lh79524 NXP Semiconductors, lh79524 Datasheet - Page 37

• Manufacturer Part Number: lh79524
• Description: Lh79524; Lh79525 System-on-chip
• Manufacturer: NXP Semiconductors

System-on-Chip
1. The timing relationship is specified as a cycle-based timing. Variations caused by clock jitter, power rail noise, and I/O conditioning will cause
2. The Write Wait States register (SWAITWRx) must be set to a minimum value of 3.
3. For each rising clock edge (HCLK) that the assertion of nWAIT lags the assertion of nCSx, another write wait state (SWAITRDx) must be
4. nWAIT delay cycles are not added for all nWAIT assertions sampled prior to WST-3. These nWAIT assertions are ignored.
5. nWAIT delay cycles are added for all nWAIT assertions sampled from WST-3 until the de-assertion of nWAIT. nWAIT delay cycles are added
6. Once nWAIT is sampled high, the current memory transaction is queued to complete.
7. Since static and dynamic memory cannot be accessed at the same time, any prolonged access (either due to nWAIT or the Extended Wait
8. Timing assumes Write Enable Delay register (SWAITWENx) is programmed to 0.
Preliminary data sheet
tIDA_nCS(x)_nWAIT
tDD_nWAIT_nCS(x)
tDD_nWAIT_nWE
tA_nWAIT
NOTES:
SQ: nWAIT Sampled and Queued
SI: nWAIT Sampled and Ignored
these timings to vary nominally. It is recommended that designers add a small margin to avoid possible corner-case conditions.
added to the minimum requirement.
once the wait state countdown has reached WST-1.
Register) that causes an SDRAM refresh failure may cause SDRAM data to be lost.
nCS(x)
nWAIT
Transaction
HCLK
Sequence
nWE
PARAMETER
tDA_nCS(x)_nWAIT
DELAY
WST-3
SQ-4
Delay from nCS(x) assertion to nWAIT assertion
Delay from nWAIT deassertion to nCS(x) deassertion
Delay from nWAIT deassertion to nWE deassertion
Assertion time of nWAIT
Table 17. nWAIT Write Sequence Parameter Definitions
DELAY
WST-2
Figure 14. nWAIT Write Sequence (SWAITWRx = 3)
SQ-3
DELAY
WST-1
tA_nWAIT
SQ-2
NXP Semiconductors
DELAY
nWAIT
DESCRIPTION
Rev. 01 — 16 July 2007
SQ-4
SQ-1
DELAY
nWAIT
SQ-3
SQ-0
DELAY
nWAIT
SQ-2
NOTES:
DELAY
nWAIT
SQ-1
tDD_nWAIT_nWE
DELAY
nWAIT
SQ-0
tDD_nWAIT_nCS(x)
MIN.
0
2
DELAY
WST-0
16,365
MAX.
6
5
CYCLE
END
nWE
LH79524/LH79525
CYCLE
nCS(x)
HCLK periods
HCLK periods
HCLK periods
HCLK periods
END
UNIT
LH79525-136
1
37