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External Clock Drive Waveforms
Figure 37. Ecternal Clock Drive
VIL1
External Clock Drive
Symbol
Parameter
1/t
Oscillator Frequency
CLCL
t
Clock Period
CLCL
t
High Time
CHCX
t
Low Time
CLCX
t
Rise Time
CLCH
t
Fall Time
CHCL
Typical Characteristics
The following charts show typical behavior. These data are characterized, but not tested. All current consumption measure-
ments are performed with all I/O pins configured as inputs and with internal pull-ups enabled. A sine wave generator with
rail to rail output is used as clock source.
The power consumption in power-down mode is independent of clock selection.
The current consumption is a function of several factors such as: operating voltage, operating frequency, loading of I/O
pins, switching rate of I/O pins, code executed and ambient temperature. The dominating factors are operating voltage and
frequency.
The current drawn from capacitive loaded pins may be estimated (for one pin) as C
V
= operating voltage and f = average switching frequency of I/O pin.
CC
The parts are characterized at frequencies higher than test limits. Parts are not guaranteed to function properly at frequen-
cies higher than the ordering code indicates.
The difference between current consumption in Power Down mode with Watchdog timer enabled and Power Down mode
with Watchdog timer disabled represents the differential current drawn by the watchdog timer.
AT90S1200
48
VIH1
V
CC
Min
0
250
100
100
= 2.7V to 4.0V
Max
Min
4
83.3
33.3
33.3
1.6
1.6
V
= 4.0V to 6.0V
CC
Max
0
12
0.5
0.5
V
*f where C
*
L
L
CC
Units
MHz
ns
ns
ns
µs
µs
= load capacitance,
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