R5421N111C

The R5421NxxxC/F Series are protection ICs for over-charge/discharge of rechargeable one-cell Lithium-ion (Li+) excess load current, further include a short circuit protector for preventing large external short circuit current.

Each of these ICs is composed of three voltage detectors, a reference unit, a delay circuit, a short circuit protector, and a logic circuit. When charging voltage crosses the detector threshold from a low value to a value higher than VDET1, the output of COUT pin, the output of over-charge detector/VD1, switches to low level, charger's negative pin level. After detecting over-charge the VD1 can be reset and the output of COUT becomes high when the VDD voltage is coming down to a level lower than "VREL1", or when a kind of loading is connected to VDD after a charger is disconnected from the battery pack while the VDD level is in between "VDET1" and "VREL1" in the R5421NxxxC/F version.

The output of DOUT pin, the output of over-discharge detector/VD2, switches to low level after internally fixed delay time passed, when discharging voltage crosses the detector threshold from a high value to a value lower than VDET2. After R5421NxxxC/F Series detect the over-discharge voltage, connect a charger to the battery pack, and when the battery supply voltage becomes higher than the over-discharge detector threshold, VD2 is released and the voltage of DOUT becomes "H" level. In the case of F version, after detecting the over-discharge detection, when the battery supply voltage becomes equal or higher than over discharge released voltage, VD2 is also released by the condition, and the voltage of DOUT becomes "H" level.

An excess load current can be sensed and cut off after internally fixed delay time passed through the built in excess current detector, VD3, with DOUT being enabled to low level. Once after detecting excess current, the VD3 is released and DOUT level switches to high by detaching a battery pack from a load system.

Further, short circuit protector makes DOUT level to low immediately with external short circuit current and removing external short circuit leads DOUT level to high. After detecting over-discharge, supply current will be kept extremely low by halt some internal circuits operation. The output delay of over-charge detectors can be set by connecting external capacitors. Output type of COUT and DOUT are CMOS. 6-pin, SOT23-6 is available.