DS8615 datasheet(4/6 Pages) NSC

4 / 6 page

Application Hints

OPERATING NOTES

The signal source is usually capacitively coupled to the in-

put At higher frequencies a 0001 mF input capacitor (C1) is

usually sufficient with larger values used at the lower fre-

quencies If the input signal is likely to be interrupted it may

be desirable to connect a 100 kX resistor between one in-

put 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 pulldown resistor

causes a loss of input sensitivity but prevents circuit oscilla-

tions under no signal (open circuit) conditions In addition in

the single ended mode a capacitor of 0001 mF (C2) should

be connected between the unused input and the ground

plane to provide a good high frequency bypass The capaci-

tor 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 provid-

ed the proper input coupling capacitor is provided

For regulated mode operation connect VS to VREG to en-

sure proper operation (see Typical Application diagram)

DS8615 Folha de dados(PDF) 4 Page - National Semiconductor (TI)