AIC1804
Three- Cell Or Four-Cell Lithium-Ion Battery
Protection IC
Analog Integrations Corporation
4F, 9 Industry E. 9th Rd, Science-Based Industrial Park, Hsinchu, Taiwan
DS-1652-03 012102
TEL: 886-3-5772500
FAX: 886-3-5772510
www.analog.com.tw
1
n
FEATURES
l
Cell Number Selection Function to Select 3 or 4
cells Protection.
l
Ultra-Low Quiescent Current at 17
A (4-Cell,
V
CELL
=3.5V).
l
Ultra-Low Power-Down Current at 2.2
A (4-Cell,
V
CELL
=2.3V)
l
Wide Supply Voltage Range: 2V to 18V.
l
Precision Overcharge Protection Voltage:
4.35V
30mV for the AIC1804A
4.30V
30mV for the AIC1804B
4.25V
30mV for the AIC1804C
4.20V
30mV for the AIC1804D
l
Externally Set Overcharge,
Overdischarge and
Overcurrent Delay Time.
l
Built-in Cell-balancing Bleeding Network under
Overcharge Condition.
l
Three Detection Levels for Overcurrent Protection.
n
APPLICATIONS
l
Protection IC for Three- or Four-Cell Lithium-Ion
Battery Packs.
n
DESCRIPTION
The AIC1804 is designed to protect the lithium-
ion battery from damage or degrading the lifetime
due to overcharging, overdischarging and
overcurrent for three-cell or four-cell lithium-ion
battery powered systems such as notebook PCs.
It can also provide the cell-balancing "bleeding"
function to automatically discharge the
overcharged cell until the overcharge condition is
released.
Safe and full utilization charging is ensured by
the accurate
30mV overcharge detection. Four
different specification values for overcharge
protection voltage are provided for various
protection requirements. The very low standby
current drains little current from the cell while in
storage.
n
TYPICAL APPLICATION CIRCUIT
0.1
F
C4
0.1
F
C2
0.1
F
C3
0.1
F
C1
R6
1M
1M
R5
R7
1M
BATT-
AIC1804
1
16
6
7
8
5
4
OC
2
CS
3
OD
TD
TI
TC
GND
9
10
13
12
15
14
UD4
R4
33K
R3
2K
UD3
11
VC3
BAT4
R2
2K
200
R1
UD2
VC2
BAT3
UD1
VCC
BAT1
VC1
BAT2
1K
R8
NSL
BATT+
FUSE
M2
M1
SI4435
SI4435
2N3906
Q1
C
TC
82nF
C
TD
82nF
C
TI
2.2nF
Protection Circuit for Four-Cell Lithium-Ion Battery Pack
AIC1804
2
n
ORDERING INFORMATION
AIC1804-XCXXX
PIN CONFIGURATION
OC
CS
TC
TOP VIEW
OD
1
3
4
2
NSL
TI
5
6
7
8
VCC
UD1
16
15
TD
VC2
VC1
UD2
UD3
14
12
11
13
VC3
UD4
10
9
GND
PACKING TYPE
TR: TAPE & REEL
TB: TUBE
PACKAGE TYPE
S: SMALL OUTLINE
OVERCHARGE
PROTECTION VOLTAGE
A: 4.35V
B: 4.30V
C: 4.25V
D: 4.20V
Example: AIC1804-ACSTR
4.35V version, in SO-16 Package &
Tape & Reel Packing Type
n
ABSOLUTE MAXIMUM RATINGS
Supply Voltage ................................................... ... ... ... ... ... ....................................... 18V
DC Voltage Applied on other Pins ............ ... ... ... ... ... ... ..... ....................................... 18V
Operating Temperature Range............................... ... ... ... ... ... ......................... -20
C~70
C
Storage Temperature Range ................................ ... ..... ... ... ..................... - 65
C ~125
C
n
TEST CIRCUIT
I
OC
S1
R
OC
1M
V
OC
1K
V
CS
R8
UD 1
AIC1804
VCC
NSL
OC
2
1
VC1
UD 3
VC3
UD4
UD 2
VC2
V
OD
OD
CS
3
4
TI
TD
6
7 TC
GND
8
5
I
CC
I
UD1
R 1 200
0.1
F
C 1
16
15
V
CC
I
C1
I
UD2
R 2 2K
0.1
F
C 2
14
13
V
C1
I
C2
I
UD3
R 3 2K
0.1
F
C 3
12
11
V
C2
I
C3
I
UD4
R 4 33K
0.1
F
C 4
10
9
V
C3
C
T D
1nF
C
T C
1nF
C
TI
2.2nF
AIC1804
3
n
ELECTRICAL CHARACTERISTICS
(T
A
=25
C, unless otherwise specified.)
