The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 26, 2003
Filed:
Nov. 02, 2001
Scott Sterrantino, Allen, TX (US);
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
A dual mode output driver circuit within the architecture of a IEEE 1394-1995 IEEE 1394b compliant physical layer (PHY) circuit address the deficiencies of driver incompatibility between the first standard, IEEE 1394-1995, and the latest standard, IEEE 1394b. This output driver circuit of a serial bus structure which directly couples to a cable in a system for digital data transfer to and from the cable over the bus structure includes a current source, a first sub-circuit portion, a second sub-circuit portion, a switch and an amplifier. The first sub-circuit portion includes a reference voltage node. The current source connects to both the first and second sub-circuit portions to provide current. The second sub-circuit portion includes an external voltage bias node and a common mode voltage node, where the external voltage bias node connects to the cable. The switch couples between the first and second sub-circuit portions to provide an internal voltage bias operation mode and an external voltage bias operation mode for the output driver circuit in response to an enable signal. The switch couples to receive a reference voltage, an internal bias voltage, and a common mode voltage. The amplifier connects the switch to the first and second sub-circuit portions to supply an amplified difference between the common mode voltage and the internal bias voltage in the internal voltage bias operation mode and to amplify the difference between the reference voltage and the common mode voltage in the external voltage bias operation mode. The amplifier provides this amplified difference to the first and second sub-circuit portions. Thereby, the dual mode driver in accordance with the invention allows either an external voltage bias to drive current that regulated over a range of external biasing or an internal voltage bias to drive current within the driver circuitry.