EL5481C/EL5482C
Quad 8ns High-Speed Comparators
where:
the tolerances of the resistors. The duty cycle can be
adjusted by changing V value.
CC
T
is the maximum ambient temperature
MAX
q
is the thermal resistance of the package
JA
1MHz to
8MHz
5V
200W
Threshold Detector
R
R
5kW
1
2
+
-
The inverting input is connected to a reference voltage
and the non-inverting input is connected to the input. As
V
OUT
1.5kW
R
3
the input passes the V
output changes state. The non-inverting and inverting
inputs may be reversed.
threshold, the comparator's
REF
C
R
4
1
2kW
0.01µF
2kW
V
+
-
IN
V
OUT
V
REF
Crystal Oscillator
A simple crystal oscillator using one comparator of an
EL5481C and EL5482C is shown below. The resistors
R
and R set the bias point at the comparator's non-
2
1
inverting input. Resistors R , R , and C set the invert-
3
4
1
ing input node at an appropriate DC average voltage
based on the output. The crystal's path provides resonant
positive feedback and stable oscillation occurs.
Although the EL5481C and EL5482C will give the cor-
rect logic output when an input is outside the common
mode range, additional delays may occur when it is so
operated. Therefore, the DC bias voltages at the inputs
are set about 500mV below the center of the common
mode range and the 200W resistor attenuates the feed-
back to the non-inverting input. The circuit will operate
with most AT-cut crystal from 1MHz to 8MHz over a
2V to 7V supply range. The output duty cycle for this
circuit is roughly 50% at 5V V , but it is affected by
CC
10
ELANTEC [ ELANTEC SEMICONDUCTOR ]
