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CY7C25652KV18-400BZI Datasheet(PDF) 6 Page - Cypress Semiconductor |
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CY7C25652KV18-400BZI Datasheet(HTML) 6 Page - Cypress Semiconductor |
6 / 31 page CY7C25632KV18 CY7C25652KV18 Document Number: 001-66482 Rev. *C Page 6 of 31 Functional Overview The CY7C25632KV18, CY7C25652KV18 are synchronous pipelined Burst SRAMs equipped with a read port and a write port. The read port is dedicated to read operations and the write port is dedicated to write operations. Data flows into the SRAM through the write port and flows out through the read port. These devices multiplex the address inputs to minimize the number of address pins required. By having separate read and write ports, the QDR II+ completely eliminates the need to “turn-around” the data bus and avoids any possible data contention, thereby simplifying system design. Each access consists of four 18-bit data transfers in the case of CY7C25632KV18, and four 36-bit data transfers in the case of CY7C25652KV18, in two clock cycles. These devices operate with a read latency of two and half cycles when DOFF pin is tied HIGH. When DOFF pin is set LOW or connected to VSS then device behaves in QDR I mode with a read latency of one clock cycle. Accesses for both ports are initiated on the positive input clock (K). All synchronous input and output timing are referenced from the rising edge of the input clocks (K and K). All synchronous data inputs (D[x:0]) pass through input registers controlled by the input clocks (K and K). All synchronous data outputs (Q[x:0]) outputs pass through output registers controlled by the rising edge of the input clocks (K and K) as well. All synchronous control (RPS, WPS, BWS[x:0]) inputs pass through input registers controlled by the rising edge of the input clocks (K and K). CY7C25632KV18 is described in the following sections. The same basic descriptions apply to CY7C25652KV18. Read Operations The CY7C25632KV18 is organized internally as four arrays of 1 M × 18. Accesses are completed in a burst of four sequential 18-bit data words. Read operations are initiated by asserting RPS active at the rising edge of the positive input clock (K). The address presented to the address inputs is stored in the read address register. Following the next two K clock rise, the corresponding lowest order 18-bit word of data is driven onto the Q[17:0] using K as the output timing reference. On the subsequent rising edge of K, the next 18-bit data word is driven onto the Q[17:0]. This process continues until all four 18-bit data words have been driven out onto Q[17:0]. The requested data is valid 0.45 ns from the rising edge of the input clock (K or K). To maintain the internal logic, each read access must be allowed to complete. Each read access consists of four 18-bit data words and takes two clock cycles to complete. Therefore, read accesses to the device can not be initiated on two consecutive K clock rises. The internal logic of the device ignores the second read request. Read accesses can be initiated on every other K clock rise. Doing so pipelines the data flow such that data is transferred out of the device on every rising edge of the input clocks (K and K). When the read port is deselected, the CY7C25632KV18 first completes the pending read transactions. Synchronous internal circuitry automatically tri-states the outputs following the next rising edge of the negative input clock (K). This enables for a seamless transition between devices without the insertion of wait states in a depth expanded memory. Write Operations Write operations are initiated by asserting WPS active at the rising edge of the positive input clock (K). On the following K clock rise the data presented to D[17:0] is latched and stored into DOFF Input PLL Turn Off Active LOW. Connecting this pin to ground turns off the PLL inside the device. The timings in the PLL turned off operation differs from those listed in this data sheet. For normal operation, this pin can be connected to a pull up through a 10 k or less pull up resistor. The device behaves in QDR I mode when the PLL is turned off. In this mode, the device can be operated at a frequency of up to 167 MHz with QDR I timing. TDO Output TDO Pin for JTAG. TCK Input TCK Pin for JTAG. TDI Input TDI Pin for JTAG. TMS Input TMS Pin for JTAG. NC N/A Not Connected to the Die. Can be tied to any voltage level. NC/144M N/A Not Connected to the Die. Can be tied to any voltage level. NC/288M N/A Not Connected to the Die. Can be tied to any voltage level. VREF Input- Reference Reference Voltage Input. Static input used to set the reference level for HSTL inputs, outputs, and AC measurement points. VDD Power Supply Power Supply Inputs to the Core of the Device. VSS Ground Ground for the Device. VDDQ Power Supply Power Supply Inputs for the Outputs of the Device. Pin Definitions (continued) Pin Name I/O Pin Description |
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