Current Sense Comparator and PWM LatchThe UC3842A, UC3843A operate as a current modecontroller, whereby output switch conduction is initiated bythe oscillator and terminated when the peak inductor currentreaches the threshold level established by the ErrorAmplifier Output/Compensation (Pin 1). Thus the errorsignal controls the peak inductor current on acycle−by−cycle basis. The current Sense Comparator PWMLatch configuration used ensures that only a single pulseappears at the Output during any given oscillator cycle. Theinductor current is converted to a voltage by inserting theground referenced sense resistor R S in series with the sourceof output switch Q1. This voltage is monitored by theCurrent Sense Input (Pin 3) and compared a level derivedfrom the Error Amp Output. The peak inductor current undernormal operating conditions is controlled by the voltage atpin 1 where: