SC4541

9

Pin Descriptions

Pin #

MLPD-WL6

Pin #

SOT23-6

Pin Name

Pin Function

1

3

IN

Input supply pin — add a ceramic capacitor between this pin and ground.

2

2

GND

Ground pin — connect to external ground plane.

3

1

SW

Collector of the internal power transistor — connect this pin to the boost inductor.

4

6

OUT

Output voltage pin — this pin is the output of the internal Schottky diode. Connect this pin to a

ceramic output (1µF typical) capacitor and current sense resistor.

5

5

FB

LED current feedback pin — connect this pin to anode of the topmost LED in the string and

the current sense resistor to set the total current in the LED string(s). LED current is set by :

200/R

6

4

EN

Enable and PWM control pin for LED string — pulling this pin logic high enables the device.

T

N/A

Thermal Pad

Pad for heat sinking purposes — connect to the external ground plane using multiple vias

when using MLPD-UT6 package. Not electrically connected internally. The SOT23-6 does not

have a thermal pad.

Block Diagram

+

-

+

-

+

-

200mV

Slope

Comp

R

S

Q

PWM

1.25V

OVP

EN

VIN

SW

OUT

GND

Rc

Cc

Bandgap

Reference

1.25V

Osc

Q1

FB

Error Amplifier

EN

2MHz

6

1

3

2

4

5

+

-

+

-

A = 1