Cable compensation circuit and power supply including the same
AssigneeSemiconductor Components Industries, LLC
InventorsGwanbon KOO, Taesung KIM
Life of this patent
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Abstract
A cable compensation circuit compensates a voltage drop in a cable coupled between a power supply and a load. The cable compensation circuit includes: a node where a voltage that depends on an input voltage of the power supply during a turn-on period of a power switch of the power supply and depends on an output voltage of the power supply during a turn-off period of the power switch is generated; a sensing RC filter generating a sense voltage that depends on a diode current by filtering the voltage of the node; and an averaging RC filter generating an average voltage by averaging the sense voltage.
Claims20
A compensation circuit for compensating for a voltage drop in a cable coupled between a power supply and a load, the compensation circuit comprising:
- a sensing resistive-capacitive (RC) filter including a first capacitor and configured to receive a voltage from an auxiliary winding of the power supply and generate a sense voltage by RC filtering the received voltage;
- and
- an averaging filter including a second capacitor and configured to generate an average voltage by averaging the sense voltage,
- wherein the power supply comprises a transformer including a primary winding, a secondary winding, and the auxiliary winding, a power switch coupled through the primary winding to an input voltage, and a rectifying diode coupled between the secondary winding and the output voltage,
- wherein the compensation circuit provides the average voltage to a feedback circuit of the power supply, and
- wherein the power supply uses the average voltage to control the power switch.
A power supply comprising:
- a transformer including a primary winding, a secondary winding, and an auxiliary winding;
- a power switch coupled through the primary winding to an input voltage;
- a rectifying diode coupled between the secondary winging and an output voltage for supplying to a load;
- a gate driver configured to control a switching operation of the power switch based on a feedback signal;
- a cable compensation circuit configured to:
- receive an auxiliary voltage from the auxiliary winding,
- generate, on a first capacitor, a sense voltage by resistive-capacitive (RC) filtering of the auxiliary voltage,
- generate, on a second capacitor, and average voltage by averaging the sense voltage;
- and
- a feedback circuit configured to generate a feedback signal based on the output voltage and the average voltage.
A method of compensating for a voltage drop in a cable coupled between a power supply and a load, the method comprising:
- generating, on an auxiliary winding of a transformer, an auxiliary voltage that is proportional to an input voltage of the power supply during a turn-on period of a power switch and is proportional to an output voltage of the power supply during a turn-off period of the power switch, wherein the output voltage is coupled through a rectifying diode to a secondary winding of the transformer, and wherein the input voltage is coupled through a primary winding of the transformer to the power switch;
- generating, using a sensing resistive-capacitive (RC) filter including a first capacitor, a sense voltage by RC filtering of the auxiliary voltage;
- and
- generating, using an averaging filter including a second capacitor, an average voltage by averaging a voltage value of the sense voltage, and
- controlling the power switch to increase a magnitude of the output voltage in response to an increase in the magnitude of the average voltage.
Dependencies are inferred from the claim text.