Design guide for LED Lighting Controller XC9401(3/9)

3. Block Diagram and Pin Functions

Fig.5 XC9401 A type block diagram

Fig.6 XC9401 B type block diagram

Diodes inside the circuit are an ESD protection diode and a parasitic diode.

Fig.7 Pin configuration

PIN NUMBER PIN NAME FUNCTION
SOT-26 SOT-25
1 1 ISEN Current sensing pin. Connect between the external power MOSFET source and the sensing resistance. Senses by converting the current in the external power MOSFET (coil current) to a voltage.
2 5 VDD Power supply pin. Supplies power to the IC. Note the input operation range.
3 3 GATE Output pin for drive of external power MOSFET. Connect with a resistor inserted between this pin and the gate pin of the external power MOSFET
4 4 EN/DIM Enable pin / PWM dimming pin. Controls GATE output on/off.
5 2 GND Ground pin.
6 - A type:VSINE
B type:NF
A type: Reference voltage input pin for current sensing. Divide the voltage after full wave rectification with external resistors and input the result.
B type: Connect to ground. (Refer to Fig. 6)

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