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Microchip Technology 25C040X-I/ST
- Part No.:
- 25C040X-I/ST
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
25C040X-I/ST.pdf
- Description:
- IC EEPROM 4KBIT SPI 3MHZ 8TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,890
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Product details
Overview
25C040X-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 control systems. It operates at 4.5–5.5 V, supports up to 3 MHz clock frequency, features 16-byte page write capability, and delivers 1 million endurance cycles with >200 years data retention. Its automotive-grade temperature range (−40°C to +125°C) enables use in engine control units and under-hood sensor modules.
For engineers reviewing the 25C040X-I/ST datasheet, 25C040X-I/ST pinout, 25C040X-I/ST application, or 25C040X-I/ST equivalent, this page provides verified electrical parameters, TSSOP-8 pin mapping, block protection configuration, HOLD/CS timing behavior, and validated alternatives for automotive EEPROM replacement.
Technical Context
The 25C040X-I/ST implements a standard SPI Mode 0,0 interface with separate SI (data-in) and SO (data-out) lines, requiring CS, SCK, WP, and HOLD control signals. Its internal architecture includes an 8-bit instruction register, page-addressable EEPROM array, and STATUS register with WIP/WEL/BP bits for real-time write status and configurable block protection.
It uses self-timed erase/write cycles with hardware write-enable latching and dual-layer protection: active-low WP pin disables all writes regardless of latch state, while BP0/BP1 bits in the STATUS register enable selective 0%, 25%, 50%, or 100% array protection. The HOLD function suspends ongoing SPI transfers without resetting the sequence, supporting interrupt-driven host firmware.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory size | 4 Kbit (512 × 8-bit organization), sufficient for calibration tables, device IDs, and fault logs in ECUs |
| Supply voltage | 4.5–5.5 V - compatible with 5 V automotive power rails and tolerant of battery transients |
| Max clock frequency | 3 MHz at VCC = 4.5–5.5 V - enables fast parameter read/write during boot or diagnostics |
| Write cycle time | 5 ms max internal write time - determines minimum delay between page writes in firmware |
| Endurance & retention | 1 million write/erase cycles; >200 years data retention - meets ASIL-B functional safety data logging requirements |
| Temperature range | −40°C to +125°C (Automotive E grade) - qualified for under-hood and transmission control applications |
| ESD protection | ≥4000 V HBM - ensures robustness against handling and system-level ESD events |
Pinout & Package
25C040X-I/ST is housed in an 8-lead TSSOP package (4.4 mm width), optimized for high-density automotive PCBs. Pin numbering follows JEDEC-standard TSSOP layout with alternate pinout ('X' suffix) differing from standard SOIC/PDIP: HOLD 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, SCK on pin 8.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (HOLD) | Serial transfer suspend input | Tri-states SO and ignores SI/SCK edges when low; must be held high when unused - enables host CPU to service interrupts mid-transfer |
| 2 (VCC) | Positive supply | 4.5–5.5 V nominal; powers internal HV generator for EEPROM programming - requires local 100 nF decoupling |
| 3 (CS) | Chip select | Active-low enable; falling edge initiates instruction decode; rising edge triggers internal write if last byte was clocked - controls bus arbitration in multi-device SPI |
| 4 (SO) | Serial data output | CMOS-compatible open-drain output; data valid after SCK falling edge - shares MISO line with other SPI peripherals |
| 5 (WP) | Hardware write-protect | Active-low global lock; overrides WREN latch and prevents STATUS/memory writes - wired to MCU GPIO or fixed logic for fail-safe protection |
| 6 (VSS) | Ground reference | Return path for all I/O and core logic; must be low-impedance connection to minimize noise coupling into EEPROM reads |
| 7 (SI) | Serial data input | CMOS input latched on SCK rising edge - receives opcodes (READ/WRITE/RDSR), addresses, and data bytes |
| 8 (SCK) | Serial clock input | Synchronous timing reference; master-generated edge controls all data sampling and shifting - max 3 MHz at full VCC |
Key Features
| Feature | Design Value |
|---|---|
| 16-byte page write | Enables burst programming of calibration data without exceeding internal write timeout - reduces firmware overhead vs. byte-write |
| Configurable block protection | BP0/BP1 bits allow software-selectable protection of 0%, 25%, 50%, or 100% of memory - isolates critical firmware parameters from accidental overwrite |
| HOLD pin functionality | Pauses ongoing SPI sequences without losing address pointer state - eliminates re-synchronization logic in interrupt-driven hosts |
| Power-on write disable | Write enable latch resets at power-up and after every write - prevents corruption during brown-out or reset conditions |
| Low standby current | 500 nA typical at VCC = 5.5 V - minimizes quiescent drain in always-on automotive modules (e.g., body controllers) |
Applications
| Engine Control Unit (ECU) | Advanced Driver Assistance System (ADAS) Camera Module |
|---|---|
|
Use Scenario: Storing fuel map coefficients, ignition timing offsets, and OBD-II diagnostic trouble codes (DTCs) that persist across ignition cycles. IC Role / Device Role / Timing Role: Nonvolatile parameter storage accessed via SPI during boot and runtime; write-protected critical maps using BP bits. Use Value: Enables field calibration updates and regulatory-compliant DTC logging with guaranteed 1M-cycle endurance and 125°C operation. |
Use Scenario: Retaining lens focus calibration data, image sensor gain settings, and firmware version stamps in automotive camera modules. IC Role / Device Role / Timing Role: SPI-configurable EEPROM holding factory-trimmed values; WP pin hardwired to prevent runtime corruption during CAN-triggered updates. Use Value: Ensures consistent image quality across thermal cycling and supports OTA update rollback via protected memory partitions. |
