My Inquiry
My Account
Microchip Technology 25AA040AT-I/ST
- Part No.:
- 25AA040AT-I/ST
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
25AA040AT-I/ST.pdf
- Description:
- IC EEPROM 4KBIT SPI 10MHZ 8TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,498
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
25AA040AT-I/ST from Microchip Technology 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, 16-byte page write, and hardware write protection via WP pin - used for nonvolatile configuration storage in microcontroller-based embedded systems.
For engineers reviewing the 25AA040AT-I/ST datasheet, 25AA040AT-I/ST pinout, 25AA040AT-I/ST application, or 25AA040AT-I/ST equivalent, key selection criteria include SPI interface compatibility, 1.8 V minimum VCC operation, HOLD functionality for interrupt-safe bus arbitration, and block-level write protection granularity (none/¼/½/all).
Technical Context
The 25AA040AT-I/ST implements a standard SPI Mode 0,0/Master-Slave interface with separate SI (data in) and SO (data out) lines, requiring CS, SCK, and HOLD control. Its internal architecture includes a 512-byte EEPROM array, page latches, status register (WIP/WEL/BP0/BP1), and high-voltage generator for erase/write cycles.
Write operations require explicit WREN instruction followed by CS high to latch enable state; writes are self-timed (≤5 ms), and page boundaries are fixed at 16-byte intervals (addresses ending in 0x00–0x0F). The HOLD pin suspends ongoing serial transfers without resetting sequence state, enabling host CPU to service higher-priority interrupts.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 4 Kbit (512 × 8-bit), sufficient for firmware calibration data, device ID, or small configuration tables |
| Interface | SPI-compatible serial bus (Mode 0,0), compatible with PIC® and most MCU SPI peripherals without bit-banging |
| Max Clock Frequency | 10 MHz at VCC ≥ 4.5 V - enables fast read/write throughput (up to ~1.25 MB/s theoretical burst read) |
| Write Cycle Time | ≤5 ms per byte or page - deterministic timing simplifies host polling or timeout handling |
| Supply Voltage Range | 1.8 V to 5.5 V - supports direct interfacing with 1.8 V, 3.3 V, and 5 V logic domains without level shifters |
| Endurance & Retention | 1,000,000 erase/write cycles and >200 years data retention - suitable for field-updatable parameters in long-lifecycle devices |
| Operating Temperature | –40°C to +85°C (Industrial grade) - validated for use in industrial controls, metering, and automotive body electronics |
Pinout & Package
25AA040AT-I/ST is packaged in an 8-lead TSSOP (ST package code), 3.0 mm × 4.4 mm body, 0.65 mm pitch, with pin 1 marked by laser dot. Pin functions are electrically identical across SOIC/PDIP/TSSOP/DFN variants.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS (Pin 1) | Chip Select Input | Active-low slave select; rising edge after valid write initiates internal write cycle; forces SO into high-Z when deasserted |
| SO (Pin 2) | Serial Data Output | Tri-state output; data shifted out MSB-first on falling edge of SCK during read; high-Z when CS high or HOLD low |
| WP (Pin 3) | Write-Protect Input | Hardware lock: low = all writes (array + STATUS) disabled regardless of WEL state; does not interrupt ongoing write |
| VSS (Pin 4) | Ground Reference | Return path for all I/O and core circuitry; must be low-impedance connection to system GND plane |
| SI (Pin 5) | Serial Data Input | Data, address, and instruction input latched on rising edge of SCK; accepts 8-bit opcodes (READ/WRITE/WREN/RDSR/etc.) |
| SCK (Pin 6) | Serial Clock Input | Synchronizes all SPI transfers; rising edge clocks SI, falling edge updates SO; max 10 MHz at 4.5–5.5 V |
| HOLD (Pin 7) | Serial Transfer Hold | Pauses active SPI sequence when pulled low while SCK is low; preserves internal state for resume without retransmission |
| VCC (Pin 8) | Power Supply | 1.8–5.5 V core and I/O supply; decoupling capacitor (0.1 µF) required within 10 mm of pin for noise immunity |
Key Features
| Feature | Design Value |
|---|---|
| Page Write Mode | Up to 16 bytes written atomically within one physical page - reduces write overhead vs. byte-by-byte for configuration blocks |
| Block Write Protection | Configurable via STATUS register (BP1/BP0) to protect none, upper 1/4 (0x180–0x1FF), upper 1/2 (0x100–0x1FF), or full array - prevents accidental firmware corruption |
