Cypress Semiconductor Corp CY7C1521KV18-250BZXC

Overview

CY7C1521KV18-250BZXC from Cypress Semiconductor is a 72-Mbit (2M × 36) DDR II synchronous pipelined SRAM with four-word burst architecture, 250 MHz input clock, double-data-rate I/O at 500 MHz, and 1.8 V core supply with HSTL I/O. It supports programmable impedance matching via ZQ, echo clocks (CQ/CQ) for timing-critical data capture, and configurable read latency (1-cycle DDR-I or 1.5-cycle DDR-II) via DOFF pin. Used in high-bandwidth packet buffering and network switch fabric memory subsystems.

For engineers reviewing the CY7C1521KV18-250BZXC datasheet, CY7C1521KV18-250BZXC pinout, CY7C1521KV18-250BZXC application, or CY7C1521KV18-250BZXC equivalent, key selection criteria include DDR-II burst timing compliance, HSTL-18 I/O voltage tolerance (1.4–1.8 V), PLL-enabled data placement accuracy, and FBGA-165 mechanical compatibility with high-density routing constraints.

Technical Context

The device implements a synchronous pipelined architecture with dual-clock domain separation: K/K clocks control address and command registration, while C/C clocks govern output data timing. Internal burst logic uses A[1:0] to generate four sequential 36-bit words without external address incrementing.

Read latency is dynamically selectable: 1 cycle (DDR-I mode) when DOFF = LOW, or 1.5 cycles (DDR-II mode) when DOFF = HIGH. Echo clocks CQ/CQ are phase-aligned to C/C and referenced to device outputs, enabling controller-side deskew without per-device delay calibration.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar DDR SRAM applications.

Compared with IS61WV102436B and SSTL28V160D, CY7C1521KV18-250BZXC provides higher bandwidth (500 MT/s vs ≤332 MT/s), configurable latency, and system-level timing simplification via echo clocks-critical for multi-SRAM synchronization in high-speed infrastructure.

Availability

CY7C1521KV18-250BZXC is available at Aetrix Electronics and suitable for network switch buffer memory, telecom line card packet FIFO, and baseband processor cache applications requiring stable component supply, long-lifecycle support, and guaranteed FBGA-165 mechanical compatibility.

Supply support for CY7C1521KV18-250BZXC 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 U.S.-based semiconductor company specializing in high-performance memory, microcontrollers, and programmable system-on-chip solutions for industrial, automotive, and communications markets.

CY7C1521KV18 belongs to Cypress's DDR II SRAM product line, engineered specifically for deterministic, low-latency, high-bandwidth buffering in telecom infrastructure, enterprise switching, and real-time signal processing systems.

FAQ

What is the function of the DOFF pin?

The DOFF pin is an active-low control that disables the internal PLL. When asserted LOW, the device operates in DDR-I mode with 1-cycle read latency and a maximum clock frequency of 167 MHz. When HIGH, it enables DDR-II mode with 1.5-cycle latency and full 250 MHz operation. Pull-up resistor (≤10 kΩ to VDDQ) is required for normal DDR-II use.

How does ZQ pin calibration work?

The ZQ pin connects to an external precision resistor (typically 240 Ω) to ground. The device measures this resistance and configures its output drivers to deliver 0.2 × RQ (e.g., 48 Ω) output impedance. This matches standard 50 Ω PCB traces and eliminates need for external series termination resistors on DQ lines.

Can C and C be omitted in system design?

Yes. When C/C are not provided, the device defaults to single-clock mode using K/K for both input and output timing. In this mode, read data is driven on K/K rising edges, and CQ/CQ are generated relative to K/K. However, echo clock functionality and flight-time deskew capability are lost, limiting maximum reliable data rate.

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

BWS[3:0] are active-low byte write select signals that enable partial-word writes. BWS0 controls D[8:0], BWS1 controls D[17:9], BWS2 controls D[26:18], and BWS3 controls D[35:27]. Only bytes with corresponding BWS asserted LOW are written; others retain prior values. All BWS are sampled synchronously on K/K rising edges.