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Method for level shifting on a digital display card for multiple devices and multiple voltages

IP.com Disclosure Number: IPCOM000010114D
Publication Date: 2002-Oct-23
Document File: 2 page(s) / 149K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for level shifting on a digital display card for multiple devices and multiple voltages. Benefits include improved design flexibility and improved throughput.

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Method for level shifting on a digital display card for multiple devices and multiple voltages

 

Disclosed is a method for level shifting on a digital display card for multiple devices and multiple voltages. Benefits include improved design flexibility and improved throughput.

Background

               Conventional digital display cards utilize a dedicated digital voltage output (DVO) channel and dedicated I2C pins that enable direct connection to digital video-out devices. These cards are subject to a constraint in that all signals must be a maximum of 1.5V on the advanced graphics processor (AGP) slot. As a result, level shifting enables I2C lines to be connected to the devices on the ADD card without damaging the graphics and memory controller hub (GMCH, see Figure 1). With a single DVO channel, a maximum of three devices can use the I2C bus. With two DVO channels, the potential exists to have five or more devices that require I2C connection. However, only three I2C pairs can be multiplexed with the AGP slot so a sharing mechanism is required.

Description

              The GMCH is a device that supports both the memory controller and graphics controller. With the graphics controller, several different options for displays are available. Displays can come from the internal graphics device, through the AGP slot on the motherboard or through the dedicated DVO port. The AGP slot is versatile and provides various options. The AGP slot provides graphics data and functions according to...