SC8821
ONE-CELL LI+ BATTERY PROTECTION CIRCUIT WITH BUILT-IN MOSFET
DESCRIPTION
SC8821 is a Li+ battery protection circuit with built-in MOSFET. It is
suitable for protecting LI+ battery against damage from over
charge, over discharge, and over current. It contains high accurate
voltage detection and delay circuits.
FEATURES
* Built-in low equivalent on-resistance (30mΩ) N-type MOSFET
* Low supply current
* Overcharge detection 4.28V, overcharge release 4.10V
* Overdischarge detection 2.50V, overchdisarge release 2.90V
* Over current detection 0.15V and short current detection 1.00V
TSSOP-8-225-0.65
* Built-in detection time delay of overcharge, overdischarge and
APPLICATIONS
overcurrent
* Charger detection
* Reset resistance for over current protection
* Wide supply voltage range
* Protection IC for One-Cell Li+ Battery
ORDERING INFORMATION
Part No.
SC8821
SC8821A
Package
TSSOP-8-225-0.65
TSSOP-8-225-0.65
0V Charging
Forbid
Allow
Marking
8821
8821A
BLOCK DIAGRAM
HANGZHOU MICROELECTRONICS CO.,LTD
Http: //www.silan.com.cn
REV:1.2
2009.05.05
Page 1 of 10
SC8821
ABSOLUTE MAXIMUM RATING
Characteristics
Supply Voltage
CSI Pin Voltage
BATN Pin Voltage
Operating Temperature
Storage Temperature
Symbol
V
DD
V
CSI
V
BN
T
opr
T
stg
Value
V
SS
-0.3 ~ V
SS
+12
V
DD
-15 ~ V
DD
+0.3
V
DD
-15 ~ V
DD
+0.3
-40 ~ + 85
-40 ~ +125
Unit
V
V
V
°C
°C
ELECTRICAL CHARACTERISTICS
(unless otherwise specified，T
amb
=25°C)
Characteristics
Operating Voltage
Operating Voltage
Current Consumption
Supply Current
Standby Current
Detection Voltage
Over Charge Detection Voltage
Over Charge Release Voltage
Over Discharge Detection Voltage
Over Discharge Release Voltage
Over Current 1 Detection Voltage
Over Current 1 Detection Current
Over Current 2(Short Current) Detection
Voltage
Over Current Reset Resistor
Charger Detection Voltage
Battery voltage when 0V charging is
forbidden
Charger voltage when 0V charging is
allowed
Delay Time
Over Charge Detection Delay Time
Over Discharge Detection Delay Time
Over Current 1 Detection Delay Time
Over Current 2(Short Current) Detection
Delay Time
T
OC
T
OD
T
OI1
T
OI2
V
DD
=3.6V~4.4V
V
DD
=3.6V~2.0V
V
DD
=3.6V
V
DD
=3.6V
150
80
5
340
200
13
5
500
300
20
50
ms
ms
ms
μs
V
OCU
V
OCR
V
ODL
V
ODR
V
OI1
I
OI1
V
OI2
R
short
V
CH
V
INH
Product SC8821
V
DD
=3.6V
V
DD
=3.6V
V
DD
=3.6V
4.24
4.05
2.40
2.80
0.13
1
0.80
400
-0.8
4.28
4.10
2.50
2.90
0.15
2
1.00
500
-0.5
4.32
4.15
2.60
3.00
0.17
3
1.20
600
-0.2
1.5
V
V
V
V
V
A
V
kΩ
V
V
I
DD
I
PD
V
DD
=3.6V
V
DD
=2.0V
3.0
0.3
6.0
0.6
μA
μA
V
DD
1.8
8.0
V
Symbol
Conditions
Min.
Typ.
Max.
Unit
V
CHA
Product SC8821A
1.55
V
HANGZHOU MICROELECTRONICS CO.,LTD
Http: //www.silan.com.cn
REV:1.2
2009.05.05
Page 2 of 10
SC8821
Characteristics
Symbol
Conditions
Min.
Typ.
Max.
Unit
Low equivalent on-resistance N-type MOSFET
Drain-Source Breakdown Voltage
Drain-Source Breakdown Current
Threshold Voltage
BVDSS
IDSS
VTH
V
G
=0V,I
D
=250μA
V
G
=0V,I
D
=1μA
V
G
=0V,V
D
=20.6V
V
G
=0V,V
D
=20V
V
G
=V
D
,I
D
=250μA
VG=2.5V, I
D
=3A
Source-Drain On-Resistance
RDSON
VG=4.5V, I
D
=1A
VG=4.5V, I
D
=3A
0.62
20.6
20
250
1
1.455
39.6
30
27.7
V
V
μA
μA
V
mΩ
mΩ
mΩ
PIN CONFIGURATION
SC8821
PIN DESCRIPTIONS
PIN No.
