# US 9,753,478 B2 · Temperature compensated current limiting mechanism > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,753,478 B2 - Document ID: US9753478B2 - Status: Granted - Kind: B2 - Application number: 14/298,805 - Filed: 2014-06-06 - Published: 2015-12-10 - Granted: 2017-09-05 - Earliest claimed: 2014-06-06 - Assignees: Electro-Motive Diesel, Inc. - Applicants: Electro-Motive Diesel, Inc. - Inventors: James F. Wiemeyer - Web page: https://patentgrep.com/patent/US9753478B2 ## CPC - G05F 3/02: Regulating voltage or current - B61L 15/0027: {Radio-based, e.g. using GSM-R} - B61L 15/0036: {Conductor-based, e.g. using CAN-Bus, train-line or optical fibres} - B61L 15/0081: {On-board diagnosis or maintenance} - G05F 1/573: with overcurrent detector - G05F: SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES - B61L: GUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC (brakes or auxiliary equipment B61H, B61K; point or crossing construction E01B) ## Abstract The present disclosure is directed to a current limiting circuit. The current limiting circuit may include a load, a first switch that controls current supplied to the load, and a first resistive network. The current limiting circuit may further include a voltage divider connected across the first resistive network and including a thermistor. The current limiting circuit may further include a first bipolar junction transistor that controls switching of the first switch. The output terminal of the voltage divider may be connected to a base junction of the first bipolar junction transistor. ## Claims ### Claim 1 A current limiting circuit comprising: a load; a first switch that controls current supplied to the load; a first resistive network; a voltage divider connected across the first resistive network and including a thermistor; and a first bipolar junction transistor that controls switching of the first switch, wherein an output terminal of the voltage divider is directly connected to a base terminal of the first bipolar junction transistor. ### Claim 2 (depends on 1) The current limiting circuit of claim 1, wherein the thermistor has a negative temperature coefficient. ### Claim 3 (depends on 1) The current limiting circuit of claim 1, wherein the first bipolar junction transistor is an NPN bipolar junction transistor. ### Claim 4 (depends on 1) The current limiting circuit of claim 1, wherein the first bipolar junction transistor is a PNP bipolar junction transistor. ### Claim 5 (depends on 1) The current limiting circuit of claim 1, wherein the first switch is a MOSFET and a collector terminal of the first bipolar junction transistor is connected to a gate of the MOSFET. ### Claim 6 (depends on 1) The current limiting circuit of claim 1, wherein the first switch is a second bipolar junction transistor and a collector terminal of the first bipolar junction transistor is connected to a base terminal of the second bipolar junction transistor. ### Claim 7 (depends on 5) The current limiting circuit of claim 5, wherein the MOSFET is a p-type MOSFET. ### Claim 8 (depends on 5) The current limiting circuit of claim 5, wherein the MOSFET is an n-type MOSFET. ### Claim 9 (depends on 1) The current limiting circuit of claim 1, wherein the thermistor is connected between base and emitter terminals of the first bipolar junction transistor. ### Claim 10 (depends on 1) The current limiting circuit of claim 1, wherein the voltage divider includes a first and second resistor in addition to the thermistor. ### Claim 11 A locomotive comprising: a first electrical module; and a second electrical module driven by the first electrical module, wherein: the second electrical module includes: a load, a first switch that controls current supplied to the load, a first resistive network, a voltage divider connected across the first resistive network and including a thermistor, and a first bipolar junction transistor that controls switching of the first switch, and an output terminal of the voltage divider is directly connected to a base terminal of the first bipolar junction transistor, wherein the thermistor is connected between the base terminal and an emitter terminal of the first bipolar junction transistor. ### Claim 12 (depends on 11) The locomotive of claim 11, wherein the thermistor has a negative temperature coefficient. ### Claim 13 (depends on 11) The locomotive of claim 11, wherein the first bipolar junction transistor is an NPN bipolar junction transistor. ### Claim 14 (depends on 11) The locomotive of claim 11, wherein the first bipolar junction transistor is a PNP bipolar junction transistor. ### Claim 15 (depends on 11) The locomotive of claim 11, wherein the first switch is a MOSFET and a collector terminal of the first bipolar junction transistor is connected to a gate of the MOSFET. ### Claim 16 (depends on 11) The locomotive of claim 11, wherein the first switch is a second bipolar junction transistor and a collector terminal of the first bipolar junction transistor is connected to a base terminal of the second bipolar junction transistor. ### Claim 17 (depends on 15) The locomotive of claim 15, wherein the MOSFET is a p-type MOSFET. ### Claim 18 (depends on 15) The locomotive of claim 15, wherein the MOSFET is an n-type MOSFET. ### Claim 19 A current limiting circuit for a locomotive comprising: a load; a first switch that controls current supplied to the load; a first resistive network; a voltage divider connected across the first resistive network and including a first resistor, a thermistor having a negative temperature coefficient, and a second resistor all directly connected in series; and a first bipolar junction transistor that controls switching of the first switch, wherein an output terminal of the voltage divider is directly connected to a base terminal of the first bipolar junction transistor, and wherein the thermistor is connected between the base terminal and an emitter terminal of the first bipolar junction transistor. ### Claim 20 (depends on 19) The current limiting circuit of claim 19, wherein the first switch is a second bipolar junction transistor, and a collector terminal of the first bipolar junction transistor is connected to a base terminal of the second bipolar junction transistor.