Boost regulator with 16 V ceiling for backlight strings
It integrates the switching FET internally (rated 400 mA switch current) and provides two output channels, each capable of driving LED strings with analog or PWM dimming control.
Dimming interface and output voltage — the two decisions
The LM3503SQ-16/NOPB supports both analog dimming (via a DC voltage on the ADIM pin) and PWM dimming (via a logic-level signal on the PWMDIM pin). This dual interface lets the backlight controller choose the dimming method that best matches the display refresh — PWM for wide dimming range, analog for low-EMI operation. The '16' in the order code suffix is the output voltage: a fixed 16 V boost. That ceiling is sized for a 3- or 4-series white LED string in a small-panel backlight, not for higher-voltage strings that would need the LM3503SQ-24 or LM3503SQ-30 variants.
Package and footprint — 16-WQFN with exposed pad
Mounting is surface-mount only; the 0.50 mm pitch QFN demands a solder-paste stencil with 0.25 mm aperture for the perimeter pads and a large central aperture for the thermal pad.
Sourcing — active production, quoted per BOM
For dual-sourcing, the closest functional match is the LM3503SQ-24/NOPB (24 V output) or LM3503SQ-30/NOPB (30 V output), but the output voltage is fixed and not adjustable, so the variant must match the LED string voltage exactly.