2 Channel TTL to RS-422 Logic Level Translator

Applications:

• Converting TTL/CMOS Signals to Differential 124 Ω RS422 Signals
• High Speed Digital Communications Systems Testing
• Differential Long Line Drivers

Features:

• f_max > 250 MHz
• 1.2 ns Typical Output Rise & Fall Times
• TTL Compatible 50 Ω Input
• 1.5 V or 1.0 V Selectable Input Threshold
• Complementary 124 Ω Outputs
• BNC Input/SMA Output Connectors for PRL-420RS
• BNC Input/Triax Output Connectors for PRL-420RSTR
• SMA I/Os for PRL-420RS-SMA
• DC Coupled I/Os
• Self-contained 1.3 x 2.9 x 3.9-in. unit including an AC/DC Adapter

Description

The PRL-420RS is a dual channel line driver and level translator. It has a single-ended TTL input and differential 124 Ω RS-422 outputs. Each channel has a 50 Ω TTL/CMOS compatible input and a pair of differential 124 Ω outputs for driving long lines, in excess of 100 ft, terminated into differential 124 Ω loads. The input threshold voltage can be selected between 1.5 V and 1.0 V using a front panel switch. The 1.0 V threshold makes it easy to interface with 3.3V TTL/CMOS devices.

The PRL-420RS outputs are designed to interface with the 124 Ω differential Serial Data/Data or Clock/Clock inputs of the data communications equipment and also for use in testing and interfacing of high speed digital communication circuits. The PRL-420RS complements other PRL-series Level Translators, such as the PRL-420ND/PD, PRL-450ND/PD, and PRL-460NPD/PND, etc., in system integration applications where interconnections among different logic signals are often necessary.

The PRL-420RS is a ready-to-use functional module housed in a 1.3 x 2.9 x 3.9-in. extruded aluminum enclosure and is supplied with a ±8.5 VAC/DC Adapter. BNC input and SMA output connectors are provided for the PRL-420RS model, Triax output connectors for the PRL-420RSTR model, and SMA I/Os for the PRL-420RS-SMA model. A block diagram showing the equivalent input and output circuits are shown in Figs. 1A and 1B.