My Inquiry
My Account
Microchip Technology 25AA040X/ST
- Part No.:
- 25AA040X/ST
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
25AA040X/ST.pdf
- Description:
- IC EEPROM 4KBIT SPI 1MHZ 8TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,417
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
25AA040X/ST from Microchip Technology Inc. is a 4 Kbit (512 × 8) SPI-compatible serial EEPROM with 1.8–5.5 V supply range, 1 MHz max clock frequency, and industrial temperature rating (–40°C to +85°C). It features hardware write protection (WP), HOLD suspend functionality, and 16-byte page write capability. Used for nonvolatile parameter storage in microcontroller-based embedded systems requiring low-power, reliable data retention.
For engineers reviewing the 25AA040X/ST datasheet, 25AA040X/ST pinout, 25AA040X/ST application, or 25AA040X/ST equivalent, key selection criteria include its 1.8 V minimum VCC operation, TSSOP-8 alternate pinout, block-level write protection (BP0/BP1), and compatibility with standard SPI Mode 0,0 and Mode 1,1 interfaces.
Technical Context
The 25AA040X/ST implements a SPI slave interface with separate SI (data in) and SO (data out) lines, CS-controlled selection, and dedicated HOLD and WP control inputs. Its internal architecture includes an 8-bit instruction register, STATUS register with WIP/WEL/BP bits, and high-voltage generator for EEPROM programming.
It supports byte and page write operations (up to 16 bytes per page), sequential read with automatic address increment, and self-timed internal write cycles completing in ≤5 ms. Write enable latch (WEL) must be set via WREN instruction prior to any write, and is reset on power-up, WRDI, WRSR, WRITE completion, or WP low assertion.
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 |
| Supply voltage | 1.8–5.5 V - enables direct interfacing with 1.8 V, 2.5 V, 3.3 V, and 5 V logic domains without level shifting |
| Max clock frequency | 1 MHz at VCC ≥ 4.5 V - defines maximum SPI transaction throughput for parameter updates or logging |
| Write endurance | 1 million erase/write cycles - supports long-term field deployment in applications requiring frequent reconfiguration |
| Data retention | >200 years at +25°C - ensures persistent storage of critical settings across product lifetime without refresh |
| Page size | 16 bytes - constrains burst write length and requires software alignment to avoid intra-page wraparound during page writes |
| Standby current | 500 nA typical - minimizes quiescent power draw in battery-powered or energy-harvesting systems |
Pinout & Package
25AA040X/ST is supplied in an 8-pin Thin Shrink Small Outline Package (TSSOP) with 0.65 mm pitch and alternate pinout versus standard TSSOP-8. This variant places HOLD on pin 1 and VCC on pin 2, optimizing board layout for noise-sensitive or compact SPI bus routing.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1: HOLD | Serial communication suspend input | Tri-states SO and ignores SI/SCK transitions while low; requires SCK low before assertion to activate |
| 2: VCC | Positive supply voltage | Accepts 1.8–5.5 V; powers internal logic and EEPROM array; decoupling capacitor required near pin |
| 3: CS | Chip select input | Active-low enable; deselecting forces SO into high-impedance state for multi-device SPI bus sharing |
| 4: SO | Serial data output | Outputs memory data on falling edge of SCK; high-impedance when CS high or HOLD active |
| 5: WP | Hardware write-protect input | Low disables all writes to memory and STATUS register; overrides WREN latch state |
| 6: VSS | Ground reference | Return path for VCC and all I/O; must be low-impedance connection to minimize noise coupling |
| 7: SI | Serial data input | Accepts instructions, addresses, and data on rising edge of SCK; latched synchronously to clock |
| 8: SCK | Serial clock input | Master-generated SPI clock; rising edge latches SI, falling edge updates SO; timing critical for AC compliance |
Key Features
| Feature | Design Value |
|---|---|
| Alternate TSSOP pinout (ST) | HOLD on pin 1 and VCC on pin 2 - improves signal integrity and routing flexibility in dense PCB layouts |
| Block write protection | BP0/BP1 bits enable selective protection of none, upper 1/4, upper 1/2, or entire 512-byte array - prevents accidental overwrites of critical sectors |
| Power-on write disable | Write enable latch resets at power-up and remains inactive until explicit WREN command - eliminates spurious writes during brown-out or reset |
| HOLD suspend function | Pauses ongoing SPI transfer without losing context; resumes from same bit position after HOLD deassertion - enables interrupt servicing without reinitialization |
| Low-voltage operation | Guaranteed functionality down to 1.8 V VCC - supports integration with ultra-low-power MCUs and energy-efficient subsystems |
Applications
| Industrial Sensor Node | Medical Diagnostic Device |
|---|---|
|
Use Scenario: Storing calibrated sensor offsets, linearization coefficients, and device-specific identification in a battery-powered environmental monitor. IC Role / Device Role / Timing Role: Nonvolatile configuration storage accessed via SPI during boot and runtime parameter updates. Use Value: Enables field recalibration without firmware update; 1.8 V operation extends battery life; 500 nA standby current minimizes drain between measurements. |
Use Scenario: Retaining patient history, test protocol versions, and safety-critical calibration logs in portable ultrasound or ECG equipment. IC Role / Device Role / Timing Role: Secure, tamper-resistant data logger interfaced to host MCU via isolated SPI bus. Use Value: BP0/BP1 bits protect diagnostic calibration data from overwrite; >200-year data retention ensures audit trail integrity across device lifecycle. |
| Smart Energy Meter | Automotive Body Control Module |
|
Use Scenario: Recording tariff schedules, meter firmware version, and accumulated kWh counters in ANSI C12.22-compliant utility meters. IC Role / Device Role / Timing Role: High-reliability parameter store supporting secure firmware updates and regulatory data logging. Use Value: 1M write cycles withstand daily billing updates; write cycle time ≤5 ms meets real-time logging deadlines; WP pin prevents corruption during power interruption. |
