High efficiency switching regulator
First Claim
1. A switching regulator for receiving an unregulated input voltage and supplying a regulated DC voltage to its output, said switching regulator comprising:
- a first series switching path including a first series power switching means, a first series inductor means, and a first catch diode means;
a second series switching path including a second series power switching means, a second series inductor means, and a second catch diode means;
means for coupling said unregulated input voltage to said first and second series power switching means;
means for summing the outputs of said first and second series inductor means and supplying said regulated DC voltage to said regulator output;
means responsive to said regulated DC output voltage for generating an error signal when said output voltage falls below a predetermined desired level;
means for alternately selecting one of said first and second series power switching means; and
means for supplying drive current to the selected one of said first and second series power switching means and for sustaining said drive current for the duration of said error signal.
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Accused Products
Abstract
An improved switching regulator converts an unregulated DC voltage into a regulated DC output voltage and maintains regulation over the entire range from maximum load current through zero load current. The improved regulator employs a plurality of series switching paths connected between the unregulated DC input and a summing node at a filter capacitor output. Each series switching path includes a power switching element, a catch diode and a series inductor. The other end of the summing node is connected through a current limiting circuit to the DC regulated output, and at least a portion of the voltage at the summing node is fed to a voltage error amplifier and used to control the duty cycle of the series switching elements. Feedback from the current limiting circuit can override the voltage error amplifier control should the maximum current limit be exceeded. The switching control means employs pulse-width modulation for adjusting the duty cycle of the series switching elements, and the technique of pulse-width modulation employed in the present invention is of the constant frequency, variable "ON" time variety, as known in the art. The switching element control means utilizes a selecting means whereby different ones of the switching elements in different ones of the series switching paths are sequentially selected such that the selected series switching element is always turned on into a non-conducting inductor and a fully-recovered catch diode so as to minimize or eliminate the power loss associated with switch turn-on; the noise usually associated with switching regulators; and the turn-on transient which is often propagated into the supply line in the switching regulators of the prior art, thereby allowing highly efficient and reliable regulation to be maintained at very low values or even no value of load current.
199 Citations
22 Claims
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1. A switching regulator for receiving an unregulated input voltage and supplying a regulated DC voltage to its output, said switching regulator comprising:
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a first series switching path including a first series power switching means, a first series inductor means, and a first catch diode means; a second series switching path including a second series power switching means, a second series inductor means, and a second catch diode means; means for coupling said unregulated input voltage to said first and second series power switching means; means for summing the outputs of said first and second series inductor means and supplying said regulated DC voltage to said regulator output; means responsive to said regulated DC output voltage for generating an error signal when said output voltage falls below a predetermined desired level; means for alternately selecting one of said first and second series power switching means; and means for supplying drive current to the selected one of said first and second series power switching means and for sustaining said drive current for the duration of said error signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. In a regulated power supply including means for transforming a first level of AC input signal into a second level of AC input signal;
- means for rectifying said second level of AC input signal;
means for filtering the output of said rectifier means; and
an improved switching regulator means for receiving the output of the DC filter means and providing a regulated DC output voltage, said improved switching regulator comprising;a plurality of N series switching paths, each of which includes a power transistor switching means, a catch diode means, and a choke coil means, each of said plurality of N series switching paths terminating in a common summing node and being connected in parallel between the output of said filtering means and said common summing node; filter capacitor means coupled between said common summing node and ground; means coupled to said common summing node for outputting said regulated DC output voltage; means coupled to said common summing node for sensing voltage output errors and for generating a control signal in response thereto; a plurality of N independent drive means each of which is associated with a corresponding one of said plurality of N series power transistor switching means for turning said series transistor power switching means on and off; counter means for sequentially enabling individual ones of said plurality of N drive means; and pulse-width modulator means having its output coupled to each of said plurality of N drive means, said pulse-width modulator means being responsive to said error signal for varying the width of the output pulse supplied to each of said plurality of N drive means such that the enabled one of said drive means will supply drive current to its respective series power transistor switching means for the duration of said modulated output pulse. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
- means for rectifying said second level of AC input signal;
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19. An improved method of switching regulation comprising the steps of:
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providing at least a first and a second series switching path, each of said paths including a power switching means, a catch diode means, and a series inductor; summing the outputs of said plurality of series switching paths at a filter capacitor to supply a regulated DC voltage output to a load; sensing differences between the summed voltage and a predetermined desired level of output voltage for generating an error signal; sequentially selecting different ones of said series power switching means; and controlling the on and off time of said selected series power switching means in accordance with the duration of said error signal. - View Dependent Claims (20)
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21. In a switching regulator for regulating a DC output voltage by varying the duty cycle of a power transistor switch by the use of pulse-width modulation techniques, the improvement comprising:
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a plurality of individual series switching paths each of which includes a power-transistor switch; means for coupling said plurality of switching paths between a source of unregulated voltage and a regulated voltage output; and means for sequentially addressing different ones of said power-transistor switches for controlling the duty cycle thereof to insure that said regulated DC output voltage remains constant.
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22. In a switching regulator system wherein constant regulated DC output voltage is provided by regulating the duty cycle of a power transistor switching means in accordance with a feed-back signal indicative of a voltage error at the output of the switching regulator, an improvement comprising:
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N switching paths coupled between a source of unregulated input voltage and the regulated output of said switching regulator system, each of said N series switching paths including a power transistor switching means, a series inductor, and a catch diode; an N-counter means for sequentially generating N unique counts, each of said N unique counts being used to address a unique one of said N power transistor switching means; and means responsive to a voltage error at the output of said switching regulator system for controlling the on and off time of said addressed power transistor switching means for restoring the regulated DC output voltage to its desired level.
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Specification