PARAMETER
TEST CONDITIONS
SYMBOL
MIN.
TYP.
MAX.
UNIT
VCC Pin Input Current in Normal
Mode
V
CELL
=3.5V
I
CC
17
26
A
VC1 Pin Input Current in Normal
Mode
V
CELL
=3.5V
I
C1
0.7
1.8
A
VC2 Pin Input Current in Normal
Mode
V
CELL
=3.5V
I
C2
0.4
1.0
A
VC3 Pin Input Current in Normal
Mode
V
CELL
=3.5V
I
C3
0.2
0.5
A
Vcc Pin Input Current in Power-
Down Mode
V
CELL
=2.3V
I
CC(PD)
2.2
4.0
A
VC1,VC2,VC3 Input Current in
Power-Down Mode
V
CELL
=2.3V
I
C(PD)
0.01
0.15
A
AIC1804A
4.32
4.35
4.38
AIC1804B
4.27
4.30
4.33
AIC1804C
4.22
4.25
4.28
Overcharge Protection Voltage
AIC1804D
V
OCP
4.17
4.20
4.23
V
Overcharge Hysteresis Voltage
V
HYS
150
200
250
mV
Overdischarge
Protection Voltage
V
ODP
2.27
2.40
2.53
V
Overdischarge Release Voltage
V
ODR
2.85
3.00
3.15
V
Overcurrent Protection Voltage
V
CELL
=3.5V
V
OIP
135
150
165
mV
Overcharge Delay Time
V
CELL1
=V
OCP
- 30mV
V
OCP
+30mV
V
CELL2
= V
CELL3
= V
CELL4
=
3.5V, C
TC
=1nF
T
OC
10
21
32
mS
Overdischarge Delay Time
V
CELL1
= 2.5V
2.3V
V
CELL2
= V
CELL3
= V
CELL4
=
3.5V, C
TD
=1nF
T
OD
10
21
32
mS
Overcurrent Delay Time (1)
V
CELL
= 3.5V,0.15V<V
CC
-
V
CS
<0.3V,C
TI
=2.2nF
T
OI1
7
15
23
mS
AIC1804
4
n
ELECTRICAL CHARACTERISTICS
(Continued)
PARAMETER
TEST CONDITIONS
SYMBOL
MIN.
TYP.
MAX.
