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Microchip Technology 25C040XT-I/ST
- Part No.:
- 25C040XT-I/ST
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
25C040XT-I/ST.pdf
- Description:
- IC EEPROM 4KBIT SPI 3MHZ 8TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,490
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Product details
Overview
25C040XT-I/ST from Microchip Technology Inc. is a 4 Kbit (512 × 8) SPI-compatible serial EEPROM designed for nonvolatile data storage in automotive and industrial systems operating from 4.5V to 5.5V. It delivers 3 MHz max clock frequency, 5 ms max write cycle time, and supports block write protection (none/¼/½/all), with endurance of 1 million erase/write cycles and >200 years data retention. It is used in engine control units, sensor calibration storage, and powertrain diagnostics modules.
For engineers reviewing the 25C040XT-I/ST datasheet, 25C040XT-I/ST pinout, 25C040XT-I/ST application, or 25C040XT-I/ST equivalent, this page provides verified technical context, validated pin functions, confirmed automotive-grade temperature operation (–40°C to +125°C), and real-world design implications for SPI bus integration, hold functionality, and hardware write-protection implementation.
Technical Context
The 25C040XT-I/ST implements a standard SPI Mode 0,0 interface with separate SI (data-in) and SO (data-out) lines, requiring CS, SCK, HOLD, and WP control signals. Its internal architecture includes an 8-bit instruction register, page-based write logic (16-byte pages), and a STATUS register with WIP, WEL, BP0/BP1 bits for real-time monitoring and configurable block protection.
It features hardware-level data integrity safeguards: power-on reset of the write-enable latch, automatic latch reset after each write, and independent WP pin assertion that disables all array and STATUS register writes regardless of WEL state. The HOLD function suspends ongoing SPI transfers without resetting internal address pointers, enabling deterministic interrupt handling in time-critical microcontroller applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 4 Kbit (512 × 8-bit organization), sufficient for firmware patch storage or multi-sensor calibration tables in compact ECUs. |
| Interface | SPI-compatible serial bus (Mode 0,0), requiring only CS, SCK, SI, SO - no I²C pull-ups or arbitration logic needed. |
| Max Clock Frequency | 3 MHz at VCC = 4.5–5.5V, enabling sub-200 μs byte reads and efficient burst transfers in high-throughput logging. |
| Write Cycle Time | 5 ms maximum internal write time per page or byte, defining minimum interval between successive write commands. |
| Temperature Range | –40°C to +125°C (Automotive E grade), qualified for under-hood deployment without derating. |
| Endurance & Retention | 1 million erase/write cycles and >200 years data retention at +125°C, supporting lifetime calibration storage in automotive service intervals. |
| VCC Range | 4.5V to 5.5V only - incompatible with 3.3V or 2.5V systems; requires dedicated 5V rail or level-shifting. |
Pinout & Package
25C040XT-I/ST is supplied in an 8-pin TSSOP package (4.4 mm body width, JEDEC MO-153 compliant) with lead finish Matte Tin (Pb-free). Pin 1 is marked by a dot or bevel; orientation follows standard TSSOP pin 1 indicator (top-left corner when notch faces up).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (HOLD) | Serial transfer suspend control | Pull low to pause active SPI sequence; must be low while SCK is low to activate; tri-states SO during hold. |
| 2 (VCC) | Positive supply | 4.5–5.5V only; no internal regulation - external 5V rail stability directly impacts timing margins and write reliability. |
| 3 (CS) | Chip select input | Active-low enable; falling edge initiates command decode; rising edge triggers internal write if last byte was clocked. |
| 4 (SO) | Serial data output | High-impedance when CS high or HOLD active; outputs data on SCK falling edge during read sequences. |
| 5 (WP) | Hardware write-protect | Low = all writes disabled (array + STATUS); overrides WREN/WEL; resets write-enable latch immediately. |
| 6 (VSS) | Ground reference | Must be connected to system ground plane; shared return path affects noise immunity on SI/SO lines. |
| 7 (SI) | Serial data input | Latches instruction/address/data on SCK rising edge; requires clean setup/hold timing per AC specs (e.g., TSU ≥ 30 ns @ 5V). |
| 8 (SCK) | Serial clock input | Master-generated clock; defines all timing windows (TCSS, TCSH, THI, TLO); max 3 MHz at full VCC range. |
