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 opto-coupled 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 peak-primary 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

Typical applications

• Industrial and Medical AC-to-DC Power Supplies, Smart Electricity Meters,Bias Supply for UPS, Server PSU, etc.
• Power Supply for Cable Modem, Television, SetTop Box, and Wireless Routers, AC-to-DC Power Supply for Appliances

More information

• Datasheet
• IC product information