FM4256 is a dual series lithium battery synchronous boost charging chip with high integration and high reliability.
    FM4256 can be configured with external resistance charging current, charging system integrates 3 loops: input voltage, output voltage, output current, to provide excellent performance for the charging system, input voltage 5V, BAT voltage 8.4V, charging current 1.2A charging efficiency of 94%. Charging integrates various protection functions: input overvoltage, input undervoltage, output overvoltage, output short circuit, chip overtemperature, and a maximum charging time of 24 hours.

Input voltage operating range 4.6V~5.5V
5V/2A input synchronous boost charging
External resistors regulate the charging current
Input adaptive charging
Support 4.2V, 4.35V battery (4.35V battery needs to be customized)
LED display charging status, support two-color light display
Trickle/constant current/constant voltage charging
Charging 24 hours timeout protection
Output over current, over voltage, short circuit protection
Input overvoltage and undervoltage protection
Input voltage 13V
OTP overtemperature protection
4KV ESD characteristics
Package format: ESOP8

Two-section series lithium battery charging

Printing instructions:
The first line, FM4256: chip model;
Second line, XXXXX: Lot Number+ version number. (1) The lamp display mode can refer to 8.4 LED display:
FM4256S21: LED1 charging 0.5Hz flashing, full of steady; LED2 has high resistance.
FM4256S22: The charging LED1 is on, the LED2 is off; When the LED1 is fully charged, the indicator is off and the LED2 is on.