PRL-4506 Pulse Research Lab 1:8 Differential Fanout Buffer System

The Pulse Research Lab PRL-4506 1:8 Differential Fanout Buffer System is a low-skew, 1:8 differential fanout buffer system with (8) complementary 50Ω back-terminated TTL outputs and two inputs. The single-ended TTL input has a selectable 50Ω or 1 KΩ to ground termination. The NECL input can be driven by single-ended NECL, differential NECL or AC-coupled sinewave signals. The TTL and NECL inputs are logically ORed; therefore a Hi level applied to either input can be used as a gate signal.

For the NECL input a toggle switch selects either single-ended or differential inputs. In the differential input mode both the NECL and NECL inputs and are terminated internally into 50Ω/-2 V, 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 NECL input only. The NECL input is switched internally to V_BB, nominally -1.3 V, and termination resistor R_T for the NECL input channel is changed to a Hi Z value. In the single-input mode, therefore, the NECL input should not be used for receiving signals. If the NECL inputs are not connected to an active signal, the switch should be in the down position.

The input resistance of the TTL input can be selected to be either 50Ω or 1 Ω by a toggle switch. The 1 KΩ input is desirable when interfacing with low power circuits. The TTL input threshold voltage is 1.0 V minimum. When over-driven, the input voltage to the internal circuit is limited to 3.5 V through a current limiting 25Ω series resistor. The output swing is typically 0-2.5 V into 50Ω or 0-5.0 V into high impedance.

All I/Os are DC coupled and have SMA connectors at the rear panel of the unit. The PRL-4506 is housed in a standard 19-in. rack-mountable enclosure with optional slide rails, powered by an internal power supply switchable for 120/240 VAC, 50-60 Hz operation.