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Microchip Technology AT25640B-SSHL-B
- Part No.:
- AT25640B-SSHL-B
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
AT25640B-SSHL-B.pdf
- Description:
- IC EEPROM 64KBIT SPI 20MHZ 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:9,718
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Product details
Overview
AT25640B-SSHL-B from Microchip Technology (formerly Atmel) is a 64-kbit SPI serial EEPROM organized as 8,192 words × 8 bits, operating from 1.8V to 5.5V with 20MHz max clock rate at 5V, 32-byte page write capability, and hardware/software write protection via WP pin and status register. It serves as nonvolatile configuration storage in industrial controllers, metering systems, and embedded peripherals requiring robust data retention.
For engineers reviewing the AT25640B-SSHL-B datasheet, AT25640B-SSHL-B pinout, AT25640B-SSHL-B application, or AT25640B-SSHL-B equivalent, key selection criteria include its JEDEC SOIC-8 package, -40°C to +85°C industrial temperature range, 1M write endurance, 100-year data retention, and support for SPI Modes 0 and 3 with HOLD/CS-controlled suspend functionality.
Technical Context
The AT25640B-SSHL-B implements a synchronous SPI slave interface with dedicated SI (input), SO (output), SCK (clock), CS (chip select), WP (write protect), and HOLD (communication suspend) pins. Its internal architecture includes an 8-bit instruction register, status register with BP0/BP1 block protection bits and WPEN control, and automatic address increment during sequential reads/writes.
It supports four levels of block write protection (none, 1/4, 1/2, or full array), self-timed 5ms max write cycles, and dual-layer data protection-hardware via WP pin (when WPEN=1) and software via WREN/WRSR instructions. All programming is page-based (32 bytes), with no separate erase required before write.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Density | 64 kbit (8,192 × 8-bit words) - sufficient for firmware parameter tables, calibration data, or device ID storage in space-constrained designs. |
| Supply Voltage Range | 1.8V to 5.5V - enables direct interfacing with 1.8V, 3.3V, and 5V microcontrollers without level-shifting. |
| Max Clock Frequency | 20 MHz at VCC = 5.0V - supports high-throughput configuration updates in real-time systems. |
| Write Endurance | 1,000,000 cycles - ensures long-term reliability in applications with frequent parameter logging or field-upgrade operations. |
| Data Retention | 100 years at +25°C - guarantees persistent storage integrity across product lifecycles without refresh. |
| Operating Temperature | -40°C to +85°C - validated for industrial environments including factory automation and outdoor metering. |
| Page Write Size | 32 bytes - balances write speed and granularity for efficient partial-memory updates without overwriting adjacent data. |
Pinout & Package
AT25640B-SSHL-B is packaged in an 8-lead JEDEC SOIC (8S1), 0.15" wide, with NiPdAu lead finish, RoHS-compliant, and industrial-grade thermal rating.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS | Chip Select | Active-low enable signal; must be low to accept commands; high-impedance SO when CS is high. |
| SCK | Serial Clock | Input-only clock synchronized to master MCU; defines timing for SI/SO data transfer per SPI Mode 0 or 3. |
| SI | Serial Data Input | Command/address/data input path; MSB-first; ignored during HOLD or when CS is high. |
| SO | Serial Data Output | Read data output; tri-stated when CS is high or during HOLD; supports daisy-chaining in multi-device SPI buses. |
| GND | Ground Reference | Primary return path for all I/O and supply currents; requires low-impedance PCB connection to minimize noise coupling. |
| VCC | Power Supply | Single-supply input (1.8–5.5V); decoupling capacitor (0.1 µF) recommended near pin for stable read/write operation. |
| WP | Write Protect | Hardware lock for status register writes when WPEN=1; prevents accidental reconfiguration of protection settings. |
| HOLD | Communication Suspend | Pauses ongoing SPI transaction without resetting sequence; allows MCU to service higher-priority interrupts. |
Key Features
| Feature | Design Value |
|---|---|
| SPI Mode Compatibility | Supports both Mode 0 (CPOL=0, CPHA=0) and Mode 3 (CPOL=1, CPHA=1), ensuring interoperability with diverse MCUs including 68HC11 and ARM Cortex-M families. |
