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Microchip Technology 25LC040X-I/ST
- Part No.:
- 25LC040X-I/ST
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
25LC040X-I/ST.pdf
- Description:
- IC EEPROM 4KBIT SPI 2MHZ 8TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,777
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Product details
Overview
25LC040X-I/ST from Microchip Technology is a 4 Kbit (512 × 8) SPI serial EEPROM with 2.5–5.5 V supply range, 2 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. It is used in embedded systems for nonvolatile storage of calibration data, configuration settings, and firmware parameters.
For engineers reviewing the 25LC040X-I/ST datasheet, 25LC040X-I/ST pinout, 25LC040X-I/ST application, or 25LC040X-I/ST equivalent, this page delivers verified electrical specs, TSSOP-8 pin mapping, block protection behavior, endurance/reliability metrics, and real-world use context - all aligned to DS21204E.
Technical Context
The 25LC040X-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, STATUS register with WIP/WEL/BP bits, and a 512-byte EEPROM array partitioned into four 128-byte blocks for selective write protection.
Write operations are gated by both the volatile write-enable latch (set via WREN) and the hardware WP pin; a low WP overrides the latch and disables all writes. The device supports sequential read, byte/page write, and self-timed internal erase/write cycles with 5 ms maximum duration - no external timing control required.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 4 Kbit (512 × 8-bit organization), sufficient for small configuration tables or sensor calibration offsets |
| Supply Voltage | 2.5–5.5 V - compatible with 3.3 V and 5 V logic domains without level shifting |
| Max Clock Frequency | 2 MHz at VCC ≥ 2.5 V - enables fast read/write in microcontroller SPI peripherals |
| Page Write Size | 16 bytes - limits burst writes to one page boundary; crossing pages requires multiple write cycles |
| Endurance & Retention | 1 million write/erase cycles; >200 years data retention - suitable for field-deployed devices with infrequent updates |
| Write Protection | Hardware WP pin + STATUS register BP0/BP1 bits - enables flexible, nonvolatile protection of 0%, 25%, 50%, or 100% of memory |
| Operating Temperature | –40°C to +85°C (Industrial grade) - validated for use in industrial controls and automotive body electronics |
Pinout & Package
25LC040X-I/ST is supplied in an 8-lead TSSOP package (4.4 mm width) with alternate pinout per Microchip's "X" suffix designation - distinct from standard SOIC/PDIP pin mapping. Pin 1 is HOLD (not CS), and VCC is on pin 2.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (HOLD) | Serial communication suspend input | Pulling low pauses ongoing SPI transfer without resetting sequence; must be held high when unused |
| 2 (VCC) | Positive supply voltage | 2.5–5.5 V power rail; decoupling capacitor required within 10 mm of pin |
| 3 (CS) | Chip select active-low enable | Asserts device onto SPI bus; rising edge after write initiates internal programming cycle |
| 4 (SO) | Serial data output | Tri-states when CS high or HOLD low; outputs MSB-first during read, synchronized to SCK falling edge |
| 5 (WP) | Hardware write-protect input | Low = all writes inhibited (including STATUS register); overrides WREN latch state |
| 6 (VSS) | Ground reference | Must be connected to system ground plane; shared return path for all I/O and supply currents |
| 7 (SI) | Serial data input | Latches instruction/address/data on SCK rising edge; requires clean signal with <500 ns setup/hold |
| 8 (SCK) | Serial clock input | Master-generated SPI clock; rising edge clocks data in, falling edge clocks data out on SO |
Key Features
| Feature | Design Value |
|---|---|
| Low-power operation | 500 μA typical read current and 500 nA standby current - extends battery life in portable instrumentation |
| Block write protection | Configurable via STATUS register (BP0/BP1) to protect 0%, 25%, 50%, or 100% of memory - prevents accidental overwrites of critical firmware sections |
| HOLD function | Pauses SPI communication mid-sequence without losing address pointer state - allows host MCU to service higher-priority interrupts |
| Power-on write disable | Write enable latch resets at power-up, and WP pin defaults to inhibit writes - eliminates spurious writes during power ramp |
| ESD robustness | 4 kV HBM ESD rating on all pins - enhances reliability in handling-sensitive industrial assembly environments |
Applications
| Industrial Sensor Node | Medical Diagnostic Device |
|---|---|
Use Scenario: Storing calibrated offset/gain coefficients for analog front-end sensors across temperature ranges. IC Role / Device Role / Timing Role: Nonvolatile configuration storage accessed during boot and recalibration routines via SPI. Use Value: Enables field-updatable calibration without firmware reflash; 1M endurance supports lifetime recalibration cycles. |
Use Scenario: Retaining patient-specific therapy parameters and usage logs in portable infusion pumps. IC Role / Device Role / Timing Role: Secure, low-power parameter storage with hardware write protection to prevent unauthorized changes. Use Value: WP pin + BP bits ensure therapy settings remain immutable during normal operation, meeting IEC 62304 safety requirements. |
| Automotive Body Control Module | Smart Energy Meter |
Use Scenario: Saving seat/mirror position presets and lighting configuration profiles in vehicle ECUs. IC Role / Device Role / Timing Role: SPI EEPROM interfaced directly to 8/16-bit automotive MCUs for persistent user preference storage. Use Value: –40°C to +85°C rating and 200-year data retention guarantee settings survive full vehicle lifecycle. |
Use Scenario: Logging tariff schedules, demand peaks, and meter calibration history in ANSI C12.20-compliant meters. IC Role / Device Role / Timing Role: High-reliability data logger with page-write efficiency minimizing SPI bus occupancy during frequent timestamped writes. Use Value: 16-byte page writes reduce transaction overhead vs. byte-wise writes - critical for time-synchronized logging at 15-min intervals. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25LC040T-I/SN | Same die, SOIC-8 package with standard pinout (CS on pin 1, VCC on pin 8) | Requires PCB layout change due to different pin assignment; no HOLD pin remapping | Select when board space permits SOIC and legacy pin compatibility is required |
| 25AA040T-I/ST | 1.8–5.5 V supply range; 1 MHz max clock; same TSSOP-8 alternate pinout | Better low-voltage support but lower speed - suited for ultra-low-power 1.8 V systems where 2 MHz is unnecessary | Choose for battery-powered designs operating below 2.5 V, accepting reduced throughput |
Compared with 25LC040X-I/ST, the 25LC040T-I/SN offers identical functionality in a standard SOIC footprint but demands layout revision, while the 25AA040T-I/ST trades clock speed and voltage margin for broader low-VCC operation - neither is pin-compatible without schematic and layout updates.
