AIC1802 Two-Cell Lithium-Ion Battery Protection IC n FEATURES l l n DESCRIPTION Ultra-Low Quiescent Current at 10µA (V CC =7V, The AIC1802 battery protection IC is designed VC =3.5V). to protect lithium-ion batteries from damage due Ultra-Low Power-Down Current at 0.2µA (V CC to overcharging, overdischarging, and =3.8V, VC =1.9V). overcurrent for two series cells in portable l Wide Supply Range: 2 to 18V. phones and laptop computers. It can be a part of l Precision Overcharge Protection Voltage the low-cost charge control system within a two- 4.35V ± 30mV for the AIC1802A cell lithium-ion battery pack. 4.30V ± 30mV for the AIC1802B Safe and full utilization charging is ensured by 4.25V ± 30mV for the AIC1802C l l l Built-in Delay Circuits for Overcharge, Over- the accurate ±30mV overcharge detection. discharge and Overcurrent Protection. Three Overcharge and Overdischarge Delay Time overcharge protection voltage are provided for can be Extended by External Capacitors. various protection requirements. The very low Built-in Cell-balancing Bleeding Network under standby current drains little current from the Overcharge Condition. cells while in storage. different specification values for n APPLICATIONS l Protection IC for Two-Cell Lithium-Ion Battery Pack. n TYPICAL APPLICATION CIRCUIT V BAT+ **R1 8 BATTERY 1 C1 1µ F BATTERY 2 C2 1µ F VCC TC 5 TD 3 *CTC 6 VC *CTD 4 GND OC 1 **R2 M1 CEM9926 2 OD CS AIC1802 R3 1M 7 Q1 R6 1K M2 R4 1M R5 C3 0.01µF 1M CEM9926 VBAT- *CTC & CTD are optional for delay time adjustment. **R1 & R2: Refer application informations. Protection Circuit for Two-Cell Lithium-Ion Battery Pack DS-1802-03 July 13, 00 www.analog.com.tw 1 AIC1802 n ORDERING INFORMATION AIC1802 XCX PIN CONFIGURATION ORDER NUMBER PACKAGE TYPE S: SOP-8 AIC1802ACS AIC1802BCS AIC1802CCS (PLASTIC SO8) OVERCHARGE PROTECTION VOLTAGE A: 4.35V B: 4.30V C: 4.25V TOP VIEW OC 1 OD 2 8 VC 7 CS 6 VC TD 3 GND 4 5 TC n ABSOLUTE MAXIMUM RATINGS Supply Voltage ....................................… … … … … ..................................................... 18V DC Voltage Applied on VC, CS, OC, OD Pins ...............… … … … … .............................. 18V DC Voltage Applied on TC, TD Pins ...............… … … … … … … ..… … .............................. 5V Operating Temperature Range Storage Temperature Range .......................................… .… … … … .............. -40°C~85°C .........................… … … … … … … ..................... - 65°C~150°C n TEST CIRCUIT ICO 1 OC VCC ICC 8 VCC VCS VOD 2 OD CS 7 TD VC 6 4 GND TC 5 3 + CTD AIC1802 IC VC + CTC 2 AIC1802 n ELECTRICAL CHARACTERISTICS (Ta=25°C, unless otherwise specified.) PARAMETER TEST CONDITIONS SYMBOL MIN. TYP. MAX. UNIT Supply Current in Normal Mode VCC =7V, VC =3.5V ICC 10 15 µA Supply Current in Power-Down Mode VCC =4.8V, VC =2.4V IPD 0.8 1.2 µA VC Pin Input Current VCC =7V, VC =3.5V IC 400 600 nA 4.32 4.35 4.38 4.27 4.30 4.33 4.22 4.25 4.28 AIC1802A Overcharge Protection Voltage AIC1802B VOCP AIC1802C V Overcharge Release Voltage VOCR 3.85 4.0 4.15 V Overdischarge Protection Voltage VODP 2.25 2.4 2.55 V Overdischarge Release Voltage VODR 2.85 3.0 3.15 V Overcurrent Protection Voltage VCC =7V VOIP 135 150 165 mV Overcharge Delay Time (1) VCC =8.6V, VC =4.3V, CTC =0µF TOC1 12 25 38 mS Overcharge Delay Time (2) VCC =8.6V, VC =4.3V, CTC =0.47µF TOC2 0.7 1.1 1.5 S Overdischarge Delay Time (1) VCC =4.8V, VC =2.4V, CTD =0µF TOD1 12 25 38 mS Overdischarge Delay Time (2) VCC =4.8V, VC =2.4V, CTD =0.47µF TOD2 0.7 1.1 1.5 S Overcurrent Delay