This document introduces the LinkSwitch-4 family of ICs, which dramatically simplifies the design of low-power CV/CC charger/adapters by eliminating an optocoupler and secondary control circuitry. The LinkSwitch-4 family adaptive BJT drive technology uses combined base and emitter switching to boost switching performance and deliver higher efficiency, wider Reverse Bias Safe Operating Area (RBSOA) margin and the flexibility to accommodate a wide range of low cost BJT. The device incorporates a multimode PWM / PFM controller with quasi-resonant switching to maximize the efficiency, meets <30 mW no-load and at the same time maintains fast transient response greater than 4.3 V with a load change from 0% to 100%.
