Download Tiny Crystal Oscillator

Tiny Crystal Oscillator
This simple oscillator circuit is made with two tiny integrated circuits in the SOT outline package. The
LP2980 is a low-dropout 3.3 volt regulator and the NC7504M5 is a single-gate AC logic IC. The crystal
may be any fundamental AT-cut from below 5 MHz to over 20 MHz. The feedback is through a voltage
divider to keep the crystal drive level low for good aging and short-term stability. The output is a 3 volt
squarewave suitable for driving high impedance loads. It may be desireable to add an additional gate
if improved load isolation is desired. Current consumption is below 2mA at 10 MHz and varies slightly
with frequency.
> 4 VDC Current drain is less than 2 mA at 10 MHz.
LP2980IM5-3.3
In
+
1uF
3.3 VDC
Out
(top view)
+
Gnd
1 megohm
4.7uF
on/off
n/c
n/c
NC7504M5
(top view)Vcc
0.01uF
47pF
100
Gnd
Inductor or capacitor
selected to tune crystal
Out
0-20pF
5 to 20 MHz
fundamental
crystal
47pF
1000
100
0.01uF
Copyright 1996 Wenzel Associates, Inc
100pF