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AIC1804
Three- Or Four-Cell Lithium-Ion Battery Protection IC
n FEATURES
l
n DESCRIPTION
The AIC1804 is designed to protect the lithiumion battery from damage or degrading the lifetime due to overcharging, overdischarging and overcurrent for three- 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.
Cell Number Selection Function to Select 3 or 4 cells Protection. Ultra-Low Quiescent Current at 17A (4-Cell, VCELL=3.5V). Ultra-Low Power-Down Current at 2.2A (4-Cell, VCELL=2.3V) Wide Supply Voltage Range: 2V to 18V. 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 Externally Set Overcharge, Overdischarge and Overcurrent Delay Time. Built-in Cell-balancing Bleeding Network under Overcharge Condition. Three Detection Levels for Overcurrent Protection.
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n
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APPLICATIONS
Protection IC for Three- or Four-Cell Lithium-Ion Battery Packs.
n
TYPICAL APPLICATION CIRCUIT
R8 1K
1 16
NSL
VCC
R1 200
SI4435
M1
SI4435 M2 R5 1M 2N3906 Q1
FUSE
BATT+
C1 0.1 F
2
BAT1 R2 2K BAT2 R3 2K BAT3 R4 R7 1M
OC
UD1 15 VC1
14
3 CS
C2 0.1 F
4 OD 5 TD
UD2 13 12 VC2 C3 0.1 F
R6 1M
CT D 82nF CT I 2.2nF
6
TI 7 TC C TC 82nF 8
UD3 11 10 VC3 C4 0.1 F
33K BAT4
GND
UD4
9
AIC1804
BATT-
Protection Circuit for Four-Cell Lithium-Ion Battery Pack
DS-1804-01 July 13, 00 www.analog.com.tw
1
AIC1804
n ORDERING INFORMATION
AIC1804 XXX PACKAGE TYPE S: SMALL OUTLINE TEMPERATURE RANGE C=0 C~70 C OVERCHARGE PROTECTION VOLTAGE A: 4.35V B: 4.30V C: 4.25V D: 4.20V ORDER NUMBER AIC1804ACS AIC1804BCS AIC1804CCS AIC1804DCS (PLASTIC SO) PIN CONFIGURATION
TOP VIEW
NSL 1 OC 2 CS 3 OD 4 TD TI 5 6
16 VCC 15 UD1 14 VC1 13 UD2 12 VC2 11 UD3 10 VC3 9 UD4
TC 7 GND 8
n ABSOLUTE MAXIMUM RATINGS
Supply Voltage ................................................... ... ... ... ... ... ....................................... 18V DC Voltage Applied on other Pins ............ ... ... ... ... ... ... ..... ....................................... 18V Operating Temperature Range............................... ... ... ... ... ... ......................... -20C~70C Storage Temperature Range ................................ ... ..... ... ... ..................... - 65C ~125C
n TEST CIRCUIT
RO C 1M IOC S1 1 VOC 2 NSL OC UD1 15 R8 V CS 1K VOD 3 4 CS OD UD2 5 TD 6 TI CTD 1nF UD3 11 C TI 2.2nF CTC 1nF 7 TC VC3 10 13 IUD2 IC 2 R3 2K C3 0.1F VC2 VC1 14 I UD1 IC 1 R2 2K C2 0.1F VC1 VCC 16 I CC R1 200 C1 0.1F V CC
VC2 12
IUD3 IC3
8
GND
UD4 9
IUD4
R4 33K C4 0.1 F
VC 3
AIC1804
2
AIC1804
n ELECTRICAL CHARACTERISTICS (Ta=25C, unless otherwise specified.)
PARAMETER TEST CONDITIONS
SYMBOL ICC
MIN.