| Power-On Write Protection | Write enable latch resets at power-up, and WP pin forces reset - eliminates spurious writes during brown-out or reset sequences |
| HOLD Functionality | Enables deterministic pause/resume of multi-byte SPI transfers - critical for real-time systems where MCU must handle urgent interrupts mid-transaction |
| Low-Power Operation | 5 µA standby current at 5.5 V and +125°C - extends battery life in always-on sensor nodes or backup memory applications |
Applications
| Industrial Sensor Calibration | Medical Device Configuration |
|---|---|
Use Scenario: Storing factory-trimmed ADC offset/gain coefficients and sensor linearization tables in portable gas analyzers. IC Role / Device Role / Timing Role: Nonvolatile parameter storage accessed at boot and during field recalibration; SPI read latency <100 ns ensures no MCU wait states. Use Value: Enables single-device calibration across production batches without firmware changes; 1M endurance supports >100 recalibrations over product lifetime. | Use Scenario: Holding user-selectable therapy parameters (dose rate, duration, alarm thresholds) in battery-powered infusion pumps. IC Role / Device Role / Timing Role: Secure, low-power configuration store with hardware WP pin tied to safety interlock - prevents runtime parameter corruption during power transitions. Use Value: Meets IEC 62304 Class C software requirements via deterministic write timing (≤5 ms) and >200-year data retention for audit logs. |
| Automotive Body Control Module | Smart Energy Meter Firmware Patch |
Use Scenario: Saving seat/mirror position presets and lighting profiles in 12 V vehicle systems with wide-input DC-DC supplies. IC Role / Device Role / Timing Role: SPI EEPROM interfaced to 3.3 V MCU; operates down to 1.8 V during cold-crank events - maintains settings even during 6 V battery dips. Use Value: Industrial temp grade (–40°C to +85°C) and 4 kV ESD rating ensure reliability in under-hood ECU environments. | Use Scenario: Storing delta patches for firmware updates in utility-grade electricity meters deployed for 20+ years. IC Role / Device Role / Timing Role: Secondary nonvolatile store holding compressed patch binaries; accessed only during secure OTA update process via isolated SPI bus. Use Value: Page write mode allows atomic 16-byte patch segment writes; block protection prevents overwrite of active bootloader section. |
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/ST | Requires 2.5–5.5 V VCC; lacks 1.8 V operation; otherwise identical pinout, timing, and feature set | Not suitable for 1.8 V systems; acceptable where supply is regulated ≥2.5 V | Select only if system VCC never drops below 2.5 V - avoids risk of write failure during brown-out |
| AT25040B-SSHL-T | Same 4 Kbit size and SPI interface but rated for 1.8–5.5 V; supports 20 MHz max clock; different STATUS register layout (no BP bits) | Lacks hardware-configurable block protection; uses software-only write enable | Prefer when higher speed or AEC-Q100 qualification needed; avoid if hardware WP or BP granularity is required |
Compared with 25LC040AT-I/ST, the 25AA040AT-I/ST enables 1.8 V operation critical for ultra-low-power designs, while AT25040B-SSHL-T offers faster clocking but removes hardware block protection - making 25AA040AT-I/ST optimal for cost-sensitive industrial systems needing robust, voltage-flexible nonvolatile storage.
Availability
25AA040AT-I/ST is available at Aetrix Electronics and suitable for industrial sensor calibration, medical device configuration, and automotive body control modules requiring stable component supply and long-term obsolescence management.
Supply support for 25AA040AT-I/ST 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, FPGA, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.
The 25AA040A family was designed for reliable, low-voltage SPI EEPROM storage in space-constrained embedded systems - emphasizing robustness, wide VCC range, and hardware-assisted data integrity.
FAQ
What is the minimum supply voltage required for reliable operation of the 25AA040AT-I/ST?
The 25AA040AT-I/ST operates reliably from 1.8 V to 5.5 V. At 1.8 V, maximum clock frequency is reduced to 3 MHz (per AC Characteristics Table 1-2), and write current drops to ≤3 mA. All features - including HOLD, WP, and page write - remain fully functional across this range, making the 25AA040AT-I/ST suitable for battery-powered or energy-harvesting systems where supply voltage may sag.
