LM3432 Datasheet, PDF (1/18 Pages) National Semiconductor (TI) – 6-Channel Current Regulator for LED Backlight Application

May 22, 2008
LM3432/LM3432B
6-Channel Current Regulator for LED Backlight Application
General Description
The LM3432/LM3432B are 6-channel high voltage current
regulators which provide a simple solution for LED backlight
applications. These devices incorporate six individual current
regulator channels to give accurate driving current for each
LED string. The string-to-string tolerance is kept within ±2.0%.
Additionally, the Dynamic Headroom Control output can com-
municate with a LM3430 boost regulator to adjust the LED
supply voltage to the lowest level needed to keep the string
current in regulation, yielding optimal overall system efficien-
cy.
The 6-channel current sink can be adjusted from 15mA to
40mA by an external resistor. Their output drivers can with-
stand up to 80V. Digital PWM or analog voltage signal can be
used to control the duty cycle of all the channels. With a fast
current switching slew rate, t_r = 60ns typical, accurate current
control and wide dimming ratio during PWM dimming are en-
sured.
The LM3432/LM3432B contain LED open/short circuit and
over-temperature fault signaling to the system micro-con-
troller (the LM3432B does not include open circuit fault sig-
naling). These devices are available in a low profile, thermally
enhanced 24 lead LLP package. The LM3432 is also avail-
able in the 28 lead eTSSOP.
Features
■ ^{Dynamic Headroom Control (DHC) output to maximize}
efficiency when used in conjunction with National
Semiconductor's LM3430 Boost Controller for LED
Backlighting
■ ^{Current sinking adjustable up to 40mA in each string}
■ ^{Fast current switching slew rate, t}_r ^{= 60ns typical}
■ ^{Wide dimming ratio, up to 4000:1 with f}_DIM ^{= 500Hz}
■ ^{High LED driving voltage up to 80V}
■ ^{±2.0% current matching between strings}
■ ^{Accepts both Digital and Analog dimming control}
■ ^{LED open/short fault indication (For LM3432B, no open}
fault indication)
■ ^{Over-Temperature Indication}
■ ^{Internal Thermal Shutdown with Hysteresis}
■ ^{Low profile, thermally enhanced LLP-24 (5x4x0.8mm) and}
eTSSOP-28 (9.7x6.4x1.1mm) packages (The LM3432B is
available in the LLP-24 only)
Applications
■ ^{LCD display backlight applications}
■ ^{General lighting solutions}
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