Part A
AT25DF081A-SSH-T
Adesto Technologies
- Lifecycle
- Active
- Stock
- 3274 PCS
- Package
- SOIC-8
- Series
- Memory
Replacement verdict
Compatible functional replacement candidate
The AT25DF021-SSHF-T is a lower-density member of the same Atmel/Microchip AT25DF SPI serial flash family as the AT25DF081A-SSH-T, sharing the same 8-lead SOIC package, SPI interface, and supply voltage range. It can serve as a functional replacement candidate where 2 Mbit of density is sufficient, but the reduced memory capacity and differing device ID must be validated against the target application before substitution.
Memory Density
Validation required
Package Type
High match
Supply Voltage Range
High match
Interface Type
High match
Parts at a glance
Part B
AT25DF021-SSHF-T
Adesto Technologies
- Lifecycle
- Active
- Stock
- 5344 PCS
- Package
- SOIC-8
- Series
- Memory
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AT25DF081A-SSH-T | AT25DF021-SSHF-T | Why it matters |
|---|---|---|---|
| Memory Density | 8 Mbit (1 MB) | 2 Mbit (256 KB) | Density determines total storage capacity; a 4x difference means the parts are not drop-in substitutes for firmware or data storage sizing. |
| Memory Organization | 1M x 8 | 256K x 8 | Byte-wide organization affects how the host addresses and accesses the array; both are x8, so bus width compatibility is preserved. |
| Interface Type | SPI (Serial Peripheral Interface) | SPI (Serial Peripheral Interface) | Matching interface ensures the same host controller and firmware protocol can communicate with either device. |
| Supply Voltage Range | 2.7 V to 3.6 V | 2.7 V to 3.6 V | Identical operating voltage range means the same power rail can supply either part without level shifting. |
| Package / Mounting | 8-SOIC, Surface Mount | 8-SOIC, Surface Mount | Same package and footprint allows board-level interchangeability without layout changes. |
| Maximum Clock Frequency | 100 MHz | 70 MHz | Clock speed affects read/program throughput; a slower maximum clock may require firmware timing adjustments. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Identical temperature ratings ensure both parts suit the same industrial-grade environmental conditions. |
| Page Size | 256 Bytes | 256 Bytes | Page size governs program granularity; matching page size keeps write routines compatible across both devices. |
| Sector Size | 64 KB | 64 KB | Sector size determines erase granularity; identical sector size preserves erase and wear-leveling logic compatibility. |
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 | AT25DF081A-SSH-T | AT25DF021-SSHF-T |
|---|---|---|
| Supplier | - | Dialog Semiconductor GmbH |
| Part Status | Active | Obsolete |
| Memory Type | Non-Volatile | Non-Volatile |
| Memory Format | FLASH | FLASH |
| Technology | FLASH | FLASH |
| Memory Size | 8Mb (256 Bytes x 4096 pages) | 2Mb (256K x 8) |
| Memory Interface | SPI | SPI |
| Clock Frequency | 100 MHz | 50 MHz |
| Write Cycle Time - Word Page | 7µs, 3ms | 7µs, 5ms |
| Voltage - Supply | 2.7V ~ 3.6V | 2.3V ~ 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 AT25DF081A-SSH-T and AT25DF021-SSHF-T?
The AT25DF081A-SSH-T is an 8-Mbit (1 MByte) SPI serial flash memory, while the AT25DF021-SSHF-T is a 2-Mbit (256 KByte) device. Both are manufactured by Adesto Technologies (now part of Dialog Semiconductor/Renesas) and share the same 8-lead SOIC (0.150" body) package and SPI interface, but they differ in density, page size, and block erase granularity.
Are the AT25DF081A-SSH-T and AT25DF021-SSHF-T pin-compatible?
Yes. Both devices are offered in the same 8-lead SOIC (SSH) package with an identical pinout: CS, SO, WP, GND, SI, SCK, HOLD, and VCC. This allows them to share a common PCB footprint, though firmware must account for the different memory densities.
What are the memory densities and organization of these two devices?
The AT25DF081A-SSH-T provides 8 Mbits organized as 4,096 pages of 256 bytes each, with 256-byte page program capability and 4-KByte, 32-KByte, and 64-KByte block erase options. The AT25DF021-SSHF-T provides 2 Mbits organized as 1,024 pages of 256 bytes each, with 256-byte page program and 4-KByte and 64-KByte block erase options.
Do both devices support the same SPI modes and clock frequencies?
Both support SPI modes 0 and 3 and are specified for operation up to 85 MHz for fast read commands. Standard read, page program, and erase operations are supported on both devices, along with JEDEC-standard manufacturer and device ID commands.
What are the operating voltage and temperature ranges for these parts?
Both the AT25DF081A-SSH-T and AT25DF021-SSHF-T operate from a single 2.7 V to 3.6 V supply. The "-T" suffix in both part numbers denotes the industrial temperature range of -40°C to +85°C, making them suitable for industrial and embedded applications.
Can the AT25DF021-SSHF-T be used as a drop-in replacement for the AT25DF081A-SSH-T?
Hardware-wise, the devices are pin-compatible in the same 8-lead SOIC package. However, they are not functionally interchangeable without firmware changes because the AT25DF021-SSHF-T has one-quarter the density (2 Mbit vs 8 Mbit) and a different device ID. Firmware that addresses the full 8-Mbit array or relies on the specific JEDEC ID will not work correctly with the smaller device.
What are the typical applications for these serial flash devices?
Both devices are commonly used for code storage, configuration data, and parameter storage in embedded systems, consumer electronics, industrial controllers, and networking equipment. The AT25DF081A-SSH-T is suited to applications requiring larger firmware images, while the AT25DF021-SSHF-T fits space- and cost-constrained designs with smaller code footprints.