Manual

962
6264A–CAP–21-May-07
AT91CAP9S500A/AT91CAP9S250A
47.4 32 kHz Crystal Oscillator Characteristics
The following characteristics are applicable to the operating temperature range: T
A
= -40°C to 85°C and worst case of
power supply, unless otherwise specified.
Notes: 1. R
S
is the equivalent series resistance, C
L
is the equivalent load capacitance.
2. C
LEXT32
is determined by taking into account internal parasitic and package load capacitance.
3. Additional board load capacitance should be subtracted from C
LEXT32
.
Table 47-5. 32 kHz Oscillator Characteristics
Symbol Parameter Conditions Min Typ Max Unit
1/(t
CP32KHz
) Crystal Oscillator Frequency 32.768 kHz
C
CRYSTAL32
Crystal Load Capacitance Crystal @ 32.768 kHz 6 12.5 pF
C
LEXT32
(2)
External Load Capacitance
C
CRYSTAL32
= 6 pF
(3)
8pF
C
CRYSTAL32
= 12.5 pF
(3)
21 pF
Duty Cycle 40 60 %
t
ST
Startup Time
R
S
= 50 kΩ, C
L
= 6pF
(1)
300 ms
R
S
= 50 kΩ, C
L
= 12.5 pF
(1)
900 ms
R
S
= 100 kΩ, C
L
= 6pF
(1)
600 ms
R
S
= 100 kΩ, C
L
= 12.5 pF
(1)
1200 ms
XIN32
XOUT32
C
LEXT32
C
LEXT32
C
CRYSTAL32
AT91CAP9
GNDBU