75V buck LED driver with PWM dimming — what it is and where it fits
The Texas Instruments LM3406HVMH/NOPB is a constant-current step-down (buck) LED driver with an integrated 1.5A switch, rated for a 6V to 75V input supply. PWM dimming is supported directly, making it suitable for automotive exterior lighting, industrial high-bay fixtures, and architectural LED strings where the bus voltage can run up to 75V. The switching frequency is programmable from 10kHz to 1MHz, letting the designer optimise inductor size against efficiency — 1MHz keeps magnetics small for space-constrained modules; lower frequencies reduce switching losses in thermally demanding enclosures.
What the 75V input and 1.5A output mean for the BOM
A 75V maximum input voltage is the headline rating on this part. It means the LM3406HVMH/NOPB can be fed directly from a 48V nominal industrial rail or an automotive 24V battery bus (including load-dump transients) without an external pre-regulator. The 1.5A continuous output current drives a single high-power LED or a series string of lower-current LEDs, depending on the forward voltage stack. The 14-HTSSOP package with exposed pad needs a thermal via array under the pad to keep junction temperature within the -40°C to 125°C operating range at full load.
Active lifecycle — no obsolescence watch needed
The LM3406HVMH/NOPB is active and ROHS3 compliant. No AEC-Q grade is listed.