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Microchip Technology AT45DB021B-SU
- Part No.:
- AT45DB021B-SU
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
AT45DB021B-SU.pdf
- Description:
- IC FLASH 2MBIT SPI 20MHZ 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,134
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Product details
Overview
AT45DB021B-SU from Microchip Technology (formerly Atmel) is a 2.7V-only serial Flash memory IC with SPI interface, organized as 1024 pages × 264 bytes (2,162,688 bits), featuring dual 264-byte SRAM buffers, 20 MHz max clock frequency, and hardware write protection. It enables code shadowing in embedded microcontroller systems requiring low-voltage, low-pin-count nonvolatile storage.
For engineers reviewing the AT45DB021B-SU datasheet, AT45DB021B-SU pinout, AT45DB021B-SU application, or AT45DB021B-SU equivalent, key selection considerations include its page-erase capability, buffer-assisted concurrent read/write operation, 5.0V-tolerant control inputs, industrial temperature range support, and compatibility with legacy AT45DB021/AT45DB021A designs.
Technical Context
The AT45DB021B-SU implements a serial Flash architecture with two independent 264-byte SRAM buffers that operate asynchronously to main memory - enabling simultaneous data reception into one buffer while reprogramming a page in Flash. Its SPI interface supports Mode 0 and Mode 3, with all instructions (e.g., Continuous Array Read at 68H/E8H, Page Erase at 81H) initiated by CS low followed by opcode and address sequences.
Internal self-timed operations-including Buffer-to-Page Program with built-in erase (tEP ≤ 20 ms), Page Erase (tPE ≤ 25 ms), and Block Erase (tBE ≤ 40 ms)-are managed by an on-chip state machine. The RDY/BUSY pin and Status Register bit 7 provide real-time busy indication, while WP and RESET pins offer hardware-level data integrity and command abort control.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Density | 2,162,688 bits (1024 × 264-byte pages) - supports full firmware image storage for 8-bit/16-bit MCUs with minimal footprint. |
| Supply Voltage | 2.7V–3.6V single supply - eliminates need for level shifters in 3.3V systems; 5.0V-tolerant SI/SCK/CS/RESET/WP simplifies mixed-voltage interfacing. |
| Max Clock Frequency | 20 MHz - enables up to ~2.5 MB/s sequential read throughput via Continuous Array Read mode. |
| Active Read Current | 4 mA typical - reduces power budget impact in battery-backed or energy-constrained applications. |
| Standby Current | 2 µA typical - supports ultra-low-power sleep modes in portable and sensor-edge devices. |
| Page Erase Time | ≤25 ms - allows rapid field updates of individual 264-byte segments without full-chip erase overhead. |
| Buffer Size | 2 × 264 bytes - enables pipelined operation: receive new data into one buffer while programming previous data to Flash. |
Pinout & Package
AT45DB021B-SU is packaged in an 8-pin SOIC (Small Outline Integrated Circuit) with gull-wing leads, RoHS-compliant, green packaging. Pin 1 is marked with a dot or bevel; device operates in commercial (0°C to +70°C) and industrial (−40°C to +85°C) temperature ranges.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS | Chip Select | Active-low enable: initiates all commands; must remain low during opcode/address/data transfer sequences. |
| SCK | Serial Clock | Input-only; controls data timing - SI sampled on rising edge, SO driven on falling edge (SPI Mode 0/3). |
| SI | Serial Input | Input-only; carries opcodes, addresses, and write data; MSB-first protocol with no internal pull-up. |
| SO | Serial Output | Output-only; returns read data and status register bits; tri-stated when CS is high. |
| WP | Write Protect | Hardware page lock: low state prevents programming of first 256 pages - critical for bootloader partition protection. |
| RESET | Chip Reset | Active-low asynchronous abort: forces idle state, terminates ongoing operation, resets internal logic. |
| RDY/BUSY | Ready/Busy Indicator | Open-drain output; pulled low during self-timed operations (program/erase/transfer); requires external 1kΩ pull-up. |