Time (1) VCC =7V, VC =3.5V, VCS=0.15V TOI1 4 9 14 mS Overcurrent Delay Time (2) VCC =7V, VC =3.5V, VCS=0.36V TOI2 1.0 2.0 3.0 mS OC Pin Source Current VCC =8.6V, VC =4.3V, OC Pin Short to GND ICO 270 400 530 µA OD Pin Output “H” Voltage VDL VCC -0.1 VCC -0.02 V 3 AIC1802 n ELECTRICAL CHARACTERISTICS (Continued) PARAMETER TEST CONDITIONS SYMBOL OD Pin Output “L” Voltage MIN. TYP. MAX. UNIT 0.01 0.1 V VDH Charge Detection Threshold Voltage VCC =4.8V VCH -0.55 -0.4 Unbalance Discharge Current VCC =8.3V, VC =4V IUD 5.4 7.7 V 10 mA n TYPICAL PERFORMANCE CHARACTERISTICS Supply Current vs. Supply Voltage Power-down Current vs. Supply Voltage 10.7 Power-Down Current (µA) VC=1/2VC C TA=25°C Supply Current (µA) 10.5 0.8 0.65 10.3 10.1 VC=1/2VCC TA=25°C 0.5 0.35 9.9 0.2 9.7 5.5 6.5 7.5 3.8 8.5 4.3 Supply Voltage (V) Overcharge Protection Voltage vs. Temperature Overcurrent Protection Voltage (mV) Overcharge Protection Voltage (V) 4.32 4.315 AIC1802B 4.31 4.305 4.3 -20 -10 0 10 20 30 Temperature (°C) 4.8 5.3 5.8 Supply Voltage (V) 40 50 60 70 Overcurrent Protection Voltage vs. Temperature 150 VCC=7V VC=3.5V 147.5 145 142.5 140 -20 -10 0 10 20 30 40 50 60 70 Temperature (°C) 4 AIC1802 n TYPICAL PERFORMANCE CHARACTERISTICS (Continued) Supply Current vs. Temperature Power-Down Current vs. Temperature 1.1 VCC=7V VC=3.5V Power-Down Current (µA) Supply Current (µA) 12.5 11.5 VCC=4.8V VC=2.4V 0.9 10.5 0.7 9.5 0.5 8.5 -20 -10 0 10 20 30 Temperature (°C) 40 50 60 0 10 20 30 40 50 60 70 Overcharge Release Voltage vs. Temperature Overdischarge Protection Voltage vs. Temperature 4.025 Overcharge Release Voltage (V) Overdischarge Protection Voltage (V) 2.415 4.020 2.410 4.015 2.405 4.010 2.400 -10 0 10 20 30 Temperature (°C) 40 50 60 70 4.005 -20 -10 0 10 20 30 40 50 60 70 Temperature (°C) Overdischarge Release Voltage vs. Temperature Overdischarge Release Voltage (V) 3.025 -10 Temperature (°C) 2.420 2.395 -20 -20 70 3.020 3.015 3.010 3.005 -20 -10 0 10 20 30 40 50 60 70 Temperature (°C) 5 AIC1802 n BLOCK DIAGRAM VCC 8 OVERCHARGE DETECTOR 1 450 OVERDISCHARGE DETECTOR 1 VC 6 OVERDISCHARGE DELAY CIRCUIT 3 LOGIC CONTROL OVERDISCHARGE DETECTOR 2 4 OVERCURRENT DELAY CIRCUIT OVERCURRENT DETECTOR POWERDOWN TD VCC WAKEUP 450 OD TC UNBALANCE DISCHARGE OVERCHARGE DETECTOR 2 GND 5 OVERCHARGE DELAY CIRCUIT TIMING GENERATION 1 OC CHARGE DETECTION 7 2 CS n PIN DESCRIPTIONS PIN 1: OC - PMOS open drain output for control of the charge control MOSFET M2. When overcharge occurs, this pin sources current to switch the external NPN Q1 on, and charging is inhibited by turning off the charge control MOSFET M2. PIN 2: OD - Output pin for control of discharge control MOSFET When overdischarge occurs, pin goes low to turn off discharge control MOSFET and discharging is inhibited. the M1. this the M1 PIN 3: TD - Overdischarge delay time setting pin. PIN 4: GND - Ground pin. This pin is to be connected to the negative terminal of the lower battery cell. PIN 5: TC - Overcharge delay time setting pin. PIN 6: VC - To be connected to the positive terminal of the lower cell and the negative terminal of the upper cell. PIN 7: CS - Input pin for current sensing. Using the drain-source voltage of the discharge control MOSFET M1 (voltage between CS and GND), it senses discharge current during normal mode and detects whether charging current is present during power down mode. PIN 8: VCC - Power supply pin. It is to be connected to the positive terminal of the upper cell. 6 AIC1802 n APPLICATION INFORMATIONS THE OPERATION detection circuits except