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Microchip Technology 25C040X/ST
- Part No.:
- 25C040X/ST
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
25C040X/ST.pdf
- Description:
- IC EEPROM 4KBIT SPI 3MHZ 8TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,901
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Product details
Overview
25C040X/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) makes it suitable for engine control units and battery management systems.
For engineers reviewing the 25C040X/ST datasheet, 25C040X/ST pinout, 25C040X/ST application, or 25C040X/ST equivalent, this page provides verified electrical specs, validated TSSOP-8 pin mapping, confirmed automotive-temp operation, and two field-tested alternative parts with documented functional trade-offs.
Technical Context
The 25C040X/ST implements a standard SPI interface with separate SI (data-in), SO (data-out), SCK (clock), CS (chip select), WP (hardware write-protect), and HOLD (communication pause) signals. Its internal architecture includes an 8-bit instruction register, page-based write logic, and a STATUS register with WIP/WEL/BP bits for real-time monitoring and block protection control.
It uses self-timed erase/write cycles with no external timing components required. The device enforces strict write enable protocol (WREN instruction + CS high assertion) and integrates power-on reset of the write latch, ensuring robust immunity to spurious writes during power transitions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory size | 4 Kbit (512 × 8-bit array), sufficient for firmware patch storage or calibration tables in ECUs |
| Supply voltage | 4.5–5.5 V - matches 5 V automotive rail systems without level-shifting |
| Max clock frequency | 3 MHz at VCC = 4.5–5.5 V - enables fast configuration reads in real-time control loops |
| Write cycle time | 5 ms max per page - deterministic latency for critical parameter updates |
| Endurance & retention | 1 million write/erase cycles; >200 years data retention - qualified for lifetime vehicle deployment |
| Temperature range | −40°C to +125°C (Automotive E grade) - validated for under-hood and transmission control environments |
| ESD protection | 4 kV HBM - meets ISO 10605 requirements for automotive electronics |
Pinout & Package
25C040X/ST is supplied in an 8-lead TSSOP package (4.4 mm width) with alternate pinout (ST suffix), differing from standard SOIC/PDIP layouts. Pin 1 is HOLD, not CS - critical for PCB layout verification.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (HOLD) | Communication suspend input | Tri-states SO and ignores SI/SCK when low; must be held high when unused to prevent bus lockup |
| 2 (VCC) | Power supply | 4.5–5.5 V nominal; decoupling capacitor required within 10 mm of pin for noise immunity |
| 3 (CS) | Chip select | Active-low enable; falling edge initiates SPI frame; rising edge triggers internal write if last byte was clocked |
| 4 (SO) | Serial data output | High-impedance when CS high; outputs MSB-first data on SCK falling edge during read |
| 5 (WP) | Hardware write-protect | Low disables all writes to memory and STATUS register; overrides WREN latch state |
| 6 (VSS) | Ground reference | Must be connected to system ground plane; shared return path for all I/Os |
| 7 (SI) | Serial data input | Latches instruction/address/data on SCK rising edge; requires clean signal integrity |
| 8 (SCK) | Serial clock input | Synchronizes all SPI transfers; max 3 MHz; rise/fall times ≤2 μs per AC spec |
Key Features
| Feature | Design Value |
|---|---|
| 16-byte page write | Enables burst programming of calibration data without exceeding internal write timeout limits |
| Block write protection | BP0/BP1 bits allow selective locking of upper 1/4, 1/2, or full array - prevents accidental overwrites of boot code |
| HOLD pin functionality | Pauses ongoing SPI transfer mid-sequence, freeing MCU to service higher-priority interrupts without reinitializing communication |
| Power-on write disable | Write enable latch resets at power-up, eliminating need for software initialization before first access |
| Automotive temperature grade | Qualified per AEC-Q100 stress test conditions for use in safety-critical vehicle subsystems |
Applications
| Engine Control Unit (ECU) | Advanced Driver Assistance System (ADAS) Camera Module |
|---|---|
|
Use Scenario: Storing adaptive fuel trim values and misfire history across ignition cycles. IC Role / Device Role / Timing Role: Nonvolatile configuration storage accessed via SPI during startup and runtime diagnostics. Use Value: Automotive-grade temperature tolerance ensures reliable logging even during extended under-hood thermal soak. |
Use Scenario: Holding lens calibration coefficients and image sensor gamma tables. IC Role / Device Role / Timing Role: SPI-configurable memory mapped by SoC during camera initialization sequence. Use Value: 3 MHz interface speed enables fast coefficient loading before video streaming begins. |
| Electric Power Steering (EPS) Controller | Onboard Charger (OBC) for EVs |
|
Use Scenario: Recording torque sensor offset drift compensation and motor winding resistance profiles. IC Role / Device Role / Timing Role: Fault-tolerant parameter store updated only during safe shutdown windows. Use Value: Hardware WP pin allows permanent locking of safety-critical parameters after factory calibration. |
Use Scenario: Saving grid synchronization settings and thermal derating thresholds across charge sessions. IC Role / Device Role / Timing Role: SPI EEPROM interfaced to isolated microcontroller for secure configuration backup. Use Value: 1M endurance supports daily updates over 10+ year vehicle lifetime without wear-out risk. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25C040T | Same die, standard SOIC-8 pinout (CS=1, SO=2), tape-and-reel packaging | Lacks HOLD pin functionality; incompatible with designs requiring mid-transfer pause | Select only if board layout uses standard SOIC footprint and HOLD is unused |
| AT25040B-SSHL-T | 4 Kbit SPI EEPROM, 2.7–5.5 V, 20 MHz max clock, 1 M endurance, SOIC-8 | Broad VCC range and higher speed but lacks automotive temp rating (−40°C to +85°C only) | Acceptable for industrial controls where ambient temperature stays below +85°C |
Compared with 25C040X/ST, 25C040T omits HOLD support and uses legacy pinout, while AT25040B-SSHL-T trades automotive qualification for wider voltage range and faster clock - making 25C040X/ST the sole choice for under-hood automotive SPI storage requiring HOLD and E-grade operation.
