74AUP1Z125 Datasheet, PDF (21/27 Pages) NXP Semiconductors – Low-power X-tal driver with enable and internal resistor

Philips Semiconductors
74AUP1Z125
Low-power X-tal driver with enable and internal resistor
74AUP1GU04
portion
74AUP1G125
portion
system
load
X1 ^{1 MΩ} X2
Xtal
C2
C1
Y
Csys Rsys
Fig 12. Crystal oscillator configuration
001aaf147
13.1.2 Testing
After the calculations are performed for a particular crystal, the oscillator circuit should be
tested. The following simple checks will verify the prototype design of a crystal controlled
oscillator circuit. Perform them after laying out the board:
• Test the oscillator over worst-case conditions (lowest supply voltage, worst-case
crystal and highest operating temperature). Adding series and parallel resistors can
simulate a worse case crystal.
• Insure that the circuit does not oscillate without the crystal.
• Check the frequency stability over a supply range greater than that which is likely to
occur during normal operation.
• Check that the start-up time is within system requirements.
As the 74AUP1Z125 isolates the system loading, once the design is optimized, the single
layout may work in multiple applications for any given crystal.
74AUP1Z125_1
Product data sheet
Rev. 01 — 3 August 2006
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
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