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Microchip Technology 25AA040AT-I/MS

Name: 25AA040AT-I/MS
Brand: Microchip Technology
SKU: 25AA040AT-I/MS
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 25AA040AT-I/MS

Manufacturer:: Microchip Technology

Category:: Memory

Package:: 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)

Datasheet:: 25AA040AT-I/MS.pdf

Description:: IC EEPROM 4KBIT SPI 10MHZ 8MSOP

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Product details

Overview

25AA040AT-I/MS from Microchip Technology Inc. is a 4 Kbit SPI Serial EEPROM with 512 × 8-bit organization, 1.8–5.5 V supply range, and industrial temperature rating (−40°C to +85°C). It supports up to 10 MHz clock frequency, page write (16 bytes), and hardware write protection via WP pin. Used for nonvolatile parameter storage in microcontroller-based embedded systems requiring low-power, high-reliability data retention.

For engineers reviewing the 25AA040AT-I/MS datasheet, 25AA040AT-I/MS pinout, 25AA040AT-I/MS application, or 25AA040AT-I/MS equivalent, key selection criteria include SPI interface compatibility, 16-byte page size, 1 µA standby current at 2.5 V, and MSOP-8 package footprint with HOLD/CS/SO/SI/SCK/VP/VSS/WP pin functionality.

Technical Context

The 25AA040AT-I/MS implements a standard SPI Mode 0,0/Motorola-compatible serial interface with separate SI (data in) and SO (data out) lines, CS-controlled device selection, and HOLD pin for transaction suspension. It uses internal high-voltage generation for EEPROM programming and includes a nonvolatile STATUS register with BP0/BP1 block protection bits.

It operates across 1.8–5.5 V with full AC timing compliance down to 1.8 V (3 MHz max), supports self-timed write cycles ≤5 ms, and features built-in power-on write protection, WREN/WRDI command protocol, and automatic address roll-over during sequential read.

Key Specifications

Parameter	Value and Actual Design Meaning
Memory Size	4 Kbit (512 × 8-bit array), sufficient for firmware configuration, calibration data, or device ID storage in space-constrained designs.
Interface	SPI-compatible serial bus (Mode 0,0), requiring only CS, SCK, SI, SO, WP, HOLD - no I²C pull-ups or arbitration logic needed.
Max Clock Frequency	10 MHz at VCC ≥ 4.5 V, enabling fast read/write throughput (up to ~1.25 MB/s theoretical burst read) in host MCU applications.
Write Page Size	16 bytes per page; page writes must not cross physical boundaries (e.g., 0x00–0x0F, 0x10–0x1F), requiring firmware address alignment.
Endurance & Retention	1,000,000 erase/write cycles and >200 years data retention at 25°C - validated for long-life industrial logging and field-upgrade storage.
Supply Current	5 mA max active read/write current at 5.5 V/10 MHz; 1 µA standby current at 2.5 V - suitable for battery-backed or energy-harvesting systems.
Temperature Range	Industrial grade: −40°C to +85°C - qualified for operation in automotive control modules, industrial sensors, and outdoor IoT edge nodes.

Pinout & Package

25AA040AT-I/MS is housed in an 8-lead MSOP (Mini Small Outline Package) with 0.65 mm lead pitch and exposed pad (optional VSS connection). Pin 1 is marked by laser dot; package conforms to JEDEC MO-187AA.

Pin/Terminal	Circuit Role	Design Meaning
CS (Pin 1)	Chip Select Input	Active-low enable: drives device into active mode; rising edge initiates internal write cycle after valid write sequence.
SO (Pin 2)	Serial Data Output	Tri-state output; data shifted out MSB-first on falling edge of SCK during READ; high-impedance when CS high or HOLD low.
WP (Pin 3)	Write-Protect Pin	Hardware lock: pulls low to disable all writes (array + STATUS); overrides WEL state; does not interrupt ongoing write cycles.
VSS (Pin 4)	Ground Reference	Primary return path for all digital and internal HV generator circuits; exposed pad may be connected to VSS for thermal/mechanical stability.
SI (Pin 5)	Serial Data Input	Instruction/address/data input latched on rising edge of SCK; accepts 8-bit opcodes (e.g., 0x03 for READ, 0x02 for WRITE).
SCK (Pin 6)	Serial Clock Input	Synchronizes all SPI transfers; rising edge clocks data in (SI), falling edge clocks data out (SO); max 10 MHz at 4.5–5.5 V.
HOLD (Pin 7)	Hold Input	Pauses ongoing SPI transaction (e.g., mid-read) without resetting state; requires SCK low before assertion; resumes on HOLD high + SCK low.
VCC (Pin 8)	Supply Voltage	1.8–5.5 V operating range; internal regulation enables stable EEPROM programming across wide input voltage rails.

Key Features

Feature	Design Value
Block Write Protection	Configurable via STATUS register (BP1/BP0): protects none, upper 1/4 (0x180–0x1FF), upper 1/2 (0x100–0x1FF), or entire array (0x000–0x1FF) - prevents accidental firmware corruption.
Self-Timed Write Cycle	≤5 ms internal erase/write completion time; eliminates need for host MCU to manage variable programming delays - simplifies driver implementation.
Low-Voltage Operation	Full functionality down to 1.8 V with 3 MHz max clock; enables direct interfacing with 1.8 V logic families and ultra-low-power MCUs without level shifters.
HOLD Functionality	Enables host MCU to service higher-priority interrupts mid-transaction (e.g., ADC sampling) and resume SPI communication without re-sending instruction/address.
Power-On Write Protection	Write enable latch resets at power-up; WP pin defaults to protection; WREN must be explicitly issued before any write - prevents spurious writes during brown-out.

Applications

Industrial Sensor Calibration Storage	Medical Device Configuration Memory
Use Scenario: Storing factory-calibrated offset/gain coefficients and sensor linearization tables in a portable blood glucose meter. IC Role / Device Role / Timing Role: Nonvolatile configuration store accessed at boot and during field recalibration; SPI interface synchronized to 2 MHz MCU clock. Use Value: Enables traceable, tamper-resistant calibration data retention over 10+ years without backup battery; 16-byte page writes align with per-channel coefficient sets.	Use Scenario: Holding user-selectable therapy parameters (dose rate, duration, alarm thresholds) in an infusion pump with audit trail requirements. IC Role / Device Role / Timing Role: Secure parameter archive with hardware write-protection (WP pin tied high only during update); STATUS register BP bits lock critical settings. Use Value: Meets IEC 62304 Class C software safety requirements via deterministic write-disable behavior and >1M endurance for frequent dose adjustments.
Automotive Body Control Module NVM	Smart Energy Meter Firmware Settings
Use Scenario: Saving seat/mirror position presets, lighting profiles, and door lock preferences in a vehicle body controller. IC Role / Device Role / Timing Role: SPI EEPROM interfaced to 8-bit automotive MCU; reads stored profiles at ignition-on; writes on user button press with WREN/WRSR sequence. Use Value: −40°C to +85°C rating ensures reliability across engine bay and cabin environments; 5 µA standby current minimizes parasitic drain on 12 V battery.	Use Scenario: Storing tariff schedules, pulse constants, and utility communication keys in a DIN-rail mounted electricity meter with 15-year design life. IC Role / Device Role / Timing Role: Long-term data vault accessed via isolated SPI interface; STATUS register write-protection prevents unauthorized key modification. Use Value: >200-year data retention and 1M endurance guarantee integrity of billing-critical parameters over full product lifecycle without refresh.

Industrial Sensor Calibration Storage

Medical Device Configuration Memory

Use Scenario: Storing factory-calibrated offset/gain coefficients and sensor linearization tables in a portable blood glucose meter.

IC Role / Device Role / Timing Role: Nonvolatile configuration store accessed at boot and during field recalibration; SPI interface synchronized to 2 MHz MCU clock.

Use Value: Enables traceable, tamper-resistant calibration data retention over 10+ years without backup battery; 16-byte page writes align with per-channel coefficient sets.

Use Scenario: Holding user-selectable therapy parameters (dose rate, duration, alarm thresholds) in an infusion pump with audit trail requirements.

IC Role / Device Role / Timing Role: Secure parameter archive with hardware write-protection (WP pin tied high only during update); STATUS register BP bits lock critical settings.

Use Value: Meets IEC 62304 Class C software safety requirements via deterministic write-disable behavior and >1M endurance for frequent dose adjustments.

Automotive Body Control Module NVM

Smart Energy Meter Firmware Settings

Use Scenario: Saving seat/mirror position presets, lighting profiles, and door lock preferences in a vehicle body controller.

IC Role / Device Role / Timing Role: SPI EEPROM interfaced to 8-bit automotive MCU; reads stored profiles at ignition-on; writes on user button press with WREN/WRSR sequence.

Use Value: −40°C to +85°C rating ensures reliability across engine bay and cabin environments; 5 µA standby current minimizes parasitic drain on 12 V battery.

Use Scenario: Storing tariff schedules, pulse constants, and utility communication keys in a DIN-rail mounted electricity meter with 15-year design life.

IC Role / Device Role / Timing Role: Long-term data vault accessed via isolated SPI interface; STATUS register write-protection prevents unauthorized key modification.

Use Value: >200-year data retention and 1M endurance guarantee integrity of billing-critical parameters over full product lifecycle without refresh.

Equivalent & Alternatives

The following parts are listed as comparable options for similar serial EEPROM applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
25LC040AT-I/MS	Requires 2.5–5.5 V supply; lacks 1.8 V operation; otherwise identical pinout, timing, and feature set.	Not suitable for 1.8 V systems; acceptable where board already uses ≥2.5 V rail and industrial temp is required.	Select 25LC040AT-I/MS only if system VCC never drops below 2.5 V and cost optimization is prioritized over voltage flexibility.
AT25040B-MAU-Y	Same 4 Kbit SPI EEPROM, but uses different STATUS register layout (SRWD bit instead of BP0/BP1); 6-pin SOT23-6 package.	Smaller footprint but no HOLD pin; lacks hardware write-protect pin (relies solely on STATUS register locking).	Choose AT25040B-MAU-Y only for space-constrained designs where HOLD is unused and WP pin functionality is implemented in firmware.

