Capacitive isolated voltage domains

• US 8,787,502 B2
• Filed: 04/24/2012
• Issued: 07/22/2014
• Est. Priority Date: 04/24/2012
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Boezen, Hendrik, Bredius, Martijn
• Primary Examiner(s): Garcia, Santiago
• Application Number:
  US13/454,739
• Publication Number:
  US 20130279550A1
• Time in Patent Office: 819 Days
• Field of Search: 375/219
• US Class Current: 375/319
• CPC Class Codes: H03M 5/04 the pulses having two levels
• CPC Class Codes: H03M 5/08 Code representation by pulse width
• CPC Class Codes: H04B 14/026 using pulse time characteristics modulation, e.g. width, position, interval
• CPC Class Codes: H04B 5/22 Capacitive coupling
• CPC Class Codes: H04L 25/0266 Arrangements for providing Galvanic isolation, e.g. by means of magnetic or capacitive coupling

Abstract

In one embodiment, a method of communicating data values over a three conductor interface is provided. Different data values are transmitted by generating and transmitting three respective signals to a receiver using three conductors. The first signal is maintained as a set voltage level. The second signal is alternated between a high voltage and a low voltage according to a carrier frequency. The third signal is alternated between the high and low voltages and is out of phased with the second signal. To transmit a first data value, the first signal is generated on a first conductor, the second signal is generated on a second conductor, and the third signal is generated on a third conductor. To transmit a second data value, the second signal is generated on the first conductor, the first signal is generated on the second conductor, and the third signal is generated on the third conductor.

Claims

1. A device comprising:

a transmitter circuit, including;

circuitry configured and arranged to respond to input data of a first value by;

generating, on a first conductor, a first output signal that is maintained at a set voltage level;

generating, on a second conductor, a second output signal that alternates between voltage levels according to a carrier frequency; and

generating, on a third conductor, a third output signal that alternates between voltage levels according to the carrier frequency and that is out of phase with the second output signal; and

circuitry configured and arranged to respond to input data of a second, different, value by;

generating, on the first conductor, the second output signal that alternates between voltage levels according to the carrier frequency;

generating, on the second conductor, the first output signal that is maintained at a set voltage level; and

generating, on the third conductor, the third output signal that alternates between voltage levels according to a carrier frequency and out of phase with the second output signal.

2. The device of claim 1, wherein the circuit further includes the first, second and third conductors and wherein each of the first, second and third conductors are connected to a corresponding and different capacitor.

3. The device of claim 1, further including a receiving circuit configured to receive signals from the conductors using capacitive coupling.

4. The device of claim 1, further including a receiving circuit configured to receive signals from the conductors using a capacitive coupling circuit configured to provide galvanic isolation between the receiving circuit and the conductors.

5. The device of claim 1, wherein the transmitter circuit is further configured to communicate the input data without the use of differential signaling.

6. The device of claim 1, further including a receiving circuit configured to receive signals from the conductors using a capacitive coupling circuit configured to provide galvanic isolation between two integrated circuit chips housing the receiving circuit and the conductors, respectively.

7. The device of claim 1, further including a receiving circuit configured and arranged to receive signals from the conductors using a capacitive coupling circuit and to decode the input data by comparing a signal level corresponding to the first conductor with a signal level corresponding to a combination of the second and third conductors.

8. The device of claim 7, wherein the receiving circuit is further configured and arranged to decode the input data by comparing a signal level of the second of the conductors with a signal level corresponding to a combination of the first and third conductors.

9. The device of claim 8, wherein the receiving circuit is further configured and arranged to drive a set-reset logic circuit in response to the comparisons.

10. The device of claim 9, wherein the receiving circuit is further configured and arranged to drive an AC detector logic circuit in response to the comparisons.

11. The device of claim 1, wherein the transmitter circuit includes:

a first driver circuit, configured and arranged to;

in response to input data of the first value, maintained the first conductor at the set voltage level; and

in response to input data of a second value, alternate the first conductor between voltage levels according to a carrier frequency;

a second driver circuit, configured and arranged to;

in response to the input data of the first value, alternate the second conductor between voltage levels according to the carrier frequency; and

in response to the input data of the second value, maintained the second conductor at the set voltage level; and

a third driver circuit, configured and arranged to alternate the third conductor between voltage levels according to the carrier frequency and out of phase with the second output signal.

12. A method for communicating between first and second voltage domains, comprising:

communicating a first data value by;

communicating, on a first conductor, a first signal that is maintained at the set voltage level;

communicating, on a second conductor, a second signal that alternates between the voltage levels according to the carrier frequency; and

communicating, on a third conductor, a third signal that alternates between voltage levels according to the carrier frequency and that is out of phase with the second signal; and

communicating a second data value by;

communicating, on the first conductor, the second signal that alternates between voltage levels according to the carrier frequency;

communicating, on the second conductor, the first signal that is maintained at the set voltage level; and

communicating, on the third conductor, the third signal that alternates between voltage levels according to the carrier frequency and is out of phase with the second signal.

13. The method of claim 12, wherein communicating the first data value includes:

encoding the first data value to produce the first, second, and third signals; and

transmitting the first, second, and third signals on the respective first, second, and third conductors.

14. The method of claim 12, wherein communicating the first data value includes:

receiving the first second and third signals on the first, second, and third conductors, decoding the first, second, and third signals to produce the first data value.