What this LED driver is and where it fits
The Texas Instruments TPS92550TZ/NOPB is a constant-current step-down (buck) LED driver in a TO-PMOD-7 power module package. It integrates the switching FET, so the external BOM stays tight — just the inductor, input/output caps, and a few passives. The 400 kHz switching frequency is a practical middle ground: fast enough to keep the inductor small, slow enough that layout parasitics don't bite you on a two-layer board. Rated for 4.5 V to 36 V input and delivering up to 450 mA per channel, this is the kind of part you reach for when you need a single-string LED driver for architectural lighting, signage, or general-purpose constant-current illumination. The -40°C to 125°C junction temperature range covers outdoor fixtures and engine-bay lighting where the ambient heat soaks through the housing.
PWM dimming and what it means for the BOM
Dimming is handled by a PWM input, which means the LED current is chopped at the dimming frequency rather than linearly reduced. That keeps the color temperature stable across the dimming range — important for architectural and display lighting where the human eye catches a color shift. The PWM pin is logic-level compatible, so a microcontroller GPIO or a dedicated PWM controller can drive it directly.
Package and thermal reality
The TO-PMOD-7 is a surface-mount power module with an exposed pad. That pad is the main thermal path — the datasheet layout recommendation shows a via array under the pad to pull heat into the board's internal copper planes. Without that via stitch, the junction temperature climbs fast above 300 mA continuous in a 70°C ambient. The module integrates the inductor and switch, so the hot spots are contained, but the board still acts as the heatsink.
Lifecycle and sourcing
It is ROHS3 compliant.