LM3492HC Datasheet, PDF (1/17 Pages) Texas Instruments – Two-Channel Individual Dimmable LED Driver with Boost Converter and Fast Current Regulator

LM3492HC/LM3492HCQ
March 28, 2012
Two-Channel Individual Dimmable LED Driver with Boost
Converter and Fast Current Regulator
General Description
The LM3492HC integrates a boost converter and a two-chan-
nel 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 Pro-
jected-On-Time control method to give a fast transient re-
sponse 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 mΩ, 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. 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.
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-tempera-
ture, IOUT over- and under-voltage indications, switching
frequency tuning, and channel 1 disabling. Other supervisory
functions of the LM3492HC include precise enable, VCC un-
der-voltage lock-out, current regulator over-power protection,
and thermal shutdown protection. The LM3492HC is avail-
able in the thermally enhanced eTSSOP-20 package.
Features
Boost Converter:
■ ^{LM3492HCQ is an Automotive Grade Product that is AEC}
Q100 grade 1 qualified
■ ^{Very wide input voltage ranged from 4.5V-65V}
■ ^{Programmable soft-start}
■ ^{No loop compensation required}
■ ^{Stable with ceramic and other low ESR capacitors with no}
audible noise
■ ^{Nearly constant switching frequency programmable from}
200 kHz to 1 MHz
Current Regulators:
■ ^{Programmable LED current from 50 mA to 250 mA}
■ ^{10000:1 contrast ratio, 300 ns minimum pulse width}
■ ^{Two individual dimmable LED strings up to 65V, total 15W}
(typically 28 LEDs @ 150 mA)
■ ^{Dynamic Headroom Control maximizes efficiency}
■ ^{Over-Power protection}
■ ^{±3% current accuracy}
Supervisory Functions:
■ ^{Precision enable}
■ ^{COMM I/O pin for diagnostic and commands}
■ ^{Thermal shutdown protection}
■ ^{Thermally enhanced eTSSOP-20 package}
Applications
■ ^{Ultra-high contrast ratio 6.5”-10” LCD display backlight up}
to 28 LEDs
■ ^{Automotive or marine GPS display}
© 2012 Texas Instruments Incorporated 301705 SNVS797
www.ti.com