What the 48% duty ceiling means for your flyback design
The TL3844BD-8 is a current-mode PWM controller from Texas Instruments that handles boost, flyback, and forward topologies — the 48% maximum duty cycle is the hard limit that governs transformer turns ratio and output voltage in a flyback. Push past 48% and the controller simply stops switching until the next cycle. Switching frequency runs up to 500 kHz, which lets you shrink the magnetic components but forces attention to layout parasitics — the 8-SOIC package has about 0.5 nH per pin of self-inductance, and the gate-drive loop needs to stay tight to avoid ringing at the FET gate.
Supply rails and temperature envelope
Vcc range is 10 V to 30 V, so it starts cleanly from a 12 V bias rail and has headroom for a 24 V industrial bus. The undervoltage lockout thresholds are fixed internally — there is no external programming pin. No AEC-Q or extended-temp rating here — this part lives in benchtop supplies, appliance PSUs, and indoor equipment where the ambient stays above freezing.
No pin-compatible second source is listed by TI, so the BOM line is single-sourced to this order code.