The RT7757 series is specifically designed to work with controllers, such as the RT7220D, to provide a total solution for USB PD or a programmable power adapter. The RT7757 provides a high power efficiency control scheme that applies the zero-voltage switching (ZVS) technology.
The RT7757 achieves a wide-range of output voltage by utilizing several innovations, including (1) By using DMAG pin, the RT7757 senses output voltage to adjust loop gain for system stability, to adjust output overvoltage protection threshold voltage to protect external devices, and to adjust current limit to meet Limited Power Source (LPS) safety requirements; (2) The RT7757 is also equipped with comprehensive protection features, including bulk-capacitor brown-in/brown-out protection, VDD overvoltage protection (VDD_OVP), output overvoltage/undervoltage protection (Output OVP/UVP), secondary rectifier short-circuit protection (SRSP), and external over-temperature protection (External OTP); (3) For constant output power regulation, a resistor connected to CS pin can be used to achieve accurate line compensation across the universal input voltage range; and (4) The RT7757 also provides various features to protect against any failures occurring at the secondary-side component, such as the RT7206 or a shunt regulator.
In applications, it is suggested that the RT7757 be used with a secondary controller RT7206 to realize a robust and safe design to prevent all potential fault conditions due to misconnection of various devices, cables, plugs and receptacles.
Applications
- USB PD, Fast Charge and Programmable Power Adapters
- General Purpose High-Efficiency Compact Size Flyback Power Converters