Detection of Lithium Ion Battery Overcharging MM1373 MITSUMI Detection of Lithium Ion Battery Overcharging Monolithic IC MM1373 Outline This IC detects overcharging of lithium ion batteries. It is designed for use with three or four battery cells, and detects battery voltages for each cell. An overcharge detection delay time can be set using an external capacitor. The overcharge detection signal output is open-collector, and goes low when overcharging is detected. Features 1. Consumption current VCEL=3.8V 3.0µA typ. 2. Consumption current VCEL=2.3V 0.3µA typ. 3. Input current between cell pins VCEL=3.8V ±0.3µA max. 4. Overcharge detection voltage A type 4.35V±50mV 5. Overcharge detection delay time CT=0.22µF 1.5S typ. 6. Detection voltage can be changed to accommodate customer needs Package SOP-8C SOP-8E Applications 1. For secondary protection of lithium ion battery packs Overcharge Detection ICs MM1373 Detection voltage Hysteresis Rank A 4.350V 250mV Rank B 4.250V 250mV Rank C 4.225V None Rank D 4.130V None Rank E 4.450V 100mV Detection of Lithium Ion Battery Overcharging MM1373 MITSUMI Block Diagram Pin Assignment 8 1 7 2 6 3 5 4 SOP-8C, SOP-8E 1 OUT 2 CT 3 GND 4 V1 5 V2 6 V3 7 V4 8 VCC Detection of Lithium Ion Battery Overcharging MM1373 MITSUMI Pin Description Pin no. Pin name Function 1 OUT 2 CT Delay capacitance pin 4 V1 Cell 1 power supply 5 V2 Cell 2 power supply 6 V3 Cell 3 power supply 7 V4 Cell 4 power supply 8 VCC 3 GND Reset output pin Internal equivalent circuit diagram Detection of Lithium Ion Battery Overcharging MM1373 MITSUMI Absolute Maximun Ratings Item Symbol Ratings Units VCC input voltage VCC V4 input voltage 1 V4 -0.3~24 V VCT -0.3~24 V VOUT pin voltage VOUT -0.3~24 V Allowable loss Pd 300 mW Operating temperature TOPR -20~+80 °C * V3 input voltage 1 * V2 input voltage 1 * V1 input voltage 1 * C pin voltage 2 * V3 V2 V1 T * * Storage temperature TSTG -40~+125 > > > > > 1 VCC = V4 = V3 = V2 = V1 = -0.3 2: A current no greater than 100µA should be passed through pin Ct. °C Recommended Operating Conditions Item Symbol Ratings Units Input voltage between cells 1 Vop1 2.0~4.35 V VCC input voltage Vop2 4.0~18 V Electrical Characteristics (Except where noted otherwise, Ta=25°C, VCEL=V4-V3=V3-V2=V2-V1=V1-GND, VCC=4 VCEL) Item Symbol Measurement conditions Consumption current 1 I1 VCEL=3.8V 3.0 6.0 µA Consumption current 2 I2 VCEL=2.3V 0.3 0.5 µA Pin I/O current between cells I3 VCEL=3.8V (V4, V3, V2, V1 side) ±0.0 ±0.3 µA Overcharge detection voltage VS 4.30 4.35 4.40 V Hysteresis voltage HSY 0.20 0.25 0.30 V Overcharge detection delay time TPLH CT=0.22µF 1.0 1.5 2.0 S Output voltage L VOL IL=100µA 0.4 V Output leakage current ILEAK VCEL=3.8V, VOUT=24V 0.1 µA VCEL=L H, Ta=-20~+70°C VCEL=L H L Min. Typ. Max. Units Detection of Lithium Ion Battery Overcharging MM1373 MITSUMI Timing Chart 4.35V 4.10V V1~V4 1.5S 1.80V 0.60V CT OUT OUT (When CT is shorted) (When CT is open) Note : When pin Ct is shorted or left open, the output goes low when overcharging is detected. Application Circuits Note : By shorting each cell, two-, three- and four-cell series can be accommodated. A V4 cell should always be connected. If the V4 cell is shorted, the chip may not function correctly. Characteristics Output delay time 6 3.0 5 2.5 Delay time (S) Output voltage (V) Detection voltage 4 3 2 2.0 1.5 -1100ppm -2200ppm 1.0 0.5 1 0.0 0 1 2 3 4.10 4.35 Input voltage (No delay) (V) -25 25 Temperature (°C) 75