Compared with 25AA040AT-I/MS, the 25LC040AT-I/MS offers identical functionality at higher minimum voltage, while the AT25040B-MAU-Y trades HOLD/WP pins and BP-level protection for smaller size - making 25AA040AT-I/MS optimal for robust, flexible, and feature-complete 1.8 V–5.5 V industrial designs.

Availability

25AA040AT-I/MS is available at Aetrix Electronics and suitable for industrial sensor calibration, medical device configuration, automotive body control, and smart energy metering applications requiring stable component supply, long-term data integrity, and RoHS-compliant packaging.

Supply support for 25AA040AT-I/MS 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 devices, and memory solutions, headquartered in Chandler, Arizona, with global manufacturing and support infrastructure.

The 25AA040A family was designed specifically for reliable, low-power, SPI-based nonvolatile data storage in resource-constrained embedded systems - emphasizing ease of integration, long-term data retention, and industrial-grade environmental resilience.

FAQ

What is the maximum clock frequency supported by the 25AA040AT-I/MS?

The 25AA040AT-I/MS supports up to 10 MHz clock frequency when VCC is 4.5–5.5 V, 5 MHz at 2.5–4.5 V, and 3 MHz at 1.8–2.5 V. These limits are defined in Table 1-2 AC Characteristics and ensure reliable setup/hold timing across voltage ranges. The 25AA040AT-I/MS must be operated within these bounds to guarantee correct SPI read/write behavior.

Does the 25AA040AT-I/MS require external components for basic SPI operation?

No, the 25AA040AT-I/MS requires no external passive components for core SPI functionality. It integrates internal voltage regulation and high-voltage generation for EEPROM programming. Only standard SPI signal routing (CS, SCK, SI, SO, WP, HOLD, VCC, VSS) is needed; no pull-up resistors, level shifters, or decoupling capacitors beyond standard PCB practice are mandated by the datasheet.

How does the HOLD pin function during an ongoing read sequence in the 25AA040AT-I/MS?

When HOLD is pulled low during an active read (with CS low and SCK toggling), the 25AA040AT-I/MS immediately places SO in high-impedance state and ignores further SCK/SI transitions. The internal address pointer and transaction state are preserved. Resuming requires bringing HOLD high while SCK is low - then normal read continuation occurs from the exact byte position where it paused.

Can the 25AA040AT-I/MS be used in a 1.8 V system without level shifting?

Yes, the 25AA040AT-I/MS is fully specified for 1.8–5.5 V operation, including AC timing (3 MHz max), DC characteristics (VIH/VIL thresholds scale with VCC), and write endurance. Its 1.8 V capability eliminates need for level shifters when interfacing with 1.8 V MCUs or FPGAs - confirmed in Tables 1-1 and 1-2 of DS21827H.

What happens to the write enable latch after a successful write operation in the 25AA040AT-I/MS?

After a successful byte, page, or STATUS register write, the write enable latch (WEL bit) in the 25AA040AT-I/MS is automatically reset to '0'. This means the next write attempt will fail unless WREN is reissued. This behavior - documented in Section 2.3 and Table 2-2 - enforces explicit write-enable discipline and prevents unintended overwrites due to noise or software errors.

25AA040AT-I/MS Specifications

Product attributes: Attribute value

Manufacturer:: Microchip Technology

Series:: -

Package/Case:: 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)

Packaging:: Tape & Reel (TR)

Product Status:: Active

Programmable:: Verified

Memory Type:: Non-Volatile

Memory Format:: EEPROM

Technology:: EEPROM

Memory Size:: 4Kbit

Memory Organization:: 512 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 ~ 85°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 8-MSOP

25AA040AT-I/MS FAQ

1.How can I place an order for 25AA040AT-I/MS through Aetrix?

Please submit a Request for Quotation (RFQ) for 25AA040AT-I/MS 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 25AA040AT-I/MS reliable?

The price and inventory of 25AA040AT-I/MS are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 25AA040AT-I/MS is usually 5 days.

3.What payment methods are accepted for 25AA040AT-I/MS?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25AA040AT-I/MS transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 25AA040AT-I/MS?

25AA040AT-I/MS orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 25AA040AT-I/MS 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 25AA040AT-I/MS?

For technical support, including 25AA040AT-I/MS datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25AA040AT-I/MS requirements.

6.How does Aetrix verify that 25AA040AT-I/MS is sourced from the original manufacturer or authorized distributors?

All 25AA040AT-I/MS 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 25AA040AT-I/MS meets industry standards.

7.What is the process for return or replacement of 25AA040AT-I/MS?

All 25AA040AT-I/MS units undergo pre-shipment inspection (PSI). If there is an issue with 25AA040AT-I/MS, 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 25AA040AT-I/MS part is unused and in its original packaging.

Return procedure for 25AA040AT-I/MS:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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