SST39F040-55-4I-WHE Microchip Integrated Circuit (Small Outline Packages) In Stock
The SST39F040-55-4I-WHE is a 4 Mbit multi-purpose parallel NOR Flash memory from Microchip with a 55 ns access time, industrial temperature range, and a small-outline package. It supports byte-wide reads and sector erase for embedded code and data storage. Available from stock with worldwide shipping.
- Manufacturer
- Microchip
- Package
- Small Outline Packages
- Pin Count
- 32
- Lifecycle
- ACTIVE
- Datasheet
- SST39F040-55-4I-WHE Datasheet PDF
- Category
- Integrated Circuit
- RoHS
- Compliant
- Lead Time
- 3–7 business days
- Shipping
- DHL Express · Worldwide
Key Features
- 4 Mbit NOR Flash with 55 ns maximum access time enables fast random-read code execution suitable for memory-mapped microprocessor designs
- Industrial temperature grade (-40 °C to +85 °C) ensures reliable operation in harsh environments such as automotive and factory automation equipment
- Sector erase architecture allows in-system firmware updates by erasing and reprogramming 4 kB sectors without erasing the entire array
Applications
The SST39F040-55-4I-WHE serves as code and data storage in embedded systems where a microprocessor or microcontroller executes firmware directly from NOR Flash in memory-mapped mode. Its 55 ns access time supports bus speeds up to 18 MHz without wait states, making it well suited for legacy 8-bit and 16-bit CPU designs in industrial controllers, BIOS storage, and communication equipment. The industrial temperature rating extends its usability to automotive body electronics, ruggedized instruments, and outdoor IoT gateways.
Compliance & Regulatory
| RoHS Status | Compliant |
| Lead-Free | Yes (Pb-Free) |
Alternate & Equivalent Parts
No known alternates. Submit an RFQ and our team can suggest alternatives.
Frequently Asked Questions
How does the 55 ns access time of SST39F040-55-4I-WHE constrain the maximum bus clock frequency for a memory-mapped CPU?
With a 55 ns maximum read cycle time, the SST39F040-55-4I-WHE can support a CPU bus running at up to approximately 18 MHz (55 ns ≈ one full cycle at 18 MHz) with zero wait states. Faster processors clocked above 18 MHz must insert at least 1 wait state to satisfy the 55 ns timing requirement, which is a standard trade-off in 8-bit and 16-bit embedded designs using legacy parallel NOR Flash.
For an industrial controller that requires in-field firmware updates, how does the sector erase capability of SST39F040-55-4I-WHE help minimize downtime?
The SST39F040-55-4I-WHE supports sector erase in 4 kB blocks, allowing the bootloader to overwrite only the application firmware sectors—typically 512 kB of the 512 kB total array—without touching the bootloader sector itself. This reduces erase-and-reprogram cycles to the minimum necessary, cutting downtime during field updates to under 10 seconds for a full 4 Mbit image write at typical Flash programming speeds.
In what temperature range does SST39F040-55-4I-WHE operate and which industrial application classes does this cover?
The SST39F040-55-4I-WHE is specified for the industrial temperature range of -40 °C to +85 °C, covering IEC 60068-2 Class B environmental conditions. This makes it compliant for outdoor industrial enclosures, HVAC controllers, factory PLC modules, automotive non-powertrain electronics, and military-grade ground support equipment where ambient temperatures routinely reach temperature extremes well beyond the 0 °C to 70 °C commercial range.
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