TYP. MAX. UNIT
17 26 A A A A A A
VCC Pin Input Current in Normal VCELL=3.5V Mode VC1 Pin Input Current in Normal VCELL=3.5V Mode VC2 Pin Input Current in Normal VCELL=3.5V Mode VC3 Pin Input Current in Normal VCELL=3.5V Mode Vcc Pin Input Current in PowerDown Mode VC1,VC2,VC3 Input Current in Power-Down Mode Overcharge Protection Voltage VCELL=2.3V
IC1
0.7
1.8
IC2
0.4
1.0
IC3
0.2
0.5
ICC(PD)
2.2
4.0
VCELL=2.3V AIC1804A AIC1804B AIC1804C AIC1804D
IC(PD) 4.32 VOCP 4.27 4.22 4.17 VHYS VODP VODR 150 2.27 2.85 135 10
0.01 4.35 4.30 4.25 4.20 200 2.40 3.00 150 21
0.15 4.38 4.33 4.28 4.23 250 2.53 3.15 165 32
V
Overcharge Hysteresis Voltage Overdischarge Protection Voltage Overdischarge Release Voltage Overcurrent Protection Voltage Overcharge Delay Time VCELL=3.5V VCELL1=VOCP - 30mV VOCP+30mV VCELL2= VCELL3= VCELL4= 3.5V, CTC=1nF Overdischarge Delay Time VCELL1= 2.5V 2.3V VCELL2= VCELL3= VCELL4= 3.5V, CTD=1nF Overcurrent Delay Time (1) VCELL= 3.5V,0.15VmV V V mV mS
VOIP TOC
TOD
10
21
32
mS
TOI1
7
15
23
mS
3
AIC1804
n ELECTRICAL CHARACTERISTICS (Ta=25C, unless otherwise specified.)
PARAMETER
Overcurrent Delay Time (2)
TEST CONDITIONS
VCELL=3.5V, 0.3VSYMBOL TOI2
MIN.
2
TYP. MAX. UNIT
4 6 mS
Overcurrent Delay Time (3) OC Pin Sink Current
VCELL=3.5V, VCC- VCS>1.0V VCELL1=4.4V, VCELL2= VCELL3= VCELL4=3.5V, OC Pin Short to VCC
TOI3 IOC
150 2.2
300 3.2
450 4.2
S mA
OD Pin Output "H" Voltage OD Pin Output " Voltage L" Charge Detection Threshold Voltage UD1 Pin Cell-Balancing Bleeding Current UD2 Pin Cell-Balancing Bleeding Current UD3 Pin Cell-Balancing Bleeding Current UD4 Pin Cell-Balancing Bleeding Current VCELL=2.3V VCELL1=4.4V, VCELL2= VCELL3= VCELL4=3.5V VCELL2=4.4V, VCELL1= VCELL3= VCELL4=3.5V VCELL3=4.4V, VCELL1= VCELL2= VCELL4=3.5V VCELL4=4.4V, VCELL1= VCELL2= VCELL3=3.5V
VDH VDL VCH IUD1 IUD2 IUD3 IUD4
V CC-0.15V V CC-0.03V
V 0.15 V V mA
0.01
VCC+0.4 V CC+0.55
6.5
9.3
12.1
6.3
9.0
11.7
mA
6.2
8.8
11.4
mA
6.4
9.2
12.0
mA
Note: VCELL means the battery cell voltage. Therefore, VCELL1 = VCC - V C1 VCELL2 = VC1 - V C2 VCELL3 = VC2 - V C3 VCELL4 = VC3
4
AIC1804
n TYPICAL PERFORMANCE CHARACTERISTICS
Vcc Pin Input Current vs. Supply Voltage Vcc Pin Power-Down Current (A)
22
Vcc Pin Power-Down Current vs. Supply Voltage
2.2
Ta=25C
2.0
Vcc Pin Input Current (A)
20
1.8
18
1.6
1.4
16
1.2
14 10.4
1.0 11.2 12.0 12.8 13.6 14.4 15.2 16.0 6.0 6.4 6.8 7.2 7.6 8.0 8.4 8.8 9.2
Supply Voltage (V)
Supply Voltage (V)
Vcc Pin Input Current vs. Temperature
22 3.0
Vcc Pin Power-Down Current vs. Temperature Vcc Pin Power-Down Current (uA)
Vcc Pin Input Current (A)
VCELL =3.5V
2.8 2.6
20
VCELL=2.3V
2.4 2.2 2.0 1.8 1.6 -20
18
16
14 -20
-10
0
10
20
30
40
50
60
70
-10
0
10
20
30
40
50
60
70
Temperature (C)
