ATMEGA169 ATMEL [ATMEL Corporation], ATMEGA169 Datasheet - Page 300

• Manufacturer Part Number: ATMEGA169
• Description: 8-bit Microcontroller with 16K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

External Clock Drive
Waveforms
External Clock Drive
Maximum Speed vs. V
300
ATmega169/V
CC
Figure 135. External Clock Drive Waveforms
Table 132. External Clock Drive
Maximum frequency is depending on V
Maximum Frequency vs. V
the maximum frequency at a given voltage in this interval, use this equation:
To calculate required voltage for a given frequency, use this equation::
Table 133. Constants used to calculate maximum speed vs. V
At 3 Volt, this gives:
Thus, when V
At 6 MHz this gives:
Thus, a maximum frequency of 6 MHz requires V
Symbol
1/t
t
t
t
t
t
∆
2.7 < V
1.8 < V
CLCL
CHCX
CLCX
CLCH
CHCL
t
Voltage and Frequency range
CLCL
CLCL
CC
CC
V
Parameter
Oscillator
Frequency
Clock Period
High Time
Low Time
Rise Time
Fall Time
Change in period
from one clock
cycle to the next
< 4.5 or 8 < Frq < 16
< 2.7 or 4 < Frq < 8
IL1
CC
V
IH1
= 3V, maximum frequency will be 9.33 MHz.
Frequency
Voltage
CC
Frequency
=
Voltage
curve is linear between 1.8V < V
1000
Min.
V
400
400
1.8
------- -
=
8
CC
0
------- -
1.8
=1.8-5.5V
8
•
(
6 4
•
=
8/1.8
Max.
CC.
(
–
=
2.0
2.0
a
3 2.7
1
2
b
–
a
As shown in Figure 136 and Figure 137, the
)
•
+
•
(
F Fy
(
1.8
V Vx
–
)
Min.
V
125
–
+
CC
50
50
0
CC
=
8
)
= 2.25V.
=2.7-5.5V
1.8/8
2.25
+
=
)
b
+
Vx
9.33
Fy
Max.
1.6
1.6
8
2
CC
CC
V
Min.
62.5
2.7
1.8
Vx
25
25
< 4.5V. To calculate
CC
0
=4.5-5.5V
2514P–AVR–07/06
Max.
0.5
0.5
16
2
Fy
8
4
Units
MHz
ns
ns
ns
µs
µs
%