What this buck LED driver brings to the board
The TI LM3402MR/NOPB is a constant-current buck LED driver in an 8-PowerSOIC package, switching at 1 MHz and delivering up to 500 mA per channel with PWM dimming. It operates from a 6 V to 42 V supply and regulates the output voltage to 40 V maximum. The internal switching FET handles the full load, so no external power transistor is needed. This part is aimed at lighting applications — architectural, signage, or general-purpose constant-current LED strings — where the 1 MHz switching keeps the inductor and capacitor small enough to fit the board area an 8-pin SOIC footprint allows.
1 MHz switching — what it buys the layout
At 1 MHz the switching period is 1 µs, which lets the designer use a physically smaller inductor than a lower-frequency buck would need. For a 500 mA load, a shielded inductor is typical.
For dual-sourcing evaluation, the closest functional sibling is the LM2703MF-ADJ/NOPB, a boost (step-up) LED driver with 350 mA output, which is a different topology — not a pin-for-pin swap.