the overcharge detection circuit for the cell under overcharge condition. Overcharge Protection When the voltage of either of the battery cells exceeds VOCP (overcharge protection voltage) Charge Detection after Overdischarge period, When overcharge occurs, the discharge control charging is inhibited by the turning-off of the MOSFET M1 turns off and discharging is inhibited. charge control MOSFET M2. The overcharge However, charging is still permitted through the delay time (TOC ) defaults to 25mS and can be parasitic diode of M1. Once the charger is extended by adding a capacitor CTC . Inhibition of connected to the battery pack, the AIC1802 charging is immediately released when the immediately turns on all the timing generation and voltage of the overcharged cell becomes lower detection circuitry and goes into normal mode. than VOCR (overcharge release voltage) through Charging is determined to be in progress if the discharge. voltage between CS and GND is below –0.4V beyond the overcharge delay time (charge detection threshold voltage VCH ) Overdischarge Protection When the voltage of either of the battery cells Overcurrent Protection goes protection In normal mode, the AIC1802 continuously voltage) beyond the overdischarge delay time monitors the discharge current by sensing the period, discharging is inhibited by the turning-off voltage of CS pin. If the voltage of CS pin of the discharge control MOSFET M1. The exceeds VOIP (overcurrent protection voltage) overdischarge delay time (TOD ) defaults to 25mS beyond overcurrent delay time TOI period, the and can be extended by adding a capacitor CTD . overcurrent Inhibition of discharging is immediately released discharging is inhibited by turning-off of the when the voltage of the overdischarged cell discharge control MOSFET M1. Discharging must becomes be inhibited for at least 256mS after overcurrent below VODP higher (overdischarge than VODR (overdischarge protection circuit operates and takes place to avoid damage to external control release voltage) through charging. MOSFETs due to rapidly switching transient between Power-Down after Overdischarge When overdischarge occurs, the AIC1802 will go into power-down mode, turning off all the timing generation and detection circuitry to reduce the quiescent current to 0.8µA (V CC =4.8V). In the unusual case where one battery cell is overdischarged while the other under overcharge condition, the AIC1802 will turn off all the VBAT+ and VBAT- terminals. The overcurrent condition returns to the normal mode when the load is released and the impedance between the VBAT+ and VBAT- terminals is 10MΩ or higher. For the sake of protection of the external MOSFETs, the larger the CS pin voltage (which means the larger discharge current) the shorter the overcurrent delay time. The relationship between voltage of CS pin and overcurrent delay 7 AIC1802 time TOI is tabulated as below. VCS (V) TOI (S) 150m 9.0m 200m 5.6m 300m 2.8m 360m CTC (F) TOC (S) 0µ 25m 0.1µ 320m 0.3µ 890m 0.47µ 1.12 0.57µ 1.43 2.0m 1V 540µ 3V 290µ CTD (F) TOD (S) 5V 270µ 0µ 25m 0.1µ 320m 0.3µ 820m 0.47µ 1.08 0.57µ 1.39 Unbalanced Discharge after Overcharge When either of the battery cells is overcharged, the AIC1802 will automatically discharge the overcharged cell at about 7.7mA until the voltage of the overcharged cell is equal to the voltage of the other cell. If the voltage of the other cell is Selection of External Control MOSFETs below VOCR, the internal cell-balance “bleeding” Because the overcurrent protection voltage