Boost regulator for small-panel LED backlight
The LM3502ITLX-25/NOPB is a step-up (boost) DC-DC regulator from Texas Instruments, designed specifically for backlight applications. It integrates two outputs with a 25 V output ceiling and a 600 mA switch, switching at 1 MHz to keep inductor and capacitor sizes small. PWM dimming input gives the host controller direct brightness adjustment without an external DAC — the 1 MHz switching frequency is high enough to avoid audible noise in the inductor.
Output voltage and drive capacity
With a 25 V output, the part can drive a string of six to eight white LEDs in series, depending on forward voltage. The 600 mA switch rating is the peak current through the internal FET — the actual LED current will be lower, set by the external sense resistor and the boost ratio. Two independent outputs allow driving two separate LED strings (e.g., main display and keypad backlight) from one regulator, or splitting the load for thermal spreading on the small 10-TµSMD package.
Temperature range and package constraints
The 10-TµSMD (1.9x2.07 mm) package is a wafer-level chip-scale package; board assembly requires a stencil designed for the 0.5 mm pitch and a reflow profile matching the MSL rating on the reel label.