Dynamic current sink for stabilizing low dropout linear regulator
First Claim
1. A dynamic current sink for stabilizing an output voltage at an output node of an LDO (Low Dropout Linear Regulator), comprising:
- a comparator, for comparing a first reference signal with a signal obtained from the LDO to generate a comparison result, wherein the comparison result indicates whether an overshoot output voltage related to the LDO occurs;
a control circuit, coupled to the comparator, for receiving the comparison result to generate a first control signal, and generating a second control signal according to the comparison result;
a first switching circuit, coupled to the output node of the LDO, a reference voltage and the first control signal, for selectively connecting or disconnecting the output node of the LDO to the reference voltage according to the first control signal;
a second switching circuit, coupled to the output node of the LDO, the reference voltage and the second control signal, for selectively connecting or disconnecting the output node of the LDO to the reference voltage according to the second control signal.
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Abstract
A dynamic current sink includes the following elements. A voltage comparator compares a reference voltage with a second control signal from an LDO (Low Dropout Linear Regulator) to generate a first control signal. A first transistor selectively pulls down a voltage at a first node according to the first control signal. The inverter is coupled between the first node and a second node. An NAND gate has a first input terminal coupled to a second transistor and a third node, a second input terminal coupled to the second node, and an output terminal coupled to a fourth node. A capacitor is coupled between the fourth node and a fifth node. A resistor is coupled between the fifth node and a ground voltage. A third transistor has a control terminal coupled to the fifth node, and selectively draws a discharge current from an output node of the LDO.
43 Citations
17 Claims
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1. A dynamic current sink for stabilizing an output voltage at an output node of an LDO (Low Dropout Linear Regulator), comprising:
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a comparator, for comparing a first reference signal with a signal obtained from the LDO to generate a comparison result, wherein the comparison result indicates whether an overshoot output voltage related to the LDO occurs; a control circuit, coupled to the comparator, for receiving the comparison result to generate a first control signal, and generating a second control signal according to the comparison result; a first switching circuit, coupled to the output node of the LDO, a reference voltage and the first control signal, for selectively connecting or disconnecting the output node of the LDO to the reference voltage according to the first control signal; a second switching circuit, coupled to the output node of the LDO, the reference voltage and the second control signal, for selectively connecting or disconnecting the output node of the LDO to the reference voltage according to the second control signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An LDO (Low Dropout Linear Regulator), comprising:
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a first comparator, for comparing a feedback voltage with a first reference signal to generate a first control signal; a first switching circuit, coupled to a supply voltage, an output node of the LDO and the first control signal, for selectively connecting or disconnecting the supply voltage to the output node of the LDO; a dynamic current sink, coupled to the output node of the LDO, for determining whether an overshoot output voltage relates to the LDO occurs to selectively provide a discharge current to the output node of the LDO or not provide the discharge current to the output node of the LDO; wherein the dynamic current sink comprises; a second comparator, for comparing a second reference signal with a signal obtained from the LDO to generate a comparison result, wherein the comparison result indicates whether the overshoot output voltage relates to the LDO occurs; a control circuit, coupled to the second comparator, for generating a second control signal and a third control signal according to the comparison result; a second switching circuit, coupled to the output node of the LDO, a reference voltage and the second control signal, for selectively connecting or disconnecting the output node of the LDO to the reference voltage according to the second control signal; and a third switching circuit, coupled to the output node of the LDO, the reference voltage and the third control signal, for selectively connecting or disconnecting the output node of the LDO to the reference voltage according to the third control signal. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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Specification