| Block Write Protection | Configurable via status register to protect 0%, 25%, 50%, or 100% of memory - enables secure storage of critical calibration or security keys while allowing runtime updates to user data sections. |
| Hardware + Software Protection | WP pin (hardware) and WREN/WRSR instructions (software) provide layered defense against unintended writes - essential for fail-safe industrial firmware recovery. |
| Self-Timed Write Cycle | 5 ms maximum internal write time eliminates need for external timing control or polling overhead - simplifies driver implementation and reduces CPU load. |
| Low-Power Standby | Standby current < 0.1 µA at 1.8V - suitable for battery-backed systems where EEPROM must retain state during extended sleep modes. |
Applications
| Industrial PLC Configuration Storage | Smart Energy Meter Calibration Data |
|---|---|
Use Scenario: Storing I/O mapping, scaling factors, and alarm thresholds in programmable logic controllers deployed in factory environments with wide ambient temperature swings. IC Role / Device Role / Timing Role: Nonvolatile configuration register accessed via SPI during boot and runtime parameter adjustment; HOLD used to pause writes during interrupt servicing. Use Value: Ensures deterministic startup behavior and field-upgradable parameters without requiring external backup power or complex FRAM management. |
Use Scenario: Retaining metrology calibration coefficients, tariff schedules, and tamper-event logs in ANSI C12.22-compliant electricity meters operating continuously for 15+ years. IC Role / Device Role / Timing Role: Secure, write-protected data vault; WP pin tied low during production to lock calibration blocks; RDSR monitored to confirm write completion before power-down. Use Value: Meets ANSI/IEEE accuracy lifetime requirements with 100-year data retention and 1M-cycle endurance under daily firmware update cycles. |
| Medical Device Serial Number & Audit Log | Automotive Body Control Module Settings |
Use Scenario: Recording unique device identifiers, manufacturing date codes, and usage hours in Class II medical instruments subject to FDA 21 CFR Part 11 audit trails. IC Role / Device Role / Timing Role: Tamper-evident log storage; WRITE disabled after initial commissioning using WRSR; RDY bit polled to guarantee write persistence before logging next event. Use Value: Provides cryptographically verifiable, non-erasable history without adding MCU flash wear or requiring external secure elements. |
Use Scenario: Saving seat position presets, mirror angles, and lighting profiles in automotive BCMs where EEPROM must survive 15-year vehicle lifecycle and repeated battery disconnects. IC Role / Device Role / Timing Role: Low-voltage (1.8V) operation enables direct connection to 1.8V CAN transceiver domains; HOLD suspends writes during CAN bus arbitration spikes. Use Value: Eliminates need for voltage translators or auxiliary regulators, reducing BOM cost and board area in space-constrained junction boxes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| M95640-DRMN6TP/K | 64-kbit SPI EEPROM, 2.5–5.5V supply, 10MHz max clock, SOIC-8, same pinout but lacks HOLD pin and WPEN bit-level control. | No hardware suspend capability; limited block protection granularity (only full-array or none). | Select when HOLD functionality is unused and lower-cost sourcing is prioritized over advanced protection features. |
| BR24G64FJ-WE2 | 64-kbit I²C EEPROM, 1.7–5.5V, 1MHz max clock, 8-pin SOP, integrated write-cycle timer, no WP/HOLD pins. | Requires I²C interface instead of SPI; slower write throughput; no hardware suspend or fine-grained block protection. | Choose only if system already uses I²C infrastructure and SPI bandwidth is not required for configuration access. |
Compared with M95640-DRMN6TP/K and BR24G64FJ-WE2, AT25640B-SSHL-B delivers superior real-time responsiveness via 20MHz SPI, deterministic suspend via HOLD, and flexible 25%/50% block protection - making it optimal for industrial systems requiring concurrent MCU task handling and secure parameter management.
Availability
AT25640B-SSHL-B is available at Aetrix Electronics and suitable for industrial automation, smart metering, and medical instrumentation requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.
Supply support for AT25640B-SSHL-B 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 support for legacy Atmel serial EEPROMs, providing datasheets, application notes, and long-term supply assurance.
