MEASURING POWER CONSUMPTION OF CIRUIT COMPONENT OPERATING IN ULTRA-LOW POWER MODE

• US 20150028887A1
• Filed: 07/29/2013
• Published: 01/29/2015
• Est. Priority Date: 07/29/2013
• Status: Active Grant

• Current Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Original Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Inventors: Hanssen, Ingar
• Granted Patent: US 9,470,725 B2
• Time in Patent Office: Days
• US Class Current: 324/601
• CPC Class Codes: G01R 21/006 Measuring power factor
• CPC Class Codes: G01R 27/2688 Measuring quality factor or dielectric loss, e.g. loss angle, or power factor power factor related to power measurements G01R21/006; testing capacitors G01R31/016
• CPC Class Codes: G01R 31/3004 Current or voltage test
• CPC Class Codes: G01R 31/31721 Power aspects, e.g. power supplies for test circuits, power saving during test for scan test G01R31/318575

Abstract

By powering an electronic component operating in an ultra-low power mode from a pre-charged measuring capacitor and measuring the time to discharge the capacitor to a trip voltage level, measurement data can be obtained. In some implementations, the capacitance of the capacitor can be obtained by adding a known current to the unknown current drawn from the capacitor and calculating the capacitance using a mathematical formula.

Claims

1. A method of obtaining measurement data from a circuit component operating in an ultra-low power mode, the method comprising:

charging a capacitor to a voltage level using a voltage source of the circuit component;

disconnecting the voltage source from an internal power system of the circuit component, enabling the capacitor to power the circuit component;

responsive to the enabling,

starting a counter;

determining that a voltage across the capacitor exceeds a trip voltage;

stopping the counter; and

obtaining measurement data for the circuit component using output of the counter.

2. The method of claim 1, where the trip voltage is calculated from a product of the voltage level and a fixed constant.

3. The method of claim 1, further comprising:

prior to charging the capacitor,

applying a known current to the capacitor for a period of time using a current sink;

determining a calibration factor using the known current and the period of time; and

obtaining the measurement data for the circuit component using the output of the counter and the calibration factor.

4. The method of claim 3, where the calibration factor is given by CΔ

V=Δ

I*Δ

t where C is the capacitance of the capacitor, Δ

V is the voltage across the capacitor, Δ

I is the known current and Δ

t is the time period.

5. The method of claim 1, where determining that a voltage across the capacitor exceeds a trip voltage, further comprises:

continuously comparing the voltage across the capacitor with the trip voltage for a discharge period; and

generating a trip signal when the voltage across the capacitor drops below the trip voltage.

6. The method of claim 1, further comprising:

determining that the circuit component has transitioned out of the ultra-low power mode; and

reconnecting the capacitor to the voltage source.

7. The method of claim 1, where the circuit component is a microcontroller.

8. The method of claim 1, further comprising:

storing measurement data for a discharge period; and

enabling access to the measurement data by another component or application.

9. A circuit for obtaining measurement data from a circuit component operating in an ultra-low power mode, comprising:

a voltage source coupled to a capacitor and configured for charging the capacitor to a voltage level using a voltage source of the circuit component;

control logic configure for disconnecting the voltage source from an internal power system of the circuit component to enable the capacitor to power the circuit component;

a counter coupled to the control logic and configured to determine a discharge period; and

a comparator having inputs coupled to the capacitor and a trip voltage, and an output coupled to the control logic, the comparator configured to compare continuously a voltage across the capacitor and the trip voltage and to generate a trip signal at the output when the voltage across the capacitor exceeds the trip voltage.

10. The circuit of claim 9, where the circuit component is a microcontroller.

11. The integrated circuit component of claim 9, further comprising a latch configured for storing measurement data and for allowing access to the measurement data by another component or application.

12. The integrated circuit component of claim 9, further comprising:

a clock coupled to the control logic and the counter, the clock configured to start and stop the counter using a clock gate signal generated by the control logic.

13. The integrated circuit component of claim 9, further comprising:

a switch configured to be selectively coupled to the voltage source to the capacitor; and

a latch having an input coupled to the output of the comparator and an output coupled to the switch, the latch configured to selectively open and close the switch in response to the trip signal.

14. The integrated circuit component of claim 9, further comprising:

a current sink configured to apply a known current to the capacitor for a period of time to allow a calibration factor to be obtained.