ST9 crystal oscillator

[gpr]

Posted on July 27, 2005 at 06:40

ST9 crystal oscillator

[gpr]

Posted on May 17, 2011 at 11:36

I've been looking into some problems with an ST9 design done by a previous engineering team and have some real issues with the crystal circuit they came up with.

The capacitor on the OSCIN side of the crystal is tied to +VCC rather than ground. And they tied an analog switch circuit to the OSCOUT side of the crystal, and it defaults to the on state during power up. This adds a bit more capacitance to the circuit on start up than the max.

Also, I'm a bit confused by the information on the oscillator in the documentation. They show an internal switched parallel resistor in one diagram, and then an external parallel resistor in another. Should I have an external resistor?

Thanks for any guidance you can give me.

George Richardson

Canberra Dover

[ This message was edited by: gprtech on 27-01-2005 22:03 ]

[kapil]

Posted on May 17, 2011 at 11:36

To see more on how to use crystal ossilator, pls download the documentation on ST9+ demostration board from the ST site