DC to DC converter with high efficiency for light loads
First Claim
1. A switching voltage regulator comprising:
- an output terminal connected to a load;
an output circuit including an inductor for storing energy and an output capacitor coupled to said output terminal which supplies a regulated voltage to said output terminal;
a switch coupled to said inductor so as to alternate an input voltage applied to said inductor in response to a switching control signal;
a rectifying circuit coupled to said inductor so as to freewheel current in said inductor and substantially prevent a reverse current through said inductor from said output terminal; and
a switching control circuit which provides said switching control signal to said switch so as to maintain said regulated voltage to said output terminal, said switching control circuit comprising;
a first circuit which monitors a voltage provided to said output terminal and generates a first feedback signal which indicates a target inductor current for providing the regulated voltage to the output terminal,a second circuit which monitors an inductor current output by said inductor to said output terminal and generates a second feedback signal which indicates the inductor current,a logic circuit with first, second and third input terminals for receiving first, second, and third control signals, respectively, and at least one output terminal for outputting said switching control signal to close said switch when said first and second control signals are active and for outputting said switching control signal to open said switch when said third control signal is active,a pulse generating circuit for providing said first control signal to said first input terminal of said logic circuit,a third circuit which provides said third control signal to said third input of said logic circuit in response to said first and second feedback signals, said third control signal being active when said second feedback signal has a greater value than said first feedback signal, anda fourth circuit responsive to said first feedback signal so as to provide said second control signal to said second input of said logic circuit, said second control signal being active when said first feedback signal has a value greater than a predetermined value.
1 Assignment
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Accused Products
Abstract
A DC to DC converter which maintains high efficiency over broad current ranges in a current mode switching regulator circuit without changing operational mode. A low ripple voltage is maintained over the entire load range and good voltage regulation is maintained with high efficiency. This is possible because the switching frequency is adjusted in accordance with the load without changing operational states, thus making it unnecessary to define plural states of operation. The timing of turning on the switch(es) varies since the switch(es) is (are) turned on when two set (ready) signals both become ready. For fixed frequency switching applications, switching pulses from a fixed frequency oscillator as a first set signal are skipped when a second set signal is not ready. On the other hand, for a variable frequency switching scheme which is implemented by driving the switching with a one-shot having a constant OFF time, the switching pulse is created after both set signals become active. A low pass filter is also used to dynamically adjust the minimum peak inductor current and to minimize ripple voltage for low load conditions so that a smaller output capacitor may be used.
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Citations
35 Claims
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1. A switching voltage regulator comprising:
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an output terminal connected to a load; an output circuit including an inductor for storing energy and an output capacitor coupled to said output terminal which supplies a regulated voltage to said output terminal; a switch coupled to said inductor so as to alternate an input voltage applied to said inductor in response to a switching control signal; a rectifying circuit coupled to said inductor so as to freewheel current in said inductor and substantially prevent a reverse current through said inductor from said output terminal; and a switching control circuit which provides said switching control signal to said switch so as to maintain said regulated voltage to said output terminal, said switching control circuit comprising; a first circuit which monitors a voltage provided to said output terminal and generates a first feedback signal which indicates a target inductor current for providing the regulated voltage to the output terminal, a second circuit which monitors an inductor current output by said inductor to said output terminal and generates a second feedback signal which indicates the inductor current, a logic circuit with first, second and third input terminals for receiving first, second, and third control signals, respectively, and at least one output terminal for outputting said switching control signal to close said switch when said first and second control signals are active and for outputting said switching control signal to open said switch when said third control signal is active, a pulse generating circuit for providing said first control signal to said first input terminal of said logic circuit, a third circuit which provides said third control signal to said third input of said logic circuit in response to said first and second feedback signals, said third control signal being active when said second feedback signal has a greater value than said first feedback signal, and a fourth circuit responsive to said first feedback signal so as to provide said second control signal to said second input of said logic circuit, said second control signal being active when said first feedback signal has a value greater than a predetermined value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A switching voltage regulator comprising:
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an output terminal connected to a load; an output circuit including an inductor for storing energy and an output capacitor coupled to said output terminal which supplies a regulated voltage to said output terminal; switching means coupled to said inductor for alternating an input voltage applied to said inductor in response to a switching control signal; rectifying means coupled to said inductor for freewheeling current in said inductor and substantially preventing a reverse current through said inductor from said output terminal; and switching control means for providing said switching control signal to said switching means so as to maintain said regulated voltage to said output terminal, said switching control means comprising; means for monitoring a voltage provided to said output terminal and for generating a first feedback signal which indicates a target inductor current for providing the regulated voltage to the output terminal, driving means responsive to said first feedback signal for selectively supplying driving pulses to said switching means as said switching control signal so as to control duty cycle switching of said switching means, and for varying a frequency of said switching by said switching means by an amount proportional to a current through said inductor when said first feedback signal has a value greater than a predetermined threshold, and a low pass filter which filters said first feedback signal so as to dynamically adjust a minimum peak inductor current through said inductor. - View Dependent Claims (17, 18, 19, 20)
