Half-bridge driver for synchronous N-channel bucks
The Texas Instruments TPS51601ADRBT is a half-bridge gate driver designed to drive two N-channel MOSFETs in a synchronous buck converter topology. It accepts a non-inverting input and delivers a 15 ns typical rise time and 10 ns fall time into the gate load, which sets the practical dead-time window for high-frequency switching. The 4.5 V to 5.5 V supply rail matches the bias from a typical PWM controller or a local 5 V regulator, so the BOM needs to budget that rail separately from the 12 V bootstrap supply for the high-side driver.
15 ns rise / 10 ns fall — what that means for the switching loop
With a 15 ns rise and 10 ns fall, the driver can charge and discharge the MOSFET gate quickly enough to keep switching losses low at frequencies up to several hundred kilohertz. The asymmetry — faster fall than rise — is intentional for synchronous bucks: the low-side FET turns off faster to prevent cross-conduction during the dead-time interval. The logic input thresholds (VIL 0.7 V, VIH 4.0 V) are compatible with 5 V PWM controllers; they also accept 3.3 V logic if the high-level output of the controller exceeds 4.0 V, which some do not — check the controller's VOH against the 4.0 V VIH spec.
Package and thermal: 8-SON (3x3) with exposed pad
The TPS51601ADRBT comes in an 8-VDFN with exposed pad, also described as an 8-SON (3x3). The small 3 mm × 3 mm footprint fits tight layouts, but the exposed pad must be soldered to a PCB copper plane and stitched with vias to the inner ground layer to carry heat away. Without that thermal via pattern, the junction temperature rises quickly above 400 mA continuous gate drive current. The part is rated for -40°C to 105°C junction temperature, which covers industrial environments — motor drives, telecom rectifiers, and outdoor power supplies — but not automotive under-hood (which typically needs 125°C or 150°C).
Lifecycle and sourcing reality
The TPS51601ADRBT carries an Active product status and ROHS3 compliance. No LTB risk, no forced redesign for a drop-in replacement.