Infineon Technologies FM1608B-PG

Overview

FM1608B-PG from Cypress Semiconductor (acquired Ramtron) is a 64Kbit bytewide ferroelectric nonvolatile RAM organized as 8,192 × 8 bits, operating at 5V with 70 ns access time and JEDEC SRAM/EEPROM-compatible 28-pin PDIP pinout. It delivers immediate nonvolatile writes (NoDelay™), 10¹² read/write endurance, and 38-year data retention at +75°C - deployed in industrial data loggers for real-time parameter storage without battery backup.

For engineers reviewing the FM1608B-PG datasheet, FM1608B-PG pinout, FM1608B-PG application, or FM1608B-PG equivalent, key selection criteria include its monolithic F-RAM architecture eliminating BBSRAM reliability risks, identical read/write cycle timing (130 ns), and compatibility with legacy SRAM controllers requiring only /CE strobing - critical for retrofitting legacy systems with enhanced nonvolatile write performance.

Technical Context

The FM1608B-PG implements a parallel-interface ferroelectric memory array where each 8-byte row undergoes a unified endurance cycle per access; address latching occurs exclusively on the falling edge of /CE, enforcing strict precharge timing (t_PC ≥ 60 ns) before subsequent cycles. Its functional truth table mandates /CE low to initiate all operations, with /WE-controlled or /CE-controlled write modes enabling flexible bus protocol integration.

Unlike EEPROM or flash, it requires no internal write-verification polling, and unlike BBSRAM, it contains no external battery or capacitor - achieving true monolithic nonvolatility via ferroelectric capacitors that retain polarization state without power. VDD must remain within 4.5–5.5 V during operation, and /CE must track VDD via pull-up resistor during power transitions to prevent spurious accesses below VDD_min.

Key Specifications

Pinout & Package

FM1608B-PG uses a 28-pin "Green"/RoHS-compliant plastic dual in-line package (PDIP) with 0.6-inch width and standard DIP footprint. Pin 1 is marked with a notch or dot; pins are numbered counter-clockwise from top-left corner.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar nonvolatile parallel-memory applications.

Compared with CY14B108L-SPXC and FM24CL64B-G, FM1608B-PG uniquely combines through-hole PDIP packaging, 5V parallel interface, and full SRAM timing compatibility - making it the only option for legacy system upgrades requiring zero hardware redesign and field-serviceable memory replacement.

Availability

FM1608B-PG is available at Aetrix Electronics and suitable for industrial data loggers, smart energy meters, PLC I/O modules, and medical diagnostic equipment requiring stable component supply, long-lifecycle support, and RoHS-compliant through-hole memory solutions.

Supply support for FM1608B-PG 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 global leader in embedded systems solutions, specializing in memory, microcontrollers, and connectivity ICs for industrial, automotive, and consumer applications.

The FM1608B-PG belongs to Cypress's F-RAM product line, engineered to replace battery-backed SRAM and EEPROM in applications demanding infinite write endurance, instant nonvolatility, and deterministic timing - particularly where reliability under shock, vibration, and wide temperature swings is critical.

FAQ

What is the minimum /CE pulse width required for reliable operation?

The FM1608B-PG requires a minimum /CE low time of 70 ns (t_CA) to ensure valid address latching and memory access completion. This matches its 70 ns access time specification and must be maintained across the full operating temperature range (0°C to +85°C) and supply voltage (4.5–5.5 V). Violating this timing may cause read corruption or failed writes.

Can FM1608B-PG be used as a direct replacement for a 6264 SRAM?

Yes, but with one critical design change: /CE must be actively strobed (falling edge triggered) for every access instead of being permanently grounded. The pinout, voltage levels, and timing (70 ns access, 130 ns cycle) match the 6264, but the FM1608B-PG requires /CE to initiate each cycle and enable precharge - a requirement absent in standard SRAMs.

Does FM1608B-PG require external decoupling capacitors?

Yes - a 0.1 µF ceramic capacitor must be placed between VDD and VSS as close as possible to pins 14 and 27. This is mandatory to suppress switching noise during rapid read/write transitions and maintain stable 5V supply during 15 mA active current bursts. Failure to include this capacitor may cause intermittent data corruption or failure to meet AC timing specifications.

How does the row-based endurance model affect data layout in firmware?

Each 8-byte boundary (e.g., addresses 0x0000–0x0007, 0x0008–0x000F) defines a physical row; every access to any byte in that row consumes one endurance cycle. To maximize lifetime, firmware should distribute frequently updated variables across non-adjacent 8-byte boundaries - for example, placing counters at 0x0100, 0x0108, 0x0110 - ensuring no single row exceeds 10¹² cycles over the product's service life.