Part Number: AT45DB321E-SHF-T

Manufacturer: Adesto Technologies

Description: IC FLASH 32MBIT SPI 85MHZ 8SOIC

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Technical Specifications of AT45DB321E-SHF-T

Datasheet  AT45DB321E-SHF-T datasheet
Category Integrated Circuits (ICs)
Family Memory
Manufacturer Adesto Technologies
Packaging Tape & Reel (TR)
Part Status Active
Format – Memory FLASH
Memory Type DataFLASH
Memory Size 32M (8192 pages x 528 bytes)
Speed 85MHz
Interface SPI, RapidS
Voltage – Supply 2.3 V ~ 3.6 V
Operating Temperature -40°C ~ 85°C (TC)
Package / Case 8-SOIC (0.209″, 5.30mm Width)
Supplier Device Package 8-SOIC

AT45DB321E-SHF-T Description

A wide range of digital audio, image, program code, and data storage applications are well suited for the Adesto® AT45DB321E, a serial-interface, sequential-access Flash memory with a 2.3V minimum. For applications demanding extremely high-speed operation, the RapidS serial interface is also supported by the AT45DB321E. The 34,603,008 bits of RAM are divided up into 8,192 pages, each of 512 or 528 bytes. The AT45DB321E additionally has two 512/528 byte SRAM buffers and the main memory.

The buffers allow receiving data while a main memory page is being reprogrammed. A system’s capacity to write a continuous data stream can be significantly improved by interleaving the data between the two buffers. Additionally, an independent 3-step read-modify-write operation can be used to handle E2PROM emulation with ease, and more system scratch pad memory can be added using the SRAM buffers. The Adesto DataFlash® employs a serial interface to access its data sequentially, unlike traditional Flash memories, which access their contents randomly using different address lines and a parallel interface.

Simple sequential access allows for a much-reduced active pin count, a more straightforward hardware layout, improved system stability, less switching noise, and smaller packages. The device is designed with high-density, low-pin-count, low-voltage, and low-power requirements for various commercial and industrial applications. The AT45DB321E can be easily reprogrammed in-system because it doesn’t require high input voltages for programming.

The device’s erase, program, and read functions are all powered by a single 2.3V to 3.6V power source. The Chip Select (CS) pin is used to enable the AT45DB321E, and the Serial Input, Serial Output, and Serial Clock (SCK) pins are used to access it. All cycles for programming and erasing are self-timed.

AT45DB321E-SHF-T Device Operation

The host processor issues command that control how the gadget operates. The falling edge of CS, the appropriate 8-bit opcode, and the intended buffer or main memory address location come next in a successful instruction. The loading of the opcode and the intended buffer or main memory address location is controlled by switching the SCK pin while the CS pin is low through the SI (Serial Input) pin. The Most Significant Bit (MSB) of each instruction, address, and piece of data is sent first.

Memory locations in the main memory array or one of the SRAM buffers are addressed using three address bytes. The number of dummy bits varies based on the operation performed and the chosen device page size. The three address bytes comprise both dummy bits and genuine device address bits. The 10 address bits needed to identify a byte address within a buffer are referred to as BFA9 – BFA0 in the datasheet when discussing buffer addressing for the standard DataFlash page size (528 bytes).

The terms PA0 -PA12 and BA9 – BA0 are used to refer to the main memory addressing, where PA12 – PA0 stands for the 13 address bits needed to indicate a page address, and BA9 – BA0 stands for the 10 address bits needed to designate a byte address within the page. Therefore, a total of 23 address bits are utilized when using the common DataFlash page size. The datasheet uses the usual terminology BFA8 – BFA0 to signify the nine address bits necessary to designate a byte address within a buffer for the “power of 2” binary page size (512 bytes).

The 13 address bits needed to define a page address are referred to as A21 – A9, and the nine address bits needed to designate a byte address within a page are referred to as A8 – A0. This is how main memory addressing is referred to. Therefore, a total of 22 address bits are used when using the binary page size.

Continuous Array Read (Opcode: E8h, Legacy Command)

By providing a clock signal, the Continuous Array Read command allows the sequential reading of an ongoing stream of data from the device; no other addressing information or control signals are required. This is accomplished by providing an initial starting address for the main memory array.

One continuous read from memory can be conducted with the DataFlash without the need for additional address sequences since it has an inbuilt address counter that automatically increases on each clock cycle. An opcode of E8h, three address bytes (the 24-bit page and byte address sequence), and four fake bytes must be inserted into the device to perform a Continuous Array Read using the typical DataFlash page size (528 bytes).

The first 13 bits of the 23-bit address sequence define which page of the main memory array to read, while the final 10 bits (BA9-BA0) provide the starting byte location within the page. To conduct a Continuous Array, Read using the binary page size (512 bytes), The device needs to be programmed with the opcode E8h, followed by three address bytes and four fake bytes. The first 13 bits identify which page of the main memory array to read, and the last nine bits of the 22-bit address sequence provide the starting byte location within the page.

The read operation needs to be initialized, which requires the fake bytes that come after the address bytes. Additional clock pulses on the SCK pin will cause data to be output on the SO (serial output) pin after the dummy bytes. The CS pin must stay low during the loading of the opcode, the reading of data, the dummy bytes, and the address bytes. When a Continuous Array Read reaches the end of a page in the main memory, the device will resume reading at the start of the following page without experiencing any delays during the page boundary crossover.


In conclusion, the AT45DB321E-SHF-T is a flexible and fast Flash memory chip that may be used for various digital storage applications. Low power requirements and in-system programmability make it perfect for industrial and commercial applications. In contrast, its serial interface and sequential access capabilities make it easier to use, reduce pin counts, and increase system stability. With its two SRAM buffers, the device can easily handle bit or byte alterability and improve data stream continuity. The Continuous Array Read command is particularly helpful, which permits the consecutive data reading. The AT45DB321E-SHF-T is a trustworthy and effective memory option for various digital storage applications.

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