Method and apparatus for sensing output inductor current in a DC-to-DC power converter
First Claim
1. A DC-to-DC power converter, comprising:
- at least one power switch connected to an input voltage source;
at least one phase sensing switch connected to said input voltage source in parallel with said at least one power switch;
a pulse width modulation circuit for generating common control pulses for said at least one power switch and said at least one phase sensing switch responsive to a current sense signal;
an output inductor connected to said at least one power switch and to a load;
a current sensor coupled to said output inductor and providing said current sense signal corresponding to current passing through an internal DC resistance of said output inductor, said current sensor further including a first filter that includes an on-state resistance of said at least one power switch.
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Accused Products
Abstract
A current sense circuit for a DC-to-DC power converter accurately senses the output inductor current without adversely affecting efficiency of the power converter. The current sense circuit produces a current sense signal having amplitude sufficiently above the noise floor so that accurate load control of the power converter is achieved. Specifically, the DC-to-DC power converter includes at least one power switch connected to an input voltage source. At least one phase sensing switch is connected to the input voltage source in parallel with the at least one power switch. A pulse width modulation circuit provides common control pulses for the at least one power switch and the at least one phase sensing switch responsive to a current sense signal. An output inductor is connected to the at least one power switch and to a load. A current sensor is coupled to the output inductor and providing the current sense signal to the pulse width modulation circuit corresponding to current passing through an internal DC resistance of the output inductor. The current sensor further includes a filter that includes an on-state resistance of the at least one power switch. The current sensor further includes a second filter adapted to remove noise from the current sense signal when the at least one phase sensing switch and the at least one power switch change state.
231 Citations
20 Claims
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1. A DC-to-DC power converter, comprising:
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at least one power switch connected to an input voltage source;
at least one phase sensing switch connected to said input voltage source in parallel with said at least one power switch;
a pulse width modulation circuit for generating common control pulses for said at least one power switch and said at least one phase sensing switch responsive to a current sense signal;
an output inductor connected to said at least one power switch and to a load;
a current sensor coupled to said output inductor and providing said current sense signal corresponding to current passing through an internal DC resistance of said output inductor, said current sensor further including a first filter that includes an on-state resistance of said at least one power switch. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. In a DC-to-DC power converter comprising at least one power switch connected to an input voltage source, at least one phase sensing switch connected to said input voltage source in parallel with said at least one power switch, a pulse width modulation circuit for generating common control pulses for said at least one power switch and said at least one phase sensing switch, and an output inductor connected to said at least one power switch and to a load, a method for sensing output current comprises the steps of:
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sensing output current passing through said output inductor using a current sensor connected to said output inductor and to said at least one phase sensing switch, the current sensor comprising a capacitor and a resistance that includes at least an on-state resistance of said at least one power switch;
generating a current sense signal corresponding to said output current; and
operating said pulse width modulation circuit to control the at least one power switch responsive to said current sense signal. - View Dependent Claims (12, 13)
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14. A control circuit for use with a DC-to-DC power converter comprising at least one power switch connected to an input voltage source, an output inductor connected to said at least one power switch and to a load, and a current sensor connected to said output inductor, the control circuit comprising:
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at least one phase sensing switch connected to said input voltage source in parallel with said at least one power switch;
a pulse width modulation circuit for generating common control pulses for said at least one power switch and said at least one phase sensing switch responsive to a current sense signal provided by said current sensor;
wherein, said current sensor is further connected to said at least one phase sensing switch, the current sensor comprising a capacitor and a resistance that includes at least an on-state resistance of said at least one power switch. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification