2 Channel TTL to RS-422 Logic Level Translator


$ 747.50


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


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


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, and Triax output connectors for the PRL-420RSTR model. A block diagram showing the equivalent input and output circuits are shown in Figs. 1A and 1B.

PRL-420RS Fig. 1A: PRL-420RS Top Cover Decal
PRL-420RSTR Fig. 1B: PRL-420RSTR Top Cover Decal

(0° C ≤ TA ≤ 35° C)*

Symbol Parameter Min Typ Max Unit Comments
RIN Input Resistance 49.5 50 50.5  
ROUT Differential Output Resistance 122.6 124 125.3  
VTOSH Input Threshold Voltage (high) 1.4 1.5 1.6 V  
VTOSL Input Threshold Voltage (low) 0.9 1.0 1.1 V  
VIL TTL input Low Level -0.5 0 0.5 V  
VOL RS-422 Output Low Level -0.05 0.0 0.2 V Diff.124 Ω load
VOH RS-422 Output High Level   2.3 2.5 V Diff.124 Ω load
IDC1 DC Input Currents, +8.5 V 185 200 mA
IDC2 DC Input Currents, -8.5 V   -255 -275 mA
VDC DC Input Voltages ±7.5 ±8.5 ±12 V  
VAC AC/DC Adapter Input Voltage 103 115 127 V  
TPLH Propagation Delay to output ↑   2   ns  
TPHL Propagation Delay to output ↓   2   ns  
tr/tf Rise/Fall Times (10%-90%)   1.2 1.4 ns Note (1)
TSKEW Skew between any 2 outputs   150 400 ps  
fmax Max Clock Frequency 250 300   MHz
Size 1.3 x 2.9 x 3.9 in.  
  Weight, excluding AC adapter 5 Oz  
  Shipping Weight, including AC adapter 4 lb  
*Unless otherwise specified, dynamic measurements are made with all outputs terminated into 50 Ω .
(1). The output rise and fall times are measured with both the Q and Q outputs terminated into 50 Ω. If an unused complementary output is left unterminated, a slight increase in rise and fall times will result.