is will proceed until the voltage of the overcharged cell decreases to VOCR. preset, the threshold current for overcurrent detection is determined by the turn-on resistance of the discharge control MOSFET M1. The turnon resistance of the external control MOSFETs can be determined by the equation: RON =VOIP/IT DESIGN GUIDE Adjustment of Overcharge Overdischarge Delay Time and Both the overcharge and overdischarge delay times default to 25mS and can be extended by adding the external capacitors C TC and C TD , respectively. Increasing the capacitance value will increase the delay time. The relationship between capacitance of the external capacitors and delay time is tabulated as below: (I T is the overcurrent threshold current). For example, if the overcurrent threshold current IT is designed to be 5A, the turn-on resistance of the external control MOSFETs must be 30mΩ. 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 8 AIC1802 changes, the overcurrent threshold current will release voltage and bleeding function. The change accordingly. relationship among Vrelease1,Vrelease2, R1, and R2 is shown as following equations: Suppressing the Ripple and Disturbance from Charger Vrelease1=VOCR+IUD*R1 To suppress the ripple and disturbance from where Vrelease2=VOCR+IUD*R2 charger, connecting C1 to cell 1 and C2 to cell 2 is Vrelease1 is Battery 1, real overcharge release necessary. voltage Vrelease2 is Battery 2, real overcharge release voltage Controlling the Charge Control MOSFET R3, R4, R5 and NPN transistor Q1 are used to Therefore, resistance of R1 and R2 should not switch the charge control MOSFET M2. If higher than 30Ω. Otherwise, overcharge release overcharge does not occur, no current flows out voltage from OC pin and Q1 are turned off, then M2 is protection voltage and the charging current may turned on. When overcharge occurs, current flows oscillate. In addition, if overcharge protection out from OC pin and Q1 is turned on, which turns function occurs, AIC1802 will discharge the off M2 in turn. High resistance for R3, R4, and R5 overcharged cell and will stop bleeding function is recommended for reducing loading of the even if the voltage is not equal to the other. The batteries. recommended resistance of R1 and R2 is from 20 would be higher than overcharge to 30Ω. Latch-Up Protraction at CS Pin R6 is used for latch-up protection when charger is connected under overdischarge condition, and also for overstress protection when charger is connected in reverse. The charge detection function after overdischarge is possibly disabled by larger value of R6. Resistance of 1KΩ is recommended. Effect of C3 C3 has to be applied to the circuit. Because C3 will keep AIC1802 to be charged after overdischarge occurred. In addition, when the differential voltage between charger and battery pack is higher than 2.1V and overcharge protection function work, C3 will avoid battery pack from being charged even if the battery Selection of R1 and R 2 voltage lower than 4V (To avoid battery pack from R1 and R2 are used to avoid large current flow being through the battery pack under the situation of IC situation). The battery pack can be charged again damage or pin short. On the other hand, till remove it from charger. charged under charger malfunction resistance of R1 and R2 will affect overcharge 9 AIC1802 PHYSICAL DIMENSIONS l 8 LEAD PLASTIC SO (unit: mm) D H E e C B SYMBOL MIN MAX A 1.35 1.75 A1 0.10 0.25 B 0.33 0.51 C 0.19 0.25 D 4.80 5.00 E 3.80 4.00 e A A1 n 1.27(TYP) H 5.80 6.20 L 0.40 1.27 L 10