Dynamic current sink for stabilizing low dropout linear regulator (LDO)
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 first voltage comparator, comparing a first reference voltage with a second control signal from the LDO, so as to generate a first control signal;
a first transistor, wherein the first transistor has a control terminal for receiving the first control signal, a first terminal coupled to a ground voltage, and a second terminal coupled to a first node;
a first current source, supplying a first current to the first node;
a first inverter, wherein the first inverter has an input terminal coupled to the first node, and an output terminal coupled to a second node;
a second current source, supplying a second current to a third node;
an NAND gate, wherein the NAND gate has a first input terminal coupled to the third node, a second input terminal coupled to the second node, and an output terminal coupled to a fourth node;
a first capacitor, coupled between the fourth node and a fifth node;
a first resistor, coupled between the fifth node and the ground voltage;
a second transistor, wherein the second transistor has a control terminal coupled to the fifth node, a first terminal coupled to the ground voltage, and a second terminal coupled to the third node; and
a third transistor, wherein the third transistor has a control terminal coupled to the fifth node, a first terminal coupled to the ground voltage, and a second terminal coupled to the output node;
wherein the third transistor is configured to selectively draw a first discharge current from the output node.
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Accused Products
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.
17 Citations
10 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 first voltage comparator, comparing a first reference voltage with a second control signal from the LDO, so as to generate a first control signal; a first transistor, wherein the first transistor has a control terminal for receiving the first control signal, a first terminal coupled to a ground voltage, and a second terminal coupled to a first node; a first current source, supplying a first current to the first node; a first inverter, wherein the first inverter has an input terminal coupled to the first node, and an output terminal coupled to a second node; a second current source, supplying a second current to a third node; an NAND gate, wherein the NAND gate has a first input terminal coupled to the third node, a second input terminal coupled to the second node, and an output terminal coupled to a fourth node; a first capacitor, coupled between the fourth node and a fifth node; a first resistor, coupled between the fifth node and the ground voltage; a second transistor, wherein the second transistor has a control terminal coupled to the fifth node, a first terminal coupled to the ground voltage, and a second terminal coupled to the third node; and a third transistor, wherein the third transistor has a control terminal coupled to the fifth node, a first terminal coupled to the ground voltage, and a second terminal coupled to the output node; wherein the third transistor is configured to selectively draw a first discharge current from the output node. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification