What the UC3844AN does in a boost or flyback supply
It drives a single external transistor with a maximum duty cycle of 48% and can switch at frequencies up to 500 kHz, which lets you shrink the transformer and output filter compared to a 100 kHz design. The controller operates from a supply voltage of 10V to 30V and includes frequency control for setting the oscillator timing. It does not support clock synchronization or synchronous rectification, so the design uses a freewheeling diode on the secondary side.
STMicroelectronics lists the UC3844AN as Obsolete. If you have an existing design using this controller, you are looking at a last-time-buy to cover remaining production or a redesign with a pin-compatible or functionally equivalent current-mode PWM controller. The 8-DIP through-hole package (8-Mini DIP) is still widely stocked by independent distributors for legacy repairs and short-run builds. Sourcing is per-RFQ — we confirm availability and current pricing at quote time against your BOM quantity.
Package and temperature — fit check for your board
The UC3844AN comes in an 8-pin DIP package (0.300-inch body width, 7.62 mm) with through-hole mounting. This is a legacy footprint — it mates with standard 0.100-inch pitch sockets or solders directly into plated through-holes. For industrial or automotive use, you would need a different part with an extended temperature grade.