Category: Hardware
Product Number: TMC9660
On the evaluation boards for the TMC9660 (STEPPER + 3-PHASE) a 16MHz 12pF crystal is used.
According to the BOM X301 "Jauch Quartz Q 16,0-JXS32-12-10/15-T1-WA-LF" is used. This is a 16MHz 12pF crystal.
According to the BOM X301 "Jauch Quartz Q 16,0-JXS32-12-10/15-T1-WA-LF" is used. This is a 16MHz 12pF crystal.
If we assume a stray capacitance of Cs=3pF, and a load capacitance of CL=12pF, with the following equation, we should add C1=C2=18pF.
On the evaluation board only 9pF was used for C301 & C302. On our circuit board with slightly shorter traces (less capacitance), the crystal fails to start up using 9pF (works with 18pF).
Are my calculations correct? Has anyone tried to actually use the external oscillator on the evaluation baords?
In the datasheet there is the recommandation to use a crystal of ESR <70Ohm and CL=9pF running at 16MHz.
Is this recommandation correct and a crystal with 9pF would perform better or should we stick to the 12pF crystal?
BR
Gabriel
Is this recommandation correct and a crystal with 9pF would perform better or should we stick to the 12pF crystal?
BR
Gabriel
