Inverse voltage-to-current conversion circuit

Patent metadata

Field	Value
Publication number	US-12413223-B2
Application number	US-202117543880-A
Country	US
Kind code	B2
Filing date	Dec 7, 2021
Priority date	Jul 27, 2017
Publication date	Sep 9, 2025
Grant date	Sep 9, 2025

Abstract

An inverse voltage-to-current conversion circuit for providing a current that is inversely related to an input voltage is disclosed. A first input terminal and a second input terminal receives the input voltage between the first and the second input terminals. A voltage-to-time converter circuit provides a time indicator pulse signal with a pulse width related to inverse magnitude of the input voltage. A time-to-voltage converter circuit provides a voltage indicator signal having a magnitude based on the pulse width of the time indicator pulse signal. A voltage-to-current converter circuit provides a current indicator signal having a magnitude proportional to the voltage indicator signal—the current indicator signal being inversely related to the magnitude of the input voltage.

First claim

What is claimed is:

1. An inverse voltage-to-current conversion circuit for providing a current that is inversely related to an input voltage, comprising:
a first input terminal and a second input terminal for receiving the input voltage between the first and the second input terminals;
a voltage-to-time converter circuit for providing a time indicator pulse signal with a pulse width related to inverse magnitude of the input voltage, wherein the voltage-to-time converter circuit comprises a first capacitor and a latch outputting the time indicator pulse signal with the pulse width, the pulse width being a charging time of the first capacitor, and the time indicator pulse signal switching from logic high to logic low when a voltage across the first capacitor reaches a reference voltage;
a time-to-voltage converter circuit for providing a voltage indicator signal having a magnitude based on the pulse width of the time indicator pulse signal; and
a voltage-to-current converter circuit for providing a current indicator signal having a magnitude proportional to the voltage indicator signal, the current indicator signal being inversely related to the magnitude of the input voltage.

2. The inverse voltage-to-current conversion circuit of claim 1 , wherein the voltage-to-time converter circuit further comprises:
a first resistor coupled to the first input terminal for sampling a first current; and
a second resistor coupled to the second input terminal for sampling a second current, wherein the first capacitor is configured to be charged by a current related to a difference between the first current and the second current.

3. The inverse voltage-to-current conversion circuit of claim 1 , wherein the time indicator pulse signal is in a time domain.

4. The inverse voltage-to-current conversion circuit of claim 1 , wherein circuit components are selected so that the current indicator signal represents a maximum current allowed.

5. The inverse voltage-to-current conversion circuit of claim 1 , wherein the current indicator signal is based on a pre-set maximum power limit for a voltage across a protective device.

6. The inverse voltage-to-current conversion circuit of claim 1 , wherein the time-to-voltage converter circuit comprises:
a reference current source configured to generate a reference current signal; and
a capacitor coupled to the reference current source through a switch controlled by the time indicator pulse signal;
wherein the time-to-voltage converter circuit is configured to charge the capacitor by the reference current source during an on-time of the time indicator pulse signal; and
to produce a voltage on the capacitor as the voltage indicator signal.

7. The inverse voltage-to-current conversion circuit of claim 1 , wherein the voltage-to-current converter circuit comprises a current regulator including an operational amplifier configured to provide an output current proportional to the voltage indicator signal.

8. A method for producing a current that is inversely proportional to a first voltage, comprising:
sensing a first voltage across a first terminal and a second terminal;
forming, by a voltage-to-time converter comprising a first capacitor and a latch, a time indicator pulse signal with a pulse width inversely related to a magnitude of the first voltage, wherein forming the time indicator pulse signal comprises:
charging the first capacitor; and
operating the latch to output the time indicator pulse signal, the pulse width being a charging time of the first capacitor, the time indicator pulse signal switching from logic high to logic low when a voltage across the first capacitor reaches a reference voltage;

forming a second voltage having a magnitude based on a length of the time indicator pulse signal; and
forming a current signal having a magnitude proportional to the second voltage.

9. The method of claim 8 , wherein the current signal is configured to have a magnitude inversely related to the first voltage.

10. The method of claim 8 , wherein the time indicator pulse signal is in a time domain.

11. The method of claim 8 , wherein forming the time indicator pulse signal further comprises:
sampling a first current at a first resistor coupled to the first terminal; and
sampling a second current at a second resistor coupled to the second terminal, wherein the first capacitor is charged by a current related to a difference between the first current and the second current.

12. The method of claim 8 , wherein the current signal represents a maximum current allowed.

13. The method of claim 8 , wherein the current signal is based on a pre-set maximum power limit for a voltage across a protective device.

14. The method of claim 8 , wherein forming the second voltage having a magnitude based on a length of the time indicator pulse signal comprises:
generating a reference current source signal using a reference current source;
charging a capacitor by the reference current source during an on-time of the time indicator pulse signal; and
producing a voltage on the capacitor as the second voltage.

15. The method of claim 14 wherein the capacitor is coupled to the reference current source through a switch controlled by the time indicator pulse signal.

Assignees

• Diodes Inc

Inventors

• Wu Wei

Classifications

• H03K2217/0054

  Gating switches, e.g. pass gates · CPC title

• G01R19/255

  using analogue/digital converters of the type with counting of pulses during a period of time proportional to voltage or current, delivered by a pulse generator with fixed frequency · CPC title

• H03K5/26

  the characteristic being duration, interval, position, frequency, or sequence · CPC title

• H03K5/24

  the characteristic being amplitude · CPC title

• H03K3/037

  Bistable circuits · CPC title