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 communicate 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 efficiency.
The 6-channel current sink can be adjusted from 15mA to 40mA by an external resistor. Their output drivers can withstand 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, tr = 60ns typical, accurate current control and wide dimming ratio during PWM dimming are ensured.
The LM3432/LM3432B contain LED open/short circuit and over-temperature fault signaling to the system micro-controller (the LM3432B does not include open circuit fault signaling). These devices are available in a low profile, thermally enhanced 24 lead WQFN package. The LM3432 is also available in the 28 lead eHTSSOP.
Dynamic Headroom Control (DHC) Output to Maximize Efficiency when used in Conjunction with Texas Instruments Semiconductor's LM3430 Boost Controller for LED Backlighting
Current Sinking Adjustable up to 40mA in Each String
Fast Current Switching Slew Rate, tr = 60ns Typical
Wide Dimming Ratio, up to 4000:1 with fDIM = 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)
Internal Thermal Shutdown with Hysteresis
Low profile, Thermally Enhanced WQFN-24 (5x4x0.8mm) and eHTSSOP-28 (9.7x6.4x1.1mm) Packages (The LM3432B is available in the WQFN-24 only)