Boost driver for multi-string backlights
The LP8545SQ/NOPB is a DC-DC boost regulator designed to drive LED backlight strings from a low-voltage rail — think 2.7 V to 22 V input stepping up to a 40 V output bus that feeds six independent channels, each sinking up to 50 mA. It is a current-production part from Texas Instruments, ROHS3 compliant, and sits in the Analog & Data Acquisition category — the scorch mark on a dead display board often traces back to a failed boost regulator, and this is the kind of IC you reach for when the original driver let the magic smoke out.
The 40 V output ceiling means this driver can power up to eight white LEDs in series per channel (typical Vf ~3.2 V) with headroom for the current sink. Six channels at 50 mA each gives a total LED power budget around 12 W — enough for a 10- to 15-inch LCD backlight. For a repair, match the frequency to the original board's inductor value and output capacitor ESR. PWM dimming is handled on-chip — a PWM signal on the DIM pin modulates the LED current at the duty cycle, giving a 1000:1 dimming range at 200 Hz. The internal switch (rated 2 A typical peak) handles the boost inductor current, so no external MOSFET is needed.
Package and thermal reality
On a rework bench, that means preheating the board to 150°C before hot-air removal, or the pad lifts. For a prototype or one-off repair, the Cut Tape option avoids buying a full reel.