APPENDIX A <REFERENCE> EXTERNAL DEVICE INTERFACE TIMINGS
A.1 DRAM (70ns)
DRAM interface setup examples – 70ns
Operating | RAS precharge | RAS cycle | CAS cycle | Refresh RAS pulse | Refresh RPC delay |
frequency | cycle |
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| width |
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20MHz | 2 | 1 | 2 | 2 | 1 |
25MHz | 2 | 1 | 2 | 2 | 1 |
33MHz | 2 | 2 | 3 | 3 | 1 |
DRAM interface timing – 70ns
DRAM interface |
| Unit: ns |
| 33MHz | 25MHz | 20MHz | ||||
| Parameter | Symbol | Min. | Max. | Cycle | Time | Cycle | Time | Cycle | Time |
<Common parameters> |
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Random read/random write cycle time | tRC | 130 | – | 7 | 210 | 5 | 200 | 5 | 250 | |
#RAS precharge time | tRP | 50 | – | 2 | 60 | 2 | 80 | 2 | 100 | |
#RAS pulse width | tRAS | 70 | 10000 | 5 | 150 | 3 | 120 | 3 | 150 | |
#CAS pulse width | tCAS | 20 | 10000 | 2.5 | 75 | 1.5 | 60 | 1.5 | 75 | |
Row address setup time | tASR | 0 | – | 0.5 | 15 | 0.5 | 20 | 0.5 | 25 | |
Row address hold time | tRAH | 10 | – | 1.5 | 45 | 0.5 | 20 | 0.5 | 25 | |
Column address setup time | tASC | 0 | – | 0.5 | 15 | 0.5 | 20 | 0.5 | 25 | |
#RAS→ | #CAS delay time | tRCD | 20 | – | 2.0 | 60 | 1.0 | 40 | 1.0 | 50 |
#RAS→ | column address delay time | tRAD | 15 | – | 1.5 | 45 | 0.5 | 20 | 0.5 | 25 |
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#RAS access time | tRAC | – | 70 | 4.5 | 135 | 2.5 | 100 | 2.5 | 125 | |
#CAS access time | tCAC | – | 20 | 2.5 | 75 | 1.5 | 60 | 1.5 | 75 | |
Address access time | tAA | – | 35 | 3.0 | 90 | 2.0 | 80 | 2.0 | 100 | |
#OE access time | tOAC | – | 20 | 4.5 | 135 | 2.5 | 100 | 2.5 | 125 | |
Output buffer | tOFF | 0 | 20 | 2 | 60 | 2 | 80 | 2 | 100 | |
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Data input hold time | tDH | 15 | – | 2.5 | 75 | 1.5 | 60 | 1.5 | 75 | |
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tPC | 45 | – | 3.0 | 90 | 2.0 | 80 | 2.0 | 100 | ||
tCP | 10 | – | 0.5 | 15 | 0.5 | 20 | 0.5 | 25 | ||
Access time after #CAS precharge | tACP | – | 40 | 3.0 | 90 | 2.0 | 80 | 2.0 | 100 | |
<Refresh cycle> |
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#CAS setup time | tCSR | 10 | – | 1.0 | 30 | 1.0 | 40 | 1.0 | 50 | |
#CAS hold time | tCHR | 10 | – | 2.5 | 75 | 1.5 | 60 | 1.5 | 75 | |
#RAS precharge→ #CAS hold time | tPPC | 10 | – | 1.0 | 30 | 1.0 | 40 | 1.0 | 50 | |
#RAS pulse width (only in refresh cycle) | tRAS | 70 | 10000 | 3.0 | 90 | 2.0 | 80 | 2.0 | 100 |
S1C33210 PRODUCT PART | EPSON |