1.9.1 XT Primary Oscillator Mode Does Not Reliably Function When the Driving Crystals are Above 3 MHz
On some devices, using the XT oscillator at the top end of its specified frequency range (3.0 - 4.0 MHz) may cause the device to cease driving the oscillator.
Work around
Use the XT mode only for frequencies lower than 3.0 MHz.
Use the HS mode if frequencies greater than 4.0 MHz on a crystal oscillator are required.
Affected Silicon Revisions
| A2 | A3 | A4 | A6 | A7 | |||
| X | X | X |