DO pin sink current 1
I
DOL1
V
VM
>1.0V, V
DO
=1.0V
50
300
A
DO pin sink current 2
I
DOL2
V
VM
>1.0V, V
DO
=0.3V
30
100
A
DO pin sink current 3
I
DOL3
V
CC
=3.6V, V
DO
=1V (Stand-by mode)
1
5
A
CO pin source current 1
I
CO1
V
CO
=V
CC
-1.0V
-20
-10
A
CO pin source current 2
I
CO2
V
CO
=V
CC
-0.3V
-15
-5
A
CO pin source current 3
I
CO3
V
CO
=V
CC
-0.3V (Stand-by mode)
-1
-0.2
A
Starting trigger voltage
V
ST
V
VM
: 0V -0.5V
-0.2
-0.1
0
V
Over-voltage charger protection
V
PRO
V
CC
=3.6V, GND-VM: voltage
-1.5
-2.5
-3.0
V
0V charge minimum voltage
V
0V
V
CC
=0V, Charger voltage
2.0
3.0
V
Note: Overcurrent detection current value is V
VM
/(FET ON resistance 2).
MITSUMI
Protection of Lithium-Ion Batteries (one cell) MM1421
MITSUMI
Note :
Measuring Circuit
Measuring circuit 1
Measuring circuit 2
0.5V or 2V
GND
GND
t VM
V
M
DO
3.0V
2.2V
-1V/100
S
VDO
GND
GND
t DO
V
CC
DO
1V/100
S
V
ALM
t
ALM
4.0V
4.5V
GND
GND
V
CC
CO
MITSUMI
Protection of Lithium-Ion Batteries (one cell) MM1421
Application Circuit
Timing Chart
Over-charge voltage
Dead time
Dead time
GND level
Charge mode
Discharge mode
Charge mode
Discharge mode
Overdischarge voltage
Dead time
Excess discharge
current mode
Excess
discharge mode
CELL pin
voltage
TD pin voltage
CO pin voltage
DO pin voltage
V
M
pin voltage
Hystarasia
This is a smaller, high-precision version of the conventional MM1301 series of lithium ion battery protection
ICs. Precision of 25mV at 0 ~ 50C is guaranteed. Also, MM1421 charging reset is overdischarge reset pin 2
voltage, and MM1491 overdischarge reset pin 2 voltage is set at 3.0 ~ 3.9V.
MITSUMI
Protection of Lithium-Ion Batteries (one cell) MM1421
Application Description
Outline
The MM1421 Series are protection IC for over-charge, over-discharge and over-current of rechargeable one-
cell Lithium-ion, further include a short circuit protector for preventing large external short circuit current.
1. Overcharge detection
The overcharge detector monitors V
CC
pin voltage. When the V
CC
voltage crosses overcharge detector
threshold VALMI (4.2V typ.) from a low value higher than the VALMI, the overcharge detector can sense a
overcharging and an external charge control Nch-MOS-FET tums to "OFF" with the resister (910k
typ.)
between the gate (CO pin) and source of FET, then CO pin "OFF".
(This resistor makes the CO pin "L". Current flows the resister on normal condition, therefore it makes the
resistance value larger because to reduce the consumption current. However it makes resistance value
smaller than 2.2M
because of relation between leak current of FET and cut-off time of FET by gate-source
capacitance. : It changes the resistance value from 910K
to 2.2M
, the consumption current can be
reduced about 2A.)
Parts List
R1 : 100
RCO : 2.2M
C1 : 1F
CTD : 0.1F/Temp. chr. code B
R2 : 4.7k
( CC1 : 0.1F/25V)
C2 : 0.047F
( CC2 : 0.1F/25V)
( CC3 : 0.1F/25V)
MITSUMI
Protection of Lithium-Ion Batteries (one cell) MM1421
2. Overdischarge detector
The voltage of V
CC
(2 pin) is observed when the battery is discharged, and V
CC
enters the mode of the
overdischarge detector under overdischarge detect voltage (2.3V typ.). The electrical discharge is stopped
by DO pin (6 pin) outputting "L", and turning off FET for the discharge.
About the release from the mode of overdischarge
Battery below the overdischarge detecting voltage through the parasitic diode of discharge FET.
The case that V
CC
becomes more than the release overdischarge detect voltage by charging, from the mode
of overdischarge, is turned on the discharge FET.
It is assumed that CO can be assumed to be "H" and charge if the voltage of the charger which connects
the charger is over 0V charging minimum operating voltage (2V typ.) at 0V in the voltage of the battery.
The delay time when overdischarge is detected is set internally (10ms typ.).
It does not enter the mode of the overdischarge detection when rising more than the overdischarge
detecting voltagein delay time even if V
CC
becomes below the overdischarge detecting voltage.
After overdischarge is detected, all circuit are stopped, and the current which IC consumes is decreased as
much as possible. (at V
CC
=1.9V : 0.05A typ.)
Image figure when over-discharge mode
MITSUMI
Protection of Lithium-Ion Batteries (one cell) MM1421
Note on use
The power supply change is suppressed by R1 and C1. However, the detecting voltage rises about (current
consumptions * resistance) when R1 is enlarged. Uses R1 below 330
.
The voltage change of ( -) terminal is suppressed by R2 and C2.
Because the case with which the capacity load is connected includes the case that short detection works,
the time constant is given to the terminal V
M
for preventing. Use R2 4.7k
fixed, and change C2 and adjust
the time constant. R1 and R2 can operate also as a part of current limit circuit against for applying excess
charging voltage or for setting cell reverce.
Please note that the case whose time constant of the terminal V
M
is larger than the time constant of the
terminal V
CC
includes the case which becomes a stand-by state when detecting short according to the
impedance of the connected battery. Please set in (R1 * C1) >
= (R2 * C2) as a standard.
Please examine the necessity of CC1, CC2, and CC3 respectively to prevent the malfunction and destruction
by ESD or the radio wave when you design the module. Please note that MM1421 of the charge release type
has the case which enters the stand-by state by the ESD and radio wave etc. because of module
patternning.
When measuring over-charge voltage in module, evaluate with the measurement figure.
(When the battry has no loads, pack-ocillates if it enters the mode of overcharge detection. Because of the
function of load detection.)
Test circuit to measure over-charge detect voltage
Power supply
Overcharge
detecting voltage
0V
-VCF
PACK
Delay time
Charge FET OFF
measuring this point
MITSUMI
Protection of Lithium-Ion Batteries (one cell) MM1421
Characteristics
External capacitor (
F)
10
1
0.1
0.01
0.01
0.1
1
Dead time of overcharge
detection : t TD (S)
Power supply voltage : V
CC
(V)
(When V
CC
: H L)
1.2
1.0
0.8
0.6
0.4
0.2
0
0
1
2
3
4
5
3
6
Power supply current : I
CC
(
A)
Power supply voltage : V
CC
(V)
(When V
CC
: H L)
60
50
40
30
20
10
0
0
1
2
3
4
5
3
6
Power supply current : I
CC
(
A)
DO pin voltage (V)
600
400
200
0.6
0.4
0.2
1.0
2.0
3.0
(Right ax is)
DO source current (
A)
DO source current (
A)
Overcharge detection time
Power supply current vs power supply voltage
When stand-by mode
Power supply current vs power supply voltage
DO source current vs DO pin voltage
V
CC
=3.6V
Note: The above specifications are representative, and are not guaranteed values.