Basic Product Information
The AT45DB321E-SHF-T is a 32-Mbit (4MB) DataFlash SPI serial Flash memory manufactured by Renesas Electronics (formerly Adesto Technologies / Atmel). It features a unique dual-SRAM buffer architecture with 528-byte DataFlash pages (or 512-byte binary pages), enabling simultaneous read-while-write and page-to-buffer transfer operations. The device operates via a standard SPI interface at clock frequencies up to 85 MHz and supports a supply voltage range of 2.3V to 3.6V. The AT45DB321E provides advanced features including page-erase granularity as small as 256 bytes (via buffer rewrite), built-in erase-before-write capability, and an Auto Page Rewrite command for data refresh in high-reliability applications. Housed in an SOIC-8 (208-mil wide) package, it is designed for code shadowing, data logging, and parameter storage in embedded systems requiring frequent small-block writes without the sector-erase overhead of standard NOR Flash.
Core Electrical Parameters
| Parameter | Value |
|---|---|
| Manufacturer | Renesas Electronics (formerly Adesto/Atmel) |
| Memory Type | NOR Flash (DataFlash) |
| Memory Density | 32 Mbit (4 MByte) |
| Memory Organization | 8,192 pages × 528 bytes (DataFlash mode) / 8,192 pages × 512 bytes (Binary page mode) |
| Extra Memory | 1 Mbit (additional) |
| SRAM Buffers | 2 × 528/512 bytes (dual buffer) |
| Interface | SPI (Mode 0 and Mode 3) |
| Max Clock Frequency | 85 MHz |
| Access Time | 7 ns |
| Supply Voltage | 2.3V ~ 3.6V |
| Active Read Current | 22 mA (max) |
| Standby Current | 15 µA (typ.) |
| Page Program Time | 4 ms (typ.) |
| Byte Program Time | 8 µs (typ.) |
| Page Erase | Supported (as small as 256 bytes via buffer rewrite) |
| Sector/Block Erase | Supported |
| Endurance | 100,000 program/erase cycles per page |
| Data Retention | 20 years |
| Operating Temperature | -40°C ~ +85°C |
| Package | SOIC-8 (208-mil wide, 5.30mm body) |
| MSL Rating | Level 1 (Unlimited) |
| ECCN | 3A991.b.1.a |
Core Features & Advantages
The AT45DB321E-SHF-T stands apart from standard SPI NOR Flash with its DataFlash architecture:
- Dual SRAM Buffer Architecture: Two independent 528/512-byte buffers allow read-while-write and buffer-to-buffer compare operations, eliminating the need to read data into the host MCU before modification — a critical advantage for data logging and frequent small updates.
- Page-Level Erase Granularity: Unlike standard NOR Flash requiring 4KB or larger sector erases, DataFlash supports erase granularity as small as 256 bytes through its buffer rewrite mechanism, dramatically reducing write amplification in logging applications.
- Auto Page Rewrite Command: A single-command data refresh operation reads a page into buffer and reprograms it, essential for maintaining data integrity in sectors with static data stored alongside frequently updated pages.
- Built-In Erase-Before-Write: Buffer-to-Main-Memory Page Program with Built-In Erase eliminates the separate erase cycle required by conventional Flash, simplifying firmware and reducing write latency.
- Binary Page Mode: A configurable 512-byte page size option provides compatibility with standard file systems that expect power-of-two page sizes, easing software integration.
- High SPI Clock Rate: 85 MHz maximum SPI clock frequency enables fast code shadowing and rapid data retrieval, reducing system boot time in embedded applications.
Typical Application Scenarios
- Data Logging in Industrial Systems: Continuous sensor data recording in factory automation, energy meters, and environmental monitoring stations, leveraging the dual-buffer write-without-erase architecture.
- Code Shadowing: Fast boot code storage for DSPs, FPGAs, and MCUs, where firmware is copied from Flash to RAM at startup via the 85 MHz SPI interface.
- Parameter and Configuration Storage: Frequent small-block writes for calibration data, user settings, and device state in medical instruments and consumer electronics.
- Voice/Audio Recording: Buffered sequential write operations ideal for voice memo and audio recording applications in communication devices.
- Firmware Over-the-Air (FOTA) Update Storage: Dual-buffer architecture enables downloading new firmware images while the system continues operating from the existing code, supporting safe A/B partition updates.
- Smart Meter Data Archive: Reliable storage of consumption records and event logs in electricity, gas, and water meters with 20-year data retention guarantee.
Market Reference Price
| Quantity | Unit Price (USD) |
|---|---|
| 1 pc | $3.50 |
| 100 pcs | $2.90 |
| 1,000 pcs | $2.50 |
| 2,000 pcs (Full Reel) | $2.40 |
Source: DigiKey and Mouser pricing, as of 2025. Prices are approximate and may vary by distributor.
Related Models Comparison
| Feature | AT45DB321E-SHF-T | AT45DB641E-SHF-T | W25Q32JVSSIQ | M25P32 |
|---|---|---|---|---|
| Manufacturer | Renesas | Renesas | Winbond | Micron |
| Density | 32 Mbit | 64 Mbit | 32 Mbit | 32 Mbit |
| Architecture | DataFlash (dual buffer) | DataFlash (dual buffer) | Standard SPI NOR | Standard SPI NOR |
| Page Size | 528/512 bytes | 528/512 bytes | 256 bytes | 256 bytes |
| SPI Clock | 85 MHz | 85 MHz | 133 MHz | 75 MHz |
| Dual/Quad I/O | No (Single SPI) | No (Single SPI) | Yes (Dual/Quad) | No |
| Erase Granularity | 256 bytes (via buffer) | 256 bytes (via buffer) | 4 KB (sector) | 256 bytes (sub-sector) |
| Supply Voltage | 2.3V ~ 3.6V | 2.3V ~ 3.6V | 2.7V ~ 3.6V | 2.7V ~ 3.6V |
| Package | SOIC-8 | SOIC-8 | SOIC-8 | SOIC-8 |