| VCC / GND | Power Supply | VCC = 2.7–3.6V; GND = reference return - decoupling capacitor (0.1 µF) required within 10 mm of pins. |
Key Features
| Feature | Design Value |
|---|---|
| Dual SRAM Buffers | Two independent 264-byte buffers allow overlapping data streaming - e.g., fill buffer 2 while programming buffer 1 to Flash - eliminating CPU wait states. |
| Continuous Array Read | Single-command sequential read across entire memory (wrap-around at end) - ideal for boot code shadowing without address management overhead. |
| Self-Timed Page Programming | No external timing control needed: built-in erase+program cycle completes in ≤20 ms - simplifies firmware update logic and reduces host MCU resource load. |
| Hardware Write Protection | WP pin disables programming of first 256 pages - provides immutable storage region for secure boot code or calibration data. |
| 5.0V-Tolerant Control Inputs | SI, SCK, CS, RESET, WP accept 0–5.0V signals - enables direct connection to 5V microcontrollers or FPGAs without level-shifting circuitry. |
Applications
| Firmware Storage | Bootloader Code Shadowing |
|---|---|
|
Use Scenario: Storing application firmware images for PIC, AVR, or ARM Cortex-M microcontrollers in space-constrained PCBs. IC Role / Device Role / Timing Role: Nonvolatile program memory accessed via SPI during MCU reset or OTA update; replaces parallel NOR Flash with 75% fewer pins. Use Value: Enables field-upgradable firmware with <25 ms page-level granularity and zero external high-voltage circuitry. |
Use Scenario: Loading executable code from Flash into RAM at system startup for faster execution on resource-limited MCUs. IC Role / Device Role / Timing Role: Serial source for continuous instruction stream using Continuous Array Read mode - no address incrementing required. Use Value: Reduces boot time by >40% vs. byte-by-byte reads; leverages internal address counter to sustain 20 MHz SCK throughput. |
| Data Logging Buffer | Secure Configuration Storage |
|
Use Scenario: Capturing sensor readings in industrial IoT gateways where power loss may occur mid-write. IC Role / Device Role / Timing Role: Dual-buffer architecture permits simultaneous acquisition (into buffer 1) and Flash commit (from buffer 2) - atomic page writes prevent partial corruption. Use Value: Guarantees data integrity across power cycles; eliminates need for wear-leveling software or external EEPROM. |
Use Scenario: Storing cryptographic keys, calibration coefficients, or device-specific identifiers in medical or automotive ECUs. IC Role / Device Role / Timing Role: Hardware WP pin locks first 256 pages - isolates immutable security-critical data from application-layer write access. Use Value: Meets IEC 62304 and ISO 26262 requirements for protected memory regions without software enforcement. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial Flash memory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| W25Q20EW | 2 Mbit density, quad SPI support, 104 MHz max clock, but no dual SRAM buffers or hardware WP pin. | Lacks buffer-assisted concurrent operation - requires host-managed buffering; no dedicated page-lock feature. | Select if higher throughput or QSPI interface is prioritized over deterministic page-erase timing and hardware data protection. |
| MX25L2006E | 2 Mbit density, standard SPI only, 80 MHz max clock, no dual buffers, no WP pin, but supports sector protection via Status Register. | Software-configurable protection requires command sequence; no hardware-level write disable for physical pin control. | Choose when cost sensitivity outweighs need for pin-level WP control and concurrent buffer operation. |
Compared with W25Q20EW and MX25L2006E, the AT45DB021B-SU uniquely delivers integrated dual buffers for true overlap operation and dedicated hardware write protection - making it optimal for safety-critical or real-time deterministic firmware update scenarios where software-managed alternatives introduce latency or reliability risk.
Availability
AT45DB021B-SU is available at Aetrix Electronics and suitable for firmware storage, bootloader shadowing, data logging, and secure configuration applications requiring stable component supply, long-term lifecycle support, and industrial temperature compliance.