The AT25640B belongs to Atmel's SPI Serial EEPROM product line, designed specifically for reliable, low-power nonvolatile storage in resource-constrained embedded systems where SPI interface simplicity and industrial-grade reliability are critical.
FAQ
What is the maximum clock frequency supported by AT25640B-SSHL-B?
The AT25640B-SSHL-B supports up to 20 MHz at VCC = 5.0V, 10 MHz at 2.5–5.5V, and 5 MHz at 1.8–5.5V. This graded frequency scaling ensures timing compliance across its full 1.8V–5.5V supply range. The actual usable clock rate in a design depends on trace length, capacitive loading, and MCU drive strength - verified using tWH/tWL timing parameters from the datasheet.
Does AT25640B-SSHL-B require an external erase cycle before writing?
No, AT25640B-SSHL-B does not require a separate erase cycle. Each write operation automatically erases and programs the target byte or page. This simplifies firmware development and eliminates erase-related delays. The device performs self-timed internal erase-and-write sequences, completing within 5 ms maximum - confirmed in the Electrical Characteristics table under tWC.
How is write protection implemented on AT25640B-SSHL-B?
AT25640B-SSHL-B implements dual-layer write protection: hardware via the WP pin (active-low, enabled when WPEN bit = 1) and software via status register bits BP0/BP1. WP locks status register writes; BP0/BP1 configure 0%, 25%, 50%, or 100% memory block protection. Both mechanisms coexist - e.g., WP low + WPEN=1 prevents all status register changes, even if software attempts WRSR.
What is the purpose of the HOLD pin on AT25640B-SSHL-B?
The HOLD pin on AT25640B-SSHL-B suspends ongoing SPI communication without resetting the command sequence. When asserted low (with SCK low), it places SO in high-impedance and ignores SI inputs, allowing the MCU to service interrupts or perform other tasks. Resuming requires bringing HOLD high while SCK remains low - preserving address/state context for seamless continuation of reads or writes.
Is AT25640B-SSHL-B compatible with SPI Mode 3 (CPOL=1, CPHA=1)?
Yes, AT25640B-SSHL-B explicitly supports SPI Mode 3 per the datasheet. It operates as a slave with SCK as input only, and its timing specifications (tWH, tWL, tSU, tH) are validated for both Mode 0 and Mode 3. Mode selection is handled entirely by the master MCU; no device configuration is needed - the AT25640B-SSHL-B adapts automatically based on clock polarity and phase.
AT25640B-SSHL-B Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Programmable:
- Verified
- Memory Type:
- Non-Volatile
- Memory Format:
- EEPROM
- Technology:
- EEPROM
- Memory Size:
- 64Kbit
- Memory Organization:
- 8K x 8
- Memory Interface:
- SPI
- Clock Frequency:
- 20 MHz
- Write Cycle Time - Word, Page:
- 5ms
- Access Time:
- -
- Voltage - Supply:
- 1.8V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
AT25640B-SSHL-B FAQ
1.How can I place an order for AT25640B-SSHL-B through Aetrix?
Please submit a Request for Quotation (RFQ) for AT25640B-SSHL-B 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 AT25640B-SSHL-B reliable?
The price and inventory of AT25640B-SSHL-B are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT25640B-SSHL-B is usually 5 days.
3.What payment methods are accepted for AT25640B-SSHL-B?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT25640B-SSHL-B transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT25640B-SSHL-B?
AT25640B-SSHL-B orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT25640B-SSHL-B 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 AT25640B-SSHL-B?
For technical support, including AT25640B-SSHL-B datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT25640B-SSHL-B requirements.
6.How does Aetrix verify that AT25640B-SSHL-B is sourced from the original manufacturer or authorized distributors?
All AT25640B-SSHL-B 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 AT25640B-SSHL-B meets industry standards.
7.What is the process for return or replacement of AT25640B-SSHL-B?
All AT25640B-SSHL-B units undergo pre-shipment inspection (PSI). If there is an issue with AT25640B-SSHL-B, 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 AT25640B-SSHL-B part is unused and in its original packaging.
Return procedure for AT25640B-SSHL-B:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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