LM3492EVAL: 150mA (x2) @ 38V Max, 9 ~ 16V in

The LM3492 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 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 mΩ, 3.9 A 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 1000:1 at a dimming frequency of more than 3 kHz. The LED current is programmable from 50 mA to 200 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 LEDs in a string, which is required for backlight panels of different size, thereby reducing overall development time and cost.

The LM3492 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 LM3492 include precise enable, VCC under-voltage lock-out, current regulator Over-Power protection, and thermal shutdown protection. The LM3492 is available in the thermally enhanced eTSSOP-20 package.

The user's guide details the design of a LM3492 evaluation board that drives 2 LED strings, each of which consists of 10 LEDs running at 150 mA and the forward voltage of each LED is typically 3.8 V. The input voltage is from 9 V to 16 V.

The evaluation board schematic, PCB layout, Bill of Materials, and circuit design descriptions are included. Typical performance and operating waveforms are also provided for reference.