TEMPERATURE VARIANCE NULLIFICATION IN AN INRUSH CURRENT SUPPRESSION CIRCUIT

• US 20100201339A1
• Filed: 02/09/2009
• Published: 08/12/2010
• Est. Priority Date: 02/09/2009
• Status: Active Grant

• Current Assignee: Rantec Power Systems, Inc.
• Original Assignee: Rantec Power Systems, Inc.
• Inventors: Newman, Ethan Beck
• Granted Patent: US 7,830,168 B2
• Time in Patent Office: Days
• US Class Current: 323/311
• CPC Class Codes: 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
• CPC Class Codes: H02M 1/36 Means for starting or stopping converters

Abstract

The temperature dependence of an inrush current suppression circuit comprising a MOSFET having an input terminal coupled to a direct current input voltage can a transistor electrically coupled to the MOSFET can be reduced by matching the temperature coefficient of a transistor to a component electrically coupled to the transistor.

Claims

1. A circuit comprising:

a metal-oxide semiconductor field-effect transistor (MOSFET) having an input terminal directly or indirectly electrically coupled to a direct current input voltage;

a transistor electrically coupled to the MOSFET, the transistor configured to cause an impedance of the MOSFET to increase in response to a sensed voltage exceeding a threshold voltage, the sensed voltage to increase in response to a rapid increase in input current;

a component electrically coupled to the transistor, the component to have a voltage drop that varies as a function of temperature.

2. The circuit of claim 1, wherein the component is a Schottky diode.

3. The circuit of claim 1, wherein the component is coupled either directly or indirectly to a base of the transistor and an emitter of the transistor.

4. The circuit of claim 1, wherein the component is connected in series to a resistor, and the resistor and component couple a base of the transistor to an emitter of the transistor.

5. The circuit of claim 1, wherein the sensed voltage comprises the voltage drop of the component.

6. The circuit of claim 1, wherein a base-to-emitter threshold voltage of the transistor has a first temperature coefficient and the component has a second temperature coefficient, and wherein the first temperature coefficient and second temperature coefficient are either both positive or both negative.

7. The circuit of claim 1, wherein the sensed voltage comprises the voltage drop of the component and a voltage drop over a resistive element, the voltage drop of the resistive element to be a function of a current of the direct current input voltage.

8. A circuit comprising:

a MOSFET having an input terminal directly or indirectly coupled to a direct current input voltage;

a transistor coupled to the MOSFET, wherein the transistor is configured to cause an impedance of the MOSFET to increase in response to a base-to-emitter voltage of the transistor exceeding a threshold voltage, the threshold voltage to decrease as temperature increases;

a component electrically coupled either directly or indirectly to the base of the transistor and to the emitter of the transistor, wherein the base-to-emitter voltage comprises a voltage drop across the component, the voltage drop across the component to decreases as temperature increases.

9. The circuit of claim 8, wherein the component is a Schottky diode.

10. The circuit of claim 8, wherein the component is connected in series to a resistor, and the base-to-emitter voltage comprises a voltage drop across the resistor.

11. The circuit of claim 8, the threshold voltage of the transistor has a first temperature coefficient and the component has a second temperature coefficient, and wherein the first temperature coefficient and second temperature coefficient are either both positive or both negative.

12. The circuit of claim 8, wherein the sensed voltage comprises the voltage drop of the component and a voltage drop over a resistive element, the voltage drop of the resistive element to be a function of a current of the direct current input voltage.

13. A circuit comprising:

a MOSFET having an input terminal directly or indirectly coupled to a direct current input voltage;

a transistor coupled to the MOSFET, wherein the transistor is configured to cause an impedance of the MOSFET to increase in response to a base-to-emitter voltage of the transistor exceeding a threshold voltage, the threshold voltage to increase as temperature decreases;

a component electrically coupled either directly or indirectly to the base of the transistor and to the emitter of the transistor, wherein the base-to-emitter voltage comprises a voltage drop across the component, the voltage drop across the component to increase as temperature decreases.

14. The circuit of claim 13, wherein the component is a Schottky diode.

15. The circuit of claim 13, wherein the component is connected in series to a resistor, and the base-to-emitter voltage comprises a voltage drop across the resistor.

16. The circuit of claim 13, the threshold voltage of the transistor has a first temperature coefficient and the component has a second temperature coefficient, and wherein the first temperature coefficient and second temperature coefficient are either both positive or both negative.

17. The circuit of claim 13, wherein the sensed voltage comprises the voltage drop of the component and a voltage drop over a resistive element, the voltage drop of the resistive element to be a function of a current of the direct current input voltage.

18. A power converter circuit comprising:

inputs configured to connect to a power source, wherein a current of greater than 4 amps is drawn from the power source during steady state operation;

an inrush current suppression circuit configured to limit inrush current to less than 9 amps in response to a line transient condition at the power source having a slew rate of 20V/μ

s, the inrush current suppression circuitry to limit inrush current to less than 9 amps when operating at −

45°

C. and 95°

C.

19. The power converter circuit of claim 18, wherein the inrush current suppression circuit comprises a metal-oxide semiconductor field-effect transistor (MOSFET) having an input terminal directly or indirectly electrically coupled to a direct current input voltage of the power source;

a transistor electrically coupled to the MOSFET, the transistor configured to cause an impedance of the MOSFET to increase in response to a sensed voltage exceeding a threshold voltage, the sensed voltage to increase in response to a rapid increase in the direct current input voltage;

a component electrically coupled to the transistor, the component to have a voltage drop that varies as a function of temperature.

20. The power converter circuit of claim 19, wherein the component is a Schottky diode.