Characteristics and principles of current mode controller UCC3802

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Characteristics and principles of current mode controller UCC3802 [Copy link]

UCC3802 is developed on the basis of UC3842. It adopts BiCMOS chip technology. Compared with the Bipolar technology of UC3842, the IC consumes less power, the circuit transmission time is short, and the reliability is high. This series of products has fewer external components, simple design, low cost, and greatly improved power supply performance and reliability. It is an ideal replacement for the UC3842 series. The principle block diagram of UCC3802, the feedback channel consists of voltage error amplifier EPA, PWM comparator, latch and drive circuit. Triggered by the clock pulse, the power tube is turned on, and the inductor current rises. But when the current rises to the threshold controlled by EPA, the PWM comparator flips, the latch is reset, the drive pulse turns off the power tube, and the inductor current decreases until the next clock pulse arrives, the latch is set, and the switch tube is turned on again. When the input voltage changes, the rising slope of the inductor current changes, and the output duty cycle changes to suppress the change of the input voltage. This is a feedforward regulation process with extremely fast response; load disturbances are regulated by changing the current threshold value of EPA.