Electricity: power supply or regulation systems – Output level responsive – Using a three or more terminal semiconductive device as the...
Reexamination Certificate
2001-06-12
2003-01-28
Patel, Rajnikant B. (Department: 2838)
Electricity: power supply or regulation systems
Output level responsive
Using a three or more terminal semiconductive device as the...
C323S287000
Reexamination Certificate
active
06512353
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to the field of regulated power sources and more specifically, to a method and apparatus for improving the response of switching regulators to load transients.
BACKGROUND OF THE INVENTION
FIG. 1
depicts, at a high level, a system
10
known to the prior art for controlling a switching regulator to regulate an output voltage. The system includes a PWM module
14
, a first comparator
18
, a second comparator
22
, a first logic element
26
and a second logic element
30
. The output of the second logic element
30
controls a switch
34
of a switching regulator. The PWM module
14
generates a pulse width modulated command signal to control the switch
34
. Whenever the first comparator
18
detects that the output voltage
38
goes out of range (i.e., decreases below a first predetermined acceptable level), the first comparator
18
, via logic element
30
, rapidly overrides the control signal generated by the PWM module
14
and controls the switch
34
until the out of range condition ends. Similarly, whenever the second comparator
22
detects that the output voltage
38
goes out of range (i.e., increases above a second predetermined acceptable level), the second comparator
22
, via logic elements
26
and
30
, rapidly overrides the control signal generated by the PWM module
14
and controls the switch
34
until the out of range condition ends. This substantially immediate exit from the PWM control can lead to undesirable effects in the regulated output voltage.
SUMMARY OF THE INVENTION
It is an object of this invention to synchronize the action taken by the out-of-range detection circuits with one or more predefined events. In one aspect, the invention relates to a method of controlling a switching regulator to regulate an output voltage. The method includes receiving a first enable signal and a second enable signal, comparing a feedback voltage representative of the output voltage to a first reference voltage and generating a first limit signal in response thereto, and generating, in response to the first enable signal, a close switch command if the first limit signal indicates that the feedback voltage is less than the first reference voltage. The method further includes comparing the feedback voltage to a second reference voltage and generating a second limit signal in response thereto, and generating, in response to the second enable signal, an open switch command if the second limit signal indicates that the feedback voltage is greater than the second reference voltage.
In one embodiment, the method includes comparing the feedback voltage to a third reference voltage and generating a threshold signal in response thereto, and inhibiting the close switch command if the threshold signal indicates that the feedback voltage is greater than the third reference voltage. In another embodiment, the method includes generating a switch control signal. In another embodiment, the step of generating the switch control signal further includes receiving a clock signal, asserting a first state of the switch control signal in response to the clock signal, and comparing the feedback voltage to a fourth reference voltage and generating a difference signal in response thereto. The step of generating the switch control signal also includes comparing the difference signal and a timed ramp signal and asserting a second state of the switch control signal in response to the comparison of the difference signal and the timed ramp signal. In another embodiment, the method includes generating the first enable signal in response to the switch control signal. In another embodiment, the method includes generating the second enable signal in response to the clock signal.
In another embodiment, the method includes receiving a switch type signal having a first state and a second state. In another embodiment, the method includes converting the switch control signal into a drive signal compatible with a p-channel switching device in response to the first state of the switch type signal and converting the switch control signal into a drive signal compatible with a n-channel switching device in response to the second state of the switch type signal. In another embodiment, the method includes using the switch control signal to control a synchronous switching regulator. In another embodiment, the method includes generating the first enable signal in response to a logical combination of a plurality of regulator signals. In another embodiment, the method includes generating the second enable signal in response to a logical combination of the plurality of regulator signals.
In another aspect, the invention relates to a method of controlling a switching regulator to regulate an output voltage. The method includes receiving an enable signal, comparing a feedback voltage representative of the output voltage to a first reference voltage and generating a limit signal in response thereto, and generating, in response to the enable signal, a close switch command if the limit signal indicates that the feedback voltage is less than the first reference voltage. In one embodiment, the method includes comparing the feedback voltage to a second reference voltage and generating a threshold signal in response thereto, and inhibiting the close switch command if the threshold signal indicates that the feedback voltage is greater than the second reference voltage.
In another embodiment, the method includes generating a switch control signal. In another embodiment, the step of generating the switch control signal also includes receiving a clock signal, asserting a first state of the switch control signal in response to the clock signal, and comparing the feedback voltage to a third reference voltage and generating a difference signal in response thereto. The method further includes comparing the difference signal and a timed ramp signal and asserting a second state of the switch control signal in response to the comparison of the difference signal and the timed ramp signal. In another embodiment, the method includes generating the enable signal in response to the switch control signal.
In another embodiment, the method includes receiving a switch type signal having a first state and a second state. In another embodiment, the method includes converting the switch control signal into a drive signal compatible with a p-channel switching device in response to the first state of the switch type signal and converting the switch control signal into a drive signal compatible with a n-channel switching device in response to the second state of the switch type signal. In another embodiment, the method includes using the switch control signal to control a synchronous switching regulator. In another embodiment, the method includes generating the enable signal in response to a logical combination of a plurality of regulator signals.
In another aspect the invention relates to a method of controlling a switching regulator to regulate an output voltage. The method includes receiving an enable signal, comparing a feedback voltage representative of the output voltage to a first reference voltage and generating a limit signal in response thereto, and generating, in response to the enable signal, an open switch command if the limit signal indicates that the feedback voltage is greater than the first reference voltage. In one embodiment, the method includes generating a switch control signal. The step of generating the switch control signal includes receiving a clock signal, asserting a first state of the switch control signal in response to the clock signal, and comparing the feedback voltage to a second reference voltage and generating a difference signal in response thereto. The step of generating the switch control signal further includes comparing the difference signal and a timed ramp signal and asserting a second state of the switch control signal in response to the comparison of the difference signal and the timed ramp signal.
In another embodiment, the method includes generating
Sanzo Christopher J.
Tuozzolo Claudio
Patel Rajnikant B.
Sipex Corporation
Testa Hurwitz & Thibeault LLP
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