Method and apparatus to authenticate a power supply

• US 8,225,111 B2
• Filed: 12/19/2005
• Issued: 07/17/2012
• Est. Priority Date: 12/19/2005
• Status: Expired due to Fees

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Balakrishnan, Balu, Bailey, Douglas John
• Primary Examiner(s): LOUIE, OSCAR A
• Application Number:
  US11/311,957
• Publication Number:
  US 20070143636A1
• Time in Patent Office: 2,402 Days
• Field of Search: None
• US Class Current: 713/300
• CPC Class Codes: H02J 1/00 Circuit arrangements for dc mains or dc distribution networks
• CPC Class Codes: H02J 13/00002 characterised by monitoring
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 10/30 State monitoring, e.g. fault, temperature monitoring, insulator monitoring, corona discharge

Abstract

A power supply that can be authenticated is disclosed. An apparatus according to aspects of the present invention includes an external power supply of an electronic product that modulates an output of the power supply with information encoded to identify the power supply to the product.

Claims

1. An external power supply of an electronic product, comprising:

a switch coupled to modulate an output of the power supply with information encoded to identify the power supply to the product, wherein the output of the power supply includes no more than two conductors to transfer the information encoded to identify the power supply and to transfer power from the power supply to the product; and

a controller coupled to provide a command signal to the switch in response to an encoder and a sense signal that senses the output of the power supply, wherein the encoder provides the information to identify the power supply to the electronic product, wherein the controller includes;

an oscillator, wherein the encoder is coupled to modify the operation of the oscillator;

an error amplifier coupled to receive a reference signal and the sense signal, wherein the encoder is coupled to modify a value of the reference signal; and

switching logic that produces the command signal in response to the oscillator, the encoder, and the error amplifier.

2. The external power supply of claim 1 wherein the encoder includes a shift register that uses a polynomial to generate a sequence of bits that encrypts a binary key.

3. The external power supply of claim 2 wherein the shift register is a linear feedback shift register.

4. The external power supply of claim 1 wherein transferring the information encoded to identify the power supply to the product is one-way communication.

5. A system, comprising:

an external power supply having an external power supply output; and

an electronic product coupled to the power supply output to receive power from the external power supply, wherein the electronic product includes a power bus monitor coupled to identify the power supply by interpreting information encoded on the external power supply output and coupled to produce an authentication signal that indicates whether or not the power supply is authorized to provide power to the electronic product, wherein the external power supply output includes no more than two conductors to transfer the information encoded on the external power supply output and to transfer power from the external power supply to the electronic product, wherein the power bus monitor includes;

a signal detector coupled to receive and demodulate the information encoded on the external power supply output into a sequence of bits;

a decoder coupled to receive the sequence of bits from the signal detector and decrypt the sequence of bits; and

a logical comparator coupled to receive the sequence of bits decrypted by the decoder, the logical comparator asserting the authentication signal indicating the external power supply is authorized when the logical comparator recognizes the sequence of bits decrypted by the decoder as a key, wherein the decoder includes a linear feedback shift register that uses an encrypting polynomial and the key to decrypt the sequence of bits.

6. A switching power supply, comprising:

a switch coupled to regulate an output of the switching power supply; and

a controller coupled to provide a command signal to the switch, the command signal having a switching frequency in response to an encoder and a sense signal that senses the output of the switching power supply, wherein the switching frequency changes in a pattern that identifies the switching power supply to an electronic product to be coupled to receive power from the switching power supply output, wherein the switching power supply output includes no more than two conductors to transfer the pattern that identifies the switching power supply and to transfer the power from the power supply to the electronic product, wherein the encoder provides information to modulate the pattern of the switching frequency to identify the power supply to the electronic product, wherein the controller includes;

an oscillator, wherein the encoder is coupled to modify the operation of the oscillator;

an error amplifier coupled to receive a reference signal and the sense signal, wherein the encoder is coupled to modify a value of the reference signal; and

switching logic that produces the command signal in response to the oscillator, the encoder, and the error amplifier.

7. The switching power supply of claim 6 wherein the encoder includes a shift register that uses a polynomial to generate a sequence of bits that encrypts a binary key.