Key Features
| Feature | Design Value |
|---|---|
| Automotive-grade temperature operation | Qualified from –40°C to +125°C (E grade), enabling direct placement in engine control modules without thermal shielding. |
| Hardware write protection via WP pin | Dedicated pin disables all nonvolatile writes instantly - critical for preventing corruption during power transients or firmware updates. |
| 16-byte page write capability | Allows up to 16 bytes to be loaded before internal write begins, reducing SPI overhead and improving effective write throughput. |
| HOLD function with address pointer preservation | Pauses SPI communication mid-sequence without losing position; resumes from same byte - essential for servicing high-priority interrupts. |
| Configurable block protection (BP0/BP1) | Four protection modes (none / upper 1/4 / upper 1/2 / full array) set via WRSR, enabling secure boot code or calibration partitioning. |
Applications
| Engine Control Unit (ECU) Calibration Storage | Automotive Sensor Module Nonvolatile Memory |
|---|---|
Use Scenario: Storing fuel map coefficients, ignition timing offsets, and adaptive learning values subject to field updates over CAN or diagnostic port. IC Role / Device Role / Timing Role: SPI-connected nonvolatile memory holding mission-critical calibration data accessed during engine startup and runtime. Use Value: 1M-cycle endurance ensures reliable updates across 15+ years of vehicle service; 125°C rating permits placement near ECU MCU without thermal isolation. |
Use Scenario: Retaining factory-trimmed offset/gain values and self-test history in wheel speed or pressure sensors exposed to under-chassis environments. IC Role / Device Role / Timing Role: Standalone EEPROM interfaced to sensor ASIC or microcontroller for persistent parameter storage with minimal pin count. Use Value: Hardware WP pin prevents accidental overwrite during sensor power cycling; >200-year data retention eliminates recalibration requirements over product lifetime. |
| Powertrain Diagnostic Event Logger | Industrial Motor Drive Firmware Patch Storage |
Use Scenario: Recording fault codes, freeze-frame data, and operational timestamps triggered by OBD-II events in transmission control modules. IC Role / Device Role / Timing Role: High-reliability serial memory buffering diagnostic records until CAN upload, with HOLD support for deterministic interrupt response. Use Value: 5 ms write time enables logging of 200+ events/sec; 3 MHz SPI allows rapid dump during service mode without CPU blocking. |
Use Scenario: Holding field-upgradable firmware patches or configuration profiles in servo drives deployed in factory automation systems. IC Role / Device Role / Timing Role: SPI EEPROM storing signed update images verified prior to execution by host ARM Cortex-M processor. Use Value: Block protection (BP1/BP0) isolates boot loader region from user patch area; 4.5–5.5V operation matches industrial 5V backplane supplies. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25AA040T-I/ST | 1.8–5.5V VCC range; 1 MHz max clock; Industrial (–40°C to +85°C) only; same 4 Kbit size and TSSOP-8 package. | Not qualified for automotive under-hood use; suitable for consumer or industrial control where 5V-only supply is unavailable. | Select when system operates below 4.5V or does not require 125°C operation; verify timing margins at lower VCC. |
| 25LC040T-I/ST | 2.5–5.5V VCC; 2 MHz max clock; Industrial temp only; identical pinout and instruction set. | Lacks automotive qualification; better suited for 3.3V embedded systems with moderate speed needs. | Choose for mixed-voltage designs needing 3.3V compatibility and higher speed than 25AA040 but without E-grade requirement. |
Compared with 25C040XT-I/ST, 25AA040T-I/ST supports wider voltage range but sacrifices automotive temperature rating and speed, while 25LC040T-I/ST offers intermediate voltage flexibility and speed but excludes 125°C operation - making 25C040XT-I/ST the sole choice for 5V automotive applications demanding full E-grade qualification.
Availability
25C040XT-I/ST is available at Aetrix Electronics and suitable for automotive powertrain control, industrial motor drive firmware storage, and sensor calibration applications requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for 25C040XT-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 devices, and memory solutions, headquartered in Chandler, Arizona, with global manufacturing and support infrastructure.