Temperature ( C) Overdischarge Protection Voltage vs. Temperature Overdischarge Protection Voltage (V)
2.42
Overcharge Protection Voltage vs. Temperature
4.30
Overcharge Protection Voltage (V)
AIC1804C
4.28
2.41
2.40
4.26
2.39
4.24
2.38
4.22
2.37
4.20
-20
0
20
40
60
70
2.36
Temperature (C)
-20
-10
0
10
Temperature (C)
20
30
40
50
60
70
5
AIC1804
n TYPICAL PERFORMANCE CHARACTERISTICS (CONTINUED)
Overcurrent Protection Voltage vs. Temperature
Overcharge/Overdischarge Delay Time (mS)
152.0
Overcharge/Overdischarge Delay Time vs. Temperature
26
Overcurrent Protection Voltage (V)
151.5
V CELL=3.5V
151.0 150.5 150.0 149.5 149.0 148.5 148.0 -20
24
CTC /CTD=1nF
22
20
18
16
-10
0
10
Temperature(C)
20
30
40
50
60
70
14 -20
-10
0
10
20
30
40
50
60
70
Temperature( C)
Overcurrent Delay Time 1 vs. Temperature
22
Overcharge Release Voltage vs. Temperature
4.08
Overcurrent Delay Time 1 (mS)
20
Overcharge Release Voltage (V)
20 30 40 50 60 70
4.07
VCELL =3.5V
18
4.06
16
4.05
14
4.04
12
4.03
10 -20 -10 0 10
4.02 -20
-10
0
10
20
30
40
50
60
70
Temperature (C)
Overdischarge Release Voltage vs. Temperature
3.01
Temperature (C)
Overdischarge Release Voltage (V)
3.00
2.99
2.98
2.97 -20
-10
0
10
Temperature (oC)
20
30
40
50
60
70
6
AIC1804
n BLOCK DIAGRAM
CS 3 VCC VC1 VC2 VC3 UD1 16 14 12 10 15
VCC-0.3V 300 Battery Voltage Sense Circuit Wake-Up Control VCC+0.4V VCC-0.15V Overcurrent Delay Circuit
4 UD2 13
VCC-1V 350
OD
UD3
11
400
Overdischarge Delay Circuit
Power-Down Control
2
OC
UD4
9
450 1.2V
Overcharge Delay Circuit
GND
8
7 TC
5
6
TD TI
n PIN DESCRIPTIONS
PIN 1: NSLInput pin for cell number selection. Connect this pin to VCC for three-cell application and to GND for four-cell application. 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. 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 PIN 5: TD PIN 6: TI PIN 7: TC PIN 8: GND Overdischarge delay time setting pin. Overcurrent delay pin. time setting
Output pin for control of discharge control M
PIN 2: OC-
Overcharge delay time setting pin. Ground pin. This pin is to be connected to the negative terminal of the battery cell BAT4. This pin is to be connected to the positive terminal of the battery cell BAT4 for cell-balancing bleeding function under overcharge condition. Input pin for battery BAT4 voltage sensing. This pin is to be connected to the positive terminal of the battery cell BAT4. This pin is to be connected to
PIN 9: UD4-
PIN 3: CS-
PIN10: VC3-
PIN11: UD3 -
7
AIC1804
the positive terminal of the battery cell BAT3 for cellbalancing 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. 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 PIN16: VCC -
This pin is to be connected to the positive ter 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.
