DS8627 Datasheet, PDF (3/4 Pages) National Semiconductor (TI) – 130/225 MHz Low Power Prescalers

Application Hints
OPERATING NOTES
The signal source is usually capacitively coupled to the in-
put At higher frequencies a 0 001 mF input capacitor is usu-
ally sufficient with larger values used at the lower frequen-
cies If the input signal is likely to be interrupted it may be
desirable to connect a 100 kX resistor between one input
and ground to stabilize the device In the single-ended
mode it is preferable to connect the resistor to the unused
input In the differential mode the resistor can be connected
to either input The addition of the 100 kX pull-down resistor
causes a loss of input sensitivity but prevents circuit oscilla-
Schematic Diagrams
tions under no signal (open circuit) conditions In addition in
the single ended mode a capacitor of 0 001 mF should be
connected between the unused input and the ground plane
to provide a good high frequency bypass The capacitor
should be made larger for lower frequencies
The input waveform may be sinusoidal but below about 20
MHz the operation of the circuit becomes dependent on the
slew rate of the input rather than amplitude A square wave
input with a slew rate of greater than 20 V ms will permit
correct operation down to lower frequencies provided the
proper input coupling capacitor is provided
Typical Application
TL F 5009 – 4
TL F 5009 – 5
TL F 5009 – 6
3