This document mainly introduces the features and characteristics of the UC3548 product, including primary power supply voltage feed-forward control, accurate DC control, accurate programmable maximum duty cycle clamp, maximum volt-second product clamp, practical operation frequency up to 1MHz, high current (2A peak) Totem Pole output driver, wide bandwidth (8MHz) current error amplifier, undervoltage lockout monitor VCC, VIN and VREF, low startup current (500µA) and other
The document describes the UC3548 family of Primary Side PWM Controllers designed to regulate isolated power supplies using voltage feedforward control. These integrated circuits reside on the primary side and utilize patented techniques to accurately control secondary side short circuit current without direct secondary measurement.
Key features include a precision reference, wide bandwidth error amplifier, oscillator, latching PWM comparator, and high-current output driver. The controllers incorporate undervoltage lockout monitors for VCC, VIN, and VREF, along with protection features to prevent transformer core saturation by limiting maximum duty cycle and volt-second product.
| Package Types | 16-pin DIL and SOIC packages only |
|---|---|
| Output Current (Pulse) | 2A Peak |
| Bandwidth | 8MHz |
| Startup Current | 500uA |
| Operating Frequency | Up to 1MHz |
| Reference Voltage Typ | 5V |
| Oscillator Frequency Typ | 250 kHz |
The UC3548 family uses voltage feedforward control to regulate the output voltage of isolated power supplies.
It accurately controls secondary side short circuit current using primary side average current mode control techniques.
The supply current drops to 500uA and the output is actively held low.