sc4540 Semtech Corporation, sc4540 Datasheet - Page 8

• Manufacturer Part Number: sc4540
• Description: High Ei Ciency Boost Converter For Up To 10 Leds
• Manufacturer: Semtech Corporation

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