1
2, 3
4
5
6, 7
8
Symbol
V
SS
V
DD
CSI
TD
BATN
DRAIN
I/O
I
I
I/O
I
I/O
I/O
Negative power input pin
Positive power input pin
Current detection input
Time delay testing terminal
Negative terminal
of charger or load
The common drain of the two N-type MOSFET
Description
FUNCTION DESCRIPTIONS
Normal State
Refer to the typical application circuit. If V
ODL
<V
DD
<V
OCU
and V
CH
<V
CSI
<V
OI1
, the charging and discharging
processes between VBAT+ and VBAT- can be operated normally.
Overcharge Detection
When enters charging state from normal state, the battery voltage can be detected from V
DD
. When the charger
is connected between V
BAT+
and V
BAT-,
if V
DD
is larger than V
OCU
over a delay time of T
OC
, then the battery
voltage enters the overcharge state,
VBAT-
current is 0 and stop charging.
HANGZHOU MICROELECTRONICS CO.,LTD
Http: //www.silan.com.cn
REV:1.2
2009.05.05
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SC8821
Release of Overcharge State
There are two ways to return to normal state from overcharge state
•
If the battery is self discharging and V
DD
<V
OCR
occurs, it returns to normal state.
•
Remove the charger and connected to a load. If V
OCR
<V
DD
<V
OCU
and V
CSI
>V
OI1
occurs, it returns to
normal state.
Overdischarge Detection
When enters discharging state from normal state, the battery voltage can be detected from V
DD
. When the load
is connected between VBAT+ and VBAT-, if V
DD
is smaller than V
ODL
and the delay time is over TOD; then the
battery voltage enters overdischarge state, VBAT- current is 0 and stop discharging. At the same time, CSI is
pulled to V
DD
with internal resistor R
CSID
. If V
CSI
>V
OI2
, the protection IC enters into Power-down mode. (Its
current consumption is lower than 0.3μA).
Release of Power-Down State
When the battery remains in Power-down state, if a charger is connected between VBAT+ and VBAT-. And
V
CH
<V
CSI
<V
OI2
& V
DD
<V
ODR
occur, it releases Power-down state. If V
DD
>V
ODR
occurs, it returns to normal
state.
Charger Detection
If a charger is connected between VBAT+ and VBAT- while the battery remains in Power-down state, and the
voltages become V
CSI
<V
CH
and V
DD
>V
ODL
, it returns to normal state.
Abnormal Charging Detection
If a charger is connected between VBAT+ and VBAT- in normal state, if V
CSI
<V
CH,
and the delay time is over
T
OC
, then VBAT- current is 0 and stop charging.
Over Current/Short Current Detection
In normal state, the load is connected between VBAT+ and VBAT- ,when the discharging current is too big
and
the CSI voltage is larger than V
OIX
(V
IO1
or V
IO2
),and the delay time is over T
OIX
(T
IO1
or T
IO2
), it means the
over current/short current state occurs. CSI is pulled to V
SS
with an internal resistor R
CSIS
, VBAT- current is 0
and VBAT- voltage is pulled to V
DD
because of the load.
Release of Over Current/Short Current State
While the protection IC remains in Over Current/Short Current state, and the load is removed or the impedance
between VBAT+ and VBAT- is larger than 500KΩ and V
CSI
<V
OI1
, it is back to normal state.
0V charging forbidden
When a charger is connected between VBAT+ and VBAT- and V
DD
<V
INH
, the current at VBAT- is 0 and battery
can not be charged..
0V charging allowed
When a charger with the voltage over V
CHA
is connected between VBAT+ and VBAT, the battery can be
charged.
Note: when a battery is connected to a protection IC at first time, the IC may not enter the normal state, it can
not discharge. If happens, please connect charger between VBAT+ and VBAT- to enter the normal state.
HANGZHOU MICROELECTRONICS CO.,LTD
Http: //www.silan.com.cn
REV:1.2
2009.05.05
Page 4 of 10
SC8821
TIMING DIAGRAM
Overcharge state
→self
discharging
→normal
state
Overcharge state→load discharging→normal state
HANGZHOU MICROELECTRONICS CO.,LTD
Http: //www.silan.com.cn
REV:1.2
2009.05.05
Page 5 of 10
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