OSH Park
Crystal Oscillator Clock Driver
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Crystal Oscillator Clock Driver
by
qwertymodo.
2
layer board of
0.40x0.50
inches
(10.16x12.70
mm).
Shared on
September 11th, 2013 18:31.
Simple crystal oscillator clock generator. Requires only external connections for Vcc, Gnd, and the clock output.
Component list
OSC: HC-49 crystal/resonator[1]
IC1: TI SN74LVC1GX04DBVR (SOT-23)
C1/C2: 0805 SMD capacitors (omit if using a resonator w/internal capacitors)[2]
RS: 0805 SMD resistor[3]
RF: 0805 SMD resistor (1M-10M)
[1] Any standard HC-49 crystal or resonator should fit. The hole pitch is 2.54mm, but slight differences shouldn’t matter. Alternatively, the Samtec SL-103-G-39 socket strip can be used to swap out crystals at will.
[2] Crystal load capacitor values calculated from the crystal’s rated load capacitance, they are NOT the same as the load capacitance. Simplifying the calculation from the datasheet gives:
C1 = C2 = 2(CL + CS)
where CL is the crystal’s rated load capacitance and CS is the IC’s stray capacitance (5pF for the SN74LVC1GX04DBVR).
e.g. for a crystal rated for 18pF load capacitance, C1 = C2 = 26pF
[3] RS should be calculated to be roughly equal to the reactance of C2 at the target frequency