50MHz Murata Resonator
Amit
Posts: 27
I am currently designing a circuit to use the SX52 and a Murata 50Mhz resonator but I have a few questions.
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1) The Ubicom data sheet says that the oscillator circuit needs two 15uF caps to ground but the Murata data sheet says that some of the resonators already have this built in.· Which ones does Parallax sell?· It seems that the different varieties also require different pad spacing so it would be really helpful if somebody knew this information.
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2) I was searching the forum for consensus on the issue of what parallel resistor to use but it seemed that most people had their own preference.· Are there any cases where you would want the 1M over the 10K or vice versa?
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3) Lastly, on page 13 of the SX Key Manual it states “When debugging, the SX chip must not have an external clock source since the SX-Key’s internal programmable oscillator must be used.” ·Does this mean that my resonator must be able to disconnect from the SX chip?· If so, do I have to worry about the added capacitance of a switch or shunt?· Or does the SX-Key over power the resonator?·
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I would appreciate any help on these issues.
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Thanks a lot!
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Amit
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1) The Ubicom data sheet says that the oscillator circuit needs two 15uF caps to ground but the Murata data sheet says that some of the resonators already have this built in.· Which ones does Parallax sell?· It seems that the different varieties also require different pad spacing so it would be really helpful if somebody knew this information.
·
2) I was searching the forum for consensus on the issue of what parallel resistor to use but it seemed that most people had their own preference.· Are there any cases where you would want the 1M over the 10K or vice versa?
·
3) Lastly, on page 13 of the SX Key Manual it states “When debugging, the SX chip must not have an external clock source since the SX-Key’s internal programmable oscillator must be used.” ·Does this mean that my resonator must be able to disconnect from the SX chip?· If so, do I have to worry about the added capacitance of a switch or shunt?· Or does the SX-Key over power the resonator?·
·
I would appreciate any help on these issues.
·
Thanks a lot!
·
Amit
Comments
2) Not sure. On my thru-hole design I didn't use one.
3) You can program the device with the resonator in place, but to debug it must be removed or disconnected.
Bean.
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-Amit
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Dave
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Dave Andreae
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dandreae@parallax.com
Http://www.parallax.com
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