The UC1524, UC2524 and UC3524 integrate all functions required for the construction of a regulated power supply, inverter switching regulator in a single chip. They can also be used as control elements for high power output applications. The UC1524 family is designed for either polarity switching regulators, transformer coupled DC-DC converters, transformer voltage doublers and polarity converter applications with fixed frequency, pulse width modulation techniques. Dual alternate outputs allow single-ended or push-pull applications. Each device includes an on-chip reference, error amplifier, programmable oscillator, flip-flop pulse steering, two uncommitted output transistors, a high gain comparator and current limit and shutdown circuitry. The UC1524 is characterized for operation over the entire military temperature range from -55°C to +125°C. The UC2524 and UC3524 are designed for operation from -25°C to +85°C and 0°C to +70°C.
UC1524 is a fixed frequency pulse width modulation voltage regulator control circuit. The regulator operates at a frequency that is programmed by a timing resistor (RT), and a timing capacitor (CT), which establishes a constant charge current for CT. This results in a linear error amplifier at the CT, which is fed by comparing the voltage ramp provided by the linear control output pulse width. The UC1524 includes an on-board 5V regulator as a reference, as well as powering the UC1524's internal control circuitry, and also useful for providing external support functions. This reference voltage is reduced by an external resistor divider to provide the wrong common-mode range reference available for the amplifier or external reference. "A second resistor divider senses the power supply output network to generate a feedback signal to the error amplifier. The output voltage of the amplifier is then compared to the voltage on the CT's linear ramp. The resulting modulation pulse is compared with high gain and then directed by the appropriate output through The transistor (Q1 or Q2) pulses to the flip-flop, which switches the output of the oscillator synchronously. The output pulse of the oscillator acts as a blanking pulse to ensure that both outputs are never simultaneously in the transition period. The blanking pulse width controls the valve CT checks. The outputs can be applied in a push-pull configuration where their frequency is half the frequency of the base oscillator, or in parallel single-ended applications where the frequency is equal to the oscillator. The output error amplifier shares the more common input current limiting and shutdown circuits which Two input signals can be covered. This common point can also be externally controllable gain to compensate, error amplifier or regulator to provide additional control.