Datasheet

381
7766F–AVR–11/10
ATmega16/32U4
Figure 29-2. Maximum Frequency vs. V
CC
, ATmega16U4/ATmega32U4
29.6 2-wire Serial Interface Characteristics
Table 29-2 describes the requirements for devices connected to the 2-wire Serial Bus. The ATmega16U4/ATmega32U4 2-
wire Serial Interface meets or exceeds these requirements under the noted conditions.
Timing symbols refer to Figure 29-3.
2.7V 4.5V 5.5V
Safe Operating Area
16 MHz
8 MHz
Table 29-2. 2-wire Serial Bus Requirements
Symbol Parameter
Condition Min Max Units
VIL
Input Low-voltage -0.5 0.3 V
CC
V
VIH
Input High-voltage 0.7 V
CC
V
CC
+ 0.5 V
Vhys
(1)
Hysteresis of Schmitt Trigger Inputs 0.05 V
CC
(2)
–V
VOL
(1)
Output Low-voltage 3 mA sink current 0 0.4 V
tr
(1)
Rise Time for both SDA and SCL 20 + 0.1C
b
(3)(2)
300 ns
tof
(1)
Output Fall Time from V
IHmin
to V
ILmax
10 pF < C
b
< 400 pF
(3)
20 + 0.1C
b
(3)(2)
250 ns
tSP
(1)
Spikes Suppressed by Input Filter 0 50
(2)
ns
I
i
Input Current each I/O Pin 0.1V
CC
< V
i
< 0.9V
CC
-10 10 µA
C
i
(1)
Capacitance for each I/O Pin – 10 pF
f
SCL
SCL Clock Frequency f
CK
(4)
> max(16f
SCL
, 250kHz)
(5)
0 400 kHz
Rp Value of Pull-up resistor
f
SCL
≤ 100 kHz
f
SCL
> 100 kHz
t
HD;STA
Hold Time (repeated) START Condition
f
SCL
≤ 100 kHz 4.0 – µs
f
SCL
> 100 kHz 0.6 – µs
t
LOW
Low Period of the SCL Clock
f
SCL
≤ 100 kHz
(6)
4.7 – µs
f
SCL
> 100 kHz
(7)
1.3 – µs
V
CC
0,4V–
3mA
----------------------------
1000ns
C
b
-------------------
Ω
V
CC
0,4V–
3mA
----------------------------
300ns
C
b
----------------
Ω