Current-mode PWM controller in an 8-pin DIP
The Texas Instruments UC2844AN is a current-mode PWM controller in the legacy 8-DIP through-hole package. It steps up, steps down, or steps up/step-down across boost, buck, flyback, and forward topologies — the function and topology set list covers the three main non-isolated and isolated converter architectures. Maximum duty cycle is 48% with a switching frequency up to 500 kHz. The 48% ceiling is typical for current-mode controllers in flyback and forward converters — it prevents transformer saturation during start-up and transient overload by limiting the on-time below 50%. Supply voltage range is 10 V to 30 V on the Vcc pin. This wide input window suits offline flyback bias windings (typically 12-18 V) or an industrial 24 V bus-derived rail. The undervoltage lockout thresholds are set internally for the UC2844 variant — the controller starts at 16 V and shuts down at 10 V, matching the 10 V minimum in the supply spec.
Single-output transistor driver with isolation capability
The output stage is a single totem-pole transistor driver — not a gate-drive integrated FET. It sources and sinks the gate charge of an external power MOSFET or IGBT through a series resistor that sets the turn-on/turn-off speed. The positive output configuration and isolation-capable flag mean the controller can drive a pulse transformer for primary-side referenced gate drive in isolated topologies like flyback and forward. No clock sync, no synchronous rectifier control — the oscillator runs free at the frequency set by the external RT/CT network. The Frequency Control feature in the spec table refers to the programmable oscillator, not an external synchronization input. For designs requiring multi-phase interleaving or external clock alignment, a different controller family is needed. The 8-DIP package (0.300" width, 7.62 mm row spacing) is a through-hole footprint that has been in production for decades. It is hand-solderable and prototyped on perfboard, but the 0.100" pin pitch constrains the layout of the high-frequency power loop — the sense resistor and output drive trace should be kept short to minimize parasitic inductance that degrades current-sense stability above 200 kHz.
Active production, ROHS3 compliant, industrial temperature range
Lifecycle status is Active per the manufacturer — no end-of-life notice, no last-time-buy window. ROHS3 compliant (fully lead-free) with no exemption conflicts for EU or UKCA markets. The UC2844AN is sourced to order through independent and authorized distribution. The 8-DIP tube packaging is standard for through-hole ICs — no reel or tape options exist for this package variant.