Switched-mode power supply with a function for detecting a broken feedback loop

US6735095B2 · kind B2 · utility

Assignee

• Infineon Technologies AG · DE

Inventors

• Marc Fahlenkamp · Geretsried, DE
• Hartmut Jasberg · Ottobrunn, DE
• Martin Feldtkeller · Munich, DE
• Harald Zoellinger · Gilching, DE

Key dates

• Filing date: Dec 27, 2002
• Grant date: May 11, 2004
• Expiry date: Dec 27, 2022

Classification

• Technology area (CPC H): Electricity
• CPC primary: H02M3/33523
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

A switched mode power supply includes a primary coil, a switch element, a secondary circuit, and a control circuit. The switch element is wired in series with the primary coil, for applying a DC voltage to the primary coil according to a control signal. The secondary circuit is coupled to the primary coil with output terminals providing an output voltage. The control circuit prepares the control signal with a feedback signal dependent on the output voltage supplied to the control circuit. The control circuit includes a signal generation circuit to create the control signal and a protection circuit. The protection circuit has the effect that no control signal is delivered to the switch element, if the feedback signal reaches the value of a first reference signal after a first period after starting the control circuit.