Part A
AT45DB642D-CNU
Adesto Technologies
- Lifecycle
- Active
- Stock
- 3548 PCS
- Package
- CASON-8
- Series
- Memória
Replacement verdict
Not a drop-in replacement
The AT45DB642D-CNU and AT45DB081B-CNU are both DataFlash memory devices in the same 8-pin CASON package, but they differ fundamentally in density, page size, and interface clock support. The AT45DB642D-CNU offers 64 Mbit with 1056-byte pages and up to 66 MHz operation, while the AT45DB081B-CNU provides 8 Mbit with 264-byte pages and up to 50 MHz operation. Because the memory density, page architecture, and timing characteristics are not interchangeable, the AT45DB081B-CNU cannot serve as a direct drop-in substitute for the AT45DB642D-CNU without firmware and design validation.
Different memory density
Different page size
Different clock frequency
Firmware adaptation required
Parts at a glance
Part B
AT45DB081B-CNU
Tecnologia Microchip
- Lifecycle
- Active
- Stock
- 3231 PCS
- Package
- VDFN-8
- Series
- Memória
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AT45DB642D-CNU | AT45DB081B-CNU | Why it matters |
|---|---|---|---|
| Memory Density | 64 Mbit | 8 Mbit | Density determines total storage capacity; an 8x difference means the two parts are not drop-in substitutes for firmware or data storage sizing. |
| Page Size | 1056 bytes (1024 + 32) | 264 bytes (256 + 8) | Page size affects write/read buffering and command addressing; different page sizes require firmware changes to buffer management and addressing. |
| Number of Pages | 8192 pages | 4096 pages | Page count combined with page size defines total array organization and the address range used by read/program/erase commands. |
| Supply Voltage Range | 2.7 V to 3.6 V | 2.7 V to 3.6 V | Operating voltage must match the host system rail; identical ranges here mean both are compatible with 3.3 V systems. |
| Interface Type | SPI (Serial Peripheral Interface) | SPI (Serial Peripheral Interface) | Both use SPI, so bus signaling and pin functions are compatible, though command sets and addressing differ. |
| Maximum Clock Frequency | 66 MHz | 20 MHz | Clock rate determines maximum data throughput; the faster part can be clocked slower, but the slower part cannot match the faster part's throughput. |
| Package / Mounting | 8-CSON (8-pad, surface mount) | 8-CSON (8-pad, surface mount) | Package and pinout must match for board-level compatibility; identical package type supports physical interchangeability. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Temperature range must cover the application environment; identical industrial ranges mean equivalent environmental tolerance. |
| Organization (Sectors/Blocks) | 64 sectors (8 pages per sector) | 16 sectors (256 pages per sector) | Sector/block architecture affects erase granularity and wear-leveling strategy; different organizations require firmware adaptation for erase operations. |
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 | AT45DB642D-CNU | AT45DB081B-CNU |
|---|---|---|
| Supplier | - | Microchip Technology |
| Part Status | Obsolete | Obsolete |
| Memory Type | Non-Volatile | Non-Volatile |
| Memory Format | FLASH | FLASH |
| Technology | FLASH | FLASH |
| Memory Size | 64Mb (1056 Bytes x 8192 pages) | 8Mb (264 Bytes x 4096 pages) |
| Memory Interface | SPI | SPI |
| Clock Frequency | 66 MHz | 20 MHz |
| Write Cycle Time - Word Page | 6ms | 14ms |
| 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 AT45DB642D-CNU and AT45DB081B-CNU DataFlash memories?
The AT45DB642D-CNU is a 64-Mbit (8-MByte) DataFlash device organized as 8192 pages of 1056 bytes, while the AT45DB081B-CNU is an 8-Mbit (1-MByte) device organized as 4096 pages of 264 bytes. The AT45DB642D-CNU supports dual-interface (SPI and RapidS) operation, whereas the AT45DB081B-CNU supports SPI only. Both are offered in an 8-lead CASON package.
Are the AT45DB642D-CNU and AT45DB081B-CNU pin-compatible?
Both devices are supplied in an 8-pad CASON package with the same pinout (SI, SO, SCK, CS, RESET, VCC, GND, and WP). However, pin compatibility alone does not guarantee interchangeability; page size, command set, and density differences must be validated against the target design.
What is the page size difference between the two devices?
The AT45DB642D-CNU uses 1056-byte pages (1024 bytes plus 32 bytes of spare area), while the AT45DB081B-CNU uses 264-byte pages (256 bytes plus 8 bytes of spare area). This affects buffer sizes, addressing, and firmware page-management logic.
Do both devices support the same supply voltage range?
Yes. Both the AT45DB642D-CNU and AT45DB081B-CNU operate from a single 2.7 V to 3.6 V supply, making them suitable for 3.3 V system designs.
What are the maximum SPI clock frequencies for these devices?
The AT45DB642D-CNU supports SPI clock frequencies up to 66 MHz. The AT45DB081B-CNU supports SPI clock frequencies up to 66 MHz as well. Designers should confirm timing parameters against the respective datasheets for the target operating conditions.
Can the AT45DB081B-CNU be used as a drop-in replacement for the AT45DB642D-CNU?
No. Although both share the same 8-pad CASON package and pinout, the density (8 Mbit vs 64 Mbit), page size (264 vs 1056 bytes), and command/addressing schemes differ. Firmware and memory maps must be revalidated before substitution.
Do both devices support the RapidS interface?
No. The AT45DB642D-CNU supports both SPI and RapidS interfaces, while the AT45DB081B-CNU supports SPI only. Systems requiring RapidS must use the AT45DB642D-CNU or another RapidS-capable device.
What are the typical operating temperature ranges for these DataFlash devices?
Both the AT45DB642D-CNU and AT45DB081B-CNU are specified for the commercial temperature range of 0°C to 70°C. Industrial-temperature variants, where available, should be confirmed via the manufacturer's ordering information.