[3]
tHD;DATis the data hold time that is measured from the falling edge of SCL; applies to data in transmission
and the acknowledge.
[4]
A device must internally provide a hold time of at least 300 ns for the SDA signal (with respect to the
VIH(min) of the SCL signal) to bridge the undefined region of the falling edge of SCL.
[5]
Cb= total capacitance of one bus line in pF.
[6]
The maximum tffor the SDA and SCL bus lines is specified at 300 ns. The maximum fall time for the SDA
output stage tfis specified at 250 ns. This allows series protection resistors to be connected in between the
SDA and the SCL pins and the SDA/SCL bus lines without exceeding the maximum specified tf.
[7]
In Fast-mode Plus, fall time is specified the same for both output stage and bus timing. If series resistors
are used, designers should allow for this when considering bus timing.
[8]
The maximum tHD;DATcould be 3.45 s and 0.9 s for Standard-mode and Fast-mode but must be less than
the maximum of tVD;DATor tVD;ACKby a transition time (see UM10204). This maximum must only be met if
the device does not stretch the LOW period (tLOW) of the SCL signal. If the clock stretches the SCL, the
data must be valid by the set-up time before it releases the clock.
[9]
tSU;DATis the data set-up time that is measured with respect to the rising edge of SCL; applies to data in
transmission and the acknowledge.
[10] A Fast-mode I2C-bus device can be used in a Standard-mode I2C-bus system but the requirement
tSU;DAT= 250 ns must then be met. This will automatically be the case if the device does not stretch the
LOW period of the SCL signal. If such a device does stretch the LOW period of the SCL signal, it must
output the next data bit to the SDA line tr(max)+ tSU;DAT= 1000 + 250 = 1250 ns (according to the
Standard-mode I2C-bus specification) before the SCL line is released. Also the acknowledge timing must
meet this set-up time.