Cypress Semiconductor Corp CY7C1321KV18-250BZC

Overview

CY7C1321KV18-250BZC from Cypress Semiconductor is a 18-Mbit synchronous pipelined DDR II SRAM configured as 512K × 36, operating at 250 MHz with 1.8 V core supply and HSTL I/O. It implements four-word burst reads/writes synchronized to dual-edge–referenced clocks (K/K for input, C/C for output), features echo clocks (CQ/CQ) for timing margin recovery, and supports programmable output impedance via ZQ pin. It is used in high-bandwidth packet buffering and network switch fabric memory subsystems.

For engineers reviewing the CY7C1321KV18-250BZC datasheet, CY7C1321KV18-250BZC pinout, CY7C1321KV18-250BZC application, or CY7C1321KV18-250BZC equivalent, key selection criteria include DDR II burst latency mode (DOFF-controlled), 36-bit wide data interface, 165-ball FBGA package compatibility, and JTAG 1149.1 test access support for system-level validation.

Technical Context

This SRAM uses a synchronous pipelined architecture with internal two-bit burst counter driven by A[1:0], delivering four sequential 36-bit words per access. Read latency is 1.5 cycles when DOFF = HIGH (DDR II mode) or 1 cycle when DOFF = LOW (DDR I mode). All address, control, and data inputs are registered on rising edges of K and K clocks.

Output data is edge-aligned to C and C clocks, with echo clocks CQ and CQ phase-matched to C and C respectively-enabling source-synchronous capture at the controller without board-level skew compensation. The device integrates a PLL for precise internal clock alignment and supports variable-strength HSTL outputs (1.4 V–VDDQ) with ZQ calibration.

Key Specifications

Pinout & Package

Package: 165-ball Fine-Pitch Ball Grid Array (FBGA), 13 mm × 15 mm × 1.4 mm body height, RoHS-compliant Pb-free option available.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-speed synchronous SRAM applications.

Compared with AS7C33256P-25TIN and IS61WV102432BLL-15BLI, CY7C1321KV18-250BZC delivers 2.2× higher effective bandwidth via DDR + burst, eliminates board-level timing skew with echo clocks, and enables production test coverage through integrated JTAG-making it uniquely suited for modern high-speed packet processing.

Availability

CY7C1321KV18-250BZC is available at Aetrix Electronics and suitable for network switch buffer memory, telecom line card packet FIFO, high-speed test equipment memory, and industrial protocol gateway cache applications requiring stable component supply across extended product lifecycles.

Supply support for CY7C1321KV18-250BZC includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Cypress Semiconductor (now part of Infineon Technologies) is a fabless semiconductor company specializing in high-performance memory, microcontrollers, and connectivity solutions for industrial, automotive, and communications markets.

CY7C1321KV18 belongs to Cypress's DDR II SRAM product line, designed specifically for deterministic, high-bandwidth buffering in packet-switched infrastructure where burst efficiency, timing margin, and testability are critical.

FAQ

What is the function of the DOFF pin on CY7C1321KV18-250BZC?

The DOFF pin selects DDR latency mode: when asserted HIGH, the device operates in DDR II mode with 1.5-cycle read latency; when LOW, it reverts to DDR I mode with 1-cycle latency. This setting affects internal pipeline staging and must be held stable during operation-no dynamic switching is supported. The pin is sampled synchronously on the K clock edge at initialization.

How does ZQ calibration work on this SRAM?

ZQ calibration adjusts the output driver impedance of DQ[35:0] and CQ/CQ pins to match the system's data bus characteristic impedance. A 240 Ω resistor connected between ZQ and ground sets nominal output impedance to 60 Ω (0.2 × 240 Ω). The calibration occurs automatically at power-up and can be retriggered via JTAG instruction. Direct connection to VDDQ enables minimum impedance mode.

Can CY7C1321KV18-250BZC operate in single-clock mode?

Yes-when C and C are left unconnected or tied to VDDQ/VSS, the device uses K and K as both input and output clocks. In this mode, read data is driven on K/K rising edges, and echo clocks CQ/CQ are generated relative to K/K. Single-clock mode sacrifices deskew capability but simplifies clock distribution in less demanding applications.

What is the purpose of BWS[3:0] signals?

BWS[3:0] are active-low byte write enables that allow selective writing of 9-bit subwords within the 36-bit DQ bus. Each BWS controls one 9-bit segment: BWS0 → D[8:0], BWS1 → D[17:9], BWS2 → D[26:18], BWS3 → D[35:27]. When a BWS is HIGH, its corresponding byte remains unchanged during write cycles-enabling efficient partial updates without read-modify-write overhead.