Feature
- Opto-Coupled Feedback Enables up to 1% Regulation
- Accurate Current Limit with Overload Timeout Protection and Delayed HiccupResponse
- Resonant-Ring Valley-Switching Operation for Highest OverallEfficiency
- 80-kHz Maximum Switching Frequency
- Frequency Dithering to Ease EMI Compliance
- Clamped Gate-Drive Output for MOSFET
- Ultra-Low Start-Up Current and Large VDD Hysteresis
- High Value Start-Up Resistor
- Low Bias Capacitance
- Fault Protections
- Input Low Line
- Output Over-Voltage
- Over-Current
- Short-Circuit
- SOT23-6 Package
- Create a Custom DesignUsing the UCC28742 with theWEBENCH? Power Designer
All trademarks are the property of their respective owners.
DescriptionThe UCC28742 off-line flyback controller is a highly integrated, 6-pin secondary-sideregulated PWM controller for efficient AC-to-DC power supplies. It is an isolated-flybackpower-supply controller that provides Constant-Voltage (CV) using an optical coupler to improvetransient response to large-load steps. This device processes information from opto-coupledfeedback and an auxiliary flyback winding for high-performance control of output voltage andcurrent.
The UCC28742 employs advanced control algorithms to achieve high operating efficiency andperformance. The drive output interfaces to a MOSFET power switch. Discontinuous conduction mode(DCM) with valley-switching reduces switching losses. Modulation of switching frequency and primarycurrent-peak amplitude (FM and AM) keeps the conversion efficiency high across the entire load andline ranges.
The controller has a maximum switching frequency of 80 kHz and always maintains controlof the peak-primary current in the transformer. A minimum switching frequency of 200 Hz facilitatesthe achievement of low no-load input power.
