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GS8662DT38BD-550 データシート(PDF) 7 Page - GSI Technology |
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GS8662DT38BD-550 データシート(HTML) 7 Page - GSI Technology |
7 / 33 page Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com. Rev: 1.00b 8/2017 7/33 © 2011, GSI Technology GS8662DT20/38BD-550/500/450/400/350 GS8662DT06/11BD-500/450/400/350 Background Separate I/O SRAMs, from a system architecture point of view, are attractive in applications where alternating reads and writes are needed. Therefore, the SigmaQuad-II+ SRAM interface and truth table are optimized for alternating reads and writes. Separate I/O SRAMs are unpopular in applications where multiple reads or multiple writes are needed because burst read or write transfers from Separate I/O SRAMs can cut the RAM’s bandwidth in half. SigmaQuad-II+ B4 SRAM DDR Read The status of the Address Input, W, and R pins are sampled by the rising edges of K. W and R high causes chip disable. A Low on the Read Enable pin, R, begins a read cycle. R is always ignored if the previous command loaded was a read command. Clocking in a High on the Read Enable pin, R, begins a read port deselect cycle. SigmaQuad-II+ B4 SRAM DDR Write The status of the Address Input, W, and R pins are sampled by the rising edges of K. W and R High causes chip disable. A Low on the Write Enable pin, W, and a High on the Read Enable pin, R, begins a write cycle. W is always ignored if the previous command was a write command. Data is clocked in by the next rising edge of K, the rising edge of K after that, the next rising edge of K, and finally by the next rising edge of K. Special Functions Byte Write and Nybble Write Control Byte Write Enable pins are sampled at the same time that Data In is sampled. A High on the Byte Write Enable pin associated with a particular byte (e.g., BW0 controls D0–D8 inputs) will inhibit the storage of that particular byte, leaving whatever data may be stored at the current address at that byte location undisturbed. Any or all of the Byte Write Enable pins may be driven High or Low during the data in sample times in a write sequence. Each write enable command and write address loaded into the RAM provides the base address for a 4-beat data transfer. The x18 version of the RAM, for example, may write 72 bits in association with each address loaded. Any 9-bit byte may be masked in any write sequence. Nybble Write (4-bit) control is implemented on the 8-bit-wide version of the device. For the x8 version of the device, “Nybble Write Enable” and “NWx” may be substituted in all the discussion above. Example x18 RAM Write Sequence using Byte Write Enables Data In Sample Time BW0 BW1 D0–D8 D9–D17 Beat 1 0 1 Data In Don’t Care Beat 2 1 0 Don’t Care Data In Beat 3 0 0 Data In Data In Beat 4 1 0 Don’t Care Data In Resulting Write Operation Byte 1 D0–D8 Byte 2 D9–D17 Byte 1 D0–D8 Byte 2 D9–D17 Byte 1 D0–D8 Byte 2 D9–D17 Byte 1 D0–D8 Byte 2 D9–D17 Written Unchanged Unchanged Written Written Written Unchanged Written Beat 1 Beat 2 Beat 3 Beat 4 |
同様の部品番号 - GS8662DT38BD-550 |
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同様の説明 - GS8662DT38BD-550 |
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