PFC shutdown circuit for light load
First Claim
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1. A power converter comprising:
- a front end stage comprising a power factor correction controller;
an output stage comprising a DC/DC controller;
light load detection circuitry coupled to detect relatively low power consumption by a load on an output of the output stage and, in response to the detection, turn off the power factor correction controller in the front end stage; and
a bias supply circuit coupled between the front end stage and the light load detection circuitry, wherein the bias supply circuit comprises;
a first transistor having a base coupled to the light load detection circuitry;
a resistor directly coupled between the first transistor and a first voltage node;
a zener diode directly coupled between the first transistor and an input return; and
a second transistor directly coupled between the first voltage node and the front end stage, wherein the second transistor includes a base coupled to a second voltage node between the first transistor and the zener diode.
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Abstract
A power converter includes a front end stage having a power factor correction controller, an output stage with a DC/DC controller, and light load detection circuitry coupled to detect relatively low power consumption by a load on an output of the output stage. In response to the detection, the power factor correction controller in the front end stage is turned off.
37 Citations
38 Claims
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1. A power converter comprising:
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a front end stage comprising a power factor correction controller; an output stage comprising a DC/DC controller; light load detection circuitry coupled to detect relatively low power consumption by a load on an output of the output stage and, in response to the detection, turn off the power factor correction controller in the front end stage; and a bias supply circuit coupled between the front end stage and the light load detection circuitry, wherein the bias supply circuit comprises; a first transistor having a base coupled to the light load detection circuitry; a resistor directly coupled between the first transistor and a first voltage node; a zener diode directly coupled between the first transistor and an input return; and a second transistor directly coupled between the first voltage node and the front end stage, wherein the second transistor includes a base coupled to a second voltage node between the first transistor and the zener diode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A power converter comprising:
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a boost power factor correction stage comprising a power factor correction controller; a DC/DC stage comprising a DC/DC controller; light load detection circuitry coupled to detect relatively low power consumption by a load on an output of the DC/DC stage and, in response to the detection, turn off the power factor correction controller in the boost power factor correction stage; and a bias supply circuit coupled between the boost factor correction stage and the light load detection circuitry, wherein the bias supply circuit comprises; a first transistor having a base coupled to the light load detection circuitry; a resistor directly coupled between the first transistor and a first voltage node; a zener diode directly coupled between the first transistor and an input return; and a second transistor directly coupled between the first voltage node and the boost factor correction stage, wherein the second transistor includes a base coupled to a second voltage node between the first transistor and the zener diode. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A power converter comprising:
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a rectifier coupled to rectify an input AC signal and output a first DC signal having a first peak amplitude; a power factor correction front end stage configured to, in a first state, receive the first DC signal output from the rectifier and output a second DC signal having a larger peak amplitude than the first peak amplitude, and in a second state, receive the first DC signal and output a third DC signal having a smaller peak amplitude than the first peak amplitude; an output stage coupled to receive either the second DC signal or the third DC signal from the power factor correction front end stage and output a regulated DC signal to power a load; load detection circuitry coupled to output a low load signal in response to detection of relatively low power consumption by the load, the power factor correction front end stage configured to switch into the second state in response to the low load signal; and a bias supply circuit coupled between the power factor correction front end stage and the load detection circuitry, wherein the bias supply circuit comprises; a first transistor having a base coupled to receive the low load signal from the load detection circuitry; a resistor directly coupled between the first transistor and a first voltage node; a zener diode directly coupled between the first transistor and an input return; and a second transistor directly coupled between the first voltage node and the power factor correction front end stage, wherein the second transistor includes a base coupled to a second voltage node between the first transistor and the zener diode. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
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Specification