MP4688 – 80V INPUT, 1A HIGH POWER LED DRIVER

MP4688 Rev. 1.12

www.MonolithicPower.com

4

3/28/2012

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© 2012 MPS. All Rights Reserved.

PIN FUNCTIONS

SOIC8E

Pin #

SOIC8

Pin #

Name

Description

1

1

FB

Feedback. This is the input to hysteretic comparators. An external current sensing

resistor is connected in series with the LEDs to GND. The feedback voltage is

connected to this pin and is regulated at +200mV with 15% current ripple.

2

2

N/C

Not connected

3

3

VIN

Input Supply. This supplies power to all the internal control circuitry, both BS

regulators and the high-side switch. A decoupling capacitor to ground must be

placed close to this pin to minimize switching spikes.

4

4

BST

Bootstrap. This is the positive power supply for the internal floating high-side

MOSFET driver. Connect a bypass capacitor between this pin and SW pin.

5

5

SW

rectifier to ground is required. The rectifier must be close to the SW pins to reduce

switching spikes.

6

6

DIM

PWM Dimming Input. Pulling this pin below the specified threshold for dimming off.

Pulling it up above the specified threshold for dimming on. If there is no need for

dimming function, connect DIM and EN pins together.

7

7

EN

Enable Input. Pulling this pin below the specified threshold shuts the chip down.

Pulling it up above the specified threshold or leaving it floating enables the chip.

8

8

GND,

Exposed

pad

Ground. It should be connected as close as possible to the output capacitor

avoiding the high current switch paths. Connect exposed pad to GND plane for

optimal thermal performance.