Part A
AT45DB321C-TU
Технология микрочипов
- Lifecycle
- Active
- Stock
- 3336 ПКС
- Series
- Память - Память
Replacement verdict
Compatible functional replacement candidate
The AT45DB642D-TU and AT45DB321C-TU share the same 28-pin TSOP-I package, SPI interface, and 2.7V–3.6V supply range, making them functionally interchangeable in many designs. However, the AT45DB642D-TU offers twice the density (64 Mbit vs. 32 Mbit) and a different page size, so firmware page-address mapping and timing must be validated before substitution.
Memory Density
High match
Package Type
High match
Supply Voltage Range
High match
Page Size and Addressing
Validation required
Parts at a glance
Part B
AT45DB642D-TU
компанией Adesto Technologies
- Lifecycle
- Active
- Stock
- 6357 ПКС
- Package
- TSOP-28
- Series
- Память
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-TU | AT45DB321C-TU | Why it matters |
|---|---|---|---|
| Memory Density | 64 Mbit | 32 Mbit | Density determines total storage capacity; a 64 Mbit device stores twice the data of a 32 Mbit device, so they are not directly interchangeable in capacity-critical designs. |
| Page Size | 1056 bytes (1024 + 32) | 528 bytes (512 + 16) | Page size affects write granularity and buffer management; firmware page-addressing logic must match the device page size. |
| Number of Pages | 8192 | 8192 | Page count combined with page size defines total array organization and the address map used by the host controller. |
| Supply Voltage Range | 2.7 V to 3.6 V | 2.7 V to 3.6 V | Operating voltage must match the system rail; identical ranges mean both can share the same power supply design. |
| Interface Type | SPI (Serial Peripheral Interface) | SPI (Serial Peripheral Interface) | Both use SPI, so the host bus protocol is compatible, though command sets and timing may still differ. |
| Maximum Clock Frequency | 66 MHz | 50 MHz | Clock rate determines maximum data throughput; a slower device may bottleneck system performance if the host runs at higher SPI speeds. |
| Package / Mounting | 28-TSOP, Surface Mount | 28-TSOP, Surface Mount | Package and footprint must match for board-level drop-in compatibility; identical packages simplify substitution. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Temperature range must cover the application environment; matching industrial ranges allow use in the same conditions. |
| Organization | 2 banks of 4096 pages | 2 banks of 4096 pages | Bank organization affects concurrent read/write operations and buffer-to-page programming behavior in firmware. |
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 | AT45DB321C-TU | AT45DB642D-TU |
|---|---|---|
| Part Status | Obsolete | Obsolete |
| Base Product Number | AT45DB321 | - |
| Digi Key Programmable | Not Verified | - |
| Memory Type | Non-Volatile | Non-Volatile |
| Memory Format | FLASH | FLASH |
| Technology | FLASH | FLASH |
| Memory Size | 32Mbit | 64Mb (1056 Bytes x 8192 pages) |
| Memory Organization | 528 Bytes x 8192 pages | - |
| Memory Interface | SPI | SPI |
| Clock Frequency | 40 MHz | 66 MHz |
| Write Cycle Time - Word, Page | 15ms | - |
| 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 |
| Packaging | Tray | - |
| Write Cycle Time - Word Page | - | 6ms |
Frequently asked questions
What are the key differences between the AT45DB642D-TU and AT45DB321C-TU DataFlash memories?
The AT45DB642D-TU is a 64-Mbit (8-MByte) DataFlash device organized as 8192 pages of 1056 bytes, while the AT45DB321C-TU is a 32-Mbit (4-MByte) device organized as 8192 pages of 528 bytes. Both are supplied in a 28-lead TSOP package and operate from a 2.7V to 3.6V supply, but they differ in density, page size, and interface speed.
Are the AT45DB642D-TU and AT45DB321C-TU pin-compatible?
Both devices are offered in the same 28-lead TSOP (TSOP-28) package with the same pinout for the SPI interface, power, and ground pins. However, because the page size and internal organization differ, firmware and page-buffer addressing must be adjusted; pin compatibility alone does not guarantee direct substitution.
What is the maximum SPI clock frequency supported by each device?
The AT45DB642D-TU supports a maximum SPI clock frequency of 66 MHz in RapidS mode. The AT45DB321C-TU supports a maximum SPI clock frequency of 50 MHz. Designs migrating between the two should verify timing margins at the higher 66 MHz rate if the faster device is used.
How do the page sizes of the AT45DB642D-TU and AT45DB321C-TU compare?
The AT45DB642D-TU uses a 1056-byte page (1024 bytes main memory plus 32 bytes of SRAM buffer per page). The AT45DB321C-TU uses a 528-byte page (512 bytes main memory plus 16 bytes of SRAM buffer per page). This difference affects buffer addressing, page-erase timing, and firmware data structures.
Can the AT45DB321C-TU be used as a drop-in replacement for the AT45DB642D-TU?
No. Although both are 28-lead TSOP DataFlash devices, the AT45DB321C-TU has half the density and a different page size (528 bytes vs. 1056 bytes). Firmware that assumes 1056-byte pages or 64-Mbit addressing will not operate correctly, so the replacement requires firmware and memory-map changes validated against the respective datasheets.
What supply voltage range do the AT45DB642D-TU and AT45DB321C-TU require?
Both devices operate from a single supply voltage of 2.7V to 3.6V, making them suitable for 3.3V systems. Designs should confirm decoupling and power-up sequencing per the manufacturer datasheets, as the two parts share the same supply specification but differ in internal density.
Do both devices support the same SPI operating modes?
Yes. Both the AT45DB642D-TU and AT45DB321C-TU support SPI modes 0 and 3, and both are compatible with the RapidS serial interface. Command sets are largely similar, but page-size-dependent commands and address lengths must be reviewed because the devices differ in density and page organization.