AN1729 is a technical application note about low cost TV power supply. The application note presents a low cost TV power supply design solution based on the L6565 QR controller, which uses a quasi-resonant flyback converter topology to achieve 1W or less standby power consumption.
This document presents a cost-effective solution for designing a Switch Mode Power Supply (SMPS) for a 14-inch TV, achieving a standby power consumption of less than 1 Watt. The design utilizes a Quasi-resonant Flyback Converter topology based on the L6565 controller to minimize switching losses and improve efficiency during standby conditions.
The note details the implementation of an enhanced burst-mode operation to further reduce average switching frequency and losses when the system is lightly loaded. It includes a complete schematic of the 60W SMPS circuit, specific electrical specifications, and explanations of the start-up circuit and feedback loop arrangements required to meet the low standby power target.
| Input Voltage range | 88 to 264 Vac |
|---|---|
| Mains frequency | 50-60 Hz |
| Maximum output power | 60 W |
| Output voltage 1 | 114V |
| Output power 1 | 55 W |
| Output voltage 2 | 14V |
| Output power 2 | 4.2 W |
| Regulator output voltage | 5V |
| Regulator max current | 70mA |
| Regulator standby current | 10mA |
| Minimum switching frequency | 70 kHz |
| Target efficiency | > 80% |
| Maximum standby consumption | <1W |
The design target is a standby power consumption of less than 1 Watt.
The design uses a Quasi-resonant Flyback Converter topology.
The L6565 QR controller is used to obtain an enhanced burst mode operation.
The maximum output power of the realized circuit is 60 W.