PIN13: UD2 -
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. 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
Overcharge Protection
When the voltage of either of the battery cells exceeds the overcharge protection voltage (V OCP) beyond the overcharge delay time (TOC ) period, charging is inhibited by the turning-off of the charge control MOSFET of M2. charging lower The is than overcharge delay time is set by the external capacitor C TC . Inhibition immediately released when the voltage of the overcharged cell becomes overcharge release voltage (V OCR or VOCP -V HYS) through discharging.
voltage of CS pin. If the voltage VCC -V CS exceeds the overcurrent protection voltage (V OIP) beyond the overcurrent delay time (TOI) 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 BATTterminals. The overcurrent condition returns to normal mode when the load is released and the impedance between the BATT+ and BATTterminals is 20M or higher. The AIC1804 is provided with the three
Overdischarge Protection
When the voltage of either of the battery cells falls below the overdischarge protection voltage (V ODP) beyond the overdischarge delay time (TOD ) 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 Inhibition of discharging TD.
overcurrent detection levels (0.15V, 0.3V and 1.0V) and the three overcurrent delay time (TOI1, TOI2 and TOI3 ) corresponding to each overcurrent detection level. TOI1 is set by the external capacitor CTI . TOI2 and T default to 4mS and OI3 300s respectively, and can not be adjusted due
8
AIC1804
to protection of external MOSFETs VCH ).
DESIGN GUIDE
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 release cell decreases (V OCR or to overcharge VOCP-VHYS). voltage
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.
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.
Setting the Overcharge and Overdischarge Delay Time
The overcharge delay time is set by the external capacitor CTC and the overdischarge delay time is set by the external capacitor CTD. The relationship between capacitance of the external capacitors and delay time is tabulated as below. CTC C TD (nF) 1 5 10 22 33 47 68 the discharge 82 100 TOC OD (mS) T 21 52 132 253 347 617 748 1004 1630
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 2.2A (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, 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
The delay time can also be approximately calculated by the following equations (if CTC , CTD 82nF) : TOC (mS) = 11.8 x CTC (nF) TOD (mS) = 11.8 x CTD (nF)
Setting the Overcurrent Delay Time 1
The overcurrent delay time 1 (TOI1 ) at 0.15V <
9
AIC1804
VCC -VCS < 0.3V is set by the external capacitor CTI , while the overcurrent delay time 2 and 3 (TOI2 and TOI3) is fixed by IC internal circuit.The relationship between capacitance of the external capacitor and delay time is tabulated as below. CTI (nF) 1 2.2 3.3 5 6.8 10 TOI (mS) 4.8 15.0 18.8 23.6 31.0 61.8 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.
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: RON =VOIP/IT (I T is the overcurrent threshold current). turn-on For example, of if the the overcurrent control threshold current T is designed to be 5A, the I resistance external 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
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.
10
AIC1804
n APPLICATION EXAMPLES
R8 1K SI4435 SI4435 M2 R5 1M 1 16 C1 0.1F 2 OC 3 CS UD1 VC1 13 UD2 12 VC2 11 UD3 10 VC3 9 GND UD4 BATTAIC1804 15 14 R1 1K 2N3906 Q1 M1 FUSE BATT+
NSL
VCC
R2 C2 1K 0.1 F R3 1K C3 0.1F R4 1K C4 0.1F BAT3 BAT2 BAT1
4 5
OD TD
R6 1M R7 1M
CTD 82nF
+
+
6 7 +
CT C 82nF
TI TC
CTI 2.2nF
8
Fig. 1 Protection Circuit for Three-Cell Lithium-Ion Battery Pack
n TIMING DIAGRAM
l Overcharge and Overdischarge Protection (VCS=VCC )
VCELL
V BAT2 V BAT4
V BAT3
VODR VODP
TOD VOC
Hi-Z
Hi-Z
0V
VOD
VCC 0V
11
AIC1804
l Overcurrent Protection (VCELL =3.5V)
>256ms VCC VCC- 0.15V VCC - 0.3V <256ms
VCS
VCC - 1V
0V
TOI1 OI1
VOD
VCC 0V 256ms <256ms
VOC
Hi-Z
n PACKAGE DIMENSIONS
l 16 LEAD PLASTIC SO (150 mil) (unit: mm) SYMBOL A A1
E H D
MIN 1.35 0.10 0.33 0.19 9.80 3.80 5.80 0.40
MAX 1.75 0.25 0.51 0.25 10.00 4.00 6.20 1.27
B C D E e
e A
1.27 (TYP)
H L
A1
B
C
L
12

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