For constant current/constant voltage secondary side control, ST has an integrated solution available for use in switch-mode power supplies that require both precise constant current and constant voltage regulation for battery chargers and adapters. The TSM1013 is one example of a device that could be used for this. It can be seen on this slide that this device has an integrated precision voltage reference for Vref and also an op-amp for current control and another op-amp for voltage control. The inputs and outputs for each the op-amps are all brought out on the IC pins.