Availability
25C040X/ST is available at Aetrix Electronics and suitable for engine control units, ADAS camera modules, electric power steering controllers, and onboard chargers requiring stable component supply across long production lifecycles.
Supply support for 25C040X/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 design and manufacturing operations.
The 25C040X/ST belongs to Microchip's legacy 25XX040 serial EEPROM product line, engineered specifically for automotive and industrial applications demanding high reliability, wide temperature operation, and hardware-level write protection.
FAQ
What is the correct pin 1 identifier for 25C040X/ST?
The 25C040X/ST uses an alternate TSSOP pinout where pin 1 is HOLD, not CS. This differs from standard SOIC/PDIP variants. Always verify orientation using the package's notch or dot marking - misalignment causes SPI communication failure. The 25C040X/ST datasheet Figure 2-1 explicitly confirms HOLD at position 1.
Does 25C040X/ST support SPI Mode 0,0 only?
Yes, the 25C040X/ST is strictly compliant with SPI Mode 0,0 (CPOL = 0, CPHA = 0): data sampled on rising SCK edge, output valid on falling edge. It does not support Mode 1,1 or other variants. This is confirmed in DS21204E-page 4 timing diagrams and Section 3.1, which states compatibility with PIC16C6X/7X microcontrollers using standard Mode 0,0.
Can 25C040X/ST be used in 3.3 V systems?
No. The 25C040X/ST requires 4.5–5.5 V supply and is not rated for 3.3 V operation. Its VIH1 threshold is 2.0 V minimum (D001), but DC characteristics table specifies VCC = 4.5–5.5 V for automotive grade, and AC timing (FCLK = 3 MHz) is only guaranteed in that range. Use 25AA040A or 25LC040A for 1.8 V or 2.5 V systems.
How does the HOLD pin affect SO during suspension?
When HOLD is pulled low during an active SPI transaction, the 25C040X/ST immediately tri-states its SO pin and ignores further SI/SCK transitions. SO remains high-impedance until HOLD is returned high while SCK is low - at which point communication resumes from the exact bit position where it paused. This behavior is defined in Section 2.6 and Figure 1-1.
Is 25C040X/ST still recommended for new designs?
No. Microchip explicitly states "Not recommended for new designs – Please use 25AA040A or 25LC040A" in DS21204E-page 1. However, 25C040X/ST remains actively manufactured and supported for legacy automotive programs requiring its specific 5 V operation, HOLD pin, and E-grade qualification - with full lifecycle coordination available through Aetrix Electronics.
25C040X/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:
- 3 MHz
- Write Cycle Time - Word, Page:
- 5ms
- Access Time:
- -
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-TSSOP
25C040X/ST FAQ
1.How can I place an order for 25C040X/ST through Aetrix?
Please submit a Request for Quotation (RFQ) for 25C040X/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/ST reliable?
The price and inventory of 25C040X/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/ST is usually 5 days.
3.What payment methods are accepted for 25C040X/ST?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25C040X/ST transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25C040X/ST?
25C040X/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25C040X/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/ST?
For technical support, including 25C040X/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25C040X/ST requirements.
6.How does Aetrix verify that 25C040X/ST is sourced from the original manufacturer or authorized distributors?
All 25C040X/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/ST meets industry standards.
7.What is the process for return or replacement of 25C040X/ST?
All 25C040X/ST units undergo pre-shipment inspection (PSI). If there is an issue with 25C040X/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/ST part is unused and in its original packaging.
Return procedure for 25C040X/ST:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
25C040X/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
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