CY7C1316BV18, CY7C1916BV18 CY7C1318BV18, CY7C1320BV18
Functional Overview
The CY7C1316BV18, CY7C1916BV18, CY7C1318BV18, and CY7C1320BV18 are synchronous pipelined Burst SRAMs equipped with a DDR interface.
Accesses are initiated on the rising edge of the positive input clock (K). All synchronous input timing is referenced from the rising edge of the input clocks (K and K) and all output timing is referenced to the rising edge of the output clocks (C/C, or K/K when in single clock mode).
All synchronous data inputs (D[x:0]) pass through input registers controlled by the rising edge of the input clocks (K and K). All synchronous data outputs (Q[x:0]) pass through output registers controlled by the rising edge of the output clocks (C/C, or K/K when in
All synchronous control (R/W, LD, BWS[0:X]) inputs pass through input registers controlled by the rising edge of the input clock (K).
CY7C1318BV18 is described in the following sections. The same basic descriptions apply to CY7C1316BV18, CY7C1916BV18, and CY7C1320BV18.
mation presented to D[17:0] is also stored into the write data register, provided BWS[1:0] are both asserted active. The 36 bits of data are then written into the memory array at the specified location. Write accesses can be initiated on every rising edge of the positive input clock (K). This pipelines the data flow such that 18 bits of data can be transferred into the device on every rising edge of the input clocks (K and K).
When Write access is deselected, the device ignores all inputs after the pending write operations are completed.
Byte Write Operations
Byte write operations are supported by the CY7C1318BV18. A write operation is initiated as described in the Write Operations section. The bytes that are written are determined by BWS0 and BWS1, which are sampled with each set of
Read Operations
The CY7C1318BV18 is organized internally as a single array of 1M x 18. Accesses are completed in a burst of two sequential
The CY7C1318BV18 first completes the pending read transac- tions, when read access is deselected. Synchronous internal circuitry automatically
Write Operations
Write operations are initiated by asserting R/W LOW and LD LOW at the rising edge of the positive input clock (K). The address presented to address inputs is stored in the write address register and the least significant bit of the address is presented to the burst counter. The burst counter increments the address in a linear fashion. On the following K clock rise the data presented to D[17:0] is latched and stored into the
Single Clock Mode
The CY7C1318BV18 can be used with a single clock that controls both the input and output registers. In this mode the device recognizes only a single pair of input clocks (K and K) that control both the input and output registers. This operation is identical to the operation if the device had zero skew between the K/K and C/C clocks. All timing parameters remain the same in this mode. To use this mode of operation, tie C and C HIGH at power on. This function is a strap option and not alterable during device operation.
DDR Operation
The CY7C1318BV18 enables
If a read occurs after a write cycle, address and data for the write are stored in registers. The write information must be stored because the SRAM cannot perform the last word write to the array without conflicting with the read. The data stays in this register until the next write cycle occurs. On the first write cycle after the read(s), the stored data from the earlier write is written into the SRAM array. This is called a posted write.
If a read is performed on the same address on which a write is performed in the previous cycle, the SRAM reads out the most current data. The SRAM does this by bypassing the memory array and reading the data from the registers.
Depth Expansion
Depth expansion requires replicating the LD control signal for each bank. All other control signals can be common between banks as appropriate.
Document Number: | Page 8 of 31 |
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