The PRL-431LP is a 1:2 Differential Fanout LVPECL Buffer module. It is an essential lab tools for applications where it is necessary to drive two different loads from a single source of single-ended or differential LVPECL signals. It can also be used for converting GHz sine wave signals into differential LVPECL signals.
A switch selects either single-ended or differential inputs, as shown in Fig. 1. In the differential input mode, both inputs D and D are terminated internally into 50 Ω/VTT*, and, therefore, either one or both inputs can accept AC-coupled signals as well. In the single input mode, signal should be connected to the D input only. The D input is switched internally to VBB**, and termination resistor RT for the D input is changed to 62 Ω. Complementary outputs of the PRL-431LP are designed for driving 50 Ω loads terminated into +1.3 V. With internal pull-down resistors, these outputs can also be AC-coupled for driving 50 Ω loads terminated to ground or to other voltages.
The PRL-431LP complementary outputs must be used together for driving differential LVPECL inputs only, because the reduced output logic swing of 400 mVPP (for short circuit protection reasons) is not logic level compatible with some single-ended LVPECL inputs.
The PRL-431LP is housed in a 1.3 x 2.9 x 2.2-in. extruded aluminum enclosure and supplied with a ±8.5 V/1.8 A AC/DC Adapter.
VTT is nominally -2.0 V for ECL, +3.0 V for PECL, and +1.3 V for LVPECL. VBB is nominally -1.3 V for ECL, +3.7 V for PECL, and 2.0 V for LVPECL.
PRL-431LP Block Diagram
(0° C ≤ TA ≤ 35° C)*
|VTT||D Input Termination Voltage (fixed)||1.18||1.30||1.43||V|
|VT1||D Input Termination Voltage||1.18||1.30||1.43||V|
|VT2||D Input Termination Voltage (variable)||1.80||2.00||2.20||V|
|VIL||Input Lo Voltage||1.35||1.48||1.67||V|
|VIH||Input Hi Voltage||2.08||2.28||2.42||V|
|VOL||Output Lo Voltage||1.35||1.48||1.61||V|
|VOH||Output Hi Voltage||2.15||2.28||2.51||V|
|IDC||DC Input Current||150||170||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 ↑||750||950||ps|
|TPHL||Propagation Delay to output ↓||750||950||ps|
|tr/tf(1)||Rise/Fall Times (20%-80%)||220||300||ps|
|TSKEW||Skew between Q & Q outputs||20||75||ps|
|FMAX(2)||Max clock frequency||2.5||3.0||GHz|
|VCMR||Common Mode Range||2.0||3.3||V|
|Size||1.3 x 2.9 x 2.2||in.|
|Weight, excluding AC adapter||5||Oz|
|Shipping weight, excluding AC adapter||4||lb.|
*All measurements are made with outputs terminated into 50 Ω/VTT, using the PRL-550LPQ4X four channel LVPECL Terminator, connected to a 50 Ω input sampling oscilloscope.
(1). The output rise and fall times are measured with both the Q and Q outputs terminated into 50 Ω/VTT. An unused complementary output must be either terminated into 50 Ω/VTT or AC coupled into a 50 Ω; otherwise, output waveform distortion and rise time degradation will occur. Use the PRL-550LPQ4X four channel LVPECL Terminator for the 50 Ω/+1.3 V termination and for connection of LVPECL signals to 50 Ω input oscilloscopes.
(2). fMAX is measured by AC coupling a sine wave to the D input using the differential input mode (switch up). The differential outputs are first divided by four, using the PRL-255LP, and then measured using the PRL-550LPQ4X, four channel LVPECL Terminator, connected to a sampling scope.