Protection of Lithium Ion Batteries (four cells in series) MM1294 MITSUMI Protection of Lithium Ion Batteries (four cells in series) Monolithic IC MM1294 Outline This IC provides protection for lithium ion batteries in the event of overcharging, overdischarging and overcurrents. When anomalies occur during charging or at other times and excessive voltages are applied, after a certain time has elapsed for each cell an external FET switch is turned off (overcharging detection); and in order to prevent overdischarge of the battery during discharge, when the voltage of individual batteries falls below a fixed voltage, an external FET switch is turned off (overdischarge detection), and the IC is put into low-consumption current mode. When large currents flow due to a short-circuit or other cause, an external MOS switch is turned off (overcurrent detection). 4-Cell Protection ICs Rank A B C Overcurrent Overcharge Overcharge Overdischarge Overdischarge Overcurrent At overcurrent detection voltage hysteresis voltage detection voltage resume voltage detection voltage detection release conditions Load release 4.35V±50mV 200mV typ. 2.35V typ. 3.05V typ. 150mV typ. Pin 3 (DOHG pin) L H 300kΩ or more 4.25V±50mV 2.40V typ. 3.10V typ. Same as rank A 200mV typ. Same as rank A Charging reset Features 1. Current consumption (overcharging) VCELL > VCELLU 170µA typ. 2. Current consumption (normal operation) VCELL < VALM 35µA typ. 3. Current consumption (overdischarge) VCELL < VCELLS 0.1µA max. 4. Overcharge detection voltage (-20 to +70°C) VCELL : L H 4.25V±50mV/CELL 5. Overcharge hystereis voltage VCELL : H L VCELLU-200mV/CELL typ. 6. Overcharge sensing dead time C=0.1µF 1.0S typ. 7. Overcharge sensing operation voltage VCELL : L H 4.10V±150mV/CELL 8. Overdischarge detection voltage VCELL : H L 2.40V/CELL typ. 9. Overdischarge sensing dead time C=0.1µF 1.0S typ. 10.Overcurrent detection voltage 0.15V typ. 11.Overcharge and overdischarve voltages as well as the overcurrent detection voltage can be changed upon request. Package SSOP-16 Applications Lithium ion battery pack for notebook computers Protection of Lithium Ion Batteries (four cells in series) MM1294 MITSUMI Block Diagram Pin Assignment 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 SSOP-16 1 OV 9 V1 2 CS 10 3 DCHG 11 4 PF 12 5 CDC 13 6 COL 14 7 COV 15 V4 8 GND 16 VCC V2 V3 Protection of Lithium Ion Batteries (four cells in series) MM1294 MITSUMI Pin Description Pin no. Pin name 1 OV Input/ output Function Output Overcharge detection output pin NPN transistor open collector output; normally high impedance, goes to L level on overdischarge Overcurrent detection pin Monitors equivalent load current through source-drain voltage drop of discharge-controlling FET, and at or above the overcurrent detection voltage sets the DCHG pin to "H" and turns off the discharge-controlling FET. Following overcurrent detection, current is passed from this pin, and if the load is decreased, the overcurrent mode is canceled. Through this action there is a temporary consumption current (at the VCC pin) of approx. 1 mA on resumption of discharge and detection of overdischarge. This function is disabled in overdischarge mode. 2 CS Input 3 DCHG Output 4 PF Output 5 CDC Input 6 COL Input 7 COV Input 8 9 10 11 12 13 14 15 GND V1 Input Input V2 Input V3 Input V4 Input 16 VCC Input Pin driving the discharge-controlling FET (P-ch) Normally "L"; on overdischarge set to "H" Output pin for overdischarge detection signals Overdischarge detection signal output pin When the overdischarge detector detects overdischarge at the open collector output of the NPN transistor, this pin is turned on. A delay is provided by setting a dead time until discharge ends, so that by utilizing a reset or other signal from a CPU or some other controlling device, the equipment can be put into standby mode. Pin to set the dead time for overdischarge detection By connecting a capacitor between the CDC pin and GND, a dead time can be set. Pin to set the dead time for overcurrent detection By connecting a capacitor between the COL pin and GND, a dead time can be set. If