The UC3578 is a PWM controller for single-switch PWM step-down converters that integrates a floating high-side gate driver. It is used to regulate a positive output voltage. Intended for use in a distributed power system, the IC allows operation from 14V to 72V input voltage which range includes the prevalent telecomm bus voltages. The output duty cycle of the UC3578 can vary between 0% and 90% for operation over the wide input voltage and load conditions. The UC3578 simplifies the design of the single switch PWM buck converter by incorporating a floating high side driver for an external N-channel MOSFET switch. It also features a 100kHz fixed frequency oscillator, an internal 2V precision reference, an error amplifier configured for voltage mode operation, and a PWM comparator with latching logic. Complementing the UC3578 are integrated circuits (ICs) that include a comparator for generating PWM pulses from the reference voltage and provide the pulses to the driver for driving the external MOSFET.
The Unitrode UC2578 and UC3578 are PWM controllers with integrated high-side floating gate drivers designed for buck step-down converters. They regulate positive output voltages with an input voltage operating range of 14V to 72V, suitable for distributed power systems and telecomm bus applications. The UC3578 specifically incorporates a 100kHz fixed frequency oscillator, an internal 2V precision reference, and an error amplifier configured for voltage mode operation.
| Operating Input Voltage Range | 14V to 72V |
|---|---|
| Internal Oscillator Frequency | 100kHz |
| Reference Voltage | 2V |
| Maximum Duty Cycle | 90% |
| Undervoltage Lockout Start Threshold | 10V to 12V |
| Gate Drive Output High Voltage | 9.5V to 11V |
The devices operate with an input voltage range from 14V to 72V.
Yes, it contains a 100kHz internal oscillator.
The output duty cycle can vary between 0% and 90%.