Microchip Technology SST39LF020-55-4I-NHE

Overview

SST39LF020-55-4I-NHE from Microchip Technology (formerly Silicon Storage Technology) is a 2 Mbit (256K × 8) CMOS Multi-Purpose Flash memory IC with single 3.0–3.6V supply operation, 55 ns read access time, and uniform 4 KByte sector-erase architecture. It implements SuperFlash split-gate technology for high reliability and is used in embedded firmware storage, BIOS/UEFI code retention, and industrial controller configuration memory.

For engineers reviewing the SST39LF020-55-4I-NHE datasheet, SST39LF020-55-4I-NHE pinout, SST39LF020-55-4I-NHE application, or SST39LF020-55-4I-NHE equivalent, key selection criteria include JEDEC-standard x8 parallel interface compatibility, 100,000-cycle endurance, 100-year data retention, industrial temperature support (−40°C to +85°C), and PLCC-32 package suitability for legacy board designs requiring socketed flash replacement.

Technical Context

The SST39LF020-55-4I-NHE uses SST's proprietary SuperFlash technology with split-gate cells and thick-oxide tunneling injectors, enabling fixed erase/program timing independent of cycle count-unlike conventional flash where timing degrades over endurance life. Its command-set architecture follows JEDEC-standard pinouts and software protocols, including three-byte Byte-Program and six-byte Sector-/Chip-Erase sequences.

It supports dual write-detection methods: Data# Polling (DQ7) and Toggle Bit (DQ6), both valid after the fourth (Program) or sixth (Erase) WE#/CE# edge. Hardware protection includes VDD power-up/down detection (<1.5V inhibit), noise/glitch immunity (<5 ns pulse rejection), and tri-state output control via CE# and OE#.

Key Specifications

Pinout & Package

32-lead PLCC (Plastic Leaded Chip Carrier), 11.43 mm × 13.97 mm body, standard pinout conforming to JEDEC MS-026AC. Pin 1 marked by corner notch; top view shown in Figure 2 of DS25023B.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar flash memory applications.

Compared with AM29LV020C-70EC and SST39VF020-70-4C-NHE, the SST39LF020-55-4I-NHE provides faster deterministic read timing and higher voltage margin for 3.3V-only systems, making it optimal for industrial controllers requiring guaranteed sub-60 ns boot latency and robustness against VDD droop.

Availability

SST39LF020-55-4I-NHE is available at Aetrix Electronics and suitable for industrial PLC firmware storage, embedded SBC BIOS retention, and legacy instrumentation calibration memory requiring stable component supply across extended product lifecycles.

Supply support for SST39LF020-55-4I-NHE 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

Microchip Technology acquired Silicon Storage Technology (SST) in 2016 and maintains full support for the SuperFlash product family, delivering high-reliability nonvolatile memory solutions for industrial, automotive, and aerospace markets.

The SST39LFxx series was designed specifically for cost-sensitive, high-reliability embedded applications requiring long data retention, robust write protection, and JEDEC-standard parallel flash compatibility - especially where socketed upgradeability and industrial temperature operation are mandatory.

FAQ

What is the exact memory organization of the SST39LF020-55-4I-NHE?

The SST39LF020-55-4I-NHE is organized as 256K × 8, providing 2,097,152 bits (262,144 bytes) of addressable nonvolatile storage. Its 18-bit address bus (A0–A17) supports full decoding, with A17 serving as the Most Significant Address (AMS) for sector selection during erase operations. This structure is explicitly defined in the DS25023B datasheet Section "Product Description" and confirmed in Table 2 (Device ID D6H).

Does the SST39LF020-55-4I-NHE support both CE#- and WE#-controlled programming?

Yes, the SST39LF020-55-4I-NHE supports both CE#- and WE#-controlled Byte-Program and Erase operations, as verified in Figures 5 and 6 of DS25023B. The timing parameters (TBP = 20 µs max, TWP = 40 ns min) apply identically regardless of control signal polarity, and the command sequences remain identical - only the active control signal (CE# or WE#) triggers latching on its respective edge.

What is the purpose of the NC pins on the SST39LF020-55-4I-NHE PLCC package?

The SST39LF020-55-4I-NHE PLCC package has four NC (No Connection) pins: 12, 16, 20, and 24. As stated in Table 1 of DS25023B, these pins are internally unconnected and must remain electrically floating - they are not tied to VDD, VSS, or any internal node. PCB layout must avoid routing traces or placing vias on these pads to prevent parasitic coupling or mechanical stress.

How does the SST39LF020-55-4I-NHE handle power-up sequencing?

The SST39LF020-55-4I-NHE requires ≥100 µs from VDD reaching 2.7V to valid Read operation (TPU-READ) and ≥100 µs to valid Program/Erase (TPU-WRITE), per Table 9 of DS25023B. During this window, CE#, OE#, and WE# must remain high (inactive) to prevent spurious commands. The device includes built-in VDD monitoring that inhibits writes below 1.5V, ensuring safe power-up behavior without external reset supervision.

Is the SST39LF020-55-4I-NHE pin-compatible with the SST39LF010 or SST39LF040?

Yes - the SST39LF020-55-4I-NHE shares identical pinout, command set, and interface timing with SST39LF010 and SST39LF040 in the same PLCC-32 package, as confirmed in Figures 2 and 3 and Table 1 of DS25023B. All three devices use JEDEC-standard x8 flash pin assignments, though address depth differs (A16 vs A17 vs A18 as AMS), requiring software address mapping alignment in multi-density designs.