# US 11,114,844 B2 · Inrush current limiter circuits and methods of limiting inrush current in a circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,114,844 B2 - Document ID: US11114844B2 - Status: Granted - Kind: B2 - Application number: 16/516,768 - Filed: 2019-07-19 - Published: 2020-01-23 - Granted: 2021-09-07 - Earliest claimed: 2018-07-20 - Assignees: Vertiv Corporation - Applicants: Vertiv Energy Systems, Inc. - Inventors: John H. Leitner - Web page: https://patentgrep.com/patent/US11114844B2 ## CPC - H02M 1/32: Means for protecting converters other than automatic disconnection - H02H 9/001: {limiting speed of change of electric quantities, e.g. soft switching on or off (progressive control of electronic switches for eliminating interferences H03K17/16)} - H02H 9/025: {Current limitation using field effect transistors} - H02M 3/00: Conversion of DC power input into DC power output - H02M 3/06: using resistors or capacitors, e.g. potential divider - H02M 3/156: with automatic control of output voltage or current, e.g. switching regulators - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) - H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H) ## Abstract A DC-DC power converter includes an input, an output, a power circuit coupled between the input and the output to convert a voltage of a DC power received at the input to a different voltage of a DC power supplied at the output, and a control circuit. The DC-DC power converter also includes a resistor coupled in an input current path to receive an inrush current from the input, a switch coupled in parallel with the resistor to selectively bypass the resistor, and a transistor coupled to control the switch in response to a voltage across the resistor. The transistor is coupled to open the switch when the voltage across the resistor is above a specified inrush threshold to permit current flow through the resistor, and to close the switch when the voltage across the resistor is below the specified inrush threshold to bypass the resistor. ## Claims ### Claim 1 A DC-DC power converter comprising: an input for receiving DC power from a power source; an output for supplying DC power to an electronic device; a power circuit coupled between the input and the output to convert a voltage of the DC power received at the input to a different voltage of the DC power supplied at the output; a control circuit coupled to control switching operation of the power circuit; a resistor coupled in an input current path to receive an inrush current from the input when the input is electrically coupled to the power source; a switch coupled in parallel with the resistor to selectively bypass the resistor; a transistor coupled to control the switch in response to a voltage across the resistor, the transistor coupled to open the switch when the voltage across the resistor is above a specified inrush threshold to permit current flow through the resistor, and to close the switch when the voltage across the resistor is below the specified inrush threshold to bypass the resistor and allow the switch to conduct current from the input; and an isolator coupled between the transistor and a node defined between the resistor and the switch to selectively enable one or more other circuits electrically coupled to the isolator in response to the voltage across the resistor. ### Claim 2 (depends on 1) The DC-DC power converter of claim 1, wherein the isolator is coupled to enable the other circuit(s) when the voltage across the resistor is above the specified inrush threshold, and to disable the other circuit(s) when the voltage across the resistor is below the specified inrush threshold. ### Claim 3 (depends on 1) The DC-DC power converter of claim 1, wherein the isolator comprises an optocoupler. ### Claim 4 (depends on 1) The DC-DC power converter of claim 1, wherein the isolator is coupled between the emitter of the transistor and the node defined between the resistor and the switch. ### Claim 5 (depends on 1) The DC-DC power converter of claim 1, wherein the switch comprises a field-effect transistor (FET). ### Claim 6 (depends on 1) The DC-DC power converter of claim 1, wherein the specified inrush threshold corresponds to a base-emitter voltage of the transistor. ### Claim 7 (depends on 1) The DC-DC power converter of claim 1, wherein the transistor is coupled to turn on when the voltage across the resistor is above the specified inrush threshold. ### Claim 8 (depends on 1) The DC-DC power converter of claim 1, wherein the node comprises a first node defined between a first end of the resistor and a first end of the switch, a base of the transistor is coupled with the first node, and a collector of the transistor is coupled with a second node defined between a second end of the resistor and second end of the switch. ### Claim 9 (depends on 1) The DC-DC power converter of claim 1, wherein a gate of the switch is coupled with a collector of the transistor. ### Claim 10 (depends on 1) The DC-DC power converter of claim 1, wherein the inrush current limiter circuit does not include a shunt or a control integrated circuit. ### Claim 11 (depends on 1) The DC-DC power converter of claim 1, further comprising a mechanical switch coupled to the transistor to allow an operator to manually short the transistor when electrically connecting the input to the power source. ### Claim 12 (depends on 1) The DC-DC power converter of claim 1, wherein the power converter is adapted for plugging into a hot bus to supply power to a cellular radio tower. ### Claim 13 (depends on 1) The DC-DC power converter of claim 1, wherein the transistor comprises an NPN transistor. ### Claim 14 (depends on 1) The DC-DC power converter of claim 1, wherein the other circuit(s) include at least one of a power conversion chip, a power relay, a circuit coupled to draw power from the input, a radio, and a light. ### Claim 15 A DC-DC power converter comprising: an input for receiving DC power from a power source; an output for supplying DC power to an electronic device; a power circuit coupled between the input and the output to convert a voltage of the DC power received at the input to a different voltage of the DC power supplied at the output; a control circuit coupled to control switching operation of the power circuit; a resistor coupled in an input current path to receive an inrush current from the input when the input is electrically coupled to the power source; a switch coupled in parallel with the resistor to selectively bypass the resistor; and an isolator coupled to selectively enable one or more other circuits electrically coupled to the isolator in response to a voltage across the resistor, the isolator coupled to enable the other circuit(s) when the voltage across the resistor is above a specified inrush threshold and to disable the other circuit(s) when the voltage across the resistor is below the specified inrush threshold. ### Claim 16 (depends on 15) The DC-DC power converter of claim 15, wherein the isolator comprises an optocoupler. ### Claim 17 (depends on 15) The DC-DC power converter of claim 15, further comprising a transistor coupled to control activation of the switch, wherein the isolator is coupled between an emitter of the transistor and a node defined between the resistor and the switch. ### Claim 18 (depends on 17) The DC-DC power converter of claim 17, wherein the specified inrush threshold corresponds to a base-emitter voltage of the transistor. ### Claim 19 An inrush current limiter circuit comprising: an input for receiving an inrush current; a resistor coupled in an input current path to receive the inrush current from the input when the input is electrically coupled to a power source; a switch coupled in parallel with the resistor to selectively bypass the resistor; a transistor coupled to control the switch in response to a voltage across the resistor, the transistor coupled to open the switch when the voltage across the resistor is above a specified inrush threshold to permit current flow through the resistor, and to close the switch when the voltage across the resistor is below the specified inrush threshold to bypass the resistor and allow the switch to conduct current from the input; and a mechanical switch coupled to the transistor to allow an operator to manually short the transistor when electrically connecting the input to the power source. ### Claim 20 (depends on 19) The inrush current limiter circuit of claim 19, further comprising an isolator coupled to selectively enable one or more other circuits electrically coupled to the isolator, in response to the voltage across the resistor.