The 25C040XT-I/ST belongs to Microchip's legacy 25XX040 serial EEPROM family, engineered specifically for cost-sensitive, high-reliability automotive and industrial applications requiring SPI-based nonvolatile storage with hardware write protection and extended temperature operation.
FAQ
What is the operating voltage range for the 25C040XT-I/ST?
The 25C040XT-I/ST operates strictly within 4.5V to 5.5V. It is not functional below 4.5V and must not be exposed to voltages exceeding 5.5V during normal operation. This narrow range reflects its optimization for 5V automotive and industrial systems, distinguishing it from the broader-range 25AA040 (1.8–5.5V) and 25LC040 (2.5–5.5V) variants. Operation outside this window may cause communication failure or data corruption.
Does the 25C040XT-I/ST support the HOLD function, and how is it implemented?
Yes, the 25C040XT-I/ST supports the HOLD function via Pin 1 (HOLD). When pulled low while SCK is low, it pauses ongoing SPI communication without resetting the internal address pointer. SI, SCK, and SO enter high-impedance states, allowing the host microcontroller to service higher-priority interrupts. Resuming requires bringing HOLD high while SCK remains low. This behavior is fully documented in DS21204E Figures 1-1 and Section 2.6.
What is the maximum clock frequency supported by the 25C040XT-I/ST?
The 25C040XT-I/ST supports a maximum clock frequency of 3 MHz when operated at VCC = 4.5–5.5V. This value is specified in Table 1-2 (AC Characteristics) of DS21204E and applies exclusively to the 25C040 variant. Lower-voltage variants (25AA040, 25LC040) have reduced maximum frequencies (1 MHz and 2 MHz respectively), confirming that 3 MHz is a key differentiator of the 25C040XT-I/ST for high-speed logging applications.
How does the write-protect (WP) pin function on the 25C040XT-I/ST?
The WP pin (Pin 5) on the 25C040XT-I/ST provides hardware-level write inhibition: when held low, it disables all writes to both the memory array and STATUS register, regardless of the state of the write-enable latch (WEL). This action also resets the WEL immediately. WP assertion takes precedence over software controls, making it essential for safeguarding critical data during power transitions or firmware updates - a feature explicitly defined in Section 2.3 and Table 3-3 of DS21204E.
Is the 25C040XT-I/ST pin-compatible with other 25XX040 family members in TSSOP-8 packaging?
Yes, the 25C040XT-I/ST uses the standard 25XX040 TSSOP-8 pinout (HOLD/VCC/CS/SO/WP/VSS/SI/SCK), matching 25AA040XT-I/ST and 25LC040XT-I/ST. However, electrical and thermal specifications differ: only the 25C040XT-I/ST is rated for –40°C to +125°C and 4.5–5.5V operation. Substituting other variants without verifying voltage and temperature compliance risks functional failure in automotive environments.
25C040XT-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:
- 3 MHz
- Write Cycle Time - Word, Page:
- 5ms
- Access Time:
- -
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-TSSOP
25C040XT-I/ST FAQ
1.How can I place an order for 25C040XT-I/ST through Aetrix?
Please submit a Request for Quotation (RFQ) for 25C040XT-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 25C040XT-I/ST reliable?
The price and inventory of 25C040XT-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 25C040XT-I/ST is usually 5 days.
3.What payment methods are accepted for 25C040XT-I/ST?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25C040XT-I/ST transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25C040XT-I/ST?
25C040XT-I/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25C040XT-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 25C040XT-I/ST?
For technical support, including 25C040XT-I/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25C040XT-I/ST requirements.
6.How does Aetrix verify that 25C040XT-I/ST is sourced from the original manufacturer or authorized distributors?
All 25C040XT-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 25C040XT-I/ST meets industry standards.
7.What is the process for return or replacement of 25C040XT-I/ST?
All 25C040XT-I/ST units undergo pre-shipment inspection (PSI). If there is an issue with 25C040XT-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 25C040XT-I/ST part is unused and in its original packaging.
Return procedure for 25C040XT-I/ST:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
25C040XT-I/ST Tags
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