SAR analog to digital converter having multiplexable ground sense pin

• US 7,411,538 B1
• Filed: 03/31/2007
• Issued: 08/12/2008
• Est. Priority Date: 03/31/2007
• Status: Expired due to Fees

• Current Assignee: Silicon Laboratories Incorporated
• Original Assignee: Silicon Laboratories Incorporated
• Inventors: Piasecki, Douglas S.
• Primary Examiner(s): Mai; Lam T
• Application Number:
  US11/695,002
• Time in Patent Office: 500 Days
• Field of Search: 341150-165
• US Class Current: 341/161
• CPC Class Codes: H03M 1/0607 Offset or drift compensation removal of offset already present on the analogue input signal H03M1/1295
• CPC Class Codes: H03M 1/123 Simultaneous, i.e. using one converter per channel but with common control or reference circuits for multiple converters
• CPC Class Codes: H03M 1/46 with digital/analogue converter for supplying reference values to converter
• CPC Class Codes: H03M 1/662 Multiplexed conversion systems
• CPC Class Codes: H03M 1/68 with conversions of different sensitivity, i.e. one conversion relating to the more significant digital bits and another conversion to the less significant bits
• CPC Class Codes: H03M 1/802 using capacitors, e.g. neuron-mos transistors, charge coupled devices

Abstract

A circuit includes a successive approximation register A/D converter for performing analog to digital conversions. The register has a ground pin and a ground sense pin. The ground sense pin is connected to a ground port of the circuit. A multiplexer connects the ground sense pin of the successive approximation register A/D converter to one of a plurality of I/O ports of the circuit package. A switch selectively connects the ground sense pin of the successive approximation register A/D converter to the ground port.

Claims

1. A circuit, comprising:

a successive approximation register A/D converter having a ground pin and a ground sense pin, wherein the ground pin is connected to a ground port of the circuit;

a multiplexer for connecting the ground sense pin of the successive approximation register A/D converter to one of a plurality of I/O ports of the circuit; and

a switch for selectively connecting the ground sense pin of the successive approximation register A/D converter to the ground port of the circuit.

2. The circuit of claim 1, wherein the multiplexer selects the one of the plurality of I/O ports of the circuit package responsive to a first control input from a first special function register.

3. The circuit of claim 1, wherein the switch selectively connects to the ground port responsive to a second control input from a second special function register.

4. The circuit of claim 1, wherein the switch disconnects the ground sense pin from the ground port and the multiplexer connects the ground sense pin to an unused one of the plurality of I/O ports of the circuit in a first mode of operation and further wherein the switch connects the ground sense pin to the ground port of the circuit in a second mode of operation.

5. A circuit, comprising:

a successive approximation register A/D converter having a ground pin and a ground sense pin, wherein the ground pin is connected to a ground port of the circuit;

a multiplexer for connecting the ground sense pin of the successive approximation register A/D converter to one of a plurality of I/O ports of the circuit, wherein the multiplexer selects the one of the plurality of I/O ports of the circuit responsive to a first control input from a first special function register;

a switch for selectively connecting the ground sense pin of the successive approximation register A/D converter to the ground port of the circuit, wherein the switch selectively connects to the ground port responsive to a second control input from a second special function register; and

wherein the switch disconnects the ground sense pin from the ground port and the multiplexer connects the ground sense pin to an unused one of the plurality of I/O ports of the circuit in a first mode of operation and further wherein the switch connects the ground sense pin to the ground port of the circuit package in a second mode of operation.

6. A method for controlling an output of a ground sense pin of a successive approximation register A/D converter in a circuit, comprising the steps of:

determining whether any I/O ports of the circuit are available for use;

if any I/O ports are available, disconnecting the ground sense pin of the successive approximation register A/D converter from a ground port and connecting an output of a multiplexer to an unused I/O port; and

if no I/O ports are available, connecting the ground sense pin of the successive approximation register A/D converter to a ground port of the circuit.

7. The method of claim 6, wherein the step of connecting an output of the multiplexer further comprises the step of connecting an output of the multiplexer to an unused I/O port responsive to a first control input from a first special function register.

8. The method of claim 6, wherein the steps of connecting the ground sense pin of the successive approximation register A/D converter further includes the step of selectively connecting to the ground port responsive to a second control input from a second special function register.

9. A circuit, comprising:

an electronic component having a ground pin and a ground sense pin, wherein the ground pin is connected to a ground port of the circuit;

a multiplexer for connecting the ground sense pin of the electronic component to one of a plurality of I/O ports of the circuit; and

a switch for selectively connecting the ground sense pin of the electronic component to the ground port of the circuit.

10. The circuit of claim 9, wherein the multiplexer selects the one of the plurality of I/O ports of the circuit responsive to a first control input from a first register.

11. The circuit of claim 9, wherein the switch selectively connects to the ground port responsive to a second control input from a second register.

12. The circuit of claim 9, wherein the switch disconnects the ground sense pin from the ground port and the multiplexer connects the ground sense pin to an unused one of the plurality of I/O ports of the circuit in a first mode of operation and further wherein the switch connects the ground sense pin to the ground port of the circuit in a second mode of operation.

13. A circuit, comprising:

an electronic component having a ground pin and a ground sense pin, wherein the ground pin is connected to a ground port of the circuit;

a multiplexer for connecting the ground sense pin of the electronic component to one of a plurality of I/O ports of the circuit;

a switch for selectively connecting the ground sense pin of the electronic component to the ground port of the circuit; and

wherein the switch disconnects the ground sense pin from the ground port and the multiplexer connects the ground sense pin to an unused one of the plurality of I/O ports of the circuit in a first mode of operation and further wherein the switch connects the ground sense pin to the ground port of the circuit in a second mode of operation.