UNIT
Overcurrent Delay Time (2)
V
CELL
=3.5V,
0.3V<V
CC
-V
CS
<1.0V
T
OI2
2
4
6
mS
Overcurrent Delay Time (3)
V
CELL
=3.5V, V
CC
V
CS
>1.0V
T
OI3
150
300
450
S
OC Pin Sink Current
V
CELL1
=4.4V,
V
CELL2
= V
CELL3
= V
CELL4
=3.5V,
OC Pin Short to V
CC
I
OC
2.2
3.2
4.2
mA
OD Pin Output "H" Voltage
V
DH
V
CC
-0.15V
V
CC
-0.03V
V
OD Pin Output "L" Voltage
V
DL
0.01
0.15
V
Charge Detection Threshold
Voltage
V
CELL
=2.3V
V
CH
V
CC
+0.4
V
CC
+0.55
V
UD1 Pin Cell-Balancing
Bleeding Current
V
CELL1
=4.4V,
V
CELL2
= V
CELL3
= V
CELL4
=3.5V
I
UD1
6.5
9.3
12.1
mA
UD2 Pin Cell-Balancing
Bleeding Current
V
CELL2
=4.4V,
V
CELL1
= V
CELL3
= V
CELL4
=3.5V
I
UD2
6.3
9.0
11.7
mA
UD3 Pin Cell-Balancing
Bleeding Current
V
CELL3
=4.4V,
V
CELL1
= V
CELL2
= V
CELL4
=3.5V
I
UD3
6.2
8.8
11.4
mA
UD4 Pin Cell-Balancing
Bleeding Current
V
CELL4
=4.4V,
V
CELL1
= V
CELL2
= V
CELL3
=3.5V
I
UD4
6.4
9.2
12.0
mA
Note: V
CELL
means the battery cell voltage. Therefore,
V
CELL1
= V
CC
V
C1
V
C
ELL2
= V
C1
V
C2
V
CELL3
= V
C2
V
C3
V
CELL4
= V
C3
AIC1804
5
n
TYPICAL PERFORMANCE CHARACTERISTICS
10.4
11.2
12.0
12.8
13.6
14.4
15.2
16.0
14
16
18
20
22
Fig. 1 Vcc Pin Input Current vs. Supply Voltage
Vcc Pin Input Current (
A)
Supply Voltage (V)
T
A
=25
C
6.0
6.4
6.8
7.2
7.6
8.0
8.4
8.8
9.2
1.0
1.2
1.4
1.6
1.8
2.0
2.2
T
A
=25
C
Fig. 2 Vcc Pin Power-Down Current vs. Supply Voltage
Vcc Pin Power-Down Current (
A)
Supply Voltage (V)
-20
-10
0
10
20
30
40
50
60
70
14
16
18
20
22
Fig. 3 Vcc Pin Input Current vs. Temperature
V
CELL
=3.5V
Vcc Pin Input Current (
A)
Temperature (
C)
-20
-10
0
10
20
30
40
50
60
70
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
V
CELL
=2.3V
Fig. 4 Vcc Pin Power-Down Current vs. Temperature
Vcc Pin Power-Down Current (
uA)
Temperature (
C)
4.20
4.22
4.24
4.26
4.28
4.30
Fig. 5 Overcharge Protection Voltage vs. Temperature
Overcharge Protection Voltage (V)
-20
0
20
40
60
70
AIC1804C
Temperature (
C)
2.36
2.37
2.38
2.39
2.40
2.41
2.42
-20
-10
0
10
20
30
40
50
60
70
Fig. 6 Overdischarge Protection Voltage vs. Temperature
Overdischarge Protection Voltage (V)
Temperature (
C)
AIC1804
6
n
TYPICAL PERFORMANCE CHARACTERISTICS
(Continued)
148.0
148.5
149.0
149.5
150.0
150.5
151.0
151.5
152.0
Fig. 7 Overcurrent Protection Voltage vs. Temperature
Overcurrent Protection Voltage (V)
-20
-10
0
10
20
30
40
50
60
70
Temperature(
C)
V
CELL
=3.5V
14
16
18
20
22
24
26
Fig. 8 Overcharge/Overdischarge Delay Time vs.
Temperature
-20
-10
0
10
20
30
40
50
60
70
C
TC
/C
TD
=1nF
Overcharge/
Overdischarge Delay Time (
mS)
Temperature(
C)
-20
-10
0
10
20
30
40
50
60
70
10
12
14
16
18
20
22
V
CELL
=3.5V
Fig. 9 Overcurrent Delay Time 1 vs. Temperature
Overcurrent Delay Time 1 (
m
S)
Temperature (
C)
Temperature (
C)
-20
-10
0
10
20
30
40
50
60
70
4.02
4.03
4.04
4.05
4.06
4.07
4.08
Fig. 10 Overcharge Release Voltage vs. Temperature
Overcharge Release Voltage (V)
-20
-10
0
10
20
30
40
50
60
70
2.97
2.98
2.99
3.00
3.01
o
Fig. 11 Overdischarge Release Voltage vs. Temperature
Overdischarge Release Voltage (V)
Temperature (
C)
AIC1804
7
n
BLOCK DIAGRAM
Battery
Voltage
Sense
Circuit
450
400
350
300
12
VC2
14
VC1
16
VCC
10
15
13
11
9
8
UD4
UD3
UD2
VC3
UD1
GND
3
CS
7
TC
6
5
Wake-Up Control
2
4
OC
OD
VCC-1V
VCC-0.3V
VCC-0.15V
VCC+0.4V
Power-Down
Control
1.2V
Overcharge Delay
Circuit
Overcurrent Delay
Circuit
TI
TD
Overdischarge Delay
Circuit
n
PIN DESCRIPTIONS
PIN 1: NSL-
Input pin for cell number
selection. Connect this pin to
VCC for three-cell application
and to GND for four-cell
application.
