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US 7,023,005 B2Granted
Gain compensation for optocoupler feedback circuit
AssigneeTexas Instruments Incorporated
InventorsDavid A. Williams, Michael G. Amaro
Life of this patent
Estimating the term…
Abstract
A feedback circuit has an optical coupler with a feedback gain control. The feedback gain control includes an active element connected to vary current flow depending on changes in gain of the optical coupler.
Claims4
A power supply, comprising:
- a power transformer having an input side and an output side;
- a rectifier connected to said output side of said power transformer and having an output at which is available an output voltage;
- a operational amplifier connected to said output of said rectifier and connected to a first reference value, said operational amplifier having an output;
- a first active element having a control input connected to said output of said operational amplifier;
- an optical coupler having an input and an output isolated from said input, said input being connected to be controlled by said first active element;
- a control circuit having an input connected to said output of said optical coupler and an output connected to said input side of said power transformer;
- a voltage divider connected to receive at least a portion of a current through said first active element and said input of said optical coupler;
- a second active element connected to selectively draw current from said first active element and said input of said optical coupler, said second active element operating relative to a second reference value to hold a gain through said optical coupler substantially constant.
5 more elements
A gain controlled feedback circuit, comprising:
- an optical coupler having an input and an output isolated from said input;
- a first transistor connected to said input of said optical coupler;
- a first operational amplifier having an output connected to a control input of said first transistor, said first operational amplifier having first and second inputs connected to a first reference value and to a value to be controlled;
- a voltage divider connected to said first transistor;
- a second operational amplifier having first and second inputs connected to a second reference value and to said voltage divider;
- and
- a second transistor having a control input connected to an output of said second operational amplifier, said second transistor having a controllable current path connected to said first transistor to draw off current from said voltage divider depending on gain variations of said optical coupler.
4 more elements
Dependencies are inferred from the claim text.