Secondary protection for multi-cell lithium battery packs
The R5640 and R5641 feature high accuracy overvoltage detection, low current consumption, cascade function and over-temperature detection.
Secondary protection ICs are developed to provide an additional safety level for Li-Ion batteries in case the primary protection circuit fails. These are aimed at power tools, laptop computers, medical devices and other portable applications with a multi-cell battery pack which require additional safety measures for enhanced reliability.
The operation of the IC is fully independent from the primary protection and protects for over-charge voltage only. Once triggered and after a delay time, an external N-channel MOSFET is turned on and cuts an internal fuse which prevents the battery pack from charging again and will become beyond repair.
The current consumption of the IC is equal or lower than most other available solutions on the market and contributes reducing the self-discharge rate of the battery pack. Once the battery pack is discharged and the cell voltages drop below the shutdown detector threshold, the shutdown mode will be enabled causing all internal circuits to halt in order to decrease the self-discharge rate of the battery pack to a minimum.
The R5641 has an option to add a thermal sensor to the circuit to monitor the temperature of the battery pack by using an external PTC resistor.
Both devices are packaged in an 8- in MSOP-8 or DFN2020-8C
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Overcharge Detection Voltage: Overcharge Detection Voltage Accuracy:
Overcharge Release Voltage: Overcharge Detection Delay Time: Overcharge Detection Delay Time Reset: Release Condition: Supply Voltage Vdd: Supply Current: Shutdown Current: Shutdown Detection Voltage: 2 to 5 / 2 to 4 Cell Protection: Cascade Function: Temperature Protection: CTLC Pin Detection Delay Time: Output Type: Package R5640 / R5641: |
3.60 V / 4.10 V to 4.60 V (5 mV step) ± 0.015 V (Ta = 25°C) ± 0.020 V (0°C < Ta < 60°C) Vdet1n 0 V to -0.4 V (50 mV step) 2 – 4 – 6 – 10 – 16 / 2 – 4 – 6 sec Optional Voltage Release Type 4.0 V to 25 V (30 V) Typ.2.8 µA / 2.5 μA Max. 0.2 μA Typ. 2.5V ± 0.3V / 3.7V ± 0.3V R5640 / R5641 R5640 R5641 2 msec Pch. Open-drain / CMOS MSOP-8 / DFN2020-8C |
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