PIN 2: OC-
NMOS open drain output
for
control of the charge control
MOSFET M2. When overcharge
occurs, this pin sinks current to
switch the
external PNP Q1 on,
and charging is inhibited by
turning off the charge
control
MOSFET M2.
PIN 3: CS-
Input pin for current sensing.
Using the drain-source voltage of
the discharge control MOSFET
M1 (voltage between VCC and
CS),
it senses discharge
current
during normal mode
and detects
whether charging
current is present
during
power-down mode.
PIN 4: OD -
Output pin for control
of discharge control MOSFET M1. When overdischarge occurs, this
PIN 5: TD
-
Overdischarge delay time setting
pin.
PIN 6: TI
-
Overcurrent
delay
time setting
pin.
PIN 7: TC
-
Overcharge
delay time setting
pin.
PIN 8: GND
-
Ground pin. This pin is to be
connected to the negative
terminal of the battery cell BAT4.
PIN 9: UD4-
This pin is to be connected to the
positive terminal of the battery
cell BAT4 for cell-balancing
bleeding function under
overcharge condition.
PIN10: VC3-
Input pin for battery BAT4
voltage sensing. This pin is to be
connected to the
positive
terminal of the battery cell BAT4.
AIC1804
8
PIN11: UD3 -
This pin is to be connected to
the positive terminal of the
battery cell BAT3 for cell-
balancing bleeding function
under overcharge condition.
PIN12: VC2 -
Input pin for battery BAT3
voltage sensing. This pin is to be
connected to the positive
terminal of the battery cell BAT3.
PIN13: UD2 - This pin is to be connected to the
positive terminal of the battery
cell BAT2 for cell-balancing
bleeding function under
overcharge condition.
PIN14: VC1 - Input pin for battery BAT2
voltage sensing. This pin is to be
connected to the positive
terminal of the battery cell BAT2.
PIN15: UD1 -
This pin is to be connected to the positive terminal of the battery BAT1 for cell-balancin
PIN16: VCC -
Power supply pin and input for
battery BAT1 voltage sensing.
This pin is to be connected to the
positive terminal of the battery
cell BAT1.
n
APPLICATION INFORMATIONS
THE OPERATION
Initialization
On initial power-up, such as connecting the
battery pack for the first time to the AIC1804, the
AIC1804 enters the power-down mode. A
charger must be applied to the AIC1804 circuit
to enable the pack.
Overcharge Protection
When the voltage of either of the battery cells
exceeds the overcharge protection voltage
(V
OCP
) beyond the overcharge delay time (T
OC
)
period, charging is inhibited by the turning-off of
the charge control MOSFET M2. The
overcharge delay time is set by the external
capacitor C
TC
. Inhibition of charging is
immediately released when the voltage of the
overcharged cell becomes lower than
overcharge release voltage (V
OCR
or
V
OCP
-V
HYS
)
through discharging.
Overdischarge Protection
When the voltage of either of the battery cells
falls below the overdischarge protection voltage
(V
ODP
) beyond the overdischarge delay time
(T
OD
) period, discharging is inhibited by the
turning-off of the discharge control MOSFET M1.
The overdischarge delay time is set by the
external capacitor C
TD
.
