Tool/software:
Hi there,
We're using a high-ohmic feedback resistor in parallel with an external oscillator (crystal). The resistor ensures the correct start-up of the crystal and prevents the dropouts, as shown as R14 below:
Sometimes you do not need to equip this resistor, because the µC itself has it internal at the clock input. I did not find any information in the data sheets of the M0G3507QPTRQ1, does the µC have this kind of feedback resistance internally or not?
For M0G3507QPTRQ1, we set the circuit shown above between pin#11 (PA5_HFXIN_FCC_IN) and pin#12 (PA6_HFCLK_IN_HFXOUT). Our oscillator generates 8MHz. The manufacturer of the crystal recommends that we use this feedback resistor.
The resistor ROSC is mentioned several times in the user guide (second link), but it is necessary for the correct operation of the internal oscillator. My question concerns the feedback resistor of the externally connected oscillator.
Can you please help me find out if M0G3507QPTRQ1 has this feedback resistor internally or not? If not, do I need to consider it externally? We checked the circuit diagram of the evaluation board and saw that a feedback resistor was not used there. I have added the wiring diagram to the attachment.
