SN74TVC16222A

22BIT VOLTAGE CLAMP

SCDS087G − APRIL 1999 − REVISED APRIL 2005

5

POST OFFICE BOX 655303

APPLICATION INFORMATION

TVC background information

In personal computer (PC) architecture, there are industry-accepted bus standards. These standards define,

among other things, the I/O voltage levels at which the bus communicates. Examples include the GTL+ host

bus, the AGP graphics port, and the PCI local bus. In new designs, the system components must communicate

with existing bus infrastructure. Providing an evolutionary upgrade path is important in the design of PC

architecture, but the existing bus standards must be preserved.

To achieve the ever-present need for smaller, faster, lighter devices that draw less power, yet have faster

performance, most new high-performance digital integrated circuits are designed and produced with advanced

submicron semiconductor process technologies. These devices have thin gate-oxide or short channel lengths

and very low absolute-maximum voltages that can be tolerated at the inputs/outputs (I/Os) without causing

damage. In many cases, the I/Os of these devices are not tolerant of the high-state voltage levels on the

preexisting buses with which they must communicate. Therefore, it became necessary to protect the I/Os of

devices by limiting the I/O voltages.

The Texas Instruments (TI

) translation voltage-clamp (TVC) family is designed specifically for protecting

sensitive I/Os (see Figure 2). The information in this data sheet describes the I/O-protection application of the

TVC family and should enable the design engineer to successfully implement an I/O-protection circuit utilizing

the TI TVC solution.

Low-Voltage

I/O Device

TVC Family

Voltage-Clamp

Device

Standard-Voltage

I/O Bus

Figure 2. Thin Gate-Oxide Protection Application