ATMEGA8_08 Datasheet, PDF (245/308 Pages) ATMEL Corporation – 8-bit with 8K Bytes In-System Programmable Flash

ATmega8(L)
Two-wire Serial Interface Characteristics
Table 101 describes the requirements for devices connected to the Two-wire Serial Bus. The ATmega8 Two-wire Serial
Interface meets or exceeds these requirements under the noted conditions.
Timing symbols refer to Figure 115.
Table 101. Two-wire Serial Bus Requirements
Symbol
V_IL
V_IH
V_hys(1)
V_OL(1)
t_r(1)
t_of(1)
t_SP(1)
I_i
C_i(1)
f_SCL
Parameter
Input Low-voltage
Input High-voltage
Hysteresis of Schmitt Trigger Inputs
Output Low-voltage
Rise Time for both SDA and SCL
Output Fall Time from V_IHmin to V_ILmax
Spikes Suppressed by Input Filter
Input Current each I/O Pin
Capacitance for each I/O Pin
SCL Clock Frequency
Rp
Value of Pull-up resistor
Condition
3 mA sink current
10 pF < C_b < 400 pF⁽³⁾
0.1V_CC < V_i < 0.9V_CC
f_CK(4) > max(16f_SCL, 250kHz)⁽⁵⁾
f_SCL ≤ 100 kHz
f_SCL > 100 kHz
t_HD;STA Hold Time (repeated) START Condition
f_SCL ≤ 100 kHz
f_SCL > 100 kHz
t_LOW
Low Period of the SCL Clock
f_SCL ≤ 100 kHz⁽⁶⁾
f_SCL > 100 kHz⁽⁷⁾
t_HIGH
High period of the SCL clock
f_SCL ≤ 100 kHz
f_SCL > 100 kHz
t_SU;STA Set-up time for a repeated START condition
f_SCL ≤ 100 kHz
f_SCL > 100 kHz
t_HD;DAT
Data hold time
f_SCL ≤ 100 kHz
f_SCL > 100 kHz
t_SU;DAT
Data setup time
f_SCL ≤ 100 kHz
f_SCL > 100 kHz
t_SU;STO Setup time for STOP condition
f_SCL ≤ 100 kHz
f_SCL > 100 kHz
t_BUF
Notes:
Bus free time between a STOP and START
f_SCL ≤ 100 kHz
condition
f_SCL > 100 kHz
1. In ATmega8, 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
Min
-0.5
0.7 V_CC
0.05 V_CC(2)
0
20 + 0.1C_b(3)(2)
20 + 0.1C_b(3)(2)
0
-10
–
0
-^V---^C----^C----–-----⁰---^,--⁴---^V---
3mA
-^V---^C----^C----–-----⁰---^,--⁴---^V---
3mA
4.0
0.6
4.7
1.3
4.0
0.6
4.7
0.6
0
0
250
100
4.0
0.6
4.7
1.3
Max
0.3 V_CC
V_CC + 0.5
–
0.4
300
250
50⁽²⁾
10
10
400
1_----0_---0_----0_---n_---s_--
C_b
3_----0_---0_----n_---s_-
C_b
–
–
–
–
–
–
–
–
3.45
0.9
–
–
–
–
–
–
Units
V
V
V
V
ns
ns
ns
µA
pF
kHz
Ω
Ω
µs
µs
µs
µs
µs
µs
µs
µs
µs
µs
ns
ns
µs
µs
µs
µs
2486T–AVR–05/08
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