Datasheet

SAM9G20
DS60001516A-page 744  2017 Microchip Technology Inc.
40.5.2 32 kHz Crystal Characteristics
40.5.3 RC Oscillator Characteristics
40.5.4 Slow Clock Selection
Table 40-13 defines the states for OSCSEL signal.
The startup counter delay for the slow clock oscillator depends on the OSCSEL signal. The 32768 Hz startup delay is 1200 ms whereas
it is 150 µs for the internal RC oscillator (refer to Table 40-13). The pin OSCSEL must be tied either to GND or VDDBU for correct operation
of the device.
Table 40-11: 32 kHz Crystal Characteristics
Symbol Parameter Conditions Min Typ Max Unit
ESR Equivalent Series Resistor Rs Crystal @ 32.768 kHz – 50 100 kΩ
C
m
Motional Capacitance Crystal @ 32.768 kHz – – 3 fF
C
SHUNT
Shunt Capacitance Crystal @ 32.768 kHz – – 2 pF
Table 40-12: RC Oscillator Characteristics
Symbol Parameter Conditions Min Typ Max Unit
1/(t
CPRCz
) Crystal Oscillator Frequency 20 32 44 kHz
Duty Cycle 45 – 55 %
t
START
Startup Time – – 75 µs
Table 40-13: Slow Clock Selection
OSCSEL Slow Clock Startup Time (Max)
0 Internal RC 150 µs
1 External 32768 Hz 1200 ms