Current-mode PWM controller for isolated supplies
The Texas Instruments UC2844D is a current-mode PWM controller designed for isolated DC-DC converters using boost, buck, flyback, or forward topologies. Its output stage is a single transistor driver, configured for positive output with isolation capability. Switching frequency reaches up to 500 kHz, with a maximum duty cycle of 48%. The supply range spans 12 V to 28 V (Vcc/Vdd), and the operating temperature covers -40°C to 85°C — suited for industrial ambient conditions without extended temperature margin.
Switching limits and control features
The 48% duty cycle ceiling means the controller cannot exceed a 48% on-time ratio per switching period — a constraint that matters for transformer reset in single-ended flyback and forward designs. Above that, the core saturates before the cycle completes. Frequency control is available as a feature, but the part lacks clock synchronization (no sync pin) and does not support synchronous rectification. The single output phase drives a power switch directly; for multi-phase or interleaved topologies, a separate controller is needed.
14-SOIC package integration
The supplier device package is 14-SOIC, delivered in Tube format. No exposed thermal pad — junction-to-ambient thermal resistance follows the standard SOIC-14 profile without a dedicated heat-sink path.