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7.11.3I2CElectricalData/Timing
7.11.3.1Inter-IntegratedCircuits(I2C)Timing
SM320C6455-EP
FIXED-POINTDIGITALSIGNALPROCESSOR
SPRS462B–SEPTEMBER2007–REVISEDJANUARY2008
Table7-52.TimingRequirementsforI2CTimings
(1)
(seeFigure7-42)
-720
-850
A-1000/-1000
NO.UNIT
-1200
STANDARDMODEFASTMODE
MINMAXMINMAX
1t
c(SCL)
Cycletime,SCL102.5µs
Setuptime,SCLhighbeforeSDAlow(fora
2t
su(SCLH-SDAL)
4.70.6µs
repeatedSTARTcondition)
Holdtime,SCLlowafterSDAlow(fora
3t
h(SCLL-SDAL)
40.6µs
STARTandarepeatedSTARTcondition)
4t
w(SCLL)
Pulseduration,SCLlow4.71.3µs
5t
w(SCLH)
Pulseduration,SCLhigh40.6µs
6t
su(SDAV-SDLH)
Setuptime,SDAvalidbeforeSCLhigh250100
(2)
ns
Holdtime,SDAvalidafterSCLlow(ForI
2
C
7t
h(SDA-SDLL)
0
(3)
0
(3)
0.9
(4)
µs
bus™devices)
Pulseduration,SDAhighbetweenSTOPand
8t
w(SDAH)
START4.71.3µs
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
Setuptime,SCLhighbeforeSDAhigh(for
13t
su(SCLH-SDAH)
40.6µs
STOPcondition)
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.
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