How does the HOLD pin function during an active SPI transaction on the 25AA040AT-I/ST?
When the HOLD pin is pulled low while SCK is low, the 25AA040AT-I/ST immediately pauses the ongoing SPI transfer - tri-stating SO, SI, and SCK inputs. Internal state (address pointer, instruction phase, and page buffer contents) is preserved. To resume, HOLD must be returned high while SCK remains low; communication continues from the exact bit position where it paused. This behavior is defined in Figure 1-1 and Section 2.1 of the 25AA040AT-I/ST datasheet.
Can the 25AA040AT-I/ST be used as a direct replacement for the 25LC040AT-I/ST in an existing design?
No - the 25AA040AT-I/ST and 25LC040AT-I/ST are not drop-in replacements due to differing VCC ranges: 25AA040AT-I/ST supports 1.8–5.5 V, while 25LC040AT-I/ST requires 2.5–5.5 V. If the host system operates below 2.5 V (e.g., 1.8 V or 2.3 V rails), substituting 25LC040AT-I/ST risks failed writes or read errors. Electrical pinout and command set are identical, but voltage compatibility must be verified per application.
What happens if a page write command crosses a 16-byte boundary on the 25AA040AT-I/ST?
If a page write command attempts to write across a 16-byte boundary (e.g., starting at address 0x0F and writing 16 bytes), the 25AA040AT-I/ST wraps the data back to the start of the same page (0x00) instead of advancing to the next page. This overwrites previously written bytes in that page. The datasheet explicitly warns against crossing page boundaries in Section 2.3 and Figure 2-3 - application firmware must enforce alignment or split writes at 0x10/0x20/… boundaries to prevent data corruption.
How is write protection implemented on the 25AA040AT-I/ST, and what are the hierarchy levels?
The 25AA040AT-I/ST implements dual-layer write protection: (1) Hardware via WP pin (low = all writes disabled), and (2) Software-configurable block protection via BP0/BP1 bits in the STATUS register. BP0/BP1 allow locking none, upper 1/4 (0x180–0x1FF), upper 1/2 (0x100–0x1FF), or full array (0x000–0x1FF). WP overrides STATUS register settings - if WP is low, BP bits are ignored. Both mechanisms reset the write enable latch (WEL) when asserted.
25AA040AT-I/ST Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Programmable:
- Not 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-TSSOP
25AA040AT-I/ST FAQ
1.How can I place an order for 25AA040AT-I/ST through Aetrix?
Please submit a Request for Quotation (RFQ) for 25AA040AT-I/ST 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/ST reliable?
The price and inventory of 25AA040AT-I/ST 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/ST is usually 5 days.
3.What payment methods are accepted for 25AA040AT-I/ST?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25AA040AT-I/ST transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25AA040AT-I/ST?
25AA040AT-I/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25AA040AT-I/ST 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/ST?
For technical support, including 25AA040AT-I/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25AA040AT-I/ST requirements.
6.How does Aetrix verify that 25AA040AT-I/ST is sourced from the original manufacturer or authorized distributors?
All 25AA040AT-I/ST 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/ST meets industry standards.
7.What is the process for return or replacement of 25AA040AT-I/ST?
All 25AA040AT-I/ST units undergo pre-shipment inspection (PSI). If there is an issue with 25AA040AT-I/ST, 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/ST part is unused and in its original packaging.
Return procedure for 25AA040AT-I/ST:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
25AA040AT-I/ST Tags
-
M24C02-WMN6TP
STMicroelectronics
-
AT24C02C-XHM-T
Microchip Technology
-
AT21CS01-STUM10-T
Microchip Technology
-
AT24C02C-SSHM-T
Microchip Technology
-
24LC01BT-I/OT
Microchip Technology
-
M24C02-FMC6TG
STMicroelectronics
-
AT24CS02-SSHM-T
Microchip Technology
-
93LC46BT-I/OT
Microchip Technology
-
AT24C04C-SSHM-T
Microchip Technology
-
24LC01BT-I/SN
Microchip Technology
-
24AA02UIDT-I/OT
Microchip Technology
-
AT24C08C-STUM-T
Microchip Technology
Tech Hub
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
