Offline buck controller in an 8-pin DIP
The LT1244CN8#PBF is an offline switching controller from Analog Devices built around a current-mode buck topology with an isolated output stage. It operates from a 10 V to 25 V supply (Vcc/Vdd) with a 16 V startup threshold and delivers a fixed 48% duty cycle at switching frequencies up to 500 kHz.
What the key specs mean for your converter design
The 48% fixed duty cycle sets the maximum on-time ratio for the external power switch — in a typical buck converter this limits the input-to-output voltage step-down ratio. For an offline flyback or forward converter the duty cycle clamp also defines the reset time for the transformer core, which directly affects the volt-second balance and core saturation margin. Switching at up to 500 kHz lets you shrink the magnetic components (transformer and output inductor) compared to a 100 kHz design, at the cost of higher switching losses in the external MOSFET. The controller does not integrate the power switch (Internal Switch(s): No), so the choice of external FET and its gate drive layout governs the practical upper frequency. The isolated output (Output Isolation: Isolated) means the feedback path crosses the isolation barrier — typically via an optocoupler or a transformer-coupled winding. This controller generates the PWM signal on the primary side; the secondary-side regulation loop must be closed through an isolated error amplifier. Frequency Control is listed as a control feature — this likely refers to an RT/CT pin or a similar oscillator-programming input that lets you set the switching frequency with an external resistor and capacitor, rather than a fixed internal oscillator.
Active production and compliance
The 8-DIP through-hole package (Supplier Device Package: 8-PDIP) is a legacy footprint that simplifies prototyping and rework but occupies more board area than a surface-mount alternative. The tube packaging (Package: Tube) indicates it ships in anti-static tubes, not tape-and-reel — relevant for pick-and-place if you plan automated assembly with tube feeders.