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Microchip Technology 25AA640AT-E/SN
- Part No.:
- 25AA640AT-E/SN
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
25AA640AT-E/SN.pdf
- Description:
- IC EEPROM 64KBIT SPI 10MHZ 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,739
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Product details
Overview
25AA640AT-E/SN from Microchip Technology Inc. is a 64-Kbit SPI Serial EEPROM with 8192 × 8-bit organization, 32-byte page size, and 1.8V–5.5V supply range. It supports up to 10 MHz clock frequency at 4.5–5.5V, features hardware write protection via WP pin and STATUS register, and delivers 1 million erase/write cycles with >200-year data retention - deployed in automotive body control modules for configuration storage.
For engineers reviewing the 25AA640AT-E/SN datasheet, 25AA640AT-E/SN pinout, 25AA640AT-E/SN application, or 25AA640AT-E/SN equivalent, key selection criteria include VCC operating range (1.8–5.5V), page write timing (≤5 ms), HOLD/CS timing margins, and AEC-Q100 qualification for extended temperature operation (-40°C to +125°C).
Technical Context
The 25AA640AT-E/SN implements an SPI-compatible serial interface with separate SI (data-in) and SO (data-out) lines, requiring CS, SCK, WP, HOLD, and VCC/VSS. It uses internal high-voltage generation for EEPROM programming and includes a status register with WIP, WEL, BP0/BP1, and WPEN bits for real-time write state and block protection control.
Its architecture supports sequential read across address boundaries with automatic rollover, byte/page write with strict 32-byte page boundary enforcement, and HOLD functionality that suspends ongoing transfers without resetting the internal address pointer - enabling interrupt servicing in resource-constrained microcontroller systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8192 × 8-bit array) - provides sufficient nonvolatile storage for firmware parameters, calibration data, and device identity in compact embedded nodes. |
| Interface | SPI Mode 0,0 and 1,1 - compatible with standard PIC® and ARM Cortex-M microcontroller SPI peripherals without protocol translation. |
| Max Clock Frequency | 10 MHz at VCC ≥ 4.5V - enables fast configuration loading during boot, reducing system initialization latency. |
| Page Size | 32 bytes - defines minimum write granularity; crossing page boundaries wraps data within the same physical page, requiring software boundary checks. |
| Write Cycle Time | ≤5 ms typical - determines minimum time between successive write commands; impacts real-time logging throughput and firmware update sequencing. |
| Endurance & Retention | 1,000,000 erase/write cycles, >200 years data retention - ensures long-term reliability in automotive and industrial applications with infrequent but critical updates. |
| Temperature Range | -40°C to +125°C (Extended grade) - validated per AEC-Q100 for under-hood and powertrain ECUs where thermal stress is severe. |
Pinout & Package
25AA640AT-E/SN is packaged in an 8-lead narrow SOIC (SN) with 150-mil body width and standard 1.27 mm pitch. Pin 1 is marked by a beveled corner or dot; package meets RoHS and Pb-free JEDEC requirements.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS (Pin 1) | Chip Select Input | Active-low enable signal; must be low for all SPI operations; rising edge initiates internal write cycle after valid command sequence. |
| SO (Pin 2) | Serial Data Output | Tri-state open-drain output; data shifted out on SCK falling edge; goes high-impedance when CS is high or HOLD is asserted. |
| WP (Pin 3) | Hardware Write-Protect Input | Low-active pin that, when enabled via WPEN bit, blocks writes to STATUS register nonvolatile bits - prevents accidental lockout of memory regions. |
| VSS (Pin 4) | Ground Reference | Primary return path for all internal logic and charge pump circuits; must be low-impedance to ensure stable write voltage generation. |
| SI (Pin 5) | Serial Data Input | Data and instruction latched on SCK rising edge; accepts 8-bit opcodes (e.g., 0x03 for READ, 0x02 for WRITE) followed by 16-bit address and payload. |
| SCK (Pin 6) | Serial Clock Input | Synchronizes all data transfers; timing constraints (e.g., THI/TLO ≥150 ns at 1.8V) define maximum sustainable clock rate across voltage range. |
