Texas Instruments UCC28742

Description

The UCC28742 off-line flyback controller is a highly integrated, 6-pin secondary-side regulated PWM controller for efficient AC-to-DC power supplies. It is an isolated-flyback power-supply controller that provides Constant-Voltage (CV) using an optical coupler to improve transient response to large-load steps. This device processes information from optocoupled feedback and an auxiliary flyback winding for high performance control of output voltage and current. The UCC28742 employs advanced control algorithms to achieve high operating efficiency and performance. 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 80 kHz and always maintains control of the peakprimary current in the transformer. A minimum switching frequency of 200 Hz facilitates the achievement of low no-load input power.

Features

• Opto-Coupled Feedback Enables up to 1%Regulation
• Accurate Current Limit with Overload Timeout Protection and Delayed Hiccup Response
• Resonant-Ring Valley-Switching Operation for Highest Overall Efficiency
• 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 Design Using the UCC28742 with the WEBENCH® Power Designer

More information

• Datasheet
• IC product information