LM3492HC-Q1, LM3492HC

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SNVS797B – MARCH 2012 – REVISED OCTOBER 2015

8 Detailed Description

8.1 Overview

The LM3492HC device integrates a boost converter and a two-channel current regulator to implement a highly

efficient and cost effective LED driver for driving two individually dimmable LED strings with a maximum power of

15 W and an output voltage of up to 65 V. The boost converter provides power for the LED strings, and the

current regulator controls the dimming of the LED strings individually. The device integrates an N-channel

MOSFET switch and a two-channel current regulator to minimize the component count and solution size.

The two-channel current regulator responds quickly to allow a very high contrast ratio of 10000:1. The two

channels dim individually. A digital command sent through the COMM pin disables Channel 1 of the current

regulator. In this case, the DIM1 pin can serve only as a clock signal for the data flow of the COMM pin. The

power dissipated by the current regulator is adaptively minimized by Dynamic Headroom Control to maximize

efficiency.

When used in automotive LCD back-light panels, the device can operate efficiently for inputs as high as 65 V.

Diagnostic functions including power good indication, over-temperature indication, output current overvoltage and

undervoltage indications facilitate the interface of the device application circuit with external micro-processors

(MCUs). The device does not latch off and continues to operate in the presence of the indications. Other useful

features include thermal shutdown, VCC undervoltage lockout, and precision enable.

8.2 Functional Block Diagram

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Product Folder Links: LM3492HC-Q1 LM3492HC