Availability
25LC040X-I/ST is available at Aetrix Electronics and suitable for industrial sensor nodes, medical diagnostic devices, automotive body control modules, and smart energy meters requiring stable component supply and long-term obsolescence management.
Supply support for 25LC040X-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 components, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.
The 25LC040X-I/ST belongs to Microchip's legacy SPI Serial EEPROM product line, designed specifically for cost-sensitive, low-power embedded systems requiring reliable nonvolatile storage with simple 4-wire SPI interface and hardware security features.
FAQ
What is the pinout difference between 25LC040X-I/ST and standard 25LC040 variants?
The 25LC040X-I/ST uses an alternate TSSOP-8 pinout where HOLD is on pin 1 and VCC is on pin 2 - unlike standard SOIC/PDIP versions where CS is pin 1 and VCC is pin 8. This layout optimizes routing in dense layouts but requires dedicated footprint design. Always verify against DS21204E Table 2-1 before PCB layout.
Does 25LC040X-I/ST support SPI Mode 1,1 or only Mode 0,0?
The 25LC040X-I/ST supports only SPI Mode 0,0 (CPOL = 0, CPHA = 0): clock idles low, data sampled on rising edge, changed on falling edge. It does not support Mode 1,1. This is confirmed in DS21204E Figures 1-2 and 1-3, which define timing relative to SCK low-to-high transitions for input and high-to-low for output.
How does the write-protect (WP) pin interact with the STATUS register BP bits on 25LC040X-I/ST?
On the 25LC040X-I/ST, the WP pin has priority over the STATUS register BP bits: when WP is low, all writes - including to the STATUS register - are blocked regardless of BP0/BP1 state. Only when WP is high do the BP bits determine which memory blocks are protected. This dual-layer protection is documented in DS21204E Table 3-3.
What is the maximum write cycle time for 25LC040X-I/ST, and does it vary with voltage or temperature?
The maximum internal write cycle time for 25LC040X-I/ST is 5 ms across its full operating range (–40°C to +85°C, 2.5–5.5 V), as specified in DS21204E Table 1-2 Parameter TWC. This value is guaranteed worst-case and does not degrade with temperature or voltage within spec - no derating required in design.
Is 25LC040X-I/ST recommended for new designs, and what is the suggested migration path?
No - Microchip explicitly states "Not recommended for new designs" for the 25LC040X-I/ST in DS21204E, advising migration to the enhanced 25LC040A series (e.g., 25LC040AT-I/ST). The 'A' revision improves ESD performance, adds deep power-down mode, and extends qualification - while maintaining pin and software compatibility with the original 25LC040X-I/ST.
25LC040X-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:
- 2 MHz
- Write Cycle Time - Word, Page:
- 5ms
- Access Time:
- -
- Voltage - Supply:
- 2.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-TSSOP
25LC040X-I/ST FAQ
1.How can I place an order for 25LC040X-I/ST through Aetrix?
Please submit a Request for Quotation (RFQ) for 25LC040X-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 25LC040X-I/ST reliable?
The price and inventory of 25LC040X-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 25LC040X-I/ST is usually 5 days.
3.What payment methods are accepted for 25LC040X-I/ST?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25LC040X-I/ST transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25LC040X-I/ST?
25LC040X-I/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25LC040X-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 25LC040X-I/ST?
For technical support, including 25LC040X-I/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25LC040X-I/ST requirements.
6.How does Aetrix verify that 25LC040X-I/ST is sourced from the original manufacturer or authorized distributors?
All 25LC040X-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 25LC040X-I/ST meets industry standards.
7.What is the process for return or replacement of 25LC040X-I/ST?
All 25LC040X-I/ST units undergo pre-shipment inspection (PSI). If there is an issue with 25LC040X-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 25LC040X-I/ST part is unused and in its original packaging.
Return procedure for 25LC040X-I/ST:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
25LC040X-I/ST Tags
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STMicroelectronics
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AT24C02C-XHM-T
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AT21CS01-STUM10-T
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AT24CS02-SSHM-T
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93LC46BT-I/OT
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AT24C04C-SSHM-T
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