View mc33063ap1 datasheet:

MC33063AP1 IL08 CONTROL CIRCUIT FOR DC-DC CONVERTER —TOP VIEW— 5 7 COMPARATOR IPK SENSE INVERTING INPUT SWITCH COLLECTER 1 8 DRIVE COLLECTOR SWITCH EMITTER 2 7 IPK SENSE 8 DRIVE COLLECTOR 3 TIMING CAPACITOR TIMING CAPACITOR 3 VCC (+5 V) 6 1 SWITCH COMPARATOR COLLECTER 4 GND 5 INVERTING INPUT 2 SWITCH EMITTER 8 DRIVE COLLECTOR 1 SWITCH COLLECTOR Q2 S Q Q1 R 100 2 SWITCH EMITTER IPK OSCILLATOR 3 7 TIMING CT IPK SENSE CAPACITOR COMPARATOR 1.25 V + REFERENCE REGULATOR _ COMPARATOR 5 INVERTING INPUT