Buck controller in an 8-pin DIP — what it is and where it fits
The LT1243CN8#PBF is a current-mode PWM buck controller from Analog Devices, designed for step-down (buck) converter applications. It drives an external transistor switch at a fixed 500 kHz switching frequency, with a maximum duty cycle of 96% — useful when the input-to-output differential is small. The controller operates from an 8.2 V to 25 V supply rail and delivers a single positive output that can be configured for isolated designs. Housed in an 8-lead PDIP (0.300" width, 7.62 mm pitch), it is a through-hole part suited for benchtop prototypes, low-to-medium volume production, or legacy board repairs where surface-mount rework is impractical.
500 kHz switching — what it means for your magnetics and BOM
Switching at 500 kHz reduces inductor and capacitor size. The controller lacks a clock-sync pin, so it runs free.
96% duty cycle — low-dropout capability
A 96% maximum duty cycle allows the output to stay regulated when the input is close to the output voltage.
Temperature grade and environment
Junction temperature range is 0°C to 100°C, suitable for commercial indoor equipment.
Lifecycle and sourcing
The LT1243CN8#PBF is listed as Active by the manufacturer — no end-of-life notice, no last-time-buy window. It is a current-production part available through independent distribution. For BOM planning, there is no LTB risk on this line.