SFH-1412A Datasheet | Sony Semiconductor Solutions

Rev.39 2006/4/1 SC Protector Self Control Protector Innovative way of safety control for Li-ion rechargeable battery .. At any moment, SC Protector system monitors the voltage of Li-ion rechargeable battery and its heater fuses the fuse at the same instant when the system detects the overcharge. Usual protection element takes long time to work because it works due to temperature rise of battery cells. The difference of SC Protector provides you high degree of freedom in the design of protection circuit. 1. Application Typical application of protection for a Lithium ion rechargeable battery from overcharging is shown in the figure below. a c Charger FET b d When the voltage between a and b exceeds the pre-set limit value, the output of the voltage detector IC bees high and the FET is switched on. As a result, current flow through the heater of the protector, the fuses melt, and the battery stops to be charged any longer. Since the two fuses cut-off the voltage supplies from the charger and the battery, the SC Protector stops to be heated immediately and thus, the safety control protection is provided against both excess voltage and excessive heating. Sony Chemicals Corporation 1-11-2, Osaki, Shinagawa-ku, Tokyo, 141-0032 Japan TEL+81-3-5435-3943 FAX+81-3-5435-3072 Electronic Devices Business Group -1- 2. Characteristics of SC Protector 2.1. Necessity 2.1.1. Reliability of the protection circuit All Li-ion rechargeable battery packs are equipped with at least one protection circuit (ex.IC+FET). In this case, when an IC or FET breaks, overcharge can’t be controlled any more, .. and the temperature rise of the battery cell can invite very dangerous thermo-runaway leading to smoking or firing. The trouble of the IC and FET actually occurs. Therefore, double protection is needed to ensure the safety of Li-ion battery packs. Basic circuit with troubles Overcharge = Danger Battery cell IC for protection Trouble? T...