Cypress Semiconductor Corp CY7C11681KV18-400BZXC

Overview

CY7C11681KV18-400BZXC from Cypress Semiconductor is a 18-Mbit synchronous pipelined DDR II+ SRAM configured as 1 M × 18, operating at 400 MHz with 2.5-cycle read latency, HSTL I/O, and dual echo clocks (CQ/CQ) for precise high-speed data capture in memory subsystems. It supports programmable output impedance via ZQ pin and features QVLD for timing-critical data validation.

For engineers reviewing the CY7C11681KV18-400BZXC datasheet, CY7C11681KV18-400BZXC pinout, CY7C11681KV18-400BZXC application, or CY7C11681KV18-400BZXC equivalent, key selection criteria include burst depth (2-word), DOFF-configurable latency (1-cycle vs. 2.5-cycle), VDDQ range (1.4–1.8 V), FBGA-165 package footprint, and JTAG 1149.1 test port integration.

Technical Context

This SRAM implements a two-word burst architecture with double data rate transfers synchronized to complementary K/K clocks. All address, control, and data signals are registered on rising edges of K or K, enabling pipelined operation and eliminating external wait states during depth expansion.

The device integrates a phase-locked loop (PLL) for accurate internal timing alignment, supports synchronous self-timed writes, and uses echo clocks (CQ/CQ) edge-aligned to K/K to simplify system-level data capture without per-pin deskew. QVLD asserts half a clock cycle before valid data appears on DQ[17:0].

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 option available.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AS7C3256B-15JIN and IS61WV102418BLL-10TLI, CY7C11681KV18-400BZXC uniquely delivers DDR bandwidth scaling, system-level timing simplification via CQ/CQ/QVLD, and field-programmable latency - making it irreplaceable in 400 MHz+ burst-oriented systems.

Availability

CY7C11681KV18-400BZXC is available at Aetrix Electronics and suitable for telecom line cards, network packet buffers, test equipment memory subsystems, and industrial real-time controllers requiring stable component supply across extended product lifecycles.

Supply support for CY7C11681KV18-400BZXC 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.

CY7C11681KV18 belongs to Cypress's QDR II+/DDR II+ SRAM product line, engineered specifically for high-bandwidth, low-latency memory subsystems in networking infrastructure and test instrumentation where deterministic timing and signal integrity are critical.

FAQ

What is the function of the DOFF pin on CY7C11681KV18-400BZXC?

The DOFF pin selects read latency mode: when asserted HIGH, the device operates in DDR II+ mode with 2.5-cycle latency; when LOW, it behaves as a DDR I device with 1-cycle latency. This configuration is sampled at power-up and remains fixed until reset. The pin must be externally tied to VDD or VSS - floating is not allowed.

How does the ZQ pin calibrate output impedance?

The ZQ pin connects to a 240 Ω resistor to VSS, enabling internal calibration circuitry to adjust output driver strength to match transmission line impedance within ±15%. Calibration occurs automatically every 1024 clock cycles and compensates for VDDQ and temperature variations - no software intervention required.

Can CY7C11681KV18-400BZXC operate with VDDQ = 1.5 V?

Yes - the device supports VDDQ from 1.4 V to 1.8 V, including 1.5 V. At 1.5 V, HSTL Class I input thresholds and output drive strength remain compliant, and ZQ calibration maintains ±15% impedance accuracy using a 240 Ω reference resistor. DC and AC specifications are fully characterized across this range.

What is the purpose of the CQ and CQ echo clocks?

CQ and CQ are free-running output clocks synchronized to K and K respectively, provided to simplify data capture in high-speed systems. They eliminate the need for external DLLs or per-pin deskew logic by delivering edge-aligned timing references that match the DQ[17:0] output transitions - reducing FPGA resource usage and improving timing margin.