Texas Instruments TMS380C26 - Manual (Page 61)

TMS380C26
NETWORK COMMPROCESSOR
SPWS010A–APRIL 1992–REVISED MARCH 1993
POST OFFICE BOX 1443
•
HOUSTON, TEXAS
77251–1443
61
PARAMETER MEASUREMENT INFORMATION
80x8x DIO read timing
NO. PARAMETER MIN MAX UNIT
255 Delay from SRDY low to either SCS or SRD high 15 ns
256 Pulse duration, SRAS high 30 ns
259† Hold of SAD high-impedance after SRD low (see Note 21) 0 ns
260 Setup of SADH0–SADH7, SADL0–SADL7, SPH and SPL valid before SRDY low 0 ns
261† Delay from SRD or SCS high to SAD high-impedance (see Note 21) 35 ns
261a Hold of output data valid after SRD or SCS high (see Note 21) 0 ns
264 Setup of SRSX, SRS0–SRS2, SCS, and SBHE valid to SRAS no longer high (see Note 22) 30 ns
265 Hold of SRSX, SRS0–SRS2, SCS, and SBHE valid after SRAS low 15 ns
266a Setup of SRAS high to SRD no longer high (see Note 22) 25 ns
267‡ Setup of SRSX, SRS0–SRS2 valid before SRD no longer high (see Note 21) 15 ns
268 Hold of SRSX, SRS0–SRS2 valid after SRD no longer low (see Note 22) 0 ns
272a Setup time of SRD, SWR, and SIACK high from previous cycle to SRD no longer high 55 ns
273a Hold time of SRD, SWR, and SIACK high after SRD high 55 ns
275 Delay from SRD and SWR, or SCS high to SRDY high (see Note 21) 35 ns
279† Delay from SRD and SWR, high to SRDY high impedance 65 ns
282a Delay from SDBEN low to SRDY low in a read cycle 35 ns
282R
Delay from SRD low to SDBEN low (see TMS380 Second Generation Token-Ring User’s Guide,
SPWU005, subsection 3.4.1.1.1), provided previous cycle completed.
55 ns
283R Delay from SRD high to SDBEN high (see Note 21) 35 ns
286 Pulse duration, SRD high between DIO accesses (see Note 21) 55 ns
† This specification is provided as an aid to board design.
‡ It is the later of SRD and SWR or SCS low that indicates the start of the cycle.
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.