Automotive current-mode PWM controller — UCC28C45QDRQ1
The Texas Instruments UCC28C45QDRQ1 is an automotive-grade (AEC-Q100) BiCMOS current-mode PWM controller designed for step-up and step-up/step-down topologies including boost, flyback, and forward converters. It integrates a single transistor driver output, operates from a 7.6 V to 18 V supply, and switches at frequencies up to 1 MHz. The 48% maximum duty cycle suits single-ended converter designs typical in automotive power supplies, DC-DC modules, and isolated bias rails.
48% duty cycle and 1 MHz switching — what they mean for the transformer
The 48% duty-cycle ceiling is a hard limit for single-ended topologies like flyback and forward converters — it prevents transformer saturation by guaranteeing a minimum reset time. At 1 MHz, the controller lets you shrink the magnetic components significantly compared to a 100 kHz design, but the 48% cap means you cannot push past the half-cycle mark even with frequency foldback. For a forward converter, the reset winding turns ratio must be sized within this window.
Temperature range and automotive qualification
Rated for -40°C to 125°C ambient, this part is built for under-hood and engine-bay environments where the thermal cycling is severe. The AEC-Q100 qualification means it has passed the full suite of stress tests — high-temperature operating life, temperature cycling, and moisture sensitivity — that consumer-grade PWM controllers skip. If your BOM calls out a Q1 suffix, the laser etch and date-code trace should match TI's automotive production lines; a mismatched font or inconsistent lot code flags potential gray-market re-marking.
Package and footprint — 8-SOIC surface mount
Housed in the standard 8-SOIC package (3.90 mm body width), the UCC28C45QDRQ1 drops into any SOIC-8 footprint without layout changes. The supplier device package is 8-SOIC. The Tape & Reel (TR) or Cut Tape (CT) options suit both prototype and production volumes. No exposed pad — thermal dissipation is through the leads and board copper, so the layout should include adequate copper pour under the part for continuous operation near the 125°C limit.
Lifecycle and compliance
The UCC28C45QDRQ1 is listed as Active with ROHS3 compliance.