Methods and apparatus for an interface
Various embodiments of the present technology may provide methods and apparatus for an interface. The interface may be configured to detect a hot unplug condition based on a first output voltage at an output terminal of a first buffer circuit and a second output voltage at an output terminal of a second buffer circuit, wherein the first and second buffer circuits receive a common input. The interface may further detect the hot unplug condition based on a difference of a peak magnitude of the first output voltage and a peak magnitude of the second output voltage.
1. An interface circuit, comprising:
a communication device, comprising: an input circuit connected in series with an output circuit; and
a detection circuit comprising:
a reference buffer comprising an input terminal connected to an output terminal of the input circuit having a first output voltage; and
a magnitude detection circuit comprising:
a first input terminal connected to an output terminal of the output circuit having a second output voltage; and
a second input terminal connected to an output terminal of the reference buffer;
wherein the magnitude detection circuit generates a first peak voltage according to the first output voltage and a second peak voltage according to the second output voltage; and
a comparator connected to an output terminal of the magnitude detection circuit and configured to
generate an output signal based on the first peak voltage and the second peak voltage, wherein the output signal indicates a hot unplug condition.
2. The interface circuit according to claim 1 , wherein the detection circuit detects the hot unplug condition within a time period defined by a real number greater than 1 with a factor in the range of 10 −15 to 10 −9 .
3. The interface circuit according to claim 1 , wherein:
the input circuit comprises a pre-driver circuit configured to modify a differential input signal at an input terminal of the interface circuit; and
the output circuit comprises a buffer amplifier configured to transfer the second output voltage to a sink device.
4. The interface circuit according to claim 1 , wherein the magnitude detection circuit comprises a first magnitude detection circuit comprising the second input terminal connected the output terminal of the reference buffer and configured to generate the first peak voltage.
5. The interface circuit according to claim 4 , wherein the magnitude detection circuit further comprises a second magnitude detection circuit comprising the first input terminal connected to the output terminal of the output circuit and configured to generate the second peak voltage.
6. The interface circuit according to claim 5 , wherein the comparator is connected to an output terminal of the first magnitude detection circuit and an output terminal of the second magnitude detection circuit, wherein the comparator is configured to compare the first peak voltage with the second peak voltage.
7. The interface circuit according to claim 1 , further comprising a control circuit connected to the detection circuit and responsive to the output signal of the detection circuit, wherein the control circuit is configured to power-down the communication device according to the output signal.
8. A method for detecting a hot unplug condition, comprising:
generating a first output voltage with a buffer amplifier according to a second output voltage of a pre-driver;
generating a reference voltage with a reference buffer according to the second output voltage of the pre-driver, wherein:
the reference buffer is connected in parallel with the buffer amplifier; and
the pre-driver is connected in series with both the reference buffer and the buffer amplifier;
detecting a peak amplitude of the first output voltage;
detecting a peak amplitude of the reference voltage;
comparing the peak amplitude of the first output voltage with the peak amplitude of the reference voltage; and
generating an output signal according to the comparison, wherein the output signal indicates the hot unplug condition.
9. The method according to claim 8 , wherein the output signal comprises:
a first value if the peak amplitude of the reference voltage is greater than the peak amplitude of the first output voltage; and
a second value if the peak amplitude of the reference voltage is less than the peak amplitude of the first output voltage.
10. The method according to claim 9 , wherein the second value corresponds to the hot unplug condition.
11. The method according to claim 8 , further comprising generating a power-down signal based on the output signal.
12. The method according to claim 8 , further comprising generating an impedance control signal based on the output signal.
13. The method according to claim 8 , wherein the detecting the hot unplug condition occurs within a time period defined by a real number greater than 1 with a factor in the range of 10 −15 to 10 −9 .
14. A system, comprising:
a host device connected to a sink device via an interface circuit, wherein the interface circuit comprises:
a communication device, comprising an input circuit connected in series with a output circuit, wherein:
the input circuit generates an intermediate voltage; and
the output circuit generates an output voltage according to the intermediate voltage; and
a detection circuit configured to detect a hot unplug condition, and comprising:
a reference buffer connected in parallel with the output circuit and in series with the input circuit, wherein the reference buffer generates a reference voltage according to the intermediate voltage;
a first peak detector connected to an output terminal of the output circuit and configured to generate a first peak signal according to the output voltage;
a second peak detector connected to an output terminal of the reference buffer and configured to generate a second peak signal according to the reference voltage; and
a comparator, connected to the first peak detector and the second peak detector, configured to generate an output signal according to the first peak signal and the second peak signal, wherein the output signal indicates the hot unplug condition.
15. The system according to claim 14 , wherein the interface circuit further comprises a control circuit connected to an output terminal of the comparator and configured to generate a control signal to power-down the communication device.
16. The system according to claim 14 , wherein the detection circuit detects the hot unplug condition within a time period defined by a real number greater than 1 with a factor in the range of 10 −15 to 10 −9 .
17. The system according to claim 14 , wherein the output signal comprises:
a first value if the peak amplitude of the reference voltage is greater than the peak amplitude of the first output voltage; and
a second value if the peak amplitude of the reference voltage is less than the peak amplitude of the first output voltage.
18. The system according to claim 17 , wherein the second value corresponds to the hot unplug condition.
19. The system according to claim 14 , wherein the reference voltage is proportional to the intermediate voltage.