Method for determining the current consumption of an active load, for example a processing unit, and associated electronic device

Patent metadata

Field	Value
Publication number	US-10634705-B2
Application number	US-201715451495-A
Country	US
Kind code	B2
Filing date	Mar 7, 2017
Priority date	Sep 16, 2016
Publication date	Apr 28, 2020
Grant date	Apr 28, 2020

Abstract

A first resistor and a second resistor are coupled in series between a voltage source and an active load. When the current drawn by the active load exceeds a current threshold corresponding to a maximum admissible voltage drop across the first resistor, a stabilization current is delivered to the node common to the series coupled first and second resistors in such a way as to stabilize the voltage on the terminals of the active load at a threshold value. In the presence of such a current in excess of the current threshold, the current consumed by the active load is measured from the voltage drop across the second resistor. Conversely, if the current is less than the current threshold, the current consumed by the active load is measured from the voltage drop across the first resistor.

First claim

The invention claimed is:

1. A method for determining a value of a current consumed by an active load fed by a first voltage source, in which a first resistor and a second resistor are connected in series between the first voltage source and a first terminal of the active load, the first resistor having a resistance value greater than a resistance value of the second resistor, the method comprising:
defining a maximum admissible voltage drop on terminals of the first resistor;
simultaneously measuring a first difference in potential on the terminals of the first resistor and a second difference in potential on terminals of the second resistor;
detecting if the first difference in potential is less than said maximum admissible voltage drop and, in response to the first difference in potential being less than said maximum admissible voltage drop, determining the value of the current consumed on the basis of the first difference in potential;
detecting if the first difference in potential is equal to said maximum admissible voltage drop and, in response to the first difference in potential being equal to the maximum admissible voltage drop, determining the value of the current consumed on the basis of the second difference in potential; and
detecting if the first difference in potential is greater than said maximum admissible voltage drop and, in response to the first difference in potential being greater than said maximum admissible voltage drop, determining the value of the current consumed on the basis of the second difference in potential.

2. The method according to claim 1 , further comprising stabilizing a voltage on the first terminal of the active load at a threshold value equal to a value of the voltage delivered by said first voltage source minus said maximum admissible voltage drop.

3. The method according to claim 2 , wherein stabilizing comprises:
comparing said voltage on the first terminal to said threshold value; and
performing stabilization if the voltage on the first terminal is less than the threshold value.

4. The method according to claim 3 , wherein performing stabilization comprises injecting a current proportional to a difference between the threshold value and the voltage on the first terminal into a common node between the series connected first and second resistors.

5. The method according to claim 2 , wherein performing stabilization occurs while determining the value of the current consumed on the basis of the second difference in potential.

6. The method according to claim 5 , wherein performing stabilization comprises injecting a current into a common node between the series connected first and second resistors.

7. The method according to claim 6 , wherein said current has a value proportional to a difference between the threshold value and the voltage on the first terminal.

8. The method according to claim 1 , wherein a ratio between the resistance value of the first resistor and the resistance value of the second resistor is between 100 and 1000.

9. The method according to claim 1 , wherein the active load includes a processing unit.

10. An electronic circuit, comprising:
an input terminal configured to be connected to a first voltage source;
an output terminal configured to be connected to an active load;
a circuit configured to determine a current consumed at said output terminal, comprising:
a first resistor and a second resistor connected in series between the input terminal and the output terminal, the first resistor having a resistance value greater than a resistance value of the second resistor;
a first measuring circuit configured to measure a first difference in potential on terminals of the first resistor;
a second measuring circuit configured to measure a second difference in potential on terminals of the second resistor;
wherein the measurement of the first and second differences in potential are performed simultaneously; and
a determination circuit configured to:
detect if the first difference in potential is less than a maximum admissible voltage drop and, in response to the first difference in potential being less than said maximum admissible voltage drop, determine the current consumed on the output terminal on the basis of the first difference in potential;
detecting if the first difference in potential is equal to said maximum admissible voltage drop and, in response to the first difference in potential being equal to said maximum admissible voltage drop, determining the value of the current consumed on the output terminal on the basis of the second difference in potential; and
detect if the first difference in potential is greater than said maximum admissible voltage drop and, in response to the first difference in potential being greater than said maximum admissible voltage drop, determine the current consumed on the output terminal on the basis of the second difference in potential.

11. The electronic circuit according to claim 10 , further comprising a stabilization circuit configured to stabilize a voltage on the output terminal at a threshold value equal to a value of a voltage delivered by said first voltage source minus the maximum admissible voltage drop.

12. The electronic circuit according to claim 11 , wherein the stabilization circuit comprises:
a comparison circuit configured to compare said voltage present on the output terminal to said threshold value; and
an additional circuit configured to stabilize the voltage present on the output terminal if the voltage present on the output terminal is less than said threshold value.

13. The electronic circuit according to claim 12 , wherein said additional circuit is configured to inject a current proportional to a difference between the voltage present on the output terminal and said threshold value into a common node between the series connected first and second resistors.

14. The electronic circuit according to claim 12 , wherein said additional circuit is activated while said determination circuit determines the current consumed on the output terminal on the basis of the second difference in potential.

15. The electronic circuit according to claim 12 ,
wherein the comparison circuit comprises a differential amplifier having an inverting input coupled to the output terminal and a non-inverting input configured to receive said threshold value; and
wherein the additional circuit comprises a transistor having a control electrode coupled to an output of the differential amplifier, a first conduction electrode coupled to an additional voltage source and a second conduction electrode coupled to a common node between the series connected first and second resistors.

16. The electronic circuit according to claim 15 , wherein said differential amplifier is configured to deliver an output voltage blocking turning on of said transistor when the voltage present on the output terminal is greater than or equal to the threshold value.

17. The electronic circuit according to claim 10 , wherein a ratio between the resistance value of the first resistor and the resistance value of the second resistor is between 100 and 1000.

18. The electronic circuit according to claim 10 ,
wherein the first measuring circuit comprises a first operational amplifier having inputs connected to the terminals of the first resistor; and
wherein the second measuring circuit comprises a second operational amplifier having inputs connected to the terminals of the second resistor.

19. The electronic circuit according to claim 10 , wherein the deter

Assignees

• St Microelectronics Alps Sas

Inventors

• Almosnino Patrick

Classifications

• G01R15/09

  Autoranging circuits · CPC title

• G05F1/625

  wherein it is irrelevant whether the variable actually regulated is AC or DC · CPC title

• G01R19/25

  using digital measurement techniques · CPC title

• G05F1/561 Primary

  Voltage to current converters (amplifiers H03F) · CPC title

• G01R19/10 Primary

  Measuring sum, difference or ratio · CPC title