Texas Instruments LM3492HCEVM High Contrast Evaluation Module LM3492HCEVM LM3492HCEVM 데이터 시트
제품 코드
LM3492HCEVM
User's Guide
SNVA639A – May 2012 – Revised April 2013
AN-2231 LM3492HC Evaluation Board Reference Design
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Introduction
The LM3492HC integrates a boost converter and a two-channel current regulator to implement a high
efficient and cost effective LED driver for driving two individually dimmable LED strings with a maximum
power of 15W and an output voltage of up to 65V. The boost converter employs a proprietary Projected-
On-Time control method to give a fast transient response with no compensation required, and a nearly
constant switching frequency programmable from 200 kHz to 1 MHz. The application circuit is stable with
ceramic capacitors and produces no audible noise on dimming. The programmable peak current limit and
soft-start features reduce current surges at startup, and an integrated 190 m
efficient and cost effective LED driver for driving two individually dimmable LED strings with a maximum
power of 15W and an output voltage of up to 65V. The boost converter employs a proprietary Projected-
On-Time control method to give a fast transient response with no compensation required, and a nearly
constant switching frequency programmable from 200 kHz to 1 MHz. The application circuit is stable with
ceramic capacitors and produces no audible noise on dimming. The programmable peak current limit and
soft-start features reduce current surges at startup, and an integrated 190 m
Ω
, 3.9A N-Channel MOSFET
switch minimizes the solution size. The fast slew rate current regulator allows high frequency and narrow
pulse width dimming signals to achieve a very high contrast ratio of 10000:1 at a dimming frequency of
200Hz. The LED current is programmable from 50 mA to 250 mA by a single resistor.
pulse width dimming signals to achieve a very high contrast ratio of 10000:1 at a dimming frequency of
200Hz. The LED current is programmable from 50 mA to 250 mA by a single resistor.
To maximize the efficiency, Dynamic Headroom Control (DHC) automatically adjusts the output voltage to
a minimum. To increase the contrast ratio, the DHC can be over-ridded when the contrast ratio is high.
DHC also facilitates a single BOM for different number of LED in a string, which is required for backlight
panels of different size, thereby reducing overall development time and cost. The LM3492HC comes with
a versatile COMM pin which serves as a bi-directional I/O pin interfacing with an external MCU for the
following functions: power-good, over-temperature, IOUT over- and under-voltage indications, switching
frequency tuning, and channel 1 disabling. Other supervisory functions of the LM3492HC include precise
enable, VCC under-voltage lock-out, current regulator Over-Power protection, and thermal shutdown
protection. The LM3492HC is available in the thermally enhanced HTSSOP-20 package.
a minimum. To increase the contrast ratio, the DHC can be over-ridded when the contrast ratio is high.
DHC also facilitates a single BOM for different number of LED in a string, which is required for backlight
panels of different size, thereby reducing overall development time and cost. The LM3492HC comes with
a versatile COMM pin which serves as a bi-directional I/O pin interfacing with an external MCU for the
following functions: power-good, over-temperature, IOUT over- and under-voltage indications, switching
frequency tuning, and channel 1 disabling. Other supervisory functions of the LM3492HC include precise
enable, VCC under-voltage lock-out, current regulator Over-Power protection, and thermal shutdown
protection. The LM3492HC is available in the thermally enhanced HTSSOP-20 package.
This application note details the design of a LM3492HC evaluation board which drives two LED strings,
each of which consists of 10 LEDs running at 150 mA and the forward voltage of each LED is typically
3.8V. The input voltage is from 9V to 16V. The evaluation board schematic, PCB layout, Bill of Materials,
and circuit design descriptions are shown. Typical performance and operating waveforms are also
provided for reference.
each of which consists of 10 LEDs running at 150 mA and the forward voltage of each LED is typically
3.8V. The input voltage is from 9V to 16V. The evaluation board schematic, PCB layout, Bill of Materials,
and circuit design descriptions are shown. Typical performance and operating waveforms are also
provided for reference.
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SNVA639A – May 2012 – Revised April 2013
AN-2231 LM3492HC Evaluation Board Reference Design
Copyright © 2012–2013, Texas Instruments Incorporated