Use Scenario: Saving seat/mirror position presets, lighting profiles, and fault codes in 12 V automotive subsystems with local 3.3 V regulation. IC Role / Device Role / Timing Role: SPI EEPROM integrated into CAN-to-local-peripheral gateway for nonvolatile user preference storage. Use Value: Industrial temperature range (–40°C to +85°C) ensures operation in under-hood environments; HOLD function allows MCU to service CAN interrupts mid-EEPROM access. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25AA040A-I/ST | Revised version with enhanced ESD robustness (>6 kV HBM), improved AC timing margins, and updated qualification per AEC-Q100 Grade 3 (for automotive variants) | Recommended for new designs; supports same pinout and instruction set but adds reliability for harsh environments | Select 25AA040A-I/ST when designing for production release or automotive-adjacent applications requiring extended qualification. |
| AT25040B-SSHL-T | 4 Kbit SPI EEPROM from Microchip (formerly Atmel); 1.8–5.5 V, 20 MHz max clock, SOIC/TSSOP packages; different STATUS register map and WP behavior | Lacks HOLD pin; uses different write-protection scheme (software-only BP bits); higher speed but no suspend capability | Choose AT25040B-SSHL-T only if higher SPI bandwidth is required and HOLD functionality is unnecessary in the system architecture. |
Compared with 25AA040X/ST, the 25AA040A-I/ST offers verified long-term reliability enhancements without layout changes, while the AT25040B-SSHL-T trades HOLD support for faster clock rates - making the former ideal for design continuity and the latter suitable for speed-critical, suspend-free systems.
Availability
25AA040X/ST is available at Aetrix Electronics and suitable for industrial sensor nodes, medical diagnostic devices, smart energy meters, and automotive body control modules requiring stable component supply and legacy design support.
Supply support for 25AA040X/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 components, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.
The 25AA040X/ST belongs to Microchip's legacy SPI Serial EEPROM product line, designed specifically for cost-sensitive, low-power embedded systems needing reliable nonvolatile storage with minimal external components and broad voltage compatibility.
FAQ
What is the operating voltage range of the 25AA040X/ST?
The 25AA040X/ST operates from 1.8 V to 5.5 V, enabling direct interface with 1.8 V, 2.5 V, 3.3 V, and 5 V microcontrollers without level shifters. This wide range supports mixed-voltage system designs and simplifies power architecture in battery-powered or multi-rail applications using the 25AA040X/ST.
Does the 25AA040X/ST support SPI Mode 0,0 and Mode 1,1?
Yes, the 25AA040X/ST is fully compatible with both SPI Mode 0,0 (CPOL = 0, CPHA = 0) and Mode 1,1 (CPOL = 1, CPHA = 1), as confirmed by its clock timing specifications and serial interface behavior. This dual-mode support ensures interoperability with diverse host controllers when implementing the 25AA040X/ST in heterogeneous embedded platforms.
How does the HOLD pin function on the 25AA040X/ST?
The HOLD pin on the 25AA040X/ST suspends ongoing SPI communication without resetting the sequence: when pulled low (with SCK low), SI/SCK/SO enter high-impedance and ignore transitions, allowing the host MCU to service interrupts. Resuming requires bringing HOLD high while SCK is low. This behavior is documented in the 25AA040X/ST datasheet Figure 1-1 and Section 2.6.
What package type and pinout does the 25AA040X/ST use?
The 25AA040X/ST uses an 8-pin TSSOP package with "alternate" pinout (ST suffix): HOLD is on pin 1, VCC on pin 2, CS on pin 3, SO on pin 4, WP on pin 5, VSS on pin 6, SI on pin 7, and SCK on pin 8. This differs from standard TSSOP-8 and must be accounted for in PCB layout when using the 25AA040X/ST.
Is the 25AA040X/ST recommended for new designs?
No - Microchip explicitly states "Not recommended for new designs" in DS21204E, advising migration to the enhanced 25AA040A-I/ST. The 25AA040X/ST remains supported for legacy repair and continuity, but new projects should evaluate the 25AA040A-I/ST for improved ESD performance, tighter AC specs, and extended qualification - especially when sourcing the 25AA040X/ST.
25AA040X/ST Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- 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:
- 1 MHz
- Write Cycle Time - Word, Page:
- 5ms
- Access Time:
- -
- Voltage - Supply:
- 1.8V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-TSSOP
25AA040X/ST FAQ
1.How can I place an order for 25AA040X/ST through Aetrix?
Please submit a Request for Quotation (RFQ) for 25AA040X/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 25AA040X/ST reliable?
The price and inventory of 25AA040X/ST are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 25AA040X/ST is usually 5 days.
3.What payment methods are accepted for 25AA040X/ST?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25AA040X/ST transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25AA040X/ST?
25AA040X/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25AA040X/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 25AA040X/ST?
For technical support, including 25AA040X/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25AA040X/ST requirements.
6.How does Aetrix verify that 25AA040X/ST is sourced from the original manufacturer or authorized distributors?
All 25AA040X/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 25AA040X/ST meets industry standards.
7.What is the process for return or replacement of 25AA040X/ST?
All 25AA040X/ST units undergo pre-shipment inspection (PSI). If there is an issue with 25AA040X/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 25AA040X/ST part is unused and in its original packaging.
Return procedure for 25AA040X/ST:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
25AA040X/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…
