Cypress Semiconductor Corp CY7C1643KV18-400BZXC

Overview

CY7C1643KV18-400BZXC from Cypress Semiconductor is a 144-Mbit QDR® II+ SRAM with 8 M × 18 organization, 450 MHz max clock (400 MHz rated), 2.0-cycle read latency, and separate read/write DDR ports delivering 900 Mbps per port. It operates at 1.8 V core and 1.4–1.8 V I/O, housed in a 165-ball FBGA (15 × 17 × 1.4 mm), and targets high-bandwidth packet buffering in network line cards.

For engineers reviewing the CY7C1643KV18-400BZXC datasheet, CY7C1643KV18-400BZXC pinout, CY7C1643KV18-400BZXC application, or CY7C1643KV18-400BZXC equivalent, key selection criteria include burst depth (4-word), echo clock timing (CQ/CQ), QVLD validity signaling, DOFF-controlled PLL mode switching, and HSTL-18 I/O compliance for backplane-adjacent memory interfaces.

Technical Context

This device implements true quad data rate architecture via independent, synchronous read and write ports-each using DDR interfaces clocked by complementary K/K inputs-enabling concurrent access without bus turnaround. Its internal 2.0-cycle pipelined read latency is fixed when DOFF = HIGH, and it reverts to QDR I mode (1-cycle latency, ≤167 MHz) when DOFF = LOW.

The SRAM uses echo clocks (CQ/CQ) edge-aligned with output data and QVLD to simplify high-speed capture; ZQ pin enables on-die impedance tuning to match system trace impedance (0.2 × RQ). All address and control signals are registered on K/K rising edges, and writes are self-timed with byte-write select (BWS0/BWS1) enabling partial-word updates without read-modify-write.

Key Specifications

Pinout & Package

Package: 165-ball fine-pitch ball grid array (FBGA), 15 mm × 17 mm × 1.4 mm body height, 0.8 mm ball pitch, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar QDR II+ SRAM applications.

Compared with IDT72T3615L10BG and IS61WV102418B, CY7C1643KV18-400BZXC uniquely delivers 400 MHz DDR concurrency, on-die impedance tuning, and source-synchronous timing-making it the sole fit for 10G+ packet buffering where deterministic latency and signal integrity are mandatory.

Availability

CY7C1643KV18-400BZXC is available at Aetrix Electronics and suitable for network packet buffering, telecom line card memory, high-speed test equipment memory, and real-time signal processing buffer applications requiring stable component supply and long-term industrial availability.

Supply support for CY7C1643KV18-400BZXC 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 U.S.-based semiconductor company specializing in high-performance memory, microcontrollers, and connectivity solutions for industrial, automotive, and communications markets.

CY7C1643KV18 belongs to Cypress's QDR II+ SRAM product line, engineered specifically for deterministic, high-bandwidth memory interfacing in networking and telecom infrastructure where concurrent access and sub-cycle timing predictability are essential.

FAQ

What is the function of the DOFF pin on CY7C1643KV18-400BZXC?

The DOFF (PLL Disable) pin is an active-low input that controls the internal phase-locked loop. When pulled HIGH, the device operates in QDR II+ mode with 2.0-cycle read latency and supports up to 400 MHz operation. When pulled LOW, the PLL is disabled and the device reverts to QDR I timing with 1-cycle latency and a maximum frequency of 167 MHz-enabling backward compatibility with legacy controllers.

How does the ZQ pin affect signal integrity in high-speed designs?

The ZQ pin connects to an external precision resistor (typically 240 Ω) to ground, enabling on-die calibration of output driver impedance for Q[17:0], CQ, and CQ signals. This achieves 0.2 × RQ (e.g., ~48 Ω) output impedance, closely matching standard 50 Ω PCB traces-reducing reflections, improving eye diagram margins, and eliminating need for external series termination resistors.

Can CY7C1643KV18-400BZXC perform simultaneous read and write operations to the same memory location?

No. While the device supports fully concurrent read and write operations to *different* addresses (due to independent ports), writing to an address currently being read from results in undefined data on the Q[17:0] bus. The architecture ensures coherency only for sequential or non-overlapping accesses; overlapping read/write to identical locations violates the timing protocol and is not supported.

What is the role of QVLD in system-level timing design?

QVLD is a synchronous output asserted coincident with the first valid word of each four-word read burst and edge-aligned with CQ/CQ. It serves as a hardware-ready signal for downstream logic (e.g., FPGA state machines or deserializers), eliminating reliance on clock-cycle counting or complex delay-locked loops to identify valid data-thereby reducing timing uncertainty by up to 200 ps in 400 MHz systems.