8. The switching power supply of claim 7 wherein the shift register is a linear feedback shift register.

9. A switching power supply, comprising:

a switch coupled to regulate an output of the switching power supply; and

a controller coupled to provide a command signal to the switch in response to an encoder and a sense signal that senses the switching power supply output, the switching power supply coupled to change a magnitude of the switching power supply output in a pattern that identifies the switching power supply to an electronic product to be coupled to receive power from the switching power supply output, wherein the switching power supply output includes no more than two conductors to transfer the pattern that identifies the switching power supply and to transfer the power from the power supply to the electronic product, wherein the encoder provides information to change the magnitude of the switching power supply output to identify the power supply to the electronic product, wherein the controller includes;

an oscillator, wherein the encoder is coupled to modify the operation of the oscillator;

an error amplifier coupled to receive a reference signal and the sense signal, wherein the encoder is coupled to modify a value of the reference signal; and

switching logic that produces the command signal in response to the oscillator, the encoder, and the error amplifier.

10. The switching power supply of claim 9 wherein the change of the magnitude of the switching power supply output is coupled to occur within a startup interval.

11. The switching power supply of claim 9 wherein the change of the magnitude of the switching power supply output is coupled to occur when an average switching frequency of the switching power supply is within a range of values.

12. The switching power supply of claim 11 wherein the magnitude of an output voltage of the switching power supply output is coupled to be modulated when the average switching frequency of the switching power supply is within the range of values.

13. The switching power supply of claim 12 wherein the magnitude of the output voltage of the switching power supply output is coupled to be modulated between an upper threshold and a lower threshold value when the average switching frequency of the switching power supply is within the range of values.

14. The switching power supply of claim 13 wherein the magnitude of the output voltage of the switching power supply output is coupled to be modulated between the upper threshold and substantially zero volts when the average switching frequency of the switching power supply is within the range of values.

15. The switching power supply of claim 9 wherein the change of the magnitude of the switching power supply output is coupled to occur when an output voltage of the switching power supply output is below a threshold value.

16. The switching power supply of claim 15 wherein the magnitude of an output of the switching power supply output is coupled to be modulated further when the output voltage of the switching power supply output is below the threshold value.

17. The switching power supply of claim 16 wherein the magnitude of an output voltage of the switching power supply output is coupled to be modulated between an upper threshold and a lower threshold value when the output voltage of the switching power supply output is below a threshold value.

18. The switching power supply of claim 17 wherein the magnitude of an output voltage of the switching power supply output is coupled to be modulated between an upper threshold and substantially zero volts when the output voltage of the switching power supply output is below the threshold value.

19. The switching power supply of claim 9 wherein the change of the magnitude of the output of the switching power supply is coupled to occur when an output current of the switching power supply is within a range of values.

20. The switching power supply of claim 9 wherein the change of the magnitude of the output of the switching power supply is coupled to occur when an output voltage of the switching power supply is within a range of values.

21. The switching power supply of claim 9 wherein the switching power supply is coupled to be identified in response to a number of transitions of the switching power supply output within a timing window.

22. The switching power supply of claim 9 wherein the encoder includes a shift register that uses a polynomial to generate a sequence of bits that encrypts a binary key.

23. The switching power supply of claim 22 wherein the shift register is a linear feedback shift register.

24. A power supply of an electronic product comprising:

a switch coupled to modulate an output of the power supply with information encoded to provide information regarding the operation of the power supply, wherein the output of the power supply includes no more than two conductors to transfer the information regarding the operation of the power supply and to transfer power from the power supply to the electronic product; and

a controller coupled to provide a command signal to the switch in response to an encoder and a sense signal that senses the output of the power supply, wherein the encoder provides information to change the magnitude of the switching power supply output to identify the power supply to the electronic product, wherein the controller includes;

an oscillator, wherein the encoder is coupled to modify the operation of the oscillator;

an error amplifier coupled to receive a reference signal and the sense signal, wherein the encoder is coupled to modify a value of the reference signal; and

switching logic that produces the command signal in response to the oscillator, the encoder, and the error amplifier.

25. The power supply of claim 24 wherein the information encoded on the output of the power supply includes information regarding the power consumption of the power supply.

26. The power supply of claim 24 wherein the information encoded on the output of the power supply includes information regarding a fault condition that exists within the power supply.