UC3843 chip is designed for the construction of highly pulsed power supply with PWM (pulse width modulation). Power output circuit is small because it is placed at its output n-channel FET powerful.
Assign legs circuit UC3843 :
Comp O - reinforce errors to compensate for the frequency response of the error amplifier is connected capacity of several tens of nF.
Vfb Rin - used to provide feedback. The value of U on this leg compared to the U, formed inside the circuit UC3843, the result of modulating the duty cycle output. Thus there is a stabilization of the output voltage of the power supply.
C / S - generates a signal, which limits the output current of the MOSFET. Upon reaching a certain current, the device does not burn, but just goes to defense.
Rt / C - output for connection RC-circuit sets the operating frequency of the integrated circuit in the generator uc3843. Usually the capacitor is several nF. The frequency is adjusted in a wide range of limited Polevikov operating frequency and the power supply transformer.
Gnd - ground output.
Out - output UC3843, going to the gate of the field VT, usually through R & VD (anode of diode has to go to the gate VT).
Vcc - the output power on UC3843AN.
Vref - Uopornogo internal source (I = 50mA, U = 5 V).
The chip UC3843AN works equally well with the mains voltage 115v, and with a voltage of 220v. Alteration from one voltage to another amounts to replacing the diode bridge and a capacitor to the desired maximum voltage.
Power Supply made on the chip UC3843 are characterized by high reliability and ease of execution.