Part A
AT25DF321A-SH-T
Technologie adesto
- Lifecycle
- Active
- Stock
- 6999 PCS
- Package
- SOIC-W-8
- Series
- Mémoire
Replacement verdict
Not a drop-in replacement
The AT25DF321A-SH-T and AT25DF041A-SSH-B are not drop-in replacements for one another. Although both are single-voltage SPI serial flash memories from the same manufacturer family, they differ fundamentally in memory density, package and pinout, and operating voltage range, so the AT25DF041A-SSH-B cannot directly substitute the AT25DF321A-SH-T in an existing design without validation and layout changes.
Different memory density
Different package and pinout
Different operating voltage range
Different interface and speed grade
Parts at a glance
Part B
AT25DF041A-SSH-B
Technologie adesto
- Lifecycle
- Active
- Stock
- 6689 PCS
- Package
- SOIC-8
- Series
- Mémoire
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AT25DF321A-SH-T | AT25DF041A-SSH-B | Why it matters |
|---|---|---|---|
| Memory Density | 32 Mbit (4 MB) | 4 Mbit (512 KB) | Density determines total storage capacity; an 8x difference means the parts are not drop-in substitutes for firmware or data storage sizing. |
| Organization | 4,194,304 x 8 bits | 524,288 x 8 bits | Byte organization affects addressable space and how the host controller maps memory; mismatched sizes require firmware/address changes. |
| Package / Case | 8-SOIC (0.209", 5.30mm width) | 8-SOIC (0.154", 3.90mm width) | Different SOIC body widths affect PCB footprint and land pattern, so the parts are not mechanically interchangeable without layout changes. |
| Supply Voltage Range | 2.7 V to 3.6 V | 2.3 V to 3.6 V | The wider low-voltage range of the 4 Mbit part allows operation in lower-voltage systems where the 32 Mbit part may be out of spec. |
| Maximum Clock Frequency | 100 MHz | 70 MHz | Clock rate determines read/program throughput; a slower interface may not meet timing requirements of a design tuned for the faster part. |
| Page Size | 256 bytes | 256 bytes | Page size governs program granularity and buffer requirements; identical page size simplifies firmware porting between the two parts. |
| Sector / Block Architecture | 4 KB sectors, 64 KB blocks | 4 KB sectors, 64 KB blocks | Matching erase granularity means erase/program routines and file-system layouts can be reused without modification. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Identical industrial temperature ratings mean both parts suit the same environmental conditions and reliability requirements. |
| Interface Type | SPI (Dual/Quad capable) | SPI (Dual capable) | Differences in supported SPI modes (Quad vs Dual) affect achievable bandwidth and the host controller configuration needed. |
| Endurance / Data Retention | 100,000 erase/program cycles; 20 years retention | 100,000 erase/program cycles; 20 years retention | Equivalent endurance and retention ratings indicate comparable long-term reliability for code and data storage use. |
Need help validating a replacement?
Send your BOM and application constraints for technical and sourcing review.
Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AT25DF321A-SH-T | AT25DF041A-SSH-B |
|---|---|---|
| Supplier | - | Dialog Semiconductor GmbH |
| Part Status | Not For New Designs | Obsolete |
| Memory Type | Non-Volatile | Non-Volatile |
| Memory Format | FLASH | FLASH |
| Technology | FLASH | FLASH |
| Memory Size | 32Mb (256 Bytes x 16384 pages) | 4Mb (512K x 8) |
| Memory Interface | SPI | SPI |
| Clock Frequency | 100 MHz | 70 MHz |
| Write Cycle Time - Word Page | 7µs, 3ms | 7µs, 5ms |
| Voltage - Supply | 2.7V ~ 3.6V | 2.7V ~ 3.6V |
| Operating Temperature | -40°C ~ 85°C (TC) | -40°C ~ 85°C (TC) |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
What are the key differences between the AT25DF321A-SH-T and AT25DF041A-SSH-B?
The AT25DF321A-SH-T is a 32-Mbit (4 MB) SPI serial flash memory, while the AT25DF041A-SSH-B is a 4-Mbit (512 KB) device. Both are part of the Adesto (formerly Atmel) AT25DF series and use the same SPI interface, but they differ in density, package, and operating voltage range. The AT25DF321A-SH-T is supplied in an 8-lead SOIC package (208-mil), whereas the AT25DF041A-SSH-B is supplied in an 8-lead SOIC package (150-mil).
Are the AT25DF321A-SH-T and AT25DF041A-SSH-B pin-compatible?
Both devices use the standard 8-lead SOIC SPI flash pinout (CS, SO, WP, GND, SI, SCK, HOLD, VCC). However, the AT25DF321A-SH-T uses a 208-mil body width SOIC-8, while the AT25DF041A-SSH-B uses a 150-mil body width SOIC-8. The pin functions are identical, but the package footprint differs, so they are not drop-in replacements on the same PCB land pattern without layout verification.
What are the operating voltage ranges for these two devices?
The AT25DF321A-SH-T operates from 2.7 V to 3.6 V. The AT25DF041A-SSH-B operates from 2.3 V to 3.6 V. Designs operating at 2.5 V should use the AT25DF041A-SSH-B, while the AT25DF321A-SH-T requires a minimum supply of 2.7 V.
What SPI clock frequencies do the AT25DF321A-SH-T and AT25DF041A-SSH-B support?
Both devices support SPI clock frequencies up to 85 MHz for standard read operations. Fast read and dual-output read commands are also supported at up to 85 MHz, subject to the timing specifications in the respective datasheets.
Do both devices support the same SPI command set?
Yes. Both the AT25DF321A-SH-T and AT25DF041A-SSH-B support the standard SPI flash command set, including Read Status Register, Read Array, Page Program, Sector Erase, Block Erase, Chip Erase, and Write Enable/Disable. They also support dual-output read and deep power-down modes. Command opcodes and behavior are consistent across the AT25DF series.
What are the erase block sizes for the AT25DF321A-SH-T and AT25DF041A-SSH-B?
Both devices offer 4-KB sector erase, 32-KB block erase, 64-KB block erase, and full-chip erase options. The AT25DF321A-SH-T contains 1024 sectors of 4 KB each, while the AT25DF041A-SSH-B contains 128 sectors of 4 KB each.
What are the operating temperature ranges for these devices?
Both the AT25DF321A-SH-T and AT25DF041A-SSH-B are specified for the industrial temperature range of -40 °C to +85 °C. The "-SH-T" and "-SSH-B" suffixes denote package and packing options, not temperature grade.
Can the AT25DF041A-SSH-B be used as a substitute for the AT25DF321A-SH-T in an existing design?
Not directly. Although both share the same SPI command set and pin functions, the AT25DF041A-SSH-B has only 4 Mbit of density versus 32 Mbit for the AT25DF321A-SH-T, and it uses a narrower 150-mil SOIC-8 package versus the 208-mil SOIC-8 of the AT25DF321A-SH-T. A substitution requires verifying memory capacity requirements, PCB land pattern compatibility, and supply voltage tolerance against the target design.