The Crystal OSC block provides an amplifier circuit which can generate a highly precise and stable digital clock signal (OUT) from a quartz crystal or ceramic resonator. When activated, the inverter amplifier is connected to PIN12 (output) and PIN13 (input). Proper feedback resistance and capacitance must be applied for the oscillation circuit to function. Please refer to the table below for recommended external component values.
Table 1. External Components Selection Table
| Frequency (MHz) | C1, C2 | Feedback Resistor |
| 5 | 33 pF | 5 kOhms |
| 10 | 22 pF | 1 kOhms |
| 15 | 15 pF | 500 Ohms |
| 20 | 10 pF | 270 Ohms |
Set the parameter ‘Enable crystal oscillator’ to Enable.
• Enable: block is enabled and connected to PIN12 (output) and PIN13 (input).
• Disable: block is shut off. PIN12 and PIN13 no longer used by this block.
A Power Down PIN that controls Crystal OSC. 1 = Power UP and 0 = Power DOWN. To fully enable a block, the components must first be activated. See ‘Activation’.
• No matrix PD:PD input disabled. Crystal OSC is always on.
• PD for crystal OSC: Control crystal OSC’s on/off state.