Rainbow Electronics ATmega32L - Manual (Page 287)

287
ATmega32(L)
2503C–AVR–10/02
Two-wire Serial Interface Characteristics
Table 120 describes the requirements for devices connected to the Two-wire Serial Bus. The ATmega32 Two-wire Serial
Interface meets or exceeds these requirements under the noted conditions.
Timing symbols refer to Figure 145.
Notes: 1. In ATmega32, this parameter is characterized and not 100% tested.
2. Required only for f
SCL
> 100 kHz.
3. C
b
= capacitance of one bus line in pF.
4. f
CK
= CPU clock frequency
Table 120. Two-wire Serial Bus Requirements
Symbol Parameter Condition Min Max Units
V
IL
Input Low-voltage -0.5 0.3 V
CC
V
V
IH
Input High-voltage 0.7 V
CC
V
CC
+ 0.5 V
V
hys
(1) Hysteresis of Schmitt Trigger Inputs 0.05 V
CC
(2) – V
V
OL
(1) Output Low-voltage 3 mA sink current 0 0.4 V
t
r
(1) Rise Time for both SDA and SCL 20 + 0.1C
b
(3)(2) 300 ns
t
of
(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
t
SP
(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
t
HIGH
High period of the SCL clock
f
SCL
≤ 100 kHz
4.0 – µs
f
SCL
> 100 kHz 0.6 – µs
t
SU;STA
Set-up time for a repeated START condition
f
SCL
≤ 100 kHz 4.7 – µs
f
SCL
> 100 kHz 0.6 – µs
t
HD;DAT
Data hold time
f
SCL
≤ 100 kHz
0 3.45 µs
f
SCL
> 100 kHz 0 0.9 µs
t
SU;DAT
Data setup time
f
SCL
≤ 100 kHz
250 – ns
f
SCL
> 100 kHz 100 – ns
t
SU;STO
Setup time for STOP condition
f
SCL
≤ 100 kHz 4.0 – µs
f
SCL
> 100 kHz 0.6 – µs
t
BUF Bus free time between a STOP and START
condition
f
SCL
≤ 100 kHz
4.7 – µs
f
SCL
> 100 kHz 1.3 – µs
V
C C
0,4V –
3mA
----------------------------
1000ns
C
b
------------------- Ω
V
C C
0,4V –
3mA
----------------------------
300ns
C
b
---------------- Ω