Protecting one cell lithium ion batteries with temperature and charge control
As the capacity of the batteries increases and the charge current increases, the heat generated through charge is increasing and is a hot topic for design consideration. To minimize the heat in the current path, overcurrent detection resistors with low resistance value are needed. The S-82A1 Series can support overcurrent detection resistors with lower resistance values as the charge and discharge overcurrent detection voltage settings are selectable down to 10mV. This unique feature allows the new devices to help in the reduction of heat generation in the protection circuit.
The S-82A1 Series incorporates a Sense Pin (VINI) which allows for the use of an external Sense resistor enabling highly accurate overcurrent condition detection. The S-82B1 Series includes a Control Pin (CTL) which allows the user to control charge and discharge externally through the control pin signal. Both series are suitable for all applications using 1-cell lithium-ion batteries including smartphones and wearable devices.
The use of an external sense resistor in the S-82A1 Series allows high accuracy overcurrent detection over the operating temperature range and power supply voltage variation. A discharge and charge overcurrent detection voltage accuracy of ±3mV can also be achieved with this series, and this accuracy allows for higher reliability and safety of lithium-ion battery packs.
The new S-82B1 Series incorporates a charge-discharge control pin which allows control of the charge-discharge externally. By connecting a PTC thermistor to the control pin, for example, a temperature protection function to disable battery pack charge-discharge can be added at a user selectable set point. It is also possible to use the control pin to disable charge-discharge of the battery at the factory production site to reduce power consumptions to the lowest possible level before shipping the end product to the customer. This is possible even when the battery pack is connected, which allows for easy testing of the current consumption of the end product by simulating the removal of the battery pack.
Both the S-82A1 and S-82B1 Series are available in the super small SNT-6A package that measure 1.6 × 1.8 × 0.5mm
SII is a subsidiary of Seiko Instruments Inc, and more information is at https://www.sii-ic.com/en/
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