Atmel ATmega48/V Preliminary page 303

Table 26-2. 2-wire Serial Bus Requirements (Continued)
Symbol Parameter
(1)
C Capacitance for each I/O Pin
i
f SCL Clock Frequency
SCL
Rp Value of Pull-up resistor
t Hold Time (repeated) START Condition
HD;STA
t Low Period of the SCL Clock
LOW
t High period of the SCL clock
HIGH
t Set-up time for a repeated START condition
SU;STA
t Data hold time
HD;DAT
t Data setup time
SU;DAT
t Setup time for STOP condition
SU;STO
Bus free time between a STOP and START
t
BUF
condition
Notes: 1. In ATmega48/88/168, this parameter is characterized and not 100% tested.
2. Required only for f
3. C = capacitance of one bus line in pF.
b
4. f = CPU clock frequency
CK
5. This requirement applies to all ATmega48/88/168 2-wire Serial Interface operation. Other devices connected to the 2-wire
Serial Bus need only obey the general f
6. The actual low period generated by the ATmega48/88/168 2-wire Serial Interface is (1/f
than 6 MHz for the low time requirement to be strictly met at f
7. The actual low period generated by the ATmega48/88/168 2-wire Serial Interface is (1/f
ment will not be strictly met for f
communicate at full speed (400 kHz) with other ATmega48/88/168 devices, as well as any other device with a proper t
acceptance margin.
2545E–AVR–02/05
> 100 kHz.
SCL
requirement.
SCL
> 308 kHz when f
SCL
Condition
(4)
f > max(16f , 250kHz)
CK SCL
≤ 100 kHz
f
SCL
f > 100 kHz
SCL
≤ 100 kHz
f
SCL
f > 100 kHz
SCL
≤ 100 kHz
(6)
f
SCL
(7)
f > 100 kHz
SCL
≤ 100 kHz
f
SCL
f > 100 kHz
SCL
≤ 100 kHz
f
SCL
f > 100 kHz
SCL
≤ 100 kHz
f
SCL
f > 100 kHz
SCL
≤ 100 kHz
f
SCL
f > 100 kHz
SCL
≤ 100 kHz
f
SCL
f > 100 kHz
SCL
≤ 100 kHz
f
SCL
f > 100 kHz
SCL
= 100 kHz.
SCL
= 8 MHz. Still, ATmega48/88/168 devices connected to the bus may
CK
ATmega48/88/168
Min
–
(5)
0
V – 0,4V
1000ns
CC
---------------- -
--------------------------- -
3mA
V – 0,4V
CC
--------------------------- -
3mA
4.0
0.6
4.7
1.3
4.0
0.6
4.7
0.6
0
0
250
100
4.0
0.6
4.7
1.3
- 2/f ), thus f
SCL CK
- 2/f ), thus the low time require-
SCL CK
Max Units
10 pF
400 kHz
Ω
C
b
300ns
Ω
------------- -
C
b
– µs
– µs
– µs
– µs
– µs
– µs
– µs
– µs
3.45 µs
0.9 µs
– ns
– ns
– µs
– µs
– µs
– µs
must be greater
CK
LOW
303