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Texas Instruments TMS380C26 User Manual

Page 75

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TMS380C26

NETWORK COMMPROCESSOR

SPWS010A–APRIL 1992–REVISED MARCH 1993

POST OFFICE BOX 1443

HOUSTON, TEXAS

77251–1443

75

PARAMETER MEASUREMENT INFORMATION

68xxx DIO read timing

NO.

PARAMETER

MIN

MAX

UNIT

255

Delay from SDTACK low to either SCS, SUDS, or SLDS high

15

ns

259†

Hold of SAD high-impedance after SUDS or SLDS low (see Note 21)

0

ns

260

Setup of SADH0–SADH7, SADL0–SADL7, SPH, and SPL valid before SDTACK low

0

ns

261†

Delay from SCS, SUDS, or SLDS high to SADH0–SADH7, SADL0–SADL7, SPH, and SPL
high-impedance (see Note 21)

35

ns

261a

Hold of output data valid after SUDS or SLDS no longer low (see Note 21)

0

ns

267

Setup of register address before SUDS or SLDS no longer high (see Note 21)

15

ns

268

Hold of register address valid after SUDS or SLDS no longer low (see Note 22)

0

ns

272

Setup of SRNW before SUDS or SLDS no longer high (see Note 21)

15

ns

273

Hold of SRNW after SUDS or SLDS high

0

ns

273a

Hold of SIACK high after SUDS or SLDS high

55

ns

275

Delay from SCS, SUDS, or SLDS high to SDTACK high (see Note 21)

35

ns

276‡

Delay from SDTACK low in the first DIO access to the SIF register to SDTACK low in the immediately fol-
lowing access to the SIF

4000

ns

279†

Delay from SUDS or SLDS high to SDTACK high impedance

65

ns

282a

Delay from SDBEN low to SDTACK low

35

ns

282R

Delay from SUDS or SLDS low to SDBEN low (see

TMS380 Second Generation Token-Ring User’s

Guide, SPWU005, subsection 3.4.1.1.1) provided the previous cycle completed

55

ns

283R

Delay from SUDS or SLDS high to SDBEN high (see Note 21)

35

ns

286

Pulse duration, SUDS or SLDS high between DIO accesses (see Note 21)

55

ns

† This specification is provided as an aid to board design.
‡ This specification has been characterized to meet stated value.
NOTES: 21. The “inactive” chip select is SIACK in DIO read and DIO write cycles, and SCS is the “inactive” chip select in interrupt acknowledge

cycles.

22. In 80x8x mode, SRAS may be used to strobe the values of SBHE, SRSX, SRS0–SRS2, and SCS. When used to do so, SRAS must

meet parameter 266a, and SBHE, SRS0–SRS2, and SCS must meet parameter 264. If SRAS is strapped high, then parameters
266a and 264 are irrelevant, and parameter 268 must be met.