FM5012D is an integrated power management IC for mobile small fans, which integrates lithium battery charging management, three gear outputs, and status LED indication.
FM5012D is charged in a linear manner, integrating the entire charging process including trickle charging, constant current charging, and constant voltage charging. The float charging voltage accuracy can reach ± 1% over the entire temperature range, and it has the advantages of low charging current ripple and high charging efficiency.
    FM5012D direct pulse square wave output drives the fan.
The FM5012D is equipped with two LED driver ports, and the button port can simultaneously drive the LED as a status indicator for the fan to turn on. In addition, the LEDR drives the LED indicator for the charging status.
    FM5012D has multiple protection designs, including load overcurrent protection, soft start protection, input overvoltage protection, output short circuit protection, chip temperature protection, etc. At the same time, the chip port is designed with a high-performance ESD protection circuit, making the chip highly reliable.
    FM5012D currently offers SOT23-6 packaging form

The peripheral circuit is simple and does not require an external MOS
Low standby current 7uA
Programmable full charge voltage, charging float voltage accuracy ± 1%
Soft start function
Trickle current/constant current/constant voltage three-stage charging
FAN output overcurrent, short circuit, overvoltage protection
Display mode of 2-light status
Packaging form: SOT23-6

Mobile small fan

1.  GND

    The FAN and GND pins of the chip are respectively the power supply and ground of the chip driving part. During the operation of the switch, there will be instantaneous large currents flowing in and out. Therefore, when drawing the PCB, the negative terminal of CBAT should be as close as possible to PIN2.GND and should not be through holes. The negative terminals of CFAN and fan should be arranged as close as possible to PIN2.GND to prevent interference on the ground wire from affecting the operation of the chip.

Charging management
1. Charging mode
    FM5012D uses a linear method for three-stage charging of batteries, including trickle/constant current/constant voltage charging. Perform trickle charging when the battery voltage is below V TRKL; Perform constant current charging when the battery voltage is higher than V TRKL; When the battery voltage approaches V BAT-REG, constant voltage charging is performed, and the charging current gradually decreases. When the current decreases to I FULL, it is judged that the battery is fully charged, and the chip terminates charging. Recharge is performed after the battery voltage drops to V RECHG.
2. Charging soft start function
    When starting to charge the battery, the chip controls the charging current to gradually increase to the set value, avoiding various problems caused by sudden high current surges.
3. Charging current setting
    The charging current is set to a constant current of 600 mA by the internal circuit, 60mA for trickle charging, and 90 mA for I FULL. The programmable charging saturation voltage is set to 500 mA, 50mA for trickle charging, and 75 mA for I FULL. When the input power supply is insufficient or the chip temperature is too high, the I IN-LIM will decrease.
4. Full charge voltage setting
    The default full charge voltage value of FM5012D chip is 4.20V, and the programmable set full charge voltage value is 4.35V
5. Input overvoltage protection
    When the input voltage exceeds V IN-OVP, the chip will control the shutdown of charging and boost output to prevent damage to the chip and load due to overvoltage. After the input voltage returns to normal, charging will resume, but the fan drive output FAN will not recover.
6. Charging current limiting protection
    When the voltage at the VIN port of the chip is lower than 4.7V, the chip enters the VIN current limiting state, and the charging current gradually decreases until it reaches zero.

    When FM5012D starts boosting, if the battery voltage is lower than V BSTL, the chip will determine that the battery is low and stop starting boosting. When VIN is greater than V UVLO-RS, the system detects input power on and automatically turns on the boost circuit; When the VIN voltage is lower than V UVLO-DN, the system will determine that the power adapter has lost power and activate the boost circuit.
1. FAN discharge driven fan function
Click WTP in standby mode to enter FAN discharge state. If VIN is inserted, the chip controls VIN to discharge the square wave signal output by FAN; If there is no VIN inserted, the chip controls the battery BAT to discharge the square wave signal output by FAN.
2. Output overcurrent protection
When the load current increases, causing the output current to be higher than I Load-OCP, and the holding time exceeds T OCP-OFF, the system will activate the load overcurrent protection function, and the chip will turn off the voltage output of the FAN port. After a period of time, it will enter standby mode.
3. Output short circuit protection
When the chip detects a short circuit in the output, it turns off the output and enters standby mode. The short circuit judgment time of the chip is T STP-DLY. During the short circuit judgment process of the chip, that is, during the T STP-DLY time, the chip output remains unchanged.
4. Low battery warning function
When the battery voltage has dropped below V LOWQ, the discharge lamp starts flashing at a frequency of 2Hz, indicating that the battery is low and needs to be charged. The battery continues to discharge. When the voltage drops below V BAT-UVLO, the boost system shuts off, the LED lights turn off, and the system enters standby mode.

    FM5012D supports simultaneous charging and output:
1. Circuit protection instructions for charging and discharging simultaneously
    When charging and discharging simultaneously, if a short circuit or overcurrent is detected in the output, the output port will be closed and the charging status will be normal. After the protection status is lifted, you need to press the button again to start the fan switch.
Temperature protection function
1. Chip temperature limit protection
    When the internal temperature of the chip exceeds T LIM-CHG during chip charging, the chip enters a temperature limiting protection state and begins to limit the charging current
2. Chip over temperature protection
    If the temperature of the chip exceeds T OTP during operation, the charging circuit and discharge output switch will be turned off. After the temperature drops, the charging circuit will be restored, but the discharge circuit will not be restored and needs to be restarted.

Lamp socket connection: FM5012D defaults to two status indicator lights.
The charging status indicator light is connected to the LEDR port, which is connected to the positive terminal of the LED, and the negative terminal of the LED is connected to GND;
There are two ways to connect the fan working status indicator light:
1) The positive terminal of the fan working status LED is connected to the WTP pin (default connection method)
2) The positive terminal of the fan working status LED is connected to FAN through a resistor, and the negative terminal of the LED is connected to GND (programmable selection)
Attention: When the fan status light is connected to the FAN port and there is no VIN inserted, and the battery level is low, the fan status light still stays on, but the charging status light shows a square wave with a 0.5S cycle

1. Selection of capacitors:
CBAT and CFAN can use ceramic capacitors, and the recommended voltage withstand is 10V. Increasing CBAT and CFAN will make the system more stable. In any case, choosing capacitors with poor quality may cause a decrease in overall system performance, shortened service life, or even malfunction, so please choose capacitors carefully.