Two-wire Serial Interface Characteristics

The following table describes the requirements for devices connected to the Two-Wire Serial Bus.

For additional information on timing symbols, refer to the figure below.

Table 1. Two-wire Serial Bus Requirements
Symbol	Parameter	Condition	Min.	Max.	Unit
V_IL	Low-level Input Voltage	–	-0.3	0.3 V_DDIO	V
V_IH	High-level Input Voltage	–	0.7 × V_DDIO	V_CC + 0.3	V
V_hys	Hysteresis of Schmitt Trigger Inputs	–	0.150	–	V
V_OL	Low-level Output Voltage	3 mA sink current	–	0.4	V
t_R	Rise Time for both TWD and TWCK		20 + 0.1C_b⁽¹⁾⁽²⁾	300	ns
t_OF	Output Fall Time from V_IHmin to V_ILmax	10 pF < C_b < 400 pF see the figure below	20 + 0.1C_b⁽¹⁾⁽²⁾	250	ns
C_i⁽¹⁾	Capacitance for each I/O Pin	–	–	10	pF
f_TWCK	TWCK Clock Frequency	–	0	400	kHz
R_P	Value of Pull-up resistor	f_TWCK ≤ 100 kHz	(V_DDIO - 0.4V) ÷ 3mA	1000ns ÷ C_b	Ω
R_P	Value of Pull-up resistor	f_TWCK > 100 kHz	(V_DDIO - 0.4V) ÷ 3mA	300ns ÷ C_b	Ω
t_LOW	Low Period of the TWCK clock	f_TWCK ≤ 100 kHz	⁽³⁾	–	µs
t_LOW	Low Period of the TWCK clock	f_TWCK > 100 kHz	⁽³⁾	–	μs
t_HIGH	High period of the TWCK clock	f_TWCK ≤ 100 kHz	⁽⁴⁾	–	μs
t_HIGH	High period of the TWCK clock	f_TWCK > 100 kHz	⁽⁴⁾	–	μs
t_HD;STA	Hold Time (repeated) START Condition	f_TWCK ≤ 100 kHz	t_HIGH	–	μs
t_HD;STA	Hold Time (repeated) START Condition	f_TWCK > 100 kHz	t_HIGH	–	μs
t_SU;STA	Set-up time for a repeated START condition	f_TWCK ≤ 100 kHz	t_HIGH	–	μs
t_SU;STA	Set-up time for a repeated START condition	f_TWCK > 100 kHz	t_HIGH	–	μs
t_HD;DAT	Data hold time	f_TWCK ≤ 100 kHz	0	3 × t_CPMCK⁽⁵⁾	μs
t_HD;DAT	Data hold time	f_TWCK > 100 kHz	0	3 ×t_CPMCK⁽⁵⁾	μs
t_SU;DAT	Data setup time	f_TWCK ≤ 100 kHz	t_{LOW -}3 × t_CPMCK⁽⁵⁾	–	ns
t_SU;DAT	Data setup time	f_TWCK > 100 kHz	t_{LOW -}3 × t_CPMCK⁽⁵⁾	–	ns
t_SU;STO	Setup time for STOP condition	f_TWCK ≤ 100 kHz	t_HIGH	–	μs
t_SU;STO	Setup time for STOP condition	f_TWCK > 100 kHz	t_HIGH	–	μs
t_HD;STA	Hold Time (repeated) START Condition	f_TWCK ≤ 100 kHz	t_HIGH	–	μs
t_HD;STA	Hold Time (repeated) START Condition	f_TWCK > 100 kHz	t_HIGH	–	μs

Notes:

1.Required only for f_TWCK > 100 kHz.
2.C_b = capacitance of one bus line in pF. Per I²C standard, C_bmax = 400pF.
3.The TWCK low period is defined as follows: t_LOW = ((CLDIV × 2^CKDIV) + 4) × t_MCK.
4.The TWCK high period is defined as follows: t_HIGH = ((CHDIV × 2^CKDIV) + 4) × t_MCK.
5.t_CPMCK= MCK bus period

Figure 1. Two-wire Serial Bus Timing