One pin error amplifier and switched soft-start for an eight pin PFC-PWM combination integrated circuit converter controller
First Claim
1. A converter controller for controlling a converter, the converter having a power factor correction stage, the power factor correction stage having a control loop for forming a regulated output voltage at an output node wherein the control loop comprises an error amplifier, the error amplifier comprising:
- a. a first resistor having a first terminal and a second terminal wherein the first terminal of the first resistor is coupled to the output node of the power factor correction stage and the second terminal of the first resistor forms an output node of the error amplifier; and
b. means for drawing a constant current from the output node of the error amplifier.
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Accused Products
Abstract
A combination PFC-PWM integrated circuit converter controller having a power factor correction stage and a pulse-width modulation stage. The power factor correction stage provides unity power factor and a regulated intermediate output voltage by sensing a current in the power factor correction circuit and by sensing the regulated intermediate output voltage in a voltage control loop. The regulated intermediate output voltage is sensed by an error amplifier that includes a current mirror. A dc supply voltage for powering the integrated circuit is generated that is representative of the regulated intermediate output voltage. The dc supply voltage is sensed for an overvoltage protection function. By sensing the intermediate regulated output voltage in the voltage control loop and by sensing the dc supply voltage for overvoltage protection, a component failure is less likely to affect both functions than if a single voltage was sensed for both functions. The pulse-width modulation stage waits a predetermined delay time after start up for the output voltage to rise before beginning the pulse-width modulation function. The delay time is determined by an amount of time taken to charge a capacitor to a predetermined voltage after start up. The capacitor is charged by a current source that is switched on and off according to a clock signal such that the capacitor is charged only a portion of time. Therefore, a larger current source may be used than otherwise which results in more reliable control of the delay time.
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Citations
27 Claims
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1. A converter controller for controlling a converter, the converter having a power factor correction stage, the power factor correction stage having a control loop for forming a regulated output voltage at an output node wherein the control loop comprises an error amplifier, the error amplifier comprising:
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a. a first resistor having a first terminal and a second terminal wherein the first terminal of the first resistor is coupled to the output node of the power factor correction stage and the second terminal of the first resistor forms an output node of the error amplifier; and b. means for drawing a constant current from the output node of the error amplifier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A converter controller for controlling a converter, the converter comprising a power factor correction stage wherein the power factor correction stage comprises means for switching coupled to alternately charge a first inductor and to discharge the first inductor into an output capacitor for forming a regulated output voltage across the output capacitor and means for forming a supply voltage for providing power to the converter controller wherein the means for forming the supply voltage comprises a second inductor inductively coupled to the first inductor, and wherein the converter controller comprises:
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a. means for controlling the means for switching in a feedback loop for maintaining the regulated output voltage at a desired level, the means for controlling coupled to the output capacitor and to the means for switching; and b. means for disabling coupled to the means for switching for disabling the means for switching when a level of voltage formed by the means for forming the supply voltage exceeds a predetermined level. - View Dependent Claims (14, 15)
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16. A converter controller for controlling a converter, the converter having a pulse-width modulation stage, the pulse width modulation stage comprising:
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a. a capacitor; b. means for charging the capacitor with a first current during periodic intervals upon start-up of the converter; c. means for charging the capacitor with a second current during alternate intervals; and d. means for preventing the pulse-width modulation function from beginning until after a voltage across the capacitor has risen to a predetermined level. - View Dependent Claims (17, 18, 19, 20, 21)
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22. An error amplifier having an input node and output node, wherein a change in an input voltage level applied to the input node results in a change in an output voltage formed at the output node wherein the change in the output voltage relative to an expected quiescent value for the output voltage is greater than the change in the input voltage relative to an expect quiescent value for the input voltage, the error amplifier comprising:
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a. a first resistor having a first terminal and a second terminal wherein the first terminal of the first resistor forms the input node for the error amplifier and the second terminal of the first resistor forms the output node for the error amplifier; and b. means for drawing a constant current through the resistor. - View Dependent Claims (23, 24, 25, 26, 27)
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Specification