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Microchip Technology 25CS640T-H/SN
- Part No.:
- 25CS640T-H/SN
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
25CS640T-H/SN.pdf
- Description:
- IC EEPROM 64KBIT SPI 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,300
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Product details
Overview
25CS640T-H/SN from Microchip Technology is a 64-Kbit SPI Serial EEPROM with 8,192 × 8-bit organization, 32-byte page size, and AEC-Q100 qualification for automotive applications. It operates from 2.5V to 5.5V, supports up to 20 MHz clock at VCC ≥ 4.5V, and integrates built-in ECC for single-bit error correction in four-byte reads.
For engineers reviewing the 25CS640T-H/SN datasheet, 25CS640T-H/SN pinout, 25CS640T-H/SN application, or 25CS640T-H/SN equivalent, this device delivers automotive-grade nonvolatile storage with dual write protection modes, factory-programmed 128-bit serial number, and programmable undervoltage lockout - critical for infotainment, ADAS sensor calibration, and ECU configuration retention.
Technical Context
The 25CS640T-H/SN implements a dedicated SPI client interface (Mode 0/3) with separate SI/SO lines and CS-controlled selection. Its memory architecture comprises 256 pages of 32 bytes each, plus a 512-bit Security register containing 128-bit read-only serial number and 32-byte user-programmable, lockable ID page.
It features two configurable write protection schemes: Legacy mode (BP[1:0] bits enabling quarter/half/full array block protection) and Enhanced mode (four independent Memory Partition registers defining software- or hardware-based per-zone protection). Undervoltage lockout is programmable via an 8-bit UVLO register with 32 selectable thresholds from 1.4V to 4.8V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8,192 × 8-bit), organized as 256 pages × 32 bytes - enables efficient firmware patching and parameter logging in constrained embedded systems. |
| Write Cycle Endurance | 4 million cycles at +25°C - supports long-term field updates in automotive ECUs without premature wear-out. |
| Data Retention | >200 years at +55°C - ensures calibration data integrity across vehicle lifetime under typical cabin thermal conditions. |
| Operating Voltage | 2.5V to 5.5V - compatible with 3.3V and 5V microcontroller I/O domains without level-shifting in body control modules. |
| Max Clock Frequency | 20 MHz at VCC ≥ 4.5V - enables fast boot-time configuration loading in real-time safety-critical subsystems. |
| ECC Capability | Corrects up to one bit error per 4-byte read - mitigates soft errors from radiation or voltage transients in under-hood environments. |
| Temperature Range | –40°C to +150°C (H-grade) - qualified per AEC-Q100 Grade 0 for direct mounting on powertrain and transmission control units. |
| ESD Protection | >4 kV HBM - withstands handling and assembly stresses in automotive manufacturing lines. |
Pinout & Package
25CS640T-H/SN is supplied in an 8-pin Wettable Flanks VDFN package (2 mm × 3 mm, 0.5 mm pitch), optimized for automated optical inspection (AOI) and solder joint reliability in high-vibration automotive applications.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS | Chip Select Input | Active-low enable signal; must be held high between transactions to place device in low-power standby (1 µA). |
| SO | Serial Data Output | Tri-state output; data shifted out MSb-first on SCK falling edge; enters high-Z when CS high or HOLD asserted. |
| WP | Write-Protect Pin | Hardware-enables partition-level write lock in Enhanced mode or STATUS register/mem-block protection in Legacy mode. |
| VSS | Ground | Reference return path for all digital and analog circuitry; exposed pad (Pin 5) must be connected to PCB ground plane. |
| SI | Serial Data Input | Accepts opcodes, addresses, and data MSb-first on SCK rising edge; latching begins after first CS low transition. |
| SCK | Serial Clock Input | Asynchronous master-generated clock; supports SPI Modes 0 and 3; timing validated up to 20 MHz at full VCC. |
| HOLD | Hold Input | Pauses ongoing SPI transaction without resetting internal state; allows host MCU to service higher-priority interrupts. |
| VCC | Supply Voltage | Primary power rail; internal UVLO circuit disables writes if voltage drops below programmable threshold (1.4–4.8 V). |
