Ripple generation in buck regulator using fixed on-time control to enable the use of output capacitor having any ESR
First Claim
1. A buck switching regulator formed on an integrated circuit and receiving an input voltage, the buck switching regulator controlling a first switch and a second switch using a fixed on-time, minimum off-time feedback control scheme to drive a switch output node for generating a switching output voltage, the switch output node being coupled to an LC filter circuit external to the integrated circuit to generate a regulated output voltage having a substantially constant magnitude on an output node, the regulated output voltage being fed back to the buck switching regulator to a voltage divider for generating a feedback voltage on a feedback voltage node, the buck switching regulator comprising:
- a first capacitor and a first resistor formed on the integrated circuit of the buck switching regulator, the first capacitor and the first resistor being connected in series between the switch output node and the feedback voltage node; and
a second capacitor coupled between the output node and the feedback voltage node,wherein the first capacitor and the first resistor generate a ripple voltage signal being related to the switching output voltage and provide the ripple voltage signal to the feedback voltage node for use in the fixed on-time, minimum off-time feedback control scheme, the magnitude of the ripple voltage signal being a function of the capacitance value of the second capacitor.
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Accused Products
Abstract
A buck switching regulator formed on an integrated circuit and receives an input voltage and provides a switching output voltage on a switch output node using a fixed on-time, minimum off-time feedback control scheme. The buck switching regulator includes a first capacitor and a first resistor formed on the integrated circuit where the first capacitor and the first resistor are connected in series between the switch output node and a feedback voltage node, and a second capacitor coupled between the DC output voltage node and the feedback voltage node. The first capacitor and the first resistor generate a ripple voltage signal being related to the switching output voltage and provide the ripple voltage signal to the feedback voltage node for use in the fixed on-time, minimum off-time feedback control scheme where the magnitude of the ripple voltage signal is a function of the capacitance value of the second capacitor.
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Citations
17 Claims
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1. A buck switching regulator formed on an integrated circuit and receiving an input voltage, the buck switching regulator controlling a first switch and a second switch using a fixed on-time, minimum off-time feedback control scheme to drive a switch output node for generating a switching output voltage, the switch output node being coupled to an LC filter circuit external to the integrated circuit to generate a regulated output voltage having a substantially constant magnitude on an output node, the regulated output voltage being fed back to the buck switching regulator to a voltage divider for generating a feedback voltage on a feedback voltage node, the buck switching regulator comprising:
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a first capacitor and a first resistor formed on the integrated circuit of the buck switching regulator, the first capacitor and the first resistor being connected in series between the switch output node and the feedback voltage node; and a second capacitor coupled between the output node and the feedback voltage node, wherein the first capacitor and the first resistor generate a ripple voltage signal being related to the switching output voltage and provide the ripple voltage signal to the feedback voltage node for use in the fixed on-time, minimum off-time feedback control scheme, the magnitude of the ripple voltage signal being a function of the capacitance value of the second capacitor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method in buck switching regulator receiving an input voltage and controlling a first switch and a second switch using a fixed on-time, minimum off-time feedback control scheme to drive a switch output node for generating a switching output voltage, the switch output node being coupled to an LC filter circuit to generate a regulated output voltage having a substantially constant magnitude on an output node, the regulated output voltage being fed back to the buck switching regulator to a voltage divider for generating a feedback voltage on a feedback voltage node, the method comprising:
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generating a ripple voltage signal from the switching output voltage; injecting the ripple voltage signal to the feedback voltage node for use in the fixed on-time, minimum off-time feedback control scheme; and adjusting the magnitude of the ripple voltage signal at the feedback voltage node using a capacitive divider. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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Specification