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7810C–AVR–10/12
Atmel ATmega328P [Preliminary]
28.8
2-wire Serial Interface Characteristics
Table 28-7 describes the requirements for devices connected to the 2-wire Serial Bus. The ATmega328P 2-wire Serial
Interface meets or exceeds these requirements under the noted conditions.
Notes:
1. In ATmega328P, this parameter is characterized and not 100% tested.
2. Required only for f
SCL > 100 kHz.
3. Cb = capacitance of one bus line in pF.
4. f
CK = CPU clock frequency
5. This requirement applies to all ATmega328P 2-wire Serial Interface operation. Other devices connected to the 2-wire Serial
Bus need only obey the general fSCL requirement.
Table 28-7.
2-wire Serial Bus Requirements
Symbol
Parameter
Condition
Min
Max
Units
V
IL
Input Low-voltage
-0.5
0.3 V
CC
V
IH
Input High-voltage
0.7 V
CC
V
CC + 0.5
V
hys
Hysteresis of Schmitt Trigger Inputs
0.05 V
CC
–V
V
OL
Output Low-voltage
3 mA sink current
0
0.4
V
t
Rise Time for both SDA and SCL
20 + 0.1C
b
300
ns
t
of
Output Fall Time from V
IHmin to VILmax
10 pF < C
20 + 0.1C
b
250
ns
t
SP
Spikes Suppressed by Input Filter
0
ns
I
i
Input Current each I/O Pin
0.1V
CC < Vi < 0.9VCC
-10
10
A
C
Capacitance for each I/O Pin
–
10
pF
f
SCL
SCL Clock Frequency
f
CK
SCL, 250kHz)
0
400
kHz
Rp
Value of Pull-up resistor
f
SCL ≤ 100 kHz
fSCL > 100 kHz
tHD;STA
Hold Time (repeated) START Condition
f
SCL ≤ 100 kHz
4.0
–
s
fSCL > 100 kHz
0.6
–
s
tLOW
Low Period of the SCL Clock
fSCL ≤ 100 kHz
4.7
–
s
fSCL > 100 kHz
1.3
–
s
tHIGH
High period of the SCL clock
fSCL ≤ 100 kHz
4.0
–
s
fSCL > 100 kHz
0.6
–
s
tSU;STA
Set-up time for a repeated START condition
fSCL ≤ 100 kHz
4.7
–
s
fSCL > 100 kHz
0.6
–
s
tHD;DAT
Data hold time
fSCL ≤ 100 kHz
0
3.45
s
fSCL > 100 kHz
0
0.9
s
tSU;DAT
Data setup time
fSCL ≤ 100 kHz
250
–
ns
fSCL > 100 kHz
100
–
ns
tSU;STO
Setup time for STOP condition
fSCL ≤ 100 kHz
4.0
–
s
fSCL > 100 kHz
0.6
–
s
tBUF
Bus free time between a STOP and START
condition
fSCL ≤ 100 kHz
4.7
–
s
fSCL > 100 kHz
1.3
–
s
VCC 0,4V
–
3mA
----------------------------
1000ns
Cb
-------------------
Ω
VCC 0,4V
–
3mA
----------------------------
300ns
Cb
----------------
Ω