8-Output Differential Fanout Buffer – Universal Differential/TTL Input, TTL Output

Applications:

• 1:8 Fanout Buffer
• Converting Differential NECL/LVPECL/RS-422 or TTL Signals to TTL
• Long Line Driver/Level Translator
• Reference Clock Distribution/Translation
• 1 PPS Distribution/IRIG-B Distribution
• Telemetry and Avionics Distribution
• Test and System Integration

Features:

• f_max > 100 MHz
• 1.5 ns Typical Rise & Fall Times for TTL
• Channel-to-channel skew less than 500 ps
• Floating 100 Ω Universal Differential Inputs Accept LVDS, LVPECL, NECL, or RS-422 Inputs
• Separate TTL input (1 V minimum) Logically ORed with the Floating Differential Input
• 8 Complementary Outputs
• SMA Connectors for LVDS/LVPECL/NECL Inputs, BNC Connectors for TTL Input
• SMA or BNC Output Connectors
• Self-contained 3.0H x 6.8W x 7.3L-in. unit includes ±8.5V/1.8A AC/DC Adapter

Description

The PRL-4108UT is a series of 1:8 fanout differential line driver modules. All models have a floating 100 Ω universal differential input suitable for accepting LVDS, LVPECL, NECL, or RS422 signals.⁽¹⁾ They also have a logically ORed, 50 Ω TTL input with a minimum 1.0 V triggering threshold. Because the inputs are ORed a Hi level applied to either input can be used as a gate signal. Please see the block diagrams for more details.

The output is TTL, available either with dual SMA or dual BNC connectors per complementary output.

The PRL-4108UT high speed fanout line driver facilitates testing of high speed digital communications circuits and distribution of satellite or telemetry signals. The product suffix specifies the input and output connectors, e.g. BNC or SMA:

Additional connector and output logic options may be available upon special order.

The floating differential input accepts differential LVDS, LVPECL, NECL, RS422, or any 75 mV minimum differential signal within a common-mode range of -2.0 V to +3.0 V. When driven by LVPECL or NECL inputs, these signals must have internal 150 Ω or 200 Ω pull down resistors, respectively (known as a “source-biased” output). The PRL-4108UT differential input is compatible with all LVPECL or NECL output signals from the PRL family of products.

The TTL input has a selectable 50 Ω/1 kΩ input load and will trigger on a minimum 1.0 V threshold. The 1 kΩ is useful for interfacing with low-power circuits.

The eight pairs of complementary outputs are back-terminated and are designed for driving long lines. See the Specifications page for output levels.

The PRL-4108UT is supplied with a ±8.5 V/1.8 A AC/DC Adapter and housed in a 3.0 x 6.8 x 6.0-in. extruded aluminum enclosure. Available accessories include voltage distribution modules and mating cables.

(1) A related series, the PRL-4108NT, has a true NECL input terminated into 50 Ω/-2 V, and can accept single-ended or differential NECL signals that do not have internal pull-downs.