Supply support for AT45DB021B-SU includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Microchip Technology acquired Atmel in 2016 and maintains full product support, documentation, and manufacturing continuity for the DataFlash family.
The AT45DB021B-SU belongs to Microchip's legacy DataFlash® serial Flash product line, designed specifically for embedded systems needing SPI-based nonvolatile memory with integrated buffering and deterministic page-level erase - targeting MCU co-processor, code storage, and data-acquisition applications.
FAQ
What is the maximum clock frequency supported by the AT45DB021B-SU?
The AT45DB021B-SU supports a maximum serial clock (SCK) frequency of 20 MHz for all read and write operations, including Continuous Array Read and Main Memory Page Read. This allows sustained data transfer rates up to approximately 2.5 MB/s under ideal conditions, provided the host controller meets setup/hold timing requirements specified in the datasheet.
Does the AT45DB021B-SU require high-voltage programming?
No, the AT45DB021B-SU does not require high-voltage programming. It operates from a single 2.7V–3.6V supply for both read and program/erase operations. All programming cycles - including Buffer-to-Page Program with built-in erase - are internally self-timed and completed using only the VCC supply voltage, eliminating the need for external charge pumps or voltage boosters.
How does the dual-buffer architecture of the AT45DB021B-SU improve system performance?
The AT45DB021B-SU's two independent 264-byte SRAM buffers enable true concurrent operation: while one buffer is being written to via SI, the other can be programmed into Flash memory - or vice versa. This eliminates CPU wait states during page reprogramming and supports continuous data streaming in logging or firmware update applications without host-side buffering overhead.
Can the AT45DB021B-SU be used as a direct replacement for AT45DB021 or AT45DB021A?
Yes, the AT45DB021B-SU is 100% compatible with AT45DB021 and AT45DB021A in pinout, command set, timing, and electrical characteristics. It retains full functional equivalence while offering improved reliability and updated manufacturing process - making it a drop-in upgrade path for existing designs using those earlier variants.
What is the purpose of the RDY/BUSY pin on the AT45DB021B-SU?
The RDY/BUSY pin on the AT45DB021B-SU is an open-drain output that goes low during any self-timed operation - including page programming, block erasing, buffer transfers, or comparisons. It provides hardware-level status feedback, allowing the host MCU to poll or interrupt on completion instead of relying solely on fixed delay timers, thereby improving timing accuracy and system responsiveness.
AT45DB021B-SU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Type:
- Non-Volatile
- Memory Format:
- FLASH
- Technology:
- FLASH
- Memory Size:
- 2Mbit
- Memory Organization:
- 264 Bytes x 1024 pages
- Memory Interface:
- SPI
- Clock Frequency:
- 20 MHz
- Write Cycle Time - Word, Page:
- 14ms
- Access Time:
- -
- Voltage - Supply:
- 2.7V ~ 3.6V
- Operating Temperature:
- -40°C ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
AT45DB021B-SU FAQ
1.How can I place an order for AT45DB021B-SU through Aetrix?
Please submit a Request for Quotation (RFQ) for AT45DB021B-SU on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for AT45DB021B-SU reliable?
The price and inventory of AT45DB021B-SU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT45DB021B-SU is usually 5 days.
3.What payment methods are accepted for AT45DB021B-SU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT45DB021B-SU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT45DB021B-SU?
AT45DB021B-SU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT45DB021B-SU order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for AT45DB021B-SU?
For technical support, including AT45DB021B-SU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT45DB021B-SU requirements.
6.How does Aetrix verify that AT45DB021B-SU is sourced from the original manufacturer or authorized distributors?
All AT45DB021B-SU products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that AT45DB021B-SU meets industry standards.
7.What is the process for return or replacement of AT45DB021B-SU?
All AT45DB021B-SU units undergo pre-shipment inspection (PSI). If there is an issue with AT45DB021B-SU, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The AT45DB021B-SU part is unused and in its original packaging.
Return procedure for AT45DB021B-SU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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