Electrical Specifications
Data Sheet
MC68HC908SR12MC68HC08SR12 — Rev. 5.0
384
Electrical Specifications
Freescale Semiconductor
Table 24-16. MMIIC Interface Input/Output Signal Timing
Characteristic
Symbol
Min
Typ
Max
Unit
Comments
Operating frequency
fSMB
10
100
kHz
MMIIC operating frequency
Bus free time
tBUF
4.7
s
Bus free time between STOP and
START condition
Repeated start hold time.
tHD.STA
4.0
s
Hold time after (repeated) START
condition. After this period, the first
clock is generated.
Repeated start setup time.
tSU.STA
4.7
s
Repeated START condition setup
time.
Stop setup time
tSU.STO
4.0
s
Stop condition setup time.
Hold time
tHD.DAT
300
ns
Data hold time.
Setup time
tSU.DAT
250
ns
Data setup time.
Clock low time-out
tTIMEOUT
25
35
ms
Clock low time-out.(1)
Clock low
tLOW
4.7
s
Clock low period
Clock high
tHIGH
4.0
s
Clock high period.(2)
Slave clock low extend time
tLOW.SEXT
25
ms
Cumulative clock low extend time
(slave device)(3)
Master clock low extend time
tLOW.MEXT
10
ms
Cumulative clock low extend time
(master device) (4)
Fall time
tF
300
ns
Clock/Data Fall Time(5)
Rise time
tR
1000
ns
Clock/Data Rise Time(5)
Notes:
1. Devices participating in a transfer will timeout when any clock low exceeds the value of TTIMEOUT min. of 25ms. Devices
that have detected a timeout condition must reset the communication no later than TTIMEOUT max of 35ms. The maximum
value specified must be adhered to by both a master and a slave as it incorporates the cumulative limit for both a master
(10 ms) and a slave (25 ms).
Software should turn-off the MMIIC module to release the SDA and SCL lines.
2. THIGH MAX provides a simple guaranteed method for devices to detect the idle conditions.
3. TLOW.SEXT is the cumulative time a slave device is allowed to extend the clock cycles in one message from the initial start
to the stop. If a slave device exceeds this time, it is expected to release both its clock and data lines and reset itself.
4. TLOW.MEXT is the cumulative time a master device is allowed to extend its clock cycles within each byte of a message as
defined from start-to-ack, ack-to-ack, or ack-to-stop.
5. Rise and fall time is defined as follows: TR = (VILMAX – 0.15) to (VIHMIN + 0.15), TF = 0.9×VDD to (VILMAX – 0.15).