Part A
AT45DB642D-CNU
Adesto Technologies
- Lifecycle
- Active
- Stock
- 3548 Stückzahl
- Package
- CASON-8
- Series
- Speicher
Replacement verdict
Not a drop-in replacement
The AT45DB642D-CNU and AT45DB041B-CNU are both SPI DataFlash devices from the same manufacturer family, but they differ fundamentally in memory density, page size, and package footprint, so the AT45DB041B-CNU cannot serve as a direct drop-in substitute for the AT45DB642D-CNU without design changes and firmware validation.
Different memory density
Different page size
Different package footprint
Firmware addressing changes required
Parts at a glance
Part B
AT45DB041B-CNU
Mikrochip-Technologie
- Lifecycle
- Active
- Stock
- 2449 Stückzahl
- Package
- VDFN-8
- Series
- Speicher
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 | AT45DB041B-CNU | Why it matters |
|---|---|---|---|
| Memory Density | 64 Mbit (8 MB) | 4 Mbit (512 KB) | Density determines total storage capacity; a 16x difference means the two parts are not drop-in substitutes for most applications. |
| Page Size | 1056 bytes (1024 + 32) | 264 bytes (256 + 8) | Page size affects write granularity and buffer requirements; firmware page-addressing logic must match the device. |
| Number of Pages | 8192 pages | 2048 pages | Page count combined with page size defines total array organization and address map. |
| 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 ease electrical compatibility. |
| Interface Type | SPI (Serial Peripheral Interface) | SPI (Serial Peripheral Interface) | Both use SPI, so bus-level compatibility exists, though command sets and timing may differ. |
| Maximum Clock Frequency | 66 MHz | 20 MHz | Clock rate determines throughput; the faster part may not be usable at full speed in a system designed for the slower one. |
| SRAM Data Buffer Size | 2 x 1056 bytes | 2 x 264 bytes | Buffer size affects programming flexibility and the maximum data chunk per buffer write operation. |
| Package / Mounting | 8-pin CASON (surface mount) | 8-pin CASON (surface mount) | Package and pinout must match for board-level interchangeability; identical packages simplify substitution. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Temperature range must cover the target environment; matching industrial ranges support similar applications. |
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 | AT45DB041B-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) | 4Mb (264 Bytes x 2048 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 the AT45DB041B-CNU?
The AT45DB642D-CNU is a 64-Mbit (8-MByte) DataFlash memory device organized as 8192 pages of 1056 bytes, while the AT45DB041B-CNU is a 4-Mbit (512-KByte) device organized as 2048 pages of 264 bytes. The AT45DB642D-CNU supports dual-interface (SPI and RapidS) operation, whereas the AT45DB041B-CNU supports SPI only. Both are offered in an 8-lead CASON package, but they differ in density, page size, and interface capability.
Are the AT45DB642D-CNU and AT45DB041B-CNU pin-compatible?
Both devices are supplied in an 8-lead CASON package with the same pin count, but pin compatibility must be verified against the respective manufacturer datasheets because the AT45DB642D-CNU includes additional interface signals (such as SO, SI, SCK, CS, RESET, and VCC/GND) that must match the target PCB land pattern and signal routing. Do not assume direct drop-in replacement without confirming pin functions and package dimensions from the official datasheets.
Can the AT45DB041B-CNU be used as a direct replacement for the AT45DB642D-CNU?
No. The AT45DB041B-CNU has only 4 Mbits of density versus 64 Mbits for the AT45DB642D-CNU, and its page size is 264 bytes versus 1056 bytes. These differences in density and page organization prevent a direct replacement without firmware and memory-map changes. The AT45DB041B-CNU also lacks the dual-interface (RapidS) capability of the AT45DB642D-CNU.
What supply voltage do the AT45DB642D-CNU and AT45DB041B-CNU require?
Both devices operate from a single 2.7V to 3.6V supply, as specified in the Atmel (now Microchip) datasheets. Designs must ensure the supply remains within this range during read, program, and erase operations.
What are the page sizes and total densities of these two DataFlash devices?
The AT45DB642D-CNU has a 64-Mbit density with 8192 pages of 1056 bytes each (8 Mbytes total). The AT45DB041B-CNU has a 4-Mbit density with 2048 pages of 264 bytes each (512 Kbytes total). These page-size differences affect buffer requirements and programming algorithms.
Do both devices support the same SPI clock frequency?
The maximum SPI clock frequency must be confirmed from the respective datasheets. The AT45DB642D-CNU supports SPI and RapidS interfaces, while the AT45DB041B-CNU supports SPI only. Because the two devices belong to different DataFlash generations, their maximum SCK frequencies and timing parameters differ and must be verified individually before designing a shared bus.
What package type do the AT45DB642D-CNU and AT45DB041B-CNU use?
Both the AT45DB642D-CNU and AT45DB041B-CNU are offered in an 8-lead CASON package. The "CNU" suffix in both part numbers denotes this package and the industrial temperature range. Package dimensions and land patterns should be confirmed from the official Microchip datasheets before layout.
Are these devices suitable for code shadowing and data logging applications?
Both are serial DataFlash memories intended for code shadowing to RAM, data logging, and firmware storage. The AT45DB642D-CNU, with its larger 64-Mbit density and 1056-byte pages, suits higher-capacity code and data storage, while the AT45DB041B-CNU suits smaller-footprint applications requiring 4 Mbits. Selection should be based on density, page size, and interface requirements verified from the datasheets.