US 7,242,150 B2 · Dimmer having a power supply monitoring circuit

Abstract

A two-wire dimmer for control of a lighting load from an alternating-current (AC) power source includes a semiconductor switch, a power supply, and a control circuit. The power supply includes an energy storage input capacitor that is able to charge only when the semiconductor switch is non-conductive. The control circuit continuously monitors the voltage on the input capacitor and automatically decreases the maximum allowable conduction time of the semiconductor switch when the voltage falls to a level that will not guarantee proper operation of the power supply. The dimmer of the present invention is able to provide the maximum possible conduction time of the semiconductor switch at high end (i.e., maximum light intensity) while simultaneously ensuring sufficient charging time for proper operation of the power supply, and hence, the dimmer.

Claims10

Dependent claims

A two-wire dimmer for control of a lighting load from a source of AC voltage, comprising:

a semiconductor switch operable to be connected between said lighting load and said source of AC voltage;
said semiconductor switch having a conducting state and a non-conducting state;
a power supply operable to draw current from said source of AC voltage when said semiconductor switch is in said non-conducting state;
and
a control circuit operable to control said semiconductor switch into said conducting state for an on-time each half-cycle of said AC voltage;
said control circuit coupled to an input of said power supply for monitoring a voltage of said power supply;
wherein said control circuit is operable to decrease said on-time when said input voltage of said power supply falls below a first predetermined voltage threshold.

4 more elements

Dependencies are inferred from the claim text.

Dimmer having a power supply monitoring circuit

Life of this patent

Dimmer having a power supply monitoring circuit

Life of this patent

Abstract

Claims10