Infineon Technologies CY7C1321KV18-250BZXCT

Overview

CY7C1321KV18-250BZXCT 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, C/C), features echo clocks (CQ/CQ) for timing margin recovery, and supports programmable output impedance via ZQ. Used in high-bandwidth packet buffering and network switch data planes.

For engineers reviewing the CY7C1321KV18-250BZXCT datasheet, CY7C1321KV18-250BZXCT pinout, CY7C1321KV18-250BZXCT application, or CY7C1321KV18-250BZXCT equivalent, key selection criteria include DDR II burst latency (1.5 cycles with DOFF HIGH), 36-bit wide I/O interface, 165-ball FBGA package compatibility, and JTAG 1149.1 test access support.

Technical Context

This device uses a synchronous pipelined architecture with internal two-bit burst counter driven by A[1:0], delivering four sequential 36-bit words per access. All address, control, and write data inputs are registered on rising edges of K and K clocks; read data is edge-aligned to C/C (or K/K in single-clock mode).

It integrates a PLL for precise data placement, echo clocks (CQ/CQ) phase-locked to C/C for receiver-side capture simplification, and on-chip self-timed write circuitry. Output drive strength is adjustable via ZQ calibration to match 40–60 Ω system trace impedance.

Key Specifications

Pinout & Package

Package: 165-ball Fine-Pitch Ball Grid Array (FBGA), 13 mm × 15 mm × 1.4 mm body height, 0.8 mm ball pitch, RoHS-compliant Pb-free finish (BZXCT suffix).

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-10TLI, CY7C1321KV18-250BZXCT delivers higher effective bandwidth via DDR and burst, tighter timing control through echo clocks and ZQ, and configurable latency-critical for modern packet-processing and baseband systems.

Availability

CY7C1321KV18-250BZXCT is available at Aetrix Electronics and suitable for network packet buffering, telecom line card memory, and industrial real-time controller buffer applications requiring stable component supply, long-lifecycle assurance, and RoHS-compliant packaging.

Supply support for CY7C1321KV18-250BZXCT 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) designs high-performance memory and programmable solutions for networking, automotive, and industrial systems, with emphasis on signal integrity and timing precision.

CY7C1321KV18 belongs to Cypress's DDR II SRAM product line, engineered specifically for high-bandwidth, low-latency buffering in packet-switched infrastructure where deterministic burst access and echo-clock–assisted data capture are essential.

FAQ

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

The DOFF (DDR Off) pin configures read latency mode: when asserted HIGH, it enables DDR II operation with 1.5-cycle read latency; when LOW, it reverts to DDR I timing with 1-cycle latency. This allows hardware-level adaptation to controller timing capabilities without firmware change, and affects internal clock-to-output timing paths as defined in the AC switching characteristics table.

How does ZQ calibration work and what external component is required?

ZQ calibration adjusts output driver impedance by comparing internal reference current against an external precision resistor (R_Q) tied between ZQ and ground. The device sets DQ/CQ output strength to 0.2 × R_Q, enabling matched 40–60 Ω drive into typical PCB traces. R_Q must be 240 Ω ±1% for 48 Ω target; direct connection to VDDQ enables minimum-impedance mode.

Can CY7C1321KV18-250BZXCT operate without C and C clocks?

Yes - in single-clock mode, the device uses K and K for both input sampling and output data timing. C/C pins become no-connect, and CQ/CQ are generated relative to K/K instead of C/C. However, echo-clock–assisted data capture and flight-time deskew are lost, reducing timing margin in multi-device systems above 200 MHz.

What is the role of BWS[3:0] during a write operation?

BWS[3:0] are active-low byte write selects that gate 9-bit data lanes: BWS0 controls D[8:0], BWS1 controls D[17:9], BWS2 controls D[26:18], and BWS3 controls D[35:27]. When a BWS bit is HIGH, the corresponding 9-bit byte is masked and unchanged; only asserted (LOW) bytes are written, enabling partial updates without read-modify-write cycles.