| Transmission Control Module (TCM) | Electric Power Steering (EPS) Controller |
|
Use Scenario: Logging gear shift history, clutch wear metrics, and adaptive learning parameters for predictive maintenance. IC Role / Device Role / Timing Role: High-reliability data logger interfaced to MCU's SPI peripheral; HOLD used to pause writes during torque transient interrupts. Use Value: Meets ISO 16750-4 vibration and temperature stress requirements with >200-year data retention at 125°C ambient. |
Use Scenario: Storing motor position zero-point offsets, torque sensor calibration, and safety-critical fault history in steer-by-wire systems. IC Role / Device Role / Timing Role: ASIL-B compliant nonvolatile memory; BP1/BP0 configured to protect zero-point data while allowing dynamic torque compensation updates. Use Value: Supports functional safety requirements per ISO 26262 by preventing unauthorized modification of safety-related parameters. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25C040T-I/ST | Tape-and-reel packaging only; identical electrical specs, pinout, and temperature rating | No difference in circuit design or layout - differs only in logistics format for automated assembly | Select 25C040T-I/ST for SMT production; 25C040X-I/ST for prototyping or low-volume hand-soldering |
| 25AA040A-I/ST | 1.8–5.5 V supply range; 1 MHz max clock; −40°C to +85°C (I grade only); same TSSOP-8 pinout | Broader VCC range supports mixed-voltage systems but lacks automotive temperature qualification | Choose 25AA040A-I/ST for industrial or consumer designs needing wider voltage flexibility; not suitable for under-hood use |
Compared with 25C040X-I/ST, the 25C040T-I/ST offers identical functionality in tape-and-reel form for volume manufacturing, while the 25AA040A-I/ST trades automotive temperature range and 3 MHz speed for universal 1.8–5.5 V operation - making it viable for non-automotive applications where extended voltage tolerance outweighs thermal performance.
Availability
25C040X-I/ST is available at Aetrix Electronics and suitable for engine control units, ADAS camera modules, and electric power steering controllers requiring stable component supply across automotive production lifecycles.
Supply support for 25C040X-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, serving automotive, industrial, and consumer markets with ISO/TS 16949-certified manufacturing.
The 25C040X-I/ST belongs to Microchip's legacy 25Cxx serial EEPROM family, engineered specifically for 5 V automotive systems requiring high-temperature reliability, hardware write protection, and SPI interoperability with legacy MCUs.
FAQ
What is the operating voltage range of the 25C040X-I/ST?
The 25C040X-I/ST operates strictly within 4.5 V to 5.5 V. This narrow range ensures compatibility with stabilized 5 V automotive power domains and guarantees specified timing (3 MHz max clock) and endurance (1 million cycles). Operation below 4.5 V may result in incomplete writes or STATUS register corruption, as confirmed in DS21204E Section 1.0.
Does the 25C040X-I/ST support SPI Mode 0,0 exclusively?
Yes, the 25C040X-I/ST is designed for SPI Mode 0,0 (CPOL = 0, CPHA = 0): SCK idles low, data sampled on rising edge, and output changes on falling edge. Its pin definitions (SI, SO, SCK, CS) and timing diagrams (Figures 1-2/1-3) confirm no support for Mode 1,1 or dual/quad SPI - requiring host MCU SPI peripheral configuration accordingly.
How does the HOLD pin function during an active write cycle?
The HOLD pin cannot suspend an internal write cycle once initiated; it only pauses serial instruction/data transfer. If HOLD is asserted during a write, the 25C040X-I/ST completes the ongoing write before entering hold state. This behavior is documented in Section 2.6 and Figure 1-1, ensuring data integrity even when host interrupts occur mid-write.
What memory protection mechanisms does the 25C040X-I/ST provide?
The 25C040X-I/ST implements three layers: (1) hardware WP pin (active-low global lock), (2) software-configurable BP0/BP1 bits for 0%/25%/50%/100% array protection, and (3) power-on reset of the write enable latch. Table 3-3 and Section 3.7 confirm these operate independently - e.g., WP low overrides BP settings and blocks all writes.
Is the 25C040X-I/ST pin-compatible with standard SOIC-8 versions of the 25C040?
No - the 'X' suffix denotes an alternate pinout specific to TSSOP packages: HOLD is on pin 1 (not pin 7), VCC on pin 2 (not pin 8), and CS on pin 3 (not pin 1). This deviation is explicitly called out in the Product Identification System (DS21204E, page 19) and requires PCB layout adjustment versus standard SOIC/PDIP footprints.
25C040X-I/ST Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tube
- 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
25C040X-I/ST FAQ
1.How can I place an order for 25C040X-I/ST through Aetrix?
Please submit a Request for Quotation (RFQ) for 25C040X-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 25C040X-I/ST reliable?
The price and inventory of 25C040X-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 25C040X-I/ST is usually 5 days.
3.What payment methods are accepted for 25C040X-I/ST?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25C040X-I/ST transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25C040X-I/ST?
25C040X-I/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25C040X-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 25C040X-I/ST?
For technical support, including 25C040X-I/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25C040X-I/ST requirements.
6.How does Aetrix verify that 25C040X-I/ST is sourced from the original manufacturer or authorized distributors?
All 25C040X-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 25C040X-I/ST meets industry standards.
7.What is the process for return or replacement of 25C040X-I/ST?
All 25C040X-I/ST units undergo pre-shipment inspection (PSI). If there is an issue with 25C040X-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 25C040X-I/ST part is unused and in its original packaging.
Return procedure for 25C040X-I/ST:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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