Programmable driver for an I/O pin of an integrated circuit

• US 6,507,215 B1
• Filed: 04/18/2001
• Issued: 01/14/2003
• Est. Priority Date: 04/18/2001
• Status: Expired due to Term

• Current Assignee: Silicon Labs CP, Inc. (Silicon Laboratories Incorporated)
• Original Assignee: Cygnal Integrated Products, Inc. (Silicon Laboratories Incorporated)
• Inventors: Storvik, Alvin C. II, Piasecki, Douglas S.
• Primary Examiner(s): Tokar, Michael
• Assistant Examiner(s): TRAN, ANH Q
• Application Number:
  US09/837,918
• Time in Patent Office: 636 Days
• Field of Search: 326/37, 326/47, 326/39, 326/41
• US Class Current: 326/41
• CPC Class Codes: G06F 13/4072 Drivers or receivers G06F13/4086 takes precedence; for multistate logic circuits H03K19/0002

Abstract

A pin interface for an integrated circuit. The pin interface includes logic gates for processing digital signals, and analog lines for carrying analog signals. The pin interface includes circuits for disabling the digital circuits when configured to carry analog signals.

Claims

1. An integrated circuit having at least two pin interfaces, comprising:

a common analog line formed in said integrated circuit; and

digital circuits formed in said integrated circuit for receiving and transmitting digital signals;

each of said pin interfaces having;

a conductive pad formed on said integrated circuit for coupling signals thereto;

an analog interface for selectively coupling said conductive pad to said common analog line, and

a digital interface for selectively coupling said conductive pad to said digital circuits.

2. The integrated circuit of claim 1, each said pin interface including an analog switch in said analog interface to control transmission of analog signals coupled thereto.

3. The integrated circuit of claim 2, wherein said analog switch in each said pin interface comprises a pair of transmission gates coupled together at a junction, and a transistor for coupling the junction to an isolation potential.

4. The integrated circuit of claim 1, wherein said digital circuits in each said pin interface includes disable circuits for disabling at least a portion of the digital circuit when at least one of said pin interfaces carries analog signals.

5. The integrated circuit of claim 4, herein digital circuits in said pin interfaces and having inputs coupled to said conductive pad are disabled during analog operation.

6. The integrated circuit of claim 1, further including circuits in said at least two pin interfaces that are operative to control said digital circuits so that in an analog mode of operation, said digital circuits driving said conductive pad are placed in a high impedance state.

7. The pin interface of claim 1, further including in combination an analog comparator having an input for monitoring voltages coupled to said pad.

8. The integrated circuit of claim 1, further including an analog multiplexer having plural inputs, a different input of said analog multiplexer coupled to each said pin interface.

9. The integrated circuit of claim 8, wherein each said pin interface includes an analog transmission gate controlled by a control signal for coupling analog signals to said analog multiplexer.

10. The integrated circuit of claim 9, further including a control register providing control signals to each said pin interface circuit for controlling the operation thereof.

11. The integrated circuit of claim 10, wherein said control register provides an output for placing a pin interface in an analog mode of operation.

12. The integrated circuit of claim 11, wherein said control register produces a first signal for controlling an analog switch during analog operation, and for disabling digital circuits during analog operation.

13. The integrated circuit of claim 1, further including a plurality of said conductive pads, and a plurality of said pin interfaces, each pin interface uniquely associated with a respective conductive pad.

14. The integrated circuit of claim 13, wherein each said pin interface is substantially identical in electrical design.

18. The integrated circuit of claim 1, wherein said analog interface and said digital interface are operable simultaneously.

15. A group of pin interfaces formed on an integrated circuit, comprising:

a common analog line, each of the pin interfaces having;

a contact pad formed on said integrated circuit,

a pair of transistors joined together at a junction to define a push-pull driver, said junction connected to said contact pad,

a first logic circuit for driving said pair of transistors into opposite states of conduction, and for driving said junction to a high impedance state,

said common analog line coupled to said contact pad for carrying analog signals; and

an analog switch coupled in said common analog line, and controlled by a control signal for controlling the coupling of analog signals on said common analog line.

16. The pin interface of claim 15, and further including a multiplexer having multiple inputs coupled to ones of said analog lines via said respective analog switches.

17. The pin interface of claim 15 further including a plurality of said groups of said pin interfaces, each group associated with a respective common analog line, and further including a multiplexer having a respective input coupled to each said common analog line.