Description
Within the semiconductor world, there are many I/O standards that have different voltage level requirements for the input voltage (VIH or VIL) and output voltage (VOH or VOL) typically based on the device operating voltage. These voltage levels define how the device communicates with other devices and the voltage levels are expressed as a bus standard. A few of these bus standards include 5 V CMOS, 5 V TTL, 3.3 V LVTTL, 2.5 V AGP graphics port and 1.5 V GTL+ host bus. Providing a migration path is important in all industry segments because system components used in new designs must communicate with components using the existing bus infrastructure even if they are operating at higher voltage levels. Since new devices are designed and produced with advanced sub-micron semiconductor process technologies, there has to be an easy way to prevent damage to the new device and translate voltage switching levels of the higher voltage legacy device.

The Philips Semiconductors Gunning Transceiver Logic Translator Voltage Clamp (GTL-TVC) family of bi-directional low voltage translators is designed in a BiCMOS process for protecting the sensitive I/Os on new advanced sub micron components. The GTL-TVC devices protect these new devices from the over voltage and ESD conditions applied by the older, legacy devices and translate the VIH and VOH switching levels. The information presented in this application note describes the I/O-protection applications and voltage translations of the GTL-TVC family and will enable the design engineer to successfully interface devices with different I/O voltage levels.