Key Features
| Feature | Design Value |
|---|---|
| Factory-Programmed 128-bit Serial Number | Uniquely identifies each unit across entire CS-series EEPROMs - eliminates line-side serialization overhead in Tier-1 production. |
| User-Programmable Lockable ID Page | 32-byte Security register section that can be permanently write-locked via software sequence - secures cryptographic keys or calibration constants. |
| Configurable Write Protection Modes | Legacy (block-based BP bits) and Enhanced (independent 4-zone partitioning) - enables flexible security policies across OEM software update frameworks. |
| JEDEC® Manufacturer ID Support | Complies with JEDEC JESD216 standard for electronic device identification - allows runtime validation of memory authenticity in secure boot flows. |
| Software Device Reset (SRST) | 7Ch opcode resets STATUS and volatile latches without power cycle - recovers from bus contention or protocol errors in mission-critical systems. |
| Programmable UVLO Threshold | 32-step adjustable lockout level (1.4–4.8 V) stored in nonvolatile UVLO register - prevents corruption during cold-cranking or battery droop events. |
Applications
| Automotive ECU Configuration Storage | ADAS Sensor Calibration Data |
|---|---|
|
Use Scenario: Storing adaptive parameters (e.g., steering angle offset, brake bias tuning) that persist across ignition cycles and survive battery disconnect. IC Role / Device Role / Timing Role: Nonvolatile configuration register holding calibrated values updated only during dealer service or OTA updates. Use Value: AEC-Q100 H-grade operation and >200-year data retention ensure parameter validity over 15+ year vehicle lifespan without recalibration. |
Use Scenario: Retaining factory-calibrated coefficients for radar/lidar time-of-flight sensors subject to thermal drift compensation. IC Role / Device Role / Timing Role: Secure, ECC-protected storage for sensor-specific correction tables accessed at boot and during runtime diagnostics. Use Value: Built-in ECC corrects single-bit errors induced by under-hood gamma exposure, preventing silent calibration corruption. |
| Infotainment System Firmware Patching | Body Control Module Parameter Logging |
|
Use Scenario: Hosting incremental firmware patches applied during vehicle software updates without requiring full flash reprogramming. IC Role / Device Role / Timing Role: Secondary code storage accessible via SPI while main MCU executes from internal flash. Use Value: 20 MHz interface speed and 4M write cycles enable rapid patch deployment across fleet-wide OTA campaigns. |
Use Scenario: Recording diagnostic trouble codes (DTCs), mileage snapshots, and door/window actuation counts for warranty analytics. IC Role / Device Role / Timing Role: Low-power logging buffer written in background during sleep mode using HOLD-assisted burst writes. Use Value: 1 µA standby current and 2.5V minimum VCC support always-on monitoring in 12V battery-powered modules. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT25C640B-MAHL-T | No integrated ECC; no programmable UVLO; lacks 128-bit serial number and lockable ID page; max 10 MHz @ 2.5V. | Targeted at cost-sensitive industrial controls where AEC-Q100 and ECC are not required. | Select only if automotive qualification, ECC, or secure ID features are unnecessary and legacy Atmel footprint compatibility is mandatory. |
| 25AA640A-I/SN | Same pinout and instruction set but lacks Enhanced Write Protection mode, Security register enhancements, and H-grade temperature support (max +125°C). | Suitable for industrial automation where extended temperature range and advanced partitioning are not needed. | Choose when migrating from older Microchip EEPROMs and full 25CS640 feature set is not required - reduces BOM complexity in non-automotive designs. |
Compared with AT25C640B-MAHL-T and 25AA640A-I/SN, the 25CS640T-H/SN provides automotive-grade reliability, ECC-protected reads, and hardware-enforced memory partitioning - making it the only option qualified for safety-critical ECU configuration storage in modern vehicles.
Availability
25CS640T-H/SN is available at Aetrix Electronics and suitable for automotive ECU configuration storage, ADAS sensor calibration, infotainment firmware patching, and body control module parameter logging requiring stable component