Comp: This pin is connected to the output of the error amplifier compensation. For normal operation of the IP necessary to compensate the frequency response of the error amplifier, to this end, to the said conclusion is usually connected capacitor of about 100 pF, a second terminal connected to terminal 2 of the IP.
Vfb: feedback input. voltage on this output is compared with the model to be formed within the IC. The comparison result modulates the duty cycle of output pulses, stabilizing thereby the output voltage SP.
C / S: signal current limit. This conclusion must be connected to a resistor in the source key transistor (CT).
Rt / Ct: output for connecting the RC-of timing chain. The operating frequency of the internal oscillator set to the connecting resistor R and the reference voltage Vref of the capacitor C (usually a capacity of about 3000 pF) to the common terminal.
Gnd: general conclusion.
Out: Output IP.
Vcc: power input IP.
Vref: the output of the internal reference voltage, its output current up to 50 mA, the voltage of 5 V.
PWM controller UC3842 has a feedback voltage and current for controlling the key stage at the n-channel MOS transistor, allowing the discharge of its input capacitance forced current of up to 0.7A. Kernel UC3842 is specially designed for long-term operation with a minimum number of external discrete components. PWM controller UC3842 different precise control of the duty cycle, temperature compensated and has a low cost. Feature UC3842 is the ability to work within a 100% duty cycle.
IC 3842 is mainly used for operation in DC-DC (converts the DC voltage of one value to another DC voltage) converter.
Power supplies made on chip UC3842 are characterized by high reliability and ease of execution.