Motorola MC68VZ328 - Manual (Page 322)

19-6 MC68VZ328 User’s Manual
AC Electrical Characteristics
19.3.4 Chip-Select Flash Write Cycle Timing
Figure 19-4 on page 19-7 shows the flash write cycle timing used by chip-select. The signal values and
units of measure for this figure are found in Table 19-6 on page 19-7. For detailed information about the
individual signals, see Chapter 6, “Chip-Select Logic.”
Table 19-5. Chip-Select Write Cycle Timing Parameters
Number Characteristic
(3.0 ± 0.3) V
Unit
Minimum Maximum
1 Address valid to CSx asserted
(bit ECDS = 0, bit ECDS = 1) 20, 20 - T/2 — ns
2 CSx asserted to UWE/LWE asserted 0 4 ns
3 CSx asserted to data-out valid — 30 ns
4 External DTACK input setup from CSx asserted — 20 + nT ns
5 CSx pulse width
(bit ECDS = 0, bit ECDS = 1)
60 + nT,
(60 + T/2) + nT
— ns
6 UWE/LWE negated before CSx is negated 10 20 ns
7 External DTACK input hold after CSx is negated 0 — ns
8 Data-out hold after CSx is negated 8 — ns
9 CSx negated to data-out in Hi-Z — 18 ns
10 CSx asserted to WE asserted (16-bit SRAM) 0 4 ns
11 WE negated before CSx is negated (16-bit SRAM) 10 20 ns
Note:
n is the number of wait-states in the current memory access cycle.
T is the system clock period.
The external DTACK input requirement is eliminated when CSx is programmed to use the internal DTACK.
CSx stands for CSA0, CSA1, CSB0, CSB1, CSC0, CSC1, CSD0, or CSD1.
A value in parentheses is used when early detection is turned on.