Inhibition of discharging
is immediately released when the voltage of the
overdischarge cell becomes higher than the
overdischarge release voltage (V
ODR
) through
charging.
Overcurrent Protection
In normal mode, the AIC1804 continuously
monitors the discharge current by sensing the
voltage of CS pin. If the voltage V
CC
-V
CS
exceeds the overcurrent protection voltage (V
OIP
)
beyond the overcurrent delay time (T
OI
)
period,
the overcurrent protection circuit operates and
discharging is inhibited by the turning-off of the
discharge control MOSFET M1. Discharging
must be inhibited for at least 256mS after
overcurrent takes place to avoid damage to
external control MOSFETs due to rapidly
switching transient between BATT+ and BATT-
terminals. The overcurrent condition returns to
normal mode when the load is released and the
impedance between the BATT+ and BATT-
terminals is 20M
or higher.
The AIC1804 is provided with the three
overcurrent detection levels (0.15V, 0.3V and
1.0V) and the three overcurrent delay time (
TOI1
,
T
OI2
and T
OI3
) corresponding to each overcurrent
detection level. T
OI1
is set by the external
capacitor C
TI
. T
OI2
and T
OI3
default to 4mS and
AIC1804
9
300
s respectively, and can not be adjusted due
to protection of external MOSFETs
Cell-Balancing Bleeding after
Overcharge
When either of the battery cells is overcharged,
the AIC1804 provides the cell-balancing
bleeding function to discharge the overcharged
cell at about 9mA until the voltage of the
overcharged cell decreases to overcharge
release voltage (V
OCR
or V
OCP
-V
HYS
).
Connecting UD1, UD2, UD3 and UD4 pins to the
positive terminals of battery cells BAT1, BAT2,
BAT3 and BAT4 accomplish this function,
respectively. Inserting resistors along UD2 pin to
BAT2 positive terminal path and UD4 pin to
BAT4 positive terminal path can decrease the
bleeding current.
Power-Down after Overdischarge
When overdischarge occurs, the AIC1804 will go
into power-down mode, turning off all the timing
generation and detection circuitry to reduce the
quiescent current to about 2.2
A (V
CC
=9.2V). In
the unusual case where one battery cell is
overdischarged while another one under
overcharge condition, the AIC1804 will turn off
all the detection circuitry except the overcharge
detection circuit for the cell under overcharge
condition.
Charge Detection after
Overdischarge
When overdischarge occurs, the discharge
control MOSFET M1 turns off and discharging is
inhibited. However, charging is still permitted
through the parasitic diode of M1. Once the
charger is connected to the battery pack, the
AIC1804 immediately turns on all the timing
generation and detection circuitry and goes into
normal mode. Charging is determined to be in
progress if the CS pin voltage is higher than
VCC + 0.4V (charge detection threshold voltage
V
CH
).
DESIGN GUIDE
Cell Number Selection
The user must configure the AIC1804 for three
or four series cells application. For three-cell
application, NSL pin should be connected
directly to VCC pin. For four-cell application,
NSL pin should be connected directly to GND
pin.
No. of Series Cells
NSL Pin
3-cell
Connected to VCC
4-cell
Connected to GND
The protection circuit for three-cell lithium-ion
battery pack is shown in application examples
Fig. 1.
Setting the Overcharge and
Overdischarge Delay Time
The overcharge delay time is set by the external
capacitor C
TC
and the overdischarge delay time
is set by the external capacitor C
TD
.
The
relationship between capacitance of the external
capacitors and delay time is tabulated as below.
C
TC
,C
TD
(nF)
T
OC
,T
OD
(mS)
1
21
5
52
10
132
22
253
33
347
47
617
68
748
82
1004
100
1630
The delay time can also be approximately
calculated by the following equations (if C
TC
, C
TD
82nF) :
T
OC
(mS)
=
11.8 x C
TC
(nF)
T
OD
(mS)
=
11.8 x C
TD
(nF)
AIC1804
10
Setting the Overcurrent Delay Time 1
The overcurrent delay time 1 (T
OI1
) at 0.15V
<
V
CC
-
V
CS
< 0.3V is set by the external capacitor
C
TI
, while the overcurrent delay time 2 and 3
(T
OI2
and T
OI3
) is fixed by IC internal circuit.The
relationship between capacitance of the external
capacitor and delay time is tabulated as below.
