The UCC28740-Q1 isolated-flyback power-supply controller regulates the output using an optical coupler to provide fast transient response to large-load steps.
An internal 700-V startup switch, dynamically controlled operating states, and a tailored modulation profile support ultra-low standby power without sacrificing startup time or output transient response.
Control algorithms in the UCC28740-Q1 allow operating efficiencies to meet or exceed applicable standards. The drive output interfaces to a MOSFET power switch. Discontinuous conduction mode (DCM) with valley-switching reduces switching losses. Modulation of switching frequency and primary current-peak amplitude (FM and AM) keeps the conversion efficiency high across the entire load and line ranges.
The controller has a maximum switching frequency of 100 kHz and always maintains control of the peak-primary current in the transformer. Protection features keep primary and secondary component stresses in check. A minimum switching frequency of 170 Hz facilitates the achievement of less than 10-mW no-load power.