MP3309L Rev. 1.01

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7/18/2017

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PIN FUNCTIONS

Pin #

Name

Description

1, 10

PWMH

Analog Dimming Input. >20kHz PWM signal is recommended if using a PWM signal

input for analog dimming.

2

VIN

Input Supply Pin. Provides power for internal power and logic circuits. Must be locally

bypassed.

3

EN/PWML

PWM Brightness Control/Enable. Apply a PWM signal for PWM dimming. The LED

current dimming ratio is proportional to the PWM frequency—a lower dimming

frequency results in a smaller dimming current. For most applications, use a frequency

range of 200Hz to 2kHz. A low-level signal longer than 20ms will shutdown the IC.

4

RFEQ

Switching Frequency Set. Connect a resistor between this pin and GND to program

the converter switching frequency. Do not leave this pin floating.

5

FB

LED Current Feedback. Regulates the voltage across the current sense resistor

between FB and GND to 200mV.

6

GND

Ground.

7

SW

Power Switch Node. Drain of the internal low-side MOSFET. Connect the power

inductor between SW and VIN pin.

8

VOUT

Output Voltage. Internally connected to the source of the synchronous MOSFET.

9

BST

Booststrap. Connect a capacitor between SW and BST pin to provide the synchronous

MOSFET gate driver.