US 5,708,577 A · Regulated power supply

Abstract

A regulated power supply includes a transformer having a primary winding coupled to an AC power line, and a secondary winding coupled to a rectifier. A storage capacitor is coupled through a switching transistor to the rectifier, where the storage capacitor provides a DC output power terminal. A control circuit having a comparator amplifier is coupled to the secondary winding and to the switching transistor, and compares the voltage from the secondary winding to a reference voltage value. The switching transistor is turned on from 0 to positive voltage values, as output by the rectifier, to regulate the voltage applied to the capacitor. The switching transistor switches off when the input voltage value equals or exceeds the reference value. Several passive circuit elements (e.g., diodes, resistor-capacitor networks, etc.) slow the turn on and turn off time of the switching transistor to help eliminate switching noises and other EMI.

Claims21

Dependent claims

A regulated power supply for use with a supply of AC power comprising:

first and second input terminals coupled to the supply of AC power and providing an AC power signal having an input frequency having a rising portion and a falling portion during each cycle;
a transformer having a primary winding coupled to the first and second input terminals and a secondary winding that outputs the AC power signal;
an input rectifier coupled to the secondary winding and rectifying the AC power signal output from the secondary winding so as to produce a rectified power signal;
a switch element coupled to an output of the rectifier to receive the rectified power signal and provide a switched power signal, the switch element being conductive during at least a portion of the rising portion of each cycle of the AC power signal;
a power storage device coupled to an output of the switch element to store the switched power signal and provide a stored power signal at an output terminal;
and
a control circuit coupled to the switch element and coupled to the secondary winding to monitor the AC power signal, the control circuit being adapted to cause the switch element to be non-conductive prior to an end of the falling portion of each cycle of the AC power signal and at a rate not greater than twice the input frequency.

4 more elements

A regulated power supply for use with a supply of AC power comprising:

first and second input terminals coupled to the supply of AC power and providing an AC power signal having an input frequency, the AC power signal having a rising portion and a falling portion during each cycle;
transformer having a primary winding coupled to the first and second input terminals and a secondary winding;
an input rectifier coupled to the secondary winding and rectifying the AC power signal so as to produce a rectified power signal;
a first switch element coupled to an output of the rectifier to receive the rectified power signal and provide a switched power signal, the switch element being conductive during at least a portion of the rising portion of each cycle of the AC power signal;
a first power storage device coupled to an output of the first switch element to store the switched power signal and provide a stored DC power signal at an output terminal;
a first voltage divider network coupled between the input rectifier and the control circuit to produce a monitored voltage value;
and
a control circuit coupled to the voltage divider network and the first switch element, the control circuit comparing a reference voltage value to the monitored voltage value and causing the first switch element to be non-conductive when the monitored voltage value is equal to the reference voltage value, prior to an end of the falling portion of each cycle of the AC power signal, and at a rate not greater than twice the input frequency.

5 more elements

Dependencies are inferred from the claim text.

Regulated power supply

Life of this patent

Regulated power supply

Life of this patent

Abstract

Claims21