2.5 V / 3.3 V Differential 2:1
Clock IN to Differential
LVPECL Clock Generator /
Divider / Fan-Out Buffer
Multi−Level Inputs w/ Internal Termination
The NB4L339 is a multi−function Clock generator featuring a 2:1
Clock multiplexer front end and simultaneously outputs a selection of
four different divide ratios from its four divider blocks; ÷1/÷2/÷4/÷8.
One divide block has a choice of ÷1 or ÷ 2.
The output of each divider block is fanned−out to two identical
differential LVPECL copies of the selected clock. All outputs provide
standard LVPECL voltage levels when externally terminated with a
50−ohm resistor to VCC − 2 V.
The differential Clock inputs incorporate internal 50−W termination
resistors and will accept LVPECL, CML or LVDS logic levels.
The common Output Enable pin (EN) is synchronous so that the
internal dividers will only be enabled/disabled when the internal clock
is in the LOW state. This avoids any chance of generating a runt clock
pulse on the internal clock when the device is enabled/disabled as can
happen with an asynchronous control. An internal runt pulse could
lead to losing synchronization between the internal divider stages. The
internal enable flip−flop is clocked on the falling edge of the input
clock. Therefore, all associated specification limits are referenced to
the negative edge of the clock input.
This device is housed in a 5x5 mm 32 pin QFN package.
• Maximum Input/Output Clock Frequency > 700 MHz
• Low Skew LVPECL Outputs, 15 ps typical
• 1 ns Typical Propagation Delay
• 150 ps Typical Rise and Fall Times
• 0.15 ps Typical RMS Phase Jitter
• 0.5 ps Typical RMS Random Clock Period Jitter
• LVPECL, CML or LVDS Input Compatible
• Operating Range: VCC = 2.375 V to 3.6 V with VEE = 0 V
• LVPECL Output Level; 750 mV Peak−to−Peak, Typical
• Internal 50−W Input Termination Provided
• Synchronous Output Enable/Disable
• Asynchronous Master Reset
• Functionally Compatible with Existing 2.5 V / 3.3 V LVEL, LVEP,
EP, and SG Devices
• −40°C to 85°C Ambient Operating Temperature
• 32−Pin QFN, 5 mm x 5 mm
• This is a Pb−Free Device
© Semiconductor Components Industries, LLC, 2012
September, 2012 − Rev. 3
A = Assembly Location
WL = Wafer Lot
YY = Year
WW = Work Week
G = Pb−Free Package
(Note: Microdot may be in either location)
Figure 1. Simplified Block Diagram
See detailed ordering and shipping information on page 11 of
this data sheet.
Publication Order Number: