TI低功率 QR Flyback PWM Controller_ UCC28740
【產品特性】Low Power Constant-Voltage Constant-Current Flyback Controller Using Opto-Coupled Feedback
1. Less than 10-mW No-Load Power Capability
2. Opto-Coupled Feedback for CV, and Primary-Side Regulation (PSR) for CC
3. Enables ±1% Voltage Regulation and ±5% Current Regulation Across Line and Load
4. 700-V Startup Switch
5. 100-kHz Maximum Switching Frequency Enables High-Power-Density Charger Designs
6. Resonant-Ring Valley-Switching Operation for Highest Overall Efficiency
7. Frequency Dithering to Ease EMI Compliance
8. Overvoltage, Low-Line, and Overcurrent Protection Functions
9. SOIC-7 Package
【產品應用】 USB-Compliant Adapters and Chargers for Consumer Electronics
Standby Supply for TV and Desktop
【文字介紹】The UCC28740 is a flyback power-supply controller which provides high-performance voltage regulation using an optically-coupled
feedback signal from a secondary-side voltage regulator.
The device provides accurate constant-current
regulation using primary-side feedback. The controller operates in discontinuous-conduction
mode (DCM) with valley-switching to minimize switching losses.
The control law provides a wide dynamic operating range of output power which allows the power-supply designer to easily achieve less
than 30-mW standby power dissipation using a standard shunt-regulator and optocoupler.
For a target of less than 10-mW standby power, careful loss-management design with a low-power regulator and high-CTR opto-coupler
During low-power operating conditions, the power-management features of the controller reduce the device operating current at switching frequencies below 32 kHz. the UCC28740 includes features in the modulator to reduce the EMI peak energy of the fundamental switching frequency and harmonics. A complete low-cost and low component-count charger-solution is realized using a straight-forward design