NB6L14 2.5 V/3.3 V 3.0 GHz Differential 1:4 LVPECL Fanout Buffer MultiLevel Inputs with Internal Termination NB6L14 Q0 Q0 Q0 V GND CC /Q0 Exposed Pad (EP) 16 15 14 13 Q1 Q1 1 12 IN /Q1 IN 50 2 11 Q1 VT VT 50 /IN Q2 3 10 VREF AC Q2 /Q2 Q2 4 9 IN EN D Q 56 7 8 CLK Q3 VREF AC Q3 Q3 V EN CC /Q3 Figure 2. QFN16 Pinout Figure 3. Logic Diagram (Top View) Table 1. EN TRUTH TABLE IN IN EN Q0:Q3 Q0:Q3 0 1 1 0 1 1 0 1 1 0 x x 0 0+ 1+ + = On next negative transition of the input signal (IN). x = Dont care. Table 2. PIN DESCRIPTION Pin Name I/O Description 1 Q1 LVPECL Output Noninverted Differential Output. Typically Terminated with 50 Resistor to V 2.0 V. CC 2 Q1 LVPECL Output Inverted Differential Output. Typically Terminated with 50 Resistor to V 2.0 V. CC 3 Q2 LVPECL Output Noninverted Differential Output. Typically Terminated with 50 Resistor to V 2.0 V. CC 4 Q2 LVPECL Output Inverted Differential Output. Typically Terminated with 50 Resistor to V 2.0 V. CC 5 Q3 LVPECL Output Noninverted Differential Output. Typically Terminated with 50 Resistor to V 2.0 V. CC 6 Q3 LVPECL Output Inverted Differential Output. Typically Terminated with 50 Resistor to V 2.0 V. CC 7 V Positive Supply Voltage CC 8 EN LVTTL/LVCMOS Synchronous Output Enable. When LOW, Q outputs will go LOW and Q outputs will go HIGH on the next negative transition of IN input. The internal DFF register is clocked on the falling edge of IN input (see Figure 20). The EN pin has an internal pullup resistor and defaults HIGH when left open. 9 IN LVPECL, CML, Inverted Differential Clock Input. Internal 50 Resistor to Termination Pin, VT. LVDS, HSTL 10 VREF AC Output Voltage Reference for capacitor coupled inputs, only. 11 VT Internal 100 centertapped Termination Pin for IN and IN. 12 IN LVPECL, CML, Noninverted Differential Clock Input. Internal 50 Resistor to Termination Pin, VT. LVDS, HSTL 13 GND Negative Supply Voltage 14 V Positive Supply Voltage CC 15 Q0 LVPECL Output Noninverted Differential Output. Typically Terminated with 50 Resistor to V 2.0 V. CC 16 Q0 LVPECL Output Inverted Differential Output. Typically Terminated with 50 Resistor to V 2.0 V. CC EP The Exposed Pad (EP) on the QFN16 package bottom is thermally connected to the die for improved heat transfer out of package. The exposed pad must be attached to a heatsinking conduit. The pad is not electrically connected to the die, but is recommended to be electrically and thermally connected to GND on the PC board. 1. In the differential configuration when the input termination pin VT, is connected to a common termination voltage or left open, and if no signal is applied on IN/IN inputs, then the device will be susceptible to selfoscillation.