2 Ch. Translator, RS422 to NECL


$ 937.25


  • Essential tool for interfacing with High speed data communications equipment
  • Converts differential 124 Ω RS-422 Triax Inputs to differential 50 Ω SMA NECL outputs


  • 400 MHz maximum Clock Rate
  • Differential 124 Ω Input terminations
  • Complementary 50 Ω NECL Outputs
  • Ready-to-Use 1.3 x 2.9 x 3.9-in. modules, include AC/DC Adapters


The PRL-422RS is a dual channel, high speed logic level translator designed specifically for use with high speed data communications applications. The PRL-422RS converts differential 124 Ω RS422 inputs to differential 50 Ω NECL outputs. A functional block diagram is shown in Fig. 1.

The inputs of the PRL-422RS consist of two triax connectors, each internally terminated with 124 Ω between the pin and the ring. They are designed to interface with the 124 Ω differential Serial Data/Data or Clock/Clock outputs from data communications equipment.

The complementary NECL outputs have SMA connectors. They are designed for driving 50 Ω loads terminated to -2 V, and with internal pull-down resistors, they can be AC-coupled to ground-referenced 50 Ω loads as well.

The PRL-422RS is housed in an attractive 1.3 x 2.9 x 3.9-in. extruded aluminum enclosure. Optional mounting brackets are available. Each unit is supplied with a ±8.5 V/1.4 A AC/DC Adapter.

Fig. 1 PRL-422RS Dual Ch. RS-422 to NECL Translator

*Since the high frequency signals to and from the 124 Ω I/O ports can not be easily measured, the 124 Ω I/O ports of these adapters were first cascaded using shielded twisted pair cables, Trompeter P/N PCGOW10PCG-36 or equivalent. Input signals were applied to the 50 Ω inputs of the PRL-422NECL, and outputs of the PRL-422RS were terminated into 50 Ω /-2 V, using the PRL-550NQ4X, four-channel ECL Terminator, connected to a 50 Ω input sampling oscilloscope.

  1. Trompeter P/N CBBJR79.
  2. Trompeter P/N PCGOW10PCG-36

(0° C ≤ TA ≤ 35° C)*

Symbol Parameter PRL-422RS Unit
Min Typ Max
RIN Input Resistance 122 124 126 Ω
VTT Input Termination Voltage   NA   V
IDC1 DC Input Current, +8.5 V   30 60 mA
IDC2 DC Input Current, -8.5 V   -130 -150 mA
VDC DC Input Voltage ±7.5 ±8.5 ±12 V
VAC AC/DC Adapter Input Voltage 103 115 127 V
tPLH Propagation Delay to output ↑   2000   ps
tPHL Propagation Delay to output ↓   2000   ps
tr/tf Rise/Fall Times1 (20%-80%)   750 850 ps
fmax Maximum Clock Frequency2 400 600   MHz
tSKEW1 Skew between outputs   20 200 ps
tSKEW2 Skew from unit to units   40 400 ps
  Input Connector Triax3  
  Output Connector SMA  
  Input Cables 124 Ω TP4  
  Output Cables 50 Ω Coax  
  Size  1.3 x 2.9 x 3.9 in.
  Weight, excluding AC adapter 7 Oz
  Shipping Weight, including AC adapter 4 lb.


(1). The 50 Ω output rise and fall times were measured with both the Q and Q outputs terminated into 50 Ω/-2 V. If one output is not terminated, both the rise and fall times will increase by approximately 15%, and output waveform degradation will occur.

(2). fMAX is measured using the differential input mode (switch up). The differential outputs are first divided by four, using the PRL-255 ÷2 and ÷4 frequency divider module, and then measured using the PRL-550NQ4X, four channel ECL Terminators, connected to a sampling scope.

(3). Trompeter P/N CBBJR79.

All PRL products with Triax connectors use Trompeter P/N CBBJR79, Right Angle Circuit Board Bulkhead Jack, 3-lug (Numbered page 10, document page 11 of 142). Any Trompeter 70-series Triax Cable Plug with 3 lugs (e.g. PL75-9, 3-lug) will mate with CBBJR79.