Am33c93a Scsi-bus Interface Controller Timing 1

(0E HEX) SEND-DTSCONNECT-MESSAGE The Send-Disconnect-Message commandis a Targetrole commandwhich may be used to disconnectfrom the SCSI bus at any time during a SCSI command sequence.This commandconsistsof sendinga Disconnect messagebyte,followedby physicaldisconnection from the bus (SCSI bus free). An interruptis generated only after transitionto bus free occurs.As an option,a messagewill automaticallybe sent Save-Data-Pointer beforethe Disconnectmessagewheneverthe lDl bit is set priorto issuingthis command. The COMMAND PHASE register is updated during executionol the Send-Disconnect-Message command to indicatebus phase status.Atter a Save-Data-Pointer messageis sent,the COMMANDPHASEwill be set to 41H. Afterthe Disconnectmessagetransfer,this register will be updatedto 42H, and after disconnectionthe COMMANDPHASEregisterwill containa 43H.

A Send-Disconnect-Message command may be terminatedby Iffi assertedwhen HA=1,or when a Disconnector Resetcommandis issued. The followingtablesummarizesthe possiblevaluesthat the COMMAND PHASE registercan take during the Send-Disconnect-Message, andtheirmeaningsrelative to commandtermination.See other @mmand descriptions lor additional values that can occur when commandchainingis used. Command Phase

Meanlng No operation occurred; typically, ATN was found to be asserted. The Save-Data-Pointermessage was transferred. The Disconnectmessagewas transferred. The bus free state occurred after the Disconnect messagewas transferred.The 33C93A is now in the disconnectedstate.

41

42 43

ELECTRICALCHARACTERISTICS ABSOLUTEMAXIMUMRATINGS -0.5 V to +7.0 V Vohageon any pin with respectto GND Operatinglemperature 0 to 70 deg. C -55 to +125 deg. C Storagetemperature Power dissipation 500 mW Input Static DischargeProtection 2000 V pin to pin Sfrasses above those listed under ABSOLUTE MAXIMUM RATINGSmay cause permanent device failure. Functionality at or above these limitsis not implied. Expsure to absolutely matrlmum ratings for extended periods may affect device reliability.

DC OPERATING CHARACTERISTICS Ta - 0 to 70oC,VCC - +5 V t0.25 V, GND = 0 V Symbol

ilL toLl lo12 VIH VIL VIHYS VOH VOLl VOL2 tcc

4-60

Characterlstlc

Mln

Max

Input Leakage

Unlts

Condltlons

pA pA

VIN-. 4 to VCC VOUT- .5 to VCC VOUT= .4 to VCC

['n V V V

Voltage

0.5

Voltage (All Others)

0.4 20

Am33G93A

V V V mA

lO - -400 ttA lO = 48.0 mA lO = 4.0 mA Ta = +25oC

SWITCHINGTESTCIRCUIT

From output undertest

Pins of the Devlce INTRO

1 0 0p F

4mA

400pA

lffiffituffiffiffiffiffiffi. BSY,SEL,UO,CID MSG,ATN,REQ,ACK

100pF

20 mA

' Actual capacitancemay vary *2Oo/o.

SWITCHINGTESTWAVEFORM All the Open Dralns t-

.ru

All OtherPlns

Am33C93A

4€1

Where: TIMING CHARACTERISTICS Timingcharacteristics are validoverthe entireoperatTcycis the internalclockcycletime; (0to 70"C)andvoltage(4.75to 5.25V) ingtemperature ranges,andarereferenced to andlroma lowvoltageof Tckinis theperiodof theclockat the CLKinput; 0.8voltsanda highvoltageof 2.0Volts.All outputsare is theclockdivisorselectedin the OWNlD assumedto havea loadcapacitance of 100picofarads. DIVISOR register. Manyol thetimingparameters thatfollowaredeiinedin witha 16 MHzclockinputto the33C93A, termsof an internalclockcycletimethat is determined Forexample, by the inputclockandthe clockdivisorselectedin the the clockdivisorselectedwouldbe 4. Therefore,the OWN lD register.This cycle time is calculatedas valueof Tcycwouldbe: follows: 62.5rls. 4 =125ns Tcyc= Tckin.DIVISOR Z Tcyc= 2

lnterface Processor/DMA CLK

Symbol

Charac{erlstlc

tcp

Clock Period

t"t

Clock High

16MHz 20 MHz 16MHz 20 MHz

Mln

Max

Unlts

62.5 50.0 28.0 20.0

125

ns ns ns ns

11853-014A

4-62

Am3ilCll3A