Accessory presence detection

Patent metadata

Field	Value
Publication number	US-9835657-B2
Application number	US-201414511780-A
Country	US
Kind code	B2
Filing date	Oct 10, 2014
Priority date	Oct 28, 2010
Publication date	Dec 5, 2017
Grant date	Dec 5, 2017

Abstract

Disclosed is an electronic circuit with a first terminal for connecting an accessory thereto, and with a functionality for detecting the presence of an accessory connected to the first terminal.

First claim

What is claimed is:

1. A method for detecting a presence of an accessory connected to a first terminal of an electronic device, the method comprising:
driving a current into the first terminal dependent on an electrical potential at the first terminal;
measuring the current at the first terminal to provide a current measurement signal;
comparing the current measurement signal with a reference signal; and
in a presence detection mode, generating a status signal dependent on the current measurement signal, wherein a presence detection occurs dependent on the comparison of the current measurement signal with the reference signal, wherein the status signal is only generated in the presence detection mode.

2. The method of claim 1 , wherein the current driven into the first terminal is selected such that a voltage at the first terminal is limited to a given maximum voltage value and such that the current is limited to a maximum current value.

3. The method of claim 1 , further comprising:
providing a transmitter or receiver circuit connected to the first terminal, wherein the accessory is connected to the first terminal;
providing an output of a controlled current source coupled to the first terminal;
providing a current measurement circuit to measure the current and provide the current measurement signal that is representative of the current at the first terminal;
providing an evaluation circuit coupled to the current measurement circuit; and
at the evaluation circuit, receiving the current measurement signal, and generating the status signal dependent on the received current measurement signal, wherein the status signal indicates whether the accessory is connected to the electronic device, and wherein the transmitter or receiver circuit, the current measurement circuit, and the evaluation circuit are provided in the electronic device.

4. The method of claim 3 , wherein the accessory is a removable component.

5. The method of claim 3 , further comprising connecting a plurality of accessories to the first terminal, wherein the status signal indicates whether or not one or more of the plurality of accessories is connected to the electronic device.

6. The method of claim 5 , further comprising coupling the current measurement circuit to the controlled current source.

7. The method of claim 5 , wherein the plurality of accessories comprises a transmitter and/or receiver circuit configured for data communication via a single line.

8. The method of claim 5 , wherein the plurality of accessories comprise a transmitter and/or receiver circuit configured for data communication, further comprising modulating a voltage at the first terminal of the transmitter and/or receiver circuit.

9. The method of claim 5 , wherein the plurality of accessories comprise a transmitter and/or receiver circuit configured for data communication, further comprising receiving/detecting an output voltage at the first terminal at the transmitter and/or receiver circuit.

10. The method of claim 3 , further comprising providing a controlled output current at an output of the controlled current source by selecting the output current from a current range ranging from a minimum current value to a maximum current value, and wherein the output current is provided such that a voltage at the first terminal is limited to a given maximum voltage value.

11. The method of claim 3 , wherein providing the current measurement circuit comprises:
providing a first current mirror having an input current path and having an output current path, wherein the input current path is connected in series with the controlled current source; and
providing an impedance connected in series with the output current path, wherein the evaluation circuit is coupled to the impedance.

12. The method of claim 11 , wherein the input current path is connected between the controlled current source and the first terminal.

13. The method of claim 12 , wherein the input current path and the output current path are connected in series with the controlled current source.

14. The method of claim 11 , wherein the input current path is connected between a terminal for supply potential and the controlled current source.

15. The method of claim 3 , wherein providing the controlled current source comprises:
providing a controllable current source having a current output coupled to the output of the controlled current source and a control input; and
providing a feedback loop coupled between the first terminal and the control input.

16. The method of claim 15 , wherein providing the feedback loop comprises providing an amplifier having a first input coupled to the first terminal, a second input receiving a reference voltage, and an output connected to the control input.

17. The method of claim 3 , wherein providing the controlled current source comprises:
providing a reference current source; and
providing a second current mirror with an input current path connected in series with the reference current source, and an output current path coupled to the output of the controlled current source.

18. The method of claim 17 , wherein the controlled current source is coupled to the first terminal only via the output.

19. The method of claim 17 , wherein providing the second current mirror further comprises:
providing an input transistor having a control terminal, and having a load path forming the input current path;
providing an output transistor having a control terminal coupled to the control terminal of the input transistor, and having a load path forming the output current path; and
providing a feedback loop coupled between the first terminal and the control terminals of the input and the output transistors.

20. The method of claim 11 , wherein providing the controlled current source comprises:
providing a reference current source; and
providing a second current mirror with an input current path connected in series with the reference current source, and an output current path coupled to the output of the controlled current source, wherein the first and second current mirrors have a common input current path.

21. The method of claim 20 , wherein providing the second current
providing an input transistor having a control terminal, and having a load path forming the input current path;
providing an output transistor having a control terminal coupled to the control terminal of the input transistor, and having a load path forming the output current path; and
providing a feedback loop coupled between the first terminal and the control terminals of the input and the output transistors.

22. The method of claim 3 , wherein generating the status signal dependent comprises:
at a first comparator stage, comparing the current measurement signal with a first reference signal and providing a first comparator signal dependent on the comparing; and
at an input of an output stage, receiving the first comparator signal or a signal dependent on the first comparator signal, and providing the status signal dependent on a signal received at the input of the output stage.

23. The method of claim 22 , wherein generating the status signal dependent further comprises:
at an enable comparator stage, comparing the current measurement signal with an enable reference signal and providing an enable comparator signal;
receiving the enable reference signal or the signal dependent on the enable reference signal at an enable input of the output stage

Assignees

• Infineon Technologies Austria Ag

Inventors

• Furtner Wolfgang

Classifications

• G01R19/145 Primary

  Indicating the presence of current or voltage · CPC title

• G01R31/66

  Testing of connections, e.g. of plugs or non-disconnectable joints (testing for incorrect line connections G01R31/55) · CPC title

• H03K5/19 Primary

  Monitoring patterns of pulse trains (indicating amplitude G01R19/00; indicating frequency G01R23/00; measuring characteristics of individual pulses G01R29/02) · CPC title

• G01R31/04

  Physics · mapped topic