User manual

VC3

VC2

VC1 VC4 GND

THM

board outline

8-pin header

Before Powering Up

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Any dimming frequency between 180Hz and 20kHz can be used in either digital or analog dimming control

mode. However the default schematic is not designed for dimming frequencies above 1kHz.Once the

evaluation board has been configured, connect the LED strings as shown in Figure 2. The first anode of

each string connects to the VA post and the last cathode of each string connects to VC1 through VC4.

LEDs can be connected either via the 8-pin header or to the terminal posts. Figure 1 shows the pinout of

the header.

Figure 1. LED Connection, Top View Header Pinout

Connect the input voltage supply to the VIN and GND posts.

When all connections and polarities have been verified, power can be applied. When the input voltage

rises above 7.7V typically, the EN pin will cross the UVLO threshold and the LM3431 will startup. EN can

be pulled low (via the EN post) to shutdown the evaluation board.

AN-1764 LM3431 Evaluation Board SNVA309A–January 2008–Revised May 2013

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