| HOLD (Pin 7) | Communication Suspend Input | Pauses active SPI transfer when pulled low while SCK is low; preserves internal address pointer and allows host to service higher-priority interrupts. |
| VCC (Pin 8) | Supply Voltage | 1.8V–5.5V operation; internal regulator powers EEPROM array and logic; standby current drops to 1 µA at 5.5V, enabling battery-backed retention. |
Key Features
| Feature | Design Value |
|---|---|
| Block Write Protection | Configurable via BP0/BP1 bits to protect none, upper 1/4 (1800h–1FFFh), upper 1/2 (1000h–1FFFh), or full array - enables secure partitioning of calibration vs. user data zones. |
| Self-Timed Internal Write | Automatic 5 ms max erase/write completion without external timing control - simplifies firmware design and eliminates need for polling delay loops. |
| Power-On Write Protection | Write enable latch resets at power-up, and WP circuitry prevents inadvertent writes during brown-out or reset sequences - critical for fail-safe automotive operation. |
| HOLD Functionality | Tri-states SO, SI, and SCK while preserving internal state - allows deterministic interruption of multi-byte reads/writes without re-synchronization overhead. |
| AEC-Q100 Qualified | Validated for automotive Extended Temperature Range (-40°C to +125°C) with full reliability testing - meets functional safety requirements for ASIL-B supporting systems. |
Applications
| Automotive Body Control Unit (BCU) | Industrial PLC I/O Module |
|---|---|
Use Scenario: Storing seat position presets, mirror angles, and lighting profiles in a vehicle's door module. IC Role / Device Role / Timing Role: Nonvolatile configuration storage accessed via SPI during power-up and user adjustment events; HOLD used during CAN message handling. Use Value: Enables personalized settings retention across ignition cycles with AEC-Q100 assurance for under-door thermal environment. | Use Scenario: Holding calibrated sensor offset/gain coefficients and field-replaceable module identification in modular I/O racks. IC Role / Device Role / Timing Role: SPI-configured parameter store updated only during commissioning or maintenance; WP pin hardwired to prevent runtime corruption. Use Value: Eliminates recalibration after power loss and supports hot-swap module replacement with persistent identity binding. |
| Medical Infusion Pump | Smart Energy Meter |
Use Scenario: Recording dose history, alarm logs, and operator audit trails in battery-backed memory. IC Role / Device Role / Timing Role: High-reliability event logger using page writes; STATUS register polled for WIP before initiating next write to avoid collision. Use Value: Guarantees 1M-cycle endurance for daily log entries over 10+ year product lifetime with tamper-resistant write protection. | Use Scenario: Storing tariff schedules, meter firmware version, and cryptographic keys in utility-grade electricity meters. IC Role / Device Role / Timing Role: Secure configuration vault with BP1/BP0 locking key storage region; WPEN bit set to enable hardware lockout. Use Value: Prevents unauthorized firmware modification and ensures regulatory compliance with encrypted key persistence. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25LC640AT-E/SN | Requires minimum 2.5V VCC; identical pinout, timing, and feature set otherwise. | Not suitable for 1.8V systems; limited to 2.5–5.5V rails such as 3.3V-only industrial controllers. | Select when system VCC is guaranteed ≥2.5V and cost sensitivity favors LC-series pricing. |
| AT25DF641A-SHN-T | 8-pin SOIC, 64 Mbit density, quad SPI interface, 85 MHz max clock; no HOLD pin; different command set. | Targeted at high-speed firmware storage, not parameter/configuration use; lacks hardware write protection granularity. | Choose only for boot code shadowing or large-data logging where quad SPI bandwidth outweighs configuration flexibility. |
Compared with 25LC640AT-E/SN, the 25AA640AT-E/SN supports lower-voltage operation critical for battery-powered nodes, while AT25DF641A-SHN-T trades pin compatibility and write protection for raw throughput - making 25AA640AT-E/SN optimal for safety-critical, low-power, and configuration-dense designs.
