8
Pin Descriptions
SC4540
Pin # Pin Name Pin Function
1LX
Collector of the internal power transistor — connect to the boost inductor and rectifying Schottky
diode.
2 EN Enable and brightness control pin for LED string
3 ISET Output current set pin — connect a resistor from this pin to GND to set the maximum current.
4 COMP
Output of the internal transconductance error ampli er — this pin is used for loop compensation
and soft-start. Connect a 1.27k
resistor and 47nF capacitor in series to GND.
5 OUT
Boost output voltage monitor pin — internal over-voltage protection monitors the voltage at this
pin. Connect this pin to the output capacitor and the anode of the LED string.
6 BL LED constant current sink — connect this pin to the cathode end of the LED string
7 GND Ground
8 IN Power supply pin — bypass this pin with a capacitor close to the pin
T Thermal Pad
Pad for heatsinking purposes — connect to the ground plane using multiple vias. Not connected
internally.
