|Package | PIN:||D | 7|
|Temp:||Q (-40 to 125)|
- Less than 10-mW No-Load Power Capability
- Optocoupled Feedback for CV, and
Primary-Side Regulation (PSR) for CC
- Enables ±1% Voltage Regulation and ±5% Current Regulation Across Line and Load
- 700-V Startup Switch
- 100-kHz Maximum Switching Frequency Enables High-Power-Density Charger Designs
- Resonant-Ring Valley-Switching Operation for Highest Overall Efficiency
- Frequency Dithering to Ease EMI Compliance
- Clamped Gate-Drive Output for MOSFET
- Overvoltage, Low-Line, and Overcurrent Protection Functions
- SOIC-7 Package
- Create a Custom Design Using the UCC28740 With the WEBENCH® Power Designer
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Texas Instruments UCC28740DR
The UCC28740 isolated-flyback power-supply controller provides Constant-Voltage (CV)using an optical coupler to improve transient response to large-load steps. Constant-Current (CC)regulation is accomplished through Primary-Side Regulation (PSR) techniques. This device processesinformation from opto-coupled feedback and an auxiliary flyback winding for precisehigh-performance control of output voltage and current.
An internal 700-V startup switch, dynamically controlled operating states, and a tailoredmodulation profile support ultra-low standby power without sacrificing startup time or outputtransient response.
Control algorithms in the UCC28740 allow operating efficiencies to meet or exceedapplicable standards. The drive output interfaces to a MOSFET power switch. Discontinuousconduction mode (DCM) with valley-switching reduces switching losses. Modulation of switchingfrequency and primary current-peak amplitude (FM and AM) keeps the conversion efficiency highacross the entire load and line ranges.
The controller has a maximum switching frequency of 100 kHz and always maintains controlof the peak-primary current in the transformer. Protection features keep primary and secondarycomponent stresses in check. A minimum switching frequency of 170 Hz facilitates the achievement ofless than 10-mW no-load power.