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AIC1811
One-Cell Lithium-Ion Battery Protection IC
n FEATURES
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n DESCRIPTION
The AIC1811 battery protection IC is designed to protect lithium-ion the battery from to damage or degrading lifetime due overcharge, and Less External
Reduction in Board Size due to Miniature Package SOT-23-5 Components.
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Ultra-Low Quiescent Current at 7A (V CC =3.5V). Ultra-Low Power-Down Current at 0.4A (V CC =2.3V). Precision Overcharge Protection Voltage 4.35V 50mV for the AIC1811A 4.30V 50mV for the AIC1811B 4.25V 50mV for the AIC1811C
overdischarge, and/or overcurrent for one-cell lithium-ion battery powered systems, such as cellular phones. The ultra-small package and less required external components make it ideal to integrate the AIC1811 into the limited space of battery pack. The accurate 50mV overcharging detection
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Built-in Delay Time Circuits for Overcharge, Over-discharge, and Overcurrent Protection. Load Detection Function during Overcharge Mode. Two Detection Levels for Overcurrent Protection.
voltage ensures safe and full utilization charging. Three 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.
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n APPLICATIONS
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Protection IC for One-Cell Lithium-Ion Battery Pack.
n TYPICAL APPLICATION CIRCUIT
BATT+ FUSE R1 BATTERY 100 C1 0.1F 2 3 GND OD OC 1 R3 AIC1811 10M BATTM2 SI9926 5 VCC CS
4
R2 51K
M1 SI9926
Protection Circuit for One-Cell Lithium-Ion Battery
DS-1811-00 June 7, 00
www.analog.com.tw
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AIC1811
n
ORDERING INFORMATION
AIC1811 XCX PACKAGE TYPE V: SOT-23-5 OVERCHARGE PROTECTION A: 4.35V B: 4.30V C: 4.25V ORDER NUMBER AIC1811ACV AIC1811BCV AIC1811CCV (SOT-23-5) PIN CONFIGURATION
TOP VIEW VCC 5 CS 4
1 OC
2 GND
3 OD
n ABSOLUTE MAXIMUM RATINGS
Supply Voltage ....................................... ... ... ... ... ..................................................... 18V 18V ........................................ ... ... ... ... ... .............. -40C~85C - 65C~125C DC Voltage Applied on other Pins .................. ... ... ... ... ... ... ... ... ... .............................. Operating Temperature Range Storage Temperature Range ............................ ... ... ... ... ... ... .....................
n TEST CIRCUIT
ICC R1 V CC 100 C1 0.1F 2 VO D 3 GND OD OC 1 R3 10M VO C S1 5 VCC CS 4 R2 VCS 51K
AIC1811
IOC
2
AIC1811
n ELECTRICAL CHARACTERISTICS (Ta=25C, unless otherwise specified.)
PARAMETER
Supply Current Power-Down Current Overcharge Protection Voltage
TEST CONDITIONS
VCC =3.5V VCC =2.3V, AIC1811A AIC1811B AIC1811C
SYMBOL ICC I PD
MIN.
TYP.
7 0.4
MAX. UNIT
11 1.0 4.40 4.35 4.30 250 2.6 3.2 220 mV V V mV V A A
4.30 VOCP 4.25 4.20 VHYS VODP 150 2.2 2.6 180
4.35 4.30 4.25 200 2.4 2.9 200
Overcharge Hysteresis Voltage Overdischarge Protection Voltage Overdischarge Release Voltage Overcurrent Protection Voltage Overcharge Delay Time VCC =3.5V VCC =VOCP-0.1 VOCP + 0.1V Overdischarge Delay Time Overcurrent Delay Time (1) Overcurrent Delay Time (2) OC Pin Source Current VCC = 2.5V 2.3V VCC =3.5V, 1V>VCS>0.2V VCC =3.5V, VCS>1V VCC =3.5V, OC pin short to GND
VODR VOIP TOC
50
100
150
mS
TOD TOI1 TOI2 IOC
50 5 150 240
100 10 300 340 VCC0.02 0.01 0.3
150 15 450 440
mS mS S A
OD Pin Output "H" Voltage
VDH VDL VCC =VOCP -50mV VLD
VCC-0.1
V 0.1 0.4 V V
OD Pin Output "L" Voltage Load Dectection Threshold Voltage Charge Detection Threshold Voltage
VCC =2.3V
VCH
-0.45
-0.3
V
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AIC1811
n BLOCK DIAGRAM
Wake-up Control -0.3V Enable Load Detected
CS
4
0.2V
0.3V
Enable
Overcurrent Delay Circuit
3 VCC 5
1V
OD
Overdischarge Delay Circuit
Power-down Control
Overcharge Delay Circuit 1.2V
GND
2
1 OC
n PIN DESCRIPTIONS
PIN 1: OC - PMOS open drain output for control of the charge control MOSFET M2. In normal mode, this PMOS turns on to pull the gate of the MOSFET M2 to high, then the MOSFET M2 turns on. When overcharge occurs, this PMOS turns off, then no current flows through R3 and the MOSFET M2 turns off. MOSFET M1 and discharging is inhibited. PIN 4: CS - Input pin for current sensing. Using the sum of drain-source voltages of the MOSFET M1 and the MOSFET M2 (voltage between CS and GND), it senses discharge current during normal mode and detects whether charge current is present during powerdown mode. It also used to detect whether load is connected during overcharge mode.
