Rainbow Electronics MAX3627 - Manual (Page 10)

MAX3627
+3.3V, Low-Jitter, Precision Clock
Generator with Multiple Outputs
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Table 1. Crystal Selection Parameters
The layout shown in Figure 5 gives approximately 2pF
of trace plus footprint capacitance per side of the crys-
tal (Y1). The dielectric material is FR4, and dielectric
thickness of the reference board is 15 mils. Using a
25MHz crystal and the capacitor values of C45 = 27pF
and C46 = 33pF, the measured output frequency accu-
racy is -1ppm at +25°C ambient temperature.
Crystal Selection
The crystal oscillator is designed to drive a fundamental
mode, AT-cut crystal resonator. See Table 1 for recom-
mended crystal specifications. See Figure 6 for external
capacitance connection.
Figure 5. Crystal Layout
X_IN
X_OUT
27pF
33pF
CRYSTAL
(C L = 18pF)
MAX3627
Figure 6. Crystal, Capacitors Connection
PARAMETER SYMBOL MIN TYP MAX UNITS
Crystal Oscillation Frequency f OSC 25 MHz
Shunt Capacitance C O 7.0 pF
Load Capacitance C L 18 pF
Equivalent Series Resistance (ESR) R S 50
Maximum Crystal Drive Level 300 μW