Ring-detect interface circuitry and method for a communication system

• US 6,480,602 B1
• Filed: 03/04/1998
• Issued: 11/12/2002
• Est. Priority Date: 04/22/1997
• Status: Expired due to Term

• Current Assignee: Silicon Laboratories Incorporated
• Original Assignee: Silicon Laboratories Incorporated
• Inventors: Fluke, Bradley J., Scott, Jeffrey W., Welland, David R., Dupuis, Timothy J., Sooch, Navdeep S.
• Primary Examiner(s): Isen, Forester W.
• Assistant Examiner(s): SINGH, RAMNANDAN P
• Application Number:
  US09/034,455
• Time in Patent Office: 1,714 Days
• Field of Search: 379/399-405, 379/399.01, 370/271, 370/280-292
• US Class Current: 379/399.01
• CPC Class Codes: H04L 25/0266 Arrangements for providing Galvanic isolation, e.g. by means of magnetic or capacitive coupling
• CPC Class Codes: H04L 25/06 Dc level restoring means; Bias distortion correction ; Decision circuits providing symbol by symbol detection
• CPC Class Codes: H04L 7/033 using the transitions of the received signal to control the phase of the synchronising-signal-generating means, e.g. using a phase-locked loop
• CPC Class Codes: H04M 1/573 Line monitoring circuits for detecting caller identification
• CPC Class Codes: H04M 11/06 Simultaneous speech and data transmission, e.g. telegraphic transmission over the same conductors
• CPC Class Codes: H04M 19/001 Current supply source at the exchanger providing current to substations
• CPC Class Codes: H04M 19/02 providing ringing current or supervisory tones, e.g. dialling tone or busy tone

Abstract

Ring-detect interface circuit is disclosed for digital DAA circuitry to provide a plurality of selectable signals, including a ring monitor signal, on a ring-detect output pin. The interface circuitry allows the digital DAA circuitry to interface with advanced controllers, such as advanced DSPs, while still being compatible with older controllers that expect only a ring monitor signal on the ring-detect pin. The interface circuitry may include a multiplexer that receives multiple status bits or signals, including the ring monitor signal, and that has its output controlled by a multiple-bit control register. In addition, the ring monitor signal may be communicated as a digital signal across an isolation barrier from phone line side circuitry to powered side circuitry and ultimately made available on the ring-detect output pin. Corresponding methods for improving compatibility of digital DAA circuitry through the ring-detect interface circuit are also disclosed.

Claims

1. A communication system, comprising:

phone line side circuitry configured to be coupled to phone lines;

powered side circuitry configured to be coupled to said phone line side circuitry through an isolation barrier; and

an interface circuit within said powered side circuitry coupled to an output pin to provide through said output pin one of a plurality of different selectable output signals,

wherein the output pin is a ring-detect output pin and one of said plurality of selectable output signals is a ring monitor signal.

2. The communication system of claim 1, further comprising said isolation barrier coupled between said phone line circuitry and said powered circuitry.

3. The communication system of claim 2, wherein digital information is transmitted across said isolation barrier.

4. The communication system of claim 3, wherein said isolation barrier comprises one or more capacitors.

5. The communication system of claim 2, wherein said interface circuitry includes a multiplexer receiving said plurality of selectable output signals and having its output controlled by a multiple-bit register.

6. The communication system of claim 5, wherein said multiple-bit register is controlled by data communicated to said powered side circuitry from an external device.

7. A method for improving compatibility in communication system, comprising:

coupling an isolation barrier between powered side circuitry and phone line side circuitry that is configured to be coupled to phone lines;

selecting one of a plurality of different selectable output signals; and

communicating said selected output signal through an output pin coupled to said powered side circuitry,

wherein the output pin is a ring-detect output pin and said selecting one of a plurality of selectable output signals comprises selecting a ring monitor signal for said output signal.

8. The method of claim 7, further comprising transmitting at least one of said plurality of selectable output signals as digital information across said isolation barrier prior to said selecting step.

9. The method of claim 8, wherein said isolation barrier is capacitive.

10. An output control circuit within a communication system capable of being coupled to phone lines for improving compatibility, comprising:

an output pin; and

an interface circuit coupled to said output pin to provide through said output pin one of a plurality of selectable different output signals, said output signals indicative of phone line status information.

11. The output circuit of claim 10, wherein the output pin is a ring-detect output pin and one of said plurality of selectable output signals is a ring monitor signal.

12. The output circuit of claim 11, wherein one of said selectable output signals is a DC loop current level.

13. The output circuit of claim 11, wherein said interface circuit comprises:

a multiplexer attached to said output pin and to said plurality of selectable output signals; and

a multiple bit register coupled to said multiplexer to control which of said plurality of selectable output signals are output by said multiplexer.

14. A method for improving compatibility for a communication system capable of being coupled to phone lines, comprising:

selecting one of a plurality of selectable different output signals, said output signals indicative of phone line status information; and

communicating said selected output signal through an output pin coupled to said powered side circuitry.

15. The method of claim 14, wherein said selecting step comprises selecting a ring monitor signal and said communicating step comprises communicating said ring monitor signal through a ring-detect output pin.