2005-07-26 09:40 PM
2011-05-17 02:36 AM
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 ]2011-05-17 02:36 AM
To see more on how to use crystal ossilator, pls download the documentation on ST9+ demostration board from the ST site