Method and apparatus for trimming current limit and frequency to maintain a constant maximum power
First Claim
1. A power supply regulator, comprising:
- a power switch coupled between first and second terminals;
a control circuit coupled to switch the power switch;
a current limit circuit coupled to the power switch and the control circuit to control a current through the power switch during operation of the power supply regulator, the current limit circuit having a peak current limit threshold (Ip); and
an oscillator coupled to provide the control circuit an oscillating signal, the control circuit to switch the power switch in response to the oscillating signal, the oscillating signal having an operating frequency (f), wherein a maximum deliverable power value of a power supply to be regulated by the power supply regulator is trimmed during manufacture of the power supply to be a substantially constant value during operation of the power supply regulator, wherein the trimming of the maximum deliverable power value is separate from the control of the current through the power switch during operation of the power supply regulator.
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Accused Products
Abstract
Methods and apparatuses to trim current limit (Ip) and frequency (f) to maintain a constant maximum power. In one aspect of the invention, a power supply regulator having a peak current limit detection threshold and an operating frequency is disclosed. The peak current limit threshold or the operating frequency are adjusted specifically to maintain the Ipm·fn product substantially constant from one power supply controller to another where m is substantially equal to 2 and n is substantially equal to 1. In another aspect of the invention, the power supply regulator has a control circuit having a control threshold current. The peak current limit threshold or the operating frequency are adjusted specifically to maintain the product of Ipm·fn divided by the control threshold current substantially constant from one power supply controller to another where m is substantially equal to 2 and n is substantially equal to 1.
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Citations
32 Claims
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1. A power supply regulator, comprising:
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a power switch coupled between first and second terminals;
a control circuit coupled to switch the power switch;
a current limit circuit coupled to the power switch and the control circuit to control a current through the power switch during operation of the power supply regulator, the current limit circuit having a peak current limit threshold (Ip); and
an oscillator coupled to provide the control circuit an oscillating signal, the control circuit to switch the power switch in response to the oscillating signal, the oscillating signal having an operating frequency (f), wherein a maximum deliverable power value of a power supply to be regulated by the power supply regulator is trimmed during manufacture of the power supply to be a substantially constant value during operation of the power supply regulator, wherein the trimming of the maximum deliverable power value is separate from the control of the current through the power switch during operation of the power supply regulator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A switched mode power supply, comprising:
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an energy transfer element having an output coupled to an output of the switched mode power supply; and
a power supply regulator coupled to an input of the switched mode power supply and an input of the energy transfer element, the power supply regulator coupled to operate at an operating frequency (f) and coupled to detect a current flowing through the input of the energy transfer element substantially equal to a peak current limit threshold (Ip) wherein a maximum deliverable power value of the switched mode rower supply is trimmed during manufacture to be a substantially constant value during operation of the power supply regulator, wherein the trimming of the maximum deliverable power value is separate from control of the current flowing through the input of the energy transfer element during operation of the power supply regulator. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method, comprising:
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trimming to a substantially constant value during manufacture of a power supply a maximum deliverable power value of the power supply to be regulated by a power supply regulator;
switching a power switch of the power supply regulator at an operating frequency (f) during operation of the power supply regulator; and
controlling a current through the power switch to keen the current through the power switch below a peak current limit threshold (Ip) during operation of the power supply regulator. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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25. A power supply regulator, comprising:
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a power switch coupled between first and second terminals;
a control circuit coupled to switch the power switch, the control circuit having a control threshold current, above which the control circuit is adapted to reduce a duty cycle at which the power switch is switched during operation of the power supply regulator;
a current limit circuit coupled to the power switch and the control circuit to control a current through the power switch during operation of the power supply regulator the current limit circuit having a peak current limit threshold (Ip); and
an oscillator coupled to provide the control circuit an oscillating signal, the control circuit to switch the power switch in response to the oscillating signal during operation of the power supply regulator, the oscillating signal having an operating frequency (f), wherein a maximum deliverable power value of a power supply to be regulated by the power supply regulator is trimmed during manufacture of the power supply to be a substantially constant value during operation of the power supply regulator, wherein the trimming of the maximum deliverable power value is separate from the control of the current through the power switch during operation of the power supply regulator. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32)
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Specification