The UCC28700-Q1 is a flyback power supply controller which provides accurate voltage and constant current regulation with primary-side feedback, eliminating the need for opto-coupler feedback circuits. The controller operates in discontinuous conduction mode with valley-switching to minimize switching losses. The modulation scheme is a combination of frequency and primary peak current modulation to provide high conversion efficiency across the load range. The control law provides a wide-dynamic operating range of output power to achieve the < 30-mW stand-by power requirement.

Another feature beneficial to achieve low stand-by power without excessive start-up time is a wide operating VDD range to allow a high-value VDD start-up resistance and low-value VDD capacitance. During low-power operating ranges the device has power management features to reduce the device operating current at operating frequencies below 44 kHz. The UCC28700-Q1 controller includes features in the modulator to reduce the EMI peak energy of the fundamental switching frequency and harmonics. Accurate voltage and constant current regulation, fast dynamic response, and fault protection are achieved with primary-side control. A complete charger solution can be realized with a straightforward design process, low cost and low component count.