C
TI
(nF)
T
OI
(mS)
1
4.8
2.2
15.0
3.3
18.8
5
23.6
6.8
31.0
10
61.8
Selection of External Control
MOSFETs
Because the overcurrent protection voltage is
preset, the threshold current for overcurrent
detection is determined by the turn-on
resistance of the discharge control MOSFET M1.
The turn-on resistance of the external control
MOSFETs can be determined by the equation:
R
ON
=V
OIP
/I
T
(I
T
is the overcurrent threshold
current). For example, if the overcurrent
threshold current I
T
is designed to be 5A, the
turn-on resistance of the external control
MOSFETs must be 30m
. Users should be
aware that turn-on resistance of the MOSFET
changes with temperature variation due to heat
dissipation. It changes with the voltage between
gate and source as well. (Turn-on resistance of
a MOSFET increases as the voltage between
gate and source decreases). Once the turn-on
resistance of the external MOSFET changes,
the overcurrent threshold current will change
accordingly.
Suppressing the Ripple and
Disturbance from Charger
To suppress the ripple and disturbance from
charger, connecting R1 to R4 and C1 to C4 is
recommended. Larger R1 will cause larger error
of battery sense voltage.
Controlling the Charge Control
MOSFET
R5, R6, R7 and NPN transistor Q1 are used to
switch the charge control MOSFET M2. If
overcharge does not occur, no current flows into
OC pin and Q1 is turned off, then M2 is turned
on. When overcharge occurs, current flows into
OC pin and Q1 is turned on, which turns off M2
in turn.
Protection at CS Pin
R8 is used for protection of IC when charger is
connected in reverse. The charge detection
function after overdischarge is possibly disabled
by larger value of R8. Resistance of 1K
is
recommended.
AIC1804
11
n
APPLICATION EXAMPLES
+
+
+
0.1
F
1K
BAT1
BAT2
BAT3
1K
R8
C4
0.1
F
C2
0.1
F
0.1
F
C3
C1
R6
1M
1M
R5
R7
1M
BATT-
C
T D
82nF
C
TI
2.2nF
C
TC
82nF
AIC1804
1
16
6
7
8
5
4
OC
2
CS
3
OD
TD
TI
TC
GND
9
10
13
12
15
14
UD4
R4
1K
R3
1K
UD3
11
VC3
R2
1K
R1
UD2
VC2
UD1
VCC
VC1
NSL
BATT+
FUSE
M2
M1
SI4435
SI4435
2N3906
Q1
Fig. 12 Protection Circuit for Three-Cell Lithium-Ion Battery Pack
n
TIMING DIAGRAM
l
Overcharge and Overdischarge Protection (V
CS
=V
CC
)
BAT4
V
BAT1
V
BAT2
V
OD
T
0V
0V
BAT3
V
CELL
OD
<T
O C
<T
T
OC
Hi-Z
Hi-Z
V
V
OC
V
OD
CC
V
OCP
V
ODP
V
ODR
V
HYS
V
OCP
V
-
AIC1804
12
l
Overcurrent Protection (V
CELL
=3.5V)
V
CC
0V
CC
V
0V
- 1V
- 0.3V
- 0.15V
OI1
T
V
CC
CC
V
CC
V
OC
V
OD
V
CS
V
<256ms
<256ms
256ms
Hi-Z
<T
OI1
OI3
<T
OI2
>256ms
T
n
PHYSICAL DIMENSIONS
l
16 LEAD PLASTIC SO (150 mil) (unit: mm)
SYMBOL
MIN
MAX
A
1.35
1.75
A1
0.10
0.25
B
0.33
0.51
C
0.19
0.25
D
9.80
10.00
E
3.80
4.00
e
1.27 (TYP)
H
5.80
6.20
L
0.40
1.27
E
e
D
B
C
A
A1
L
H
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