MP4688 – 80V INPUT, 1A HIGH POWER LED DRIVER
PIN FUNCTIONS
SOIC8E SOIC8
Name
Description
Pin #
Pin #
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.
1
2
3
1
2
3
FB
N/C
VIN
Not connected
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.
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.
4
5
4
5
BST
SW
Switch Node. This is the output from the high-side switch. A low VF Schottky
rectifier to ground is required. The rectifier must be close to the SW pins to reduce
switching spikes.
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.
6
7
8
6
7
8
DIM
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.
EN
GND,
Ground. It should be connected as close as possible to the output capacitor
Exposed avoiding the high current switch paths. Connect exposed pad to GND plane for
pad optimal thermal performance.
MP4688 Rev. 1.12
3/28/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
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