# US 2013/0154601 A1 · Regulator transient over-voltage protection > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0154601 A1 - Document ID: US20130154601A1 - Status: Published application - Kind: A1 - Application number: 13/331,321 - Filed: 2011-12-20 - Published: 2013-06-20 - Earliest claimed: 2011-12-20 - Inventors: Kenneth P. Snowdon; Hrvoje Jasa - Web page: https://patentgrep.com/patent/US20130154601A1 ## CPC - G05F 1/571: with overvoltage detector - G05F: SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES ## Abstract This document discusses, among other things, apparatus and methods for providing over-voltage transient protection of a voltage regulator. In an example, an apparatus can include a first transistor including a control node and first and second switch nodes, and a low-pass filter configured to couple to the control node of the first transistor and to switch the first transistor to a first state when a voltage change of the supply voltage exceeds a threshold. The first transistor, in the first state, can be configured to couple a control node of a second transistor to the supply voltage to protect components coupled to a regulator transistor. ## Claims ### Claim 1 A system comprising: a first transistor; a second transistor; and a low-pass filter; wherein the first transistor is configured to detect a voltage transient using the low-pass filter and to turn off the second transistor to protect components coupled to the second transistor from the voltage transient. ### Claim 2 (depends on 1) The system of claim 1, wherein the first transistor includes a control node and is configured to receive a supply voltage at the control node through the low-pass filter. ### Claim 3 (depends on 2) The system of claim 2, wherein the second transistor is configured to receive the supply voltage through the first transistor when the first transistor detects the voltage transient using the low-pass filter. ### Claim 4 (depends on 1) The system of claim 1, including low voltage components configured to receive a regulated voltage from the second transistor, wherein the first transistor and the low-pass filter are configured to protect the low voltage components from the voltage transient. ### Claim 5 (depends on 1) The system of claim 1, wherein the voltage transient includes a supply voltage increase above a loop bandwidth of a voltage regulator including the second transistor. ### Claim 6 (depends on 1) The system of claim 1, wherein the second transistor includes an output transistor of a regulator circuit, and wherein voltage transient includes a supply voltage increase above a loop bandwidth of the regulator circuit. ### Claim 7 (depends on 1) The system of claim 1, wherein the first transistor includes a control node and first and second switch nodes; and wherein the first switch node is configured to couple to a supply voltage. ### Claim 8 (depends on 7) The system of claim 7, wherein the second switch node is configured to be coupled to a control node of the second transistor. ### Claim 9 (depends on 7) The system of claim 7, wherein the low-pass filter includes a resistor-capacitor (RC) network. ### Claim 10 (depends on 9) The system of claim 9, wherein the control node of the first transistor is coupled directly to a capacitor of the RC network. ### Claim 11 (depends on 10) The system of claim 10, wherein the capacitor is coupled directly to ground. ### Claim 12 (depends on 11) The system of claim 11, wherein a resistor of the RC network is coupled between the control node of the first transistor and the supply voltage. ### Claim 13 (depends on 1) The system of claim 1, wherein the first transistor includes a PMOS transistor and wherein the second transistor includes a PMOS transistor. ### Claim 14 A method comprising: detecting a voltage transient using a first transistor and a resistor capacitor (RC) network; and turning off a second transistor to protect components coupled to the second transistor from the voltage transient. ### Claim 15 (depends on 14) The method of claim 14, wherein detecting a voltage transient includes detecting a voltage transient of a supply voltage using the first transistor and the resistor capacitor (RC) network. ### Claim 16 (depends on 14) The method of claim 14, wherein detecting a voltage transient includes delaying a response of the control node of the first transistor from following the voltage transient using a capacitor of the RC network. ### Claim 17 (depends on 16) The method claim 16, wherein turning off the second transistor includes switching the first transistor to an on-state using the delayed response of the control node of the first transistor to the transient voltage. ### Claim 18 (depends on 17) The method of claim 17, wherein turning off the second transistor includes coupling a control node of the second transistor to the voltage source using the on-state of the first transistor. ### Claim 19 An apparatus comprising: a first transistor including a control node and first and second switch nodes, the first switch node configured to receive a supply voltage, the second switch node configured to couple to a control node of a second transistor, the first transistor, in a first state, configured to couple the control node of the second transistor to the supply voltage to protect components coupled to the regulator transistor; and a low-pass filter configured to couple to the control node of the first transistor and to switch the first transistor to the first state when a voltage change of the supply voltage exceeds a threshold. ### Claim 20 (depends on 19) The apparatus of claim 19, wherein the first transistor includes a PMOS transistor and wherein the second transistor includes a PMOS transistor. ### Claim 21 (depends on 19) The apparatus of claim 19, wherein an integrated circuit includes the first transistor and the low-pass filter. ### Claim 22 (depends on 19) The apparatus of claim 19, wherein the low-pass filter includes a resistor-capacitor (RC) network. ### Claim 23 A voltage regulator comprising: a regulator transistor configured to receive a supply voltage and provide a regulated output voltage; a regulator controller configured to control the regulator transistor; a protection circuit configured to detect a transient voltage within the supply voltage and to maintain the regulator transistor in an off-state during the voltage transient, wherein the protection circuit includes: a first transistor; and a resistor-capacitor (RC) network; wherein the first transistor is configured to detect a voltage transient using the RC network and to maintain the regulator transistor on an off-state to protect components coupled to the second transistor from the voltage transient; wherein the first transistor includes a control node and is configured to receive the supply voltage at the control node through the RC network; wherein the control node of the first transistor is coupled directly to a capacitor of the RC network; wherein the first transistor includes first and second switch nodes, the first switch node configured to couple to the supply voltage, and the second switch node configured to couple to a control node of the regulator transistor; wherein the regulator transistor is configured to receive the supply voltage through the first transistor when the first transistor detects the voltage transient using the RC network; wherein the voltage transient includes a supply voltage increase above a loop bandwidth of the voltage regulator. ### Claim 24 (depends on 22) The voltage regulator of claim 22, wherein an integrated circuit includes the regulator controller and the protection circuit.