AT45DB081E-SHN-T

The AT45DB081E-SHN-T is an 8Mbit (1MByte) DataFlash serial NOR flash memory from Renesas Electronics, originally developed by Atmel. Unlike standard SPI flash devices, the DataFlash architecture integrates two 264-byte SRAM buffers that allow page data accumulation and background programming, enabling efficient write operations without blocking read access. The device supports SPI-compatible serial interface (Mode 0 and 3) with clock rates up to 85MHz, plus dual-output SPI that doubles effective read throughput to 170Mbps. Each 264-byte page includes 8 bytes of ECC data for enhanced data integrity. The USON-8 (4 x 3mm) package provides a minimal footprint for space-constrained designs, while the 2.5V to 3.6V supply range supports direct connection to 3.3V systems.

DataFlash Architecture

Unlike standard NOR flash that requires erase-before-write at sector boundaries, the AT45DB081E uses a page-based programming model. Each 264-byte page (256 data + 8 ECC) can be individually programmed without prior erasure. The two internal SRAM buffers (Buffer 1 and Buffer 2) allow the host to accumulate data into a buffer while the other buffer is being programmed into the flash array, enabling simultaneous read and write operations.

Buffer-to-Page Programming

The typical write sequence involves: (1) loading data into an SRAM buffer via SPI, (2) issuing a Buffer-to-Page transfer command that programs the buffer contents into the flash array. This two-step process allows the host to verify data before committing to flash. A direct Page-Program command combines both steps into a single operation for simpler firmware.

Dual-SPI Read

In dual-output mode, the SO pin and SI pin both output data on alternating clock edges, doubling the data rate from 1 bit per clock to 2 bits per clock. At 85MHz clock, this achieves 170Mbps effective throughput, significantly faster than standard SPI read for large data transfers such as boot code loading.

ECC and Data Integrity

Each 264-byte page includes 8 bytes of internal ECC data. The ECC logic transparently detects and corrects single-bit errors during read operations, enhancing long-term data reliability. The 100,000 program/erase cycle endurance per page and 20-year data retention ensure robust long-term storage.

• Data logging and parameter storage in embedded systems where the dual SRAM buffer architecture enables simultaneous read and write operations
• Firmware and boot code storage requiring fast dual-SPI read at 170Mbps for rapid startup
• Audio and image storage in consumer electronics needing page-based ECC for data integrity
• Industrial calibration and configuration data storage requiring 100K cycle endurance and 20-year retention
• Wearable and IoT devices where compact USON-8 (4x3mm) footprint and 15µA standby conserve board space and battery