DP8496 datasheet(85/92 Pages) NSC

85 / 92 page

70 AC Specifications (Continued)

727 SCSI ASYNCHRONOUS INFORMATION OUT PHASE AS INITIATOR

TLF11212 – 61

Symbol

Parameter

Min

Typ

Max

Units

271

iodz

IO Valid to SCSI Data Valid

272

pcreq

Phase Change to REQ

273

sds

Data Setup to ACK

(Note 4)

274

reqlackl

REQ Low to ACK Low (Note 1)

235

275

sdh

Data Hold from REQ

0ns

276

reqhackh

REQ High to ACK High (Note 3)

277

phack

Phase Hold from ACK High

Note 1

Transfer Period (in Synchronous Transfer register) e 0 If Transfer Period e 1 then add an additional bcp

Note 2

bcp refers to the BCLK period in use This formula is tested only at the frequencies listed in Table 81

Note 3

This value is not valid for the very last transfer ACK will stay asserted

Note 4

This value is programmable It is a functon of the BCLK Frequency bits in SUP1 register and the SCSI clock bits in SDIF2 register

The SCSI 1 specification (including cable skew) is 55 ns The SCSI 2 specification (including cable skew) is 25 ns

SCSI Clock Bits (10)

BCLK

Freq

(10)

Where 10 is defined as bcp b k k is a characterization constant

Where 15 is defined as bcp a bc b k bc is either bcl or bch

Where 20 is defined as 2 bcp b k k is a characterization constant

All SCSI signals are active-high on the DP8497

DP8496 Datasheet(PDF) 85 Page - National Semiconductor (TI)

DP8496 Datasheet(HTML) 85 Page - National Semiconductor (TI)

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