PIN 2: GND - Ground pin. This pin is to be connected to the negative terminal of the battery cell. PIN 3: OD - Output pin for control of discharge control MOSFET When overdischarge occurs, pin goes low to turn off the M1. this the
PIN 5: VCC - Power supply pin. This pin is to be connected to the positive terminal of the battery cell.
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AIC1811
n APPLICATION INFORMATIONS
THE OPERATION
Overcharge Protection
When the voltage of the battery cell 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 M2. The overcharge delay time is fixed to 100mS by IC internal circuit. The overcharge condition is released in two cases: 1. The voltage of the battery cell becomes lower than the overcharge release voltage (V OCR or VOCP- VHYS) through self-discharge. 2. The voltage of the battery cell falls below the overcharge protection voltage (V OCP) and a load is connected. When the battery voltage is above VOCP, the overcharge condition is never released even a load is connected to the pack. overcurrent protection circuit operates and discharging is inhibited by the turning-off of the discharge control MOSFET M1. The overcurrent condition returns to the normal mode when the load is released and the impedance between the BATT+ and BATT- terminals is 20M or higher. The AIC1811 is provided with the two overcurrent detection levels (0.2V and 1V) and the two overcurrent delay time (TOI1 and TOI2) corresponding to each overcurrent detection level.
Load Detection after Overcharge
The load detection function after overcharge is implemented by detecting the CS pin voltage. Once a load is connected to the battery pack after overcharge, discharge current flows through the parasitic diode of MOSFET M2 and there is a diode voltage drop between CS and GND. Load is determined to be connected to the pack if the CS pin voltage is above load detection threshold
Overdischarge Protection
When the voltage of the battery cell goes 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 defaults to 100mS. Inhibition of discharging is immediately released when the voltage of the battery cell becomes higher than overdischarge release voltage (V ODR) through charging.
voltage (V LD ).
Power-Down after Overdischarge
When overdischarge occurs, the AIC1811 will go into power-down mode, turning off all the timing generation and detection circuitry to reduce the quiescent current to 0.4A (V CC =2.3V). At the same time, the CS pin is pull-high to VCC through a high resistance resistor.
Charge Detection after Overdischarge Overcurrent Protection
In normal mode, the AIC1811 continuously monitors the discharge current by sensing the voltage of CS pin. If the voltage of CS pin exceeds the overcurrent protection voltage (V OIP) beyond the overcurrent delay time (TOI) period, the 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 AIC1811 immediately turns on all the timing generation and
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AIC1811
detection circuitry. Charging is determined to be in progress if the voltage between CS and GND is below charge detection threshold voltage (V CH ).
between gate and source decreases). Once the turn-on resistance of the external MOSFET changes, the overcurrent threshold current will change accordingly.
DESIGN GUIDE
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/ (2 x I ) T (IT is the overcurrent threshold current). For example, if the overcurrent threshold current I is T designed to be 3A, the turn-on resistance of the external control MOSFETs must be 33m. 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
Suppressing the Ripple and Disturbance from Charger
To suppress the ripple and disturbance from charger, connecting R1, C1 to VCC pin is recommended.
Protection at CS pin
R2 is used for latch-up protection when charger is connected under overdischarge condition and overstress protection at reverse connecting of a charger. Larger value of R2 reduces the charger leakage current in overcharge mode, but possibly disables the charge detection of function 51K after is overdischarge. recommended. Resistance
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AIC1811
n TIMING DIAGRAM
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Overcharge and Overdischarge Protection
TOC TOC
VCC
VOCP VOCP-VHYS VODR VODP
TOD
VOC
VCC
Hi-Z
Hi-Z
VOD
VCC
0V
charger connected
load connected
charger connected
load connected
charger connected
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Overcurrent Protection (VCC=3.5V)
VCC
1V
VBATT0.2V 0V T OI1 VOD
VCC 0V
VOC
VCC
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AIC1811
n PHYSICAL DIMENSIONS
l SOT-25 (unit: mm)
D C L HE
SYMBOL A A1 A2 b C
MIN 1.00 -- 0.70 0.35 0.10 2.70 1.40 2.60 0.37 1
MAX 1.30 0.10 0.90 0.50 0.25 3.10 1.80 3.00 -- 9
e
1
D E e H L 1
A2
A
1.90 (TYP)
A1 b
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SOT-23-5 MARKING
Part No. AIC1811ACV AIC1811BCV AIC1811CCV Marking EA0A EA0B EA0C
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