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5.13.1I2CElectricalData/Timing
10
8
4
3
7
12
5
6
14
2
3
13
Stop Start Repeated
Start
Stop
SDA
SCL
1
11 9
TMS320DM355
DigitalMediaSystem-on-Chip(DMSoC)
SPRS463A–SEPTEMBER2007–REVISEDSEPTEMBER2007
5.13.1.1Inter-IntegratedCircuits(I2C)Timing
Table5-33.TimingRequirementsforI2CTimings
(1)
(seeFigure5-39)
DM355
STANDARD
NO.FASTMODEUNIT
MODE
MINMAXMINMAX
1t
c(SCL)
Cycletime,SCL102.5μs
Setuptime,SCLhighbeforeSDAlow(forarepeatedSTART
2t
su(SCLH-SDAL)
4.70.6μs
condition)
Holdtime,SCLlowafterSDAlow(foraSTARTandarepeated
3t
h(SCLL-SDAL)
40.6μs
STARTcondition)
4t
w(SCLL)
Pulseduration,SCLlow4.71.3μs
5t
w(SCLH)
Pulseduration,SCLhigh40.6μs
6t
su(SDAV-SCLH)
Setuptime,SDAvalidbeforeSCLhigh250100
(2)
ns
7t
h(SDA-SCLL)
Holdtime,SDAvalidafterSCLlow(ForI
2
Cbus™devices)0
(3)
0
(3)
0.9
(4)
μs
Pulseduration,SDAhighbetweenSTOPandSTART
8t
w(SDAH)
4.71.3μs
conditions
9t
r(SDA)
Risetime,SDA100020+0.1C
b
(5)
300ns
10t
r(SCL)
Risetime,SCL100020+0.1C
b
(5)
300ns
11t
f(SDA)
Falltime,SDA30020+0.1C
b
(5)
300ns
12t
f(SCL)
Falltime,SCL30020+0.1C
b
(5)
300ns
13t
su(SCLH-SDAH)
Setuptime,SCLhighbeforeSDAhigh(forSTOPcondition)40.6μs
14t
w(SP)
Pulseduration,spike(mustbesuppressed)050ns
15C
b
(5)
Capacitiveloadforeachbusline400400pF
(1)TheI2CpinsSDAandSCLdonotfeaturefail-safeI/Obuffers.Thesepinscouldpotentiallydrawcurrentwhenthedeviceispowered
down.
(2)AFast-modeI
2
C-bus™devicecanbeusedinaStandard-modeI
2
C-bus™system,buttherequirementt
su(SDA-SCLH)
≥250nsmustthen
bemet.ThiswillautomaticallybethecaseifthedevicedoesnotstretchtheLOWperiodoftheSCLsignal.Ifsuchadevicedoesstretch
theLOWperiodoftheSCLsignal,itmustoutputthenextdatabittotheSDAlinet
r
max+t
su(SDA-SCLH)
=1000+250=1250ns
(accordingtotheStandard-modeI
2
C-BusSpecification)beforetheSCLlineisreleased.
(3)Adevicemustinternallyprovideaholdtimeofatleast300nsfortheSDAsignal(referredtotheV
IHmin
oftheSCLsignal)tobridgethe
undefinedregionofthefallingedgeofSCL.
(4)Themaximumt
h(SDA-SCLL)
hasonlytobemetifthedevicedoesnotstretchthelowperiod[t
w(SCLL)
]oftheSCLsignal.
(5)C
b
=totalcapacitanceofonebuslineinpF.IfmixedwithHS-modedevices,fasterfall-timesareallowed.
Figure5-39.I2CReceiveTimings
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