Controller for switching power converter driving BJT based on primary side adaptive digital control
First Claim
1. A switching power converter comprising:
- a transformer coupled between an input voltage and an output of the switching power converter, the transformer including a primary winding coupled to the input voltage and a secondary winding coupled to the output of the switching power converter;
a switch coupled to the primary winding of the transformer, current through the primary winding being generated while the switch is turned on and not being generated while the switch is turned off; and
a controller configured to generate a control signal to turn on or turn off the switch, the switch being turned on responsive to the control signal being in a first state and the switch being turned off responsive to the control signal being in a second state,wherein the controller is further configured to generate the control signal in the second state to turn off the switch responsive to a sensed signal indicative of the current through the primary winding exceeding a peak current threshold for peak current switching of the switching power converter, wherein a slope of increase of the sensed signal indicative of the current through the primary winding is substantially proportional to the input voltage to the switching power converter and is a proxy for the input voltage.
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Accused Products
Abstract
A controller of an AC/DC flyback switching power supply uses adaptive digital control approaches to control the switching operation of a BJT power switch based on primary-side feedback to regulate the secondary-side constant output voltage and output current, without using the input line voltage. Switching-cycle by switching-cycle peak current control and limit are achieved based on the sensed primary-side current rather than the input line voltage in both constant-voltage and constant-current modes, operating in PWM, PFM and/or combinations of a plurality of PWM and PFM modes. The controller IC does not need a separate pin and ADC circuitry for sensing the input line voltage. The controller IC directly drives the BJT base, and dynamically adjusts the BJT base current amplitude cycle by cycle based on load change.
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Citations
23 Claims
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1. A switching power converter comprising:
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a transformer coupled between an input voltage and an output of the switching power converter, the transformer including a primary winding coupled to the input voltage and a secondary winding coupled to the output of the switching power converter; a switch coupled to the primary winding of the transformer, current through the primary winding being generated while the switch is turned on and not being generated while the switch is turned off; and a controller configured to generate a control signal to turn on or turn off the switch, the switch being turned on responsive to the control signal being in a first state and the switch being turned off responsive to the control signal being in a second state, wherein the controller is further configured to generate the control signal in the second state to turn off the switch responsive to a sensed signal indicative of the current through the primary winding exceeding a peak current threshold for peak current switching of the switching power converter, wherein a slope of increase of the sensed signal indicative of the current through the primary winding is substantially proportional to the input voltage to the switching power converter and is a proxy for the input voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A switching power converter comprising:
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a transformer coupled between an input voltage and an output of the switching power converter, the transformer including a primary winding coupled to the input voltage and a secondary winding coupled to the output of the switching power converter; a switch coupled to the primary winding of the transformer, current through the primary winding being generated while the switch is turned on and not being generated while the switch is turned off; and a controller configured to generate a control signal to turn on or turn off the switch, the switch being turned on responsive to the control signal being in a first state and the switch being turned off responsive to the control signal being in a second state, wherein the controller does not receive the input voltage for regulation of output voltage or output current of the switching power converter and uses a slope of increase of a sensed signal indicative of the current through the primary winding as a proxy for the input voltage. - View Dependent Claims (12, 13, 14, 15, 16)
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17. In a controller, a method of controlling a switching power converter, the switching power converter including a transformer coupled between an input voltage and an output of the switching power converter, the transformer including a primary winding coupled to the input voltage and a secondary winding coupled to the output of the switching power converter, and a switch coupled to the primary winding of the transformer, current through the primary winding being generated while the switch is turned on and not being generated while the switch is turned off, the method comprising:
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generating a control signal to turn on the switch, the switch being turned on responsive to the control signal being in a first state; and generating the control signal in a second state to turn off the switch, responsive to a sensed signal indicative of the current in the primary winding of the transformer exceeding a peak current threshold for peak current switching of the switching power converter, wherein a slope of increase of the sensed signal indicative of the current through the primary winding is substantially proportional to the input voltage to the switching power converter and is a proxy for the input voltage. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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Specification