Datasheet

294
ATmega325/3250/645/6450
2570K–AVR–04/07
Figure 131. Maximum Frequency vs. V
CC
(8 - 16 MHz).
SPI Timing
Characteristics
See Figure 132 and Figure 133 for details.
Note: 1. In SPI Programming mode the minimum SCK high/low period is:
- 2 t
CLCL
for f
CK
< 12 MHz
- 3 t
CLCL
for f
CK
> 12 MHz
16 MHz
8 MHz
2.7V 4.5V 5.5V
Safe Operating Area
Table 124. SPI Timing Parameters
Description Mode Min Typ Max
1 SCK period Master See Table 67
ns
2 SCK high/low Master 50% duty cycle
3 Rise/Fall time Master 3.6
4 Setup Master 10
5HoldMaster 10
6 Out to SCK Master 0.5 • t
sck
7 SCK to out Master 10
8 SCK to out high Master 10
9SS
low to out Slave 15
10 SCK period Slave 4 • t
ck
11 SCK high/low
(1)
Slave 2 • t
ck
12 Rise/Fall time Slave 1.6 µs
13 Setup Slave 10
ns
14 Hold Slave t
ck
15 SCK to out Slave 15
16 SCK to SS high Slave 20
17 SS
high to tri-state Slave 10
18 SS
low to SCK Slave 20 • t
ck