LMH0346 New crystal

Pablo baizan

Other Parts Discussed in Thread: LMH0346

In my company we have this crystal, ecliptek EA3250FA18-27.00, we have very interesting in this part because is mil certificate. The problem is the parameter drive level 100 uW max. This crystal is compatible with LMH0346? what is the cap load value for this crystal?

Thanks you

over 9 years ago

0 Nasser Mohammadi over 9 years ago

TI__Guru* 93670 points

27MHz KDS 1B427000ZZ0A.pdfHi Pablo,

Please attached note recommended crystal for the LMH0346 reference clock. As you can see typical drive level is about 10 uW while maximum could be 260uW. Also, loading Capacitance is about 18pF.

Regards,,nasser

0 Pablo baizan over 9 years ago in reply to Nasser Mohammadi

Prodigy 80 points

Thanks you for you help
ok, i undestand that the drive level is not problem. This is my first design using a different to the recommended crystal and i don´t undestand well the crystal parameters. For my crystal CL=18pf and CL = ((CX1 x CX2) / (CX1 + CX2)) + Cstray
where:
Cstray = the stray capacitance in the oscillator circuit, which will normally be in the 2pF to 5pF range.
Assuming that CX1=CX2 and Cstray=5pF:
CX1 = CX2 = 2(18pF - 5pF) = 26pF

Is 26pF a good value of cap?

Regards, Pablo

0 Nasser Mohammadi over 9 years ago in reply to Pablo baizan

TI__Guru* 93670 points

Hi Pablo,

Actually the drive level is important. CX1=CX2 depends on the drive level of the crystal. I suggest if you could please consulate your crystal supplier.

Regards,,nasser

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LMH0346 New crystal