Shutdown circuit for a switching power supply
AssigneeMotorola, Inc.
InventorArman V. Dolikian
Life of this patent
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Abstract
A switching mode power supply provides a D.C. output voltage having a value related to the duty cycle of the supply's controlled oscillator produced signal. The inventive shutdown circuit inhibits operation of the supply if the duty cycle increases to a value indicative of failure of the supply to produce a minimum desired output voltage. Operation of the supply is inhibited for a predetermined shutdown interval following which a restart cycle deactivates the shutdown circuit for a period to allow the supply to attempt to establish its desired output.
Claims3
A shutdown circuit for a switching type power supply having a fixed reference oscillator with an output wherein the voltage produced by the supply is a function of the output from a controlled oscillator, comprising:
- low voltage sense means for comparing the output of the controlled oscillator to the output of the fixed reference oscillator, and generating an inhibit signal in response to a predetermined relationship between the fixed reference oscillator output and the output from the controlled oscillator;
- shutdown timer means coupled to the low voltage sense means for inhibiting operation of the power supply for a predetermined time interval in response to said inhibit signal.
Dependencies are inferred from the claim text.