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21. A switching voltage regulator comprising:
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an output terminal connected to a load; an output circuit including an inductor for storing energy and an output capacitor coupled to said output terminal which supplies a regulated voltage to said output terminal; switching means coupled to said inductor for alternating an input voltage applied to said inductor in response to a switching control signal; rectifying means coupled to said inductor for freewheeling current in said inductor and substantially preventing a reverse current through said inductor from said output terminal; and switching control means for providing said switching control signal to said switching means so as to maintain said regulated voltage to said output terminal, said switching control means comprising; means for monitoring a voltage provided to said output terminal and for generating a first feedback signal which indicates a target inductor current for providing the regulated voltage to the output terminal, and driving means responsive to said first feedback signal for selectively supplying driving pulses to said switching means as said switching control signal so as to control duty cycle switching of said switching means, and for varying a frequency of said switching by said switching means by an amount proportional to a current through said inductor when said first feedback signal has a value greater than a Predetermined threshold, said driving means comprising; means for monitoring an inductor current output by said inductor to said output terminal and for generating a second feedback signal which indicates the inductor current, gating means responsive to first, second, and third control signals for outputting said switching control signal to close said switching means when said first and second control signals are active and for outputting said switching control signal to open said switching means when said third control signal is active, pulse generating means for providing said first control signal to said gating means, means for providing said third control signal to said gating means in response to said first and second feedback signals, said third control signal being active when said second feedback signal has a greater value than said first feedback signal, and means responsive to said first feedback signal for providing said second control signal to said gating means, said second control signal being active when said first feedback signal has a value greater than a predetermined value. - View Dependent Claims (22, 23, 24)
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25. A switching voltage regulator comprising:
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an output terminal connected to a load; an output circuit including an inductor for storing energy and an output capacitor coupled to said output terminal which supplies a regulated voltage to said output terminal; switching means coupled to said inductor for alternating an input voltage applied to said inductor in response to a switching control signal; rectifying means coupled to said inductor for freewheeling current in said inductor and substantially preventing a reverse current through said inductor from said output terminal; and switching control means for providing said switching control signal to said switching means so as to maintain said regulated voltage to said output terminal, said switching control means comprising; means for monitoring a voltage provided to said output terminal and for generating a first feedback signal which indicates a target inductor current for providing the regulated voltage to the output terminal, and driving means responsive to said first feedback signal for selectively supplying driving pulses to said switching means as said switching control signal so as to control duty cycle switching of said switching means, and for varying a frequency of said switching by said switching means by an amount proportional to a current through said inductor when said first feedback signal has a value greater than a predetermined threshold, wherein said switching voltage regulator is a step up voltage regulator, whereby said regulated voltage is greater than said input voltage. - View Dependent Claims (26, 27)
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28. A switching voltage regulator comprising:
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an output terminal connected to a load; an output circuit including an inductor for storing energy and an output capacitor coupled to said output terminal which supplies a regulated voltage to said output terminal; switching means coupled to said inductor for alternating an input voltage applied to said inductor in response to a switching control signal; rectifying means coupled to said inductor for freewheeling current in said inductor and substantially preventing a reverse current through said inductor from said output terminal; and switching control means for providing said switching control signal to said switching means so as to maintain said regulated voltage to said output terminal, said switching control means comprising; means for monitoring a voltage provided to said output terminal and for generating a first feedback signal which indicates a target inductor current for providing the regulated voltage to the output terminal, and driving means responsive to said first feedback signal for selectively supplying driving pulses to said switching means as said switching control signal so as to control duty cycle switching of said switching means, and for varying a frequency of said switching by said switching means by an amount proportional to a current through said inductor when said first feedback signal has a value greater than a predetermined threshold, wherein said switching voltage regulator is a buck-boost voltage regulator, whereby said regulated voltage is selectively less than or greater than said input voltage. - View Dependent Claims (29, 30)
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31. A method of controlling a switching voltage regulator comprising an output terminal connected to a load, an output circuit including an inductor for storing energy and an output capacitor coupled to said output terminal which supplies a regulated voltage to said output terminal, switching means coupled to said inductor for alternating an input voltage applied to said inductor in response to a switching control signal, and rectifying means coupled to said inductor for freewheeling current in said inductor and substantially preventing a reverse current through said inductor from said output terminal, said method comprising the steps of:
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monitoring a voltage Provided to said output terminal and for generating a first feedback signal which indicates a target inductor current for providing the regulated voltage to the output terminal; selectively supplying driving pulses to control duty cycle switching of said switching means so as to maintain said regulated voltage to said output terminal in accordance with said first feedback signal; varying a frequency of said switching by said switching means by an amount proportional to a load current when said first feedback signal has a value less than a predetermined threshold; and low pass filtering said first feedback signal so as to dynamically adjust a minimum peak inductor current through said inductor. - View Dependent Claims (32, 33, 34, 35)
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Specification