Availability
25AA640AT-E/SN is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC modules, and medical device data logging requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for 25AA640AT-E/SN 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 Inc. is a leading provider of microcontrollers, analog components, and memory solutions, headquartered in Chandler, Arizona, with global manufacturing and support infrastructure.
The 25AA640A family was designed specifically for automotive and industrial applications demanding robust nonvolatile storage with AEC-Q100 qualification, low-voltage operation, and hardware-enforced write protection - targeting ECU configuration, calibration, and event logging.
FAQ
What is the maximum clock frequency supported by the 25AA640AT-E/SN across its full voltage range?
The 25AA640AT-E/SN supports up to 10 MHz at VCC = 4.5–5.5V, 5 MHz at VCC = 2.5–4.5V, and 3 MHz at VCC = 1.8–2.5V. These limits are defined by AC timing parameters including THI, TLO, and TSU, and must be verified per operating voltage in actual PCB layout due to trace capacitance effects. The 25AA640AT-E/SN does not support overclocking beyond these specifications.
How does the HOLD pin function during an active SPI read sequence in the 25AA640AT-E/SN?
When HOLD is pulled low during an active 25AA640AT-E/SN read sequence (with CS low and SCK low), the device immediately tri-states SO, SI, and SCK while preserving the internal address pointer and serial state. Communication resumes from the exact bit position upon HOLD returning high while SCK remains low - enabling deterministic pause/resume without retransmission or address reinitialization.
Can the 25AA640AT-E/SN be used in a 1.8V system without level shifting?
Yes, the 25AA640AT-E/SN is fully specified for 1.8V operation: VIH1 = 0.7×VCC (≥1.26V), VIL1 = 0.3×VCC (≤0.54V), and ICC Read = 2.5 mA at 2.5V/5 MHz - confirming direct interfacing with 1.8V microcontrollers. Its 1.8V–5.5V VCC range eliminates need for external level shifters in mixed-voltage designs.
What happens if a page write crosses a 32-byte boundary in the 25AA640AT-E/SN?
If a page write command attempts to cross a 32-byte boundary in the 25AA640AT-E/SN, data wrap around to the start of the current page instead of advancing to the next page. For example, writing 32 bytes starting at address 0x001F fills 0x001F–0x003E, then overwrites 0x0000–0x001D. This behavior requires firmware to enforce page-aligned writes or split payloads at boundaries.
Is the 25AA640AT-E/SN pin-compatible with the 25LC640AT-E/SN?
Yes, the 25AA640AT-E/SN and 25LC640AT-E/SN share identical 8-lead SOIC (SN) packaging, pinout, AC/DC electrical characteristics, instruction set, and timing diagrams. The only functional difference is the minimum VCC: 1.8V for 25AA640AT-E/SN versus 2.5V for 25LC640AT-E/SN - making them drop-in replacements in 2.5–5.5V systems.
25AA640AT-E/SN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- 10 MHz
- Write Cycle Time - Word, Page:
- 5ms
- Access Time:
- -
- Voltage - Supply:
- 1.8V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
25AA640AT-E/SN FAQ
1.How can I place an order for 25AA640AT-E/SN through Aetrix?
Please submit a Request for Quotation (RFQ) for 25AA640AT-E/SN 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 25AA640AT-E/SN reliable?
The price and inventory of 25AA640AT-E/SN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 25AA640AT-E/SN is usually 5 days.
3.What payment methods are accepted for 25AA640AT-E/SN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25AA640AT-E/SN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25AA640AT-E/SN?
25AA640AT-E/SN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25AA640AT-E/SN 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 25AA640AT-E/SN?
For technical support, including 25AA640AT-E/SN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25AA640AT-E/SN requirements.
6.How does Aetrix verify that 25AA640AT-E/SN is sourced from the original manufacturer or authorized distributors?
All 25AA640AT-E/SN 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 25AA640AT-E/SN meets industry standards.
7.What is the process for return or replacement of 25AA640AT-E/SN?
All 25AA640AT-E/SN units undergo pre-shipment inspection (PSI). If there is an issue with 25AA640AT-E/SN, 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 25AA640AT-E/SN part is unused and in its original packaging.
Return procedure for 25AA640AT-E/SN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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