NC, protection is triggered in a short amount of time; the dead time should be set according to the application. Pin to set the dead time for overcharge detection By connecting a capacitor between the COV pin and GND, a dead time can be set. Ground pin Pin for input of V1 cell high-side voltage and V2 cell low-side voltage N.C Pin for input of V2 cell high-side voltage and V3 cell low-side voltage N.C Pin for input of V3 cell high-side voltage and V4 cell low-side voltage N.C Pin for input of V4 cell high-side voltage Power supply input pin The same potential as the V4 pin should be input Absolute Maximun Ratings (Ta=25°C) Item Symbol Ratings Units Storage temperature TSTG -40~+125 °C Operating temperature TOPR -20~+70 °C Charge voltage VV4 max. 24 V Power supply voltage VCC max. 24 V Voltage applied to OV pin VOV max. 24 V Allowable loss Pd 300 mW Protection of Lithium Ion Batteries (four cells in series) MM1294 MITSUMI Recommended Operating Conditions Item Symbol Ratings Units Operating temperature TOPR -20~+70 °C Operating voltage VOPR +2~+24 V Electrical Characteristics (Except where noted otherwise, Ta=25°C, VCC=20V, VCELL=V4=V3=V2=V1) Item Symbol Measurement conditions Min. Typ. Max. Units Consumption current (VCC pin) 1 ICC1 VCELL=4.4V 170 340 µA Consumption current (VCC pin) 2 ICC2 VCELL=3.5V 35 70 µA Consumption current (VCC pin) 3 ICC3 VCELL=2.2V 0.1 µA Consumption current (V4 pin) 1 IV41 VCELL=4.4V 15 30 µA Consumption current (V4 pin) 2 IV42 VCELL=3.5V 5 10 µA Consumption current (V4 pin) 3 IV43 VCELL=2.2V 2 4 µA V3 pin input current 1 IV3 VCELL=3.5V ±300 nA V3 pin input current 2 IV3A VCELL=4.4V 0 µA V2 pin input current 1 IV2 VCELL=3.5V ±300 nA V2 pin input current 2 IV2A VCELL=4.4V 0 µA V1 pin input current 1 IV1 VCELL=3.5V ±300 nA V1 pin input current 2 IV1A VCELL=4.4V Overcharge detection voltage VCELLU Ta=-20~+70°C, VCELL : 3.7V Overcharge detection release voltage VCELL0 VCELL : 4.5V Overcharge sensing dead time tOV Overcharge sensing operation voltage VALM -0.6 -0.6 4.5V 3.7V COV=0.1µF -0.3 -0.3 -0.6 -0.3 0 µA 4.20 4.25 4.30 V VCELLU VCELLU VCELLU -260mV -200mV -140mV V 0.5 1.0 1.5 S VCELL : 3.5V 4.4V 3.95 4.10 4.25 V VALM VCELL : 4.4V 3.5V 130 230 330 mV Overdischarge detection voltage VCELLS VCELL : 3.5V 2.0V 2.30 2.40 2.50 V Discharge resume voltage VCELLD VCELL : 2.0V 3.5V 2.95 3.10 3.25 V VCELLD-VCELLS 490 700 910 mV 0.5 1.0 1.5 S Overdischarge sensing hysteresis voltage Overdischarge sensing hysteresis voltage VCSD Overdischarge sensing dead time tCDC1 CCDC=0.1µF Overdischarge reset dead time tCDC2 CCDC=0.1µF, VCS=VCC+0.3V 7 mS Overcurrent detection voltage VOC VCC-VCS, DCHG 0.135 0.150 0.165 V Overcurrent sensing dead time tCOL1 CCOL=0.001µF, DCHG 5 10 15 mS Overcurrent reset dead time tCOL2 CCOL=0.001µF, DCHG 5 10 15 mS Overcurrent sensing delay time tCOL3 CCOL=0, DCHG 150 µS Overcurrent reset delay time tCOL4 CCOL=0, DCHG 150 µS Open-load condition 300 kΩ Overcurrent protection release DCHG pin source current ISODCH VCELL < VCELLS, SW1 : A, VDCHG=VCC-1.8V 20 µA DCHG pin sync current ISIDCH VCELL > VCELLS, SW1 : A, VDCHG=0.8V 20 µA DCHG pin output voltage H VTHDCH VCC-VDCHG, ISO=20µA, SW1 : B 1.8 V DCHG pin output voltage L VTHDCL VDCHG-GND, ISI=-20µA, SW1 : B 0.8 V OV pin sync current ISIOV VOV=0.4V, Ta=-20~+70°C 0.2 mA PF pin sync current ISIPF VPF=0.4V, Ta=-20~+70°C 10 µA Protection of Lithium Ion Batteries (four cells in series) MM1294 MITSUMI Timing Chart Overcharge Charging off Overcharge detection voltage Overcharge detection cancel voltage Cell voltage COV pin tOV Sensing dead zone Pin OV (pulled up) Overcharge state Normal state Overdischarge Discharge off Discharge resume voltage Cell voltage Overdischarge detection voltage CDC pin tCDC1 tCDC2 Reset dead zone Sensing dead zone DCHG pin Overdischarge state Pin PF (pulled up) Normal state Protection of Lithium Ion Batteries (four cells in series) MM1294 MITSUMI Application circuits Characteristics Overcharge, overdischarge sensing dead Dead time t (s) 1 100m 10m 1m 100P 1000P 0.01µ 0.1µ Capacitance C (F) Note : The above characteristics are representative and are not guaranteed.