59.2.1 Crystal Oscillators
| Signal Name | Recommended Pin Connection | Description | |
|---|---|---|---|
| XIN XOUT 3 to 20 MHz Crystal Oscillator in Normal Mode |
Crystals between 3 and 20 MHz USB High/Full Speed Host/Device peripherals require a 12 or 16 MHz clock. Capacitors on XIN and XOUT (Crystal Load Capacitance dependent) |
Crystal Load Capacitance to check
(CCRYSTAL). Example: for a 12 MHz crystal with a load capacitance of CCRYSTAL = 15 pF, external capacitors are required: CLEXT = 12 pF. |
|
| XIN XOUT 3 to 20 MHz Crystal Oscillator in Bypass Mode |
XIN: external clock source XOUT: can be left unconnected USB High/Full speed Host/Device peripherals require a 12 or 16 MHz clock. |
VDDIO square wave signal External clock source up to 20 MHz Duty Cycle: 40 to 60% |
|
| XIN XOUT 3 to 20 MHz Crystal Oscillator Disabled |
XIN: can be left unconnected XOUT: can be left unconnected USB High/Full-speed Host/Device peripherals are not functional with Main RC oscillator. |
Typical nominal frequency 12 MHz (Main RC Oscillator) Duty Cycle: 45 to 55% |
|
| XIN32 XOUT32 Slow Clock Oscillator |
32.768 kHz Crystal Capacitors on XIN32 and XOUT32 (Crystal Load Capacitance dependent) |
Crystal load capacitance to check
(CCRYSTAL32). Example: for a 32.768 kHz crystal with a load capacitance of CCRYSTAL32 = 7 pF, external capacitors are required: CLEXT32 = 11 pF. |
|
| XIN32 XOUT32 Slow Clock Oscillator in Bypass Mode |
XIN32: external clock source XOUT32: can be left unconnected |
VDDIO square wave signal External clock source up to 44 kHz Duty Cycle: 40 to 60% |
|
| XIN32 XOUT32 Slow Clock Oscillator Disabled |
XIN32: can be left unconnected XOUT32: can be left unconnected |
Typical nominal frequency 32 kHz
(internal 32 kHz RC oscillator) Duty Cycle: 45 to 55% |