The PRL-422NECL is a dual channel, high speed logic level translator designed specifically for use with high speed data communications applications. The PRL-422NECL converts single ended or differential 50 Ω NECL inputs to differential 124 Ω RS422 outputs. A functional block diagram is shown in Fig. 1.
The differential inputs of the PRL-422NECL have SMA connectors. A switch selects either single-ended or differential inputs. In the differential input mode, both inputs D and D are terminated internally into 50 Ω/-2 V, and, therefore, either one or both inputs can accept AC coupled signals as well. In the single input mode, signals should be connected to the D inputs only. The D inputs are switched internally to VBB, nominally -1.3 V, and termination resistors RT's for the D input channels are changed to 62 Ω.
The outputs of the PRL-422NECL have two triax connectors, and they are designed to interface with the 124 Ω differential Serial Data/Data or Clock/Clock inputs of the data communications equipment. Internal pull-down resistors enable these outputs to drive differential 75 Ω loads as well.
The PRL-422NECL 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/1.8 A AC/DC Adapter.
*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.
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.
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 Terminator, connected to a sampling 'scope.
Trompeter P/N CBBJR79.
Trompeter P/N PCGOW10PCG-36
(0° C ≤ TA ≤ 35° C)*
|VTT||Input Termination Voltage||-1.8||-2.0||-2.2||V|
|IDC1||DC Input Current, +8.5 V||30||60||mA|
|IDC2||DC Input Current, -8.5 V||-250||-300||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%)||NA||ps|
|fmax||Maximum Clock Frequency2||400||600||MHz|
|tSKEW1||Skew between outputs||20||200||ps|
|tSKEW2||Skew from unit to unit||40||400||ps|
|Input Cables||50 Ω Coax|
|Output Cables||124 Ω TP4|
|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.