DIGITAL POWER MONITORING CIRCUIT AND SYSTEM

• US 20080234954A1
• Filed: 02/29/2008
• Published: 09/25/2008
• Est. Priority Date: 03/01/2007
• Status: Active Grant

• Current Assignee: Infineon Technologies Americas Corp. (Infineon Technologies AG)
• Original Assignee: International Rectifier Corporation (Infineon Technologies AG)
• Inventors: Foran, Ryan
• Granted Patent: US 8,280,655 B2
• Time in Patent Office: Days
• US Class Current: 702/60
• CPC Class Codes: G01R 21/133 by using digital technique

Abstract

A digital power monitoring circuit for monitoring power through an output inductor of a switching power supply in accordance with an embodiment of the present application includes a first analog to digital converter receiving a current sense signal indicative of the current through the output inductor and providing a first digital signal including information regarding the current through the output inductor, a second analog to digital converter receiving a signal indicative of the output voltage of the switching power supply and providing a second digital signal containing information regarding the output voltage of the switching power supply; and a convolver circuit operable to receive the first digital signal and the second digital signal and to provide a third digital signal including information regarding the power through the output inductor based on the first and second digital signals.

Claims

1. A digital power monitoring circuit for monitoring power through an output inductor of a switching power supply comprises:

a first analog to digital converter receiving a current sense signal indicative of the current through the output inductor and providing a first digital signal including information regarding the current through the output inductor;

a second analog to digital converter receiving a signal indicative of the output voltage of the switching power supply and providing a second digital signal containing information regarding the output voltage of the switching power supply; and

a convolver circuit operable to receive the first digital signal and the second digital signal and to provide a third digital signal including information regarding the power dissipated across the output inductor based on the first and second digital signals.

2. The digital power monitoring circuit of claim 1, further comprising a filter circuit operative to filter the third digital signal and to provide an output indicative of an average power dissipated by the output inductor.

3. The digital power monitoring circuit of claim 1, wherein the filter circuit comprises:

a counter that receives the third digital signal;

an interval timer operable to provide an interval signal to the counter after a defined averaging interval, wherein the interval signal resets the counter such that the output of the counter indicates the average power dissipated by the output inductor over the interval; and

a latch circuit operable to output and hold the average power dissipated based on the interval signal from the interval timer.

4. The digital power monitoring circuit of claim 1, wherein the first analog to digital converter is a first delta sigma type analog to digital converter and the first digital signal is a continuous stream of ones and zeros where the ones density reflects information regarding the current through the output conductor.

5. The digital power monitoring circuit of claim 4, wherein the second analog to digital converter is a second delta sigma type analog to digital converter and the second digital signal is a continuous stream of ones and zeros where the ones density reflects information regarding the output voltage of the switching power supply.

6. The digital power monitoring circuit of claim 5, further comprising a current sense circuit connected to the switching power supply and operable to provide a current sense signal having a voltage that is indicative of the current through the output inductor of the switching power supply.

7. The digital power monitoring circuit of claim 6, wherein the first delta sigma analog to digital converter receives the current sense signal and the output voltage and provides the first digital signal based on a comparison between the current sense signal and the output voltage.

8. The digital power monitoring circuit of claim 7, wherein the second delta sigma analog to digital converter receives the output voltage as an input and provides the second digital signal based on a comparison of the output voltage to a reference voltage.

9. The digital power monitoring circuit of claim 8, wherein the convolver circuit convolves the first digital signal with the second digital signal to produce the third digital signal.

10. The digital power monitoring circuit of claim 9, wherein the convolver circuit provides single bit convolution.

11. The digital power monitoring circuit of claim 10, wherein the convolver circuit comprises an AND gate that receives the first and second digital signals as inputs and provides the third digital signal as an output.

12. The digital power monitoring circuit of claim 9, wherein the convolver circuit provides multiple bit convolution.

13. The digital power monitoring circuit of claim 10, wherein the convolver circuit provides multiple AND gates that receive the first and second digital signals as inputs and provide the third digital signal as an output.

14. The digital power monitoring circuit of claim 1, wherein the digital power monitoring circuit is implemented in an integrated circuit.

15. The digital power monitoring circuit of claim 1, wherein the switching power supply and the digital power monitoring circuit are implemented in a single integrated circuit.

16. The digital power monitoring circuit of claim 1, further comprising:

a multiplexor provided with the first digital signal, the second digital signal and the third digital signal as inputs and operative to selectively provide one of the first digital signal, the second digital signal and the third digital signal an output signal.

17. The digital power monitoring circuit of claim 16, further comprising:

a filter circuit connected to an output of the multiplexor and operative to filter the output signal of the multiplexor circuit to provide an filter output signal that is indicative of an average of one of the first digital signal, the second digital signal and the third digital signal based on which of these digital signals is selectively provided as the output signal of the multiplexor.