AT90USB64/128
Figure 30-2. Maximum Frequency vs. VCC, AT90USB64/128
30.6 2-wire Serial Interface Characteristics
Table 30-2 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 30-3.
Table 30-2. 2-wire Serial Bus Requirements
Symbol Parameter
Condition
Min
-0.5
Max
0.3 VCC
VCC + 0.5
–
Units
V
Input Low-voltage
VIL
Input High-voltage
0.7 VCC
V
VIH
(1)
(2)
Hysteresis of Schmitt Trigger Inputs
Output Low-voltage
0.05 VCC
V
Vhys
(1)
3 mA sink current
10 pF < Cb < 400 pF(3)
0.1VCC < Vi < 0.9VCC
0
0.4
V
VOL
(1)
tr
(3)(2)
(3)(2)
Rise Time for both SDA and SCL
Output Fall Time from VIHmin to VILmax
Spikes Suppressed by Input Filter
Input Current each I/O Pin
Capacitance for each I/O Pin
SCL Clock Frequency
20 + 0.1Cb
300
ns
ns
ns
µA
pF
kHz
(1)
tof
20 + 0.1Cb
250
0
-10
–
50(2)
(1)
tSP
Ii
10
Ci(1)
10
fSCL
fCK(4) > max(16fSCL, 250kHz)(5)
0
400
VCC – 0,4V
fSCL ≤ 100 kHz
1000ns
-------------------
Cb
----------------------------
Ω
Ω
3mA
Rp
Value of Pull-up resistor
VCC – 0,4V
fSCL > 100 kHz
300ns
---------------
Cb
----------------------------
3mA
fSCL ≤ 100 kHz
fSCL > 100 kHz
fSCL ≤ 100 kHz(6)
4.0
0.6
4.7
1.3
–
–
–
–
µs
µs
µs
µs
tHD;STA
Hold Time (repeated) START Condition
Low Period of the SCL Clock
tLOW
f
SCL > 100 kHz(7)
403
7593A–AVR–02/06
ATMEL [ ATMEL ]
