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. 21, 2007
Filed:
Sep. 16, 2005
Chi-hung Hui, Saratoga, CA (US);
Xianxin LI, Milpitas, CA (US);
Chi-Hung Hui, Saratoga, CA (US);
Xianxin Li, Milpitas, CA (US);
Pericom Semiconductor Corp., San Jose, CA (US);
Abstract
A bus switch chip is limited to operating with a power-supply voltage of 1.8 volts relative to a 0-volt ground. Differential bus signals switched through the bus switch chip swing from 2.7 to 3.3 volts, well above the chip's specified power-supply voltage. The bus switch chip is level-shifted by applying a 1.5-volt signal as the chip's ground, and a 3.3-volt signal as its power supply, so the chip's net power supply is within the specification at 1.8 volts. High-Definition Multimedia Interface (HDMI) and Digital Visual Interface (DVI) require that the differential signals are never driven to ground. However, some non-compliant video transmitters drive differential signals to ground when disabled. External pullup resistors or internal pullup transistors in the bus switch chip are added to the bus signals from non-compliant transmitters to pull disabled signals above the 1.5-volt chip ground to prevent damage from signals below the chip's 1.5-volt ground.