Datasheet

393
7593L–AVR–09/12
AT90USB64/128
Figure 31-2. Maximum frequency vs. V
CC
, Atmel AT90USB64/128.
31.6 2-wire serial interface characteristics
Table 31-2 describes the requirements for devices connected to the 2-wire Serial Bus. The AT90USB64/128 2-wire Serial
Interface meets or exceeds these requirements under the noted conditions.
Timing symbols refer to Figure 31-3 on page 394.
16MHz
8MHz
Table 31-2. 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
Vhys
(1)
Hysteresis of Schmitt Trigger Inputs 0.05 V
CC
(2)
–
VOL
(1)
Output Low-voltage 3mA sink current 0 0.4
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
10pF < C
b
< 400pF
(3)
20 + 0.1C
b
(3)(2)
250
tSP
(1)
Spikes Suppressed by Input Filter 0 50
(2)
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
≤ 100kHz
f
SCL
> 100kHz
V
CC
0.4V–
3mA
----------------------------
1000ns
C
b
-------------------
Ω
V
CC
0.4V–
3mA
----------------------------
300ns
C
b
----------------