Browse Prior Art Database

Over-Current Detection for Switching Regulator Power Supplies

IP.com Disclosure Number: IPCOM000035657D
Original Publication Date: 1989-Jul-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Schrader, RE: AUTHOR

Abstract

Disclosed is a sensing technique that will provide an interrupt signal when a switching regulator power supply has consistently exceeded a load current threshold for a preset period of time.

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Over-Current Detection for Switching Regulator Power Supplies

Disclosed is a sensing technique that will provide an interrupt signal when a switching regulator power supply has consistently exceeded a load current threshold for a preset period of time.

The output voltage of a switching regulator power supply is adjusted by a control waveform flowing from the regulator section to the output filter section of the power supply. The control waveform is a constant frequency variable duty cycle current pulse waveform. The current pulse amplitude of this waveform is directly proportional to the load current being delivered by the power supply. Because of the proportionality between the amplitude of the control waveform and the load current flowing from the power supply, a threshold can be defined for the control waveform amplitude that represents an output over-current condition.

In normal operation, a power supply can have an over-current condition for a short period of time (several cycles of the control waveform). If the over-current condition exists for longer than a predetermined number of cycles, the power supply is delivering too much current to the load and an interrupt signal is required. The interrupt signal is generated when a summation of the control waveform cycles that are above the over-current threshold is larger preset value. The summation is slowly reduced (not less than zero) when no over-current pulses are present in the control waveform.

As shown in the figure, an examp...