SWITCHED MODE POWER SUPPLY WITH A SIMPLIFIED START-UP SUPPLY

摘要

A switched mode power supply (SMPS) is disclosed in which a simple primary side controller is used to send a single pulse of energy to the secondary side to switch on an output voltage controller. The pulse is sent across the main power train and a filtering arrangement is provided on the secondary side to minimise the energy at the output of the SMPS while maximising the energy supplied to the output voltage controller. Advantageously, the SMPS is configured such that the maximum amount of energy transferred from the primary side to the secondary side during a start-up operation is inherently limited. Protection against short circuit conditions and malfunctions is therefore provided without requiring complicated circuitry.

主权项

1. A switched mode power supply comprising:
a transformer having a primary side and a secondary side; an input to the switched mode power supply arranged on the primary side; a main output of the switched mode power supply arranged on the secondary side; an output voltage controller arranged on the secondary side and operable to control an output voltage at the main output of the switched mode power supply; a power supply circuit arranged to provide a power supply on the secondary side, wherein the power supply circuit is operable to receive power from the primary side via the transformer and to output power to the main output and also to the output voltage controller; an energy storage unit arranged on the primary side and operable to receive and store a finite amount of energy from the input to the switched mode power supply and to output a finite energy pulse to the transformer; and a control module arranged on the primary side and operable to switch on the output voltage controller by releasing stored energy from the energy storage unit as a finite energy pulse, such that, in a start-up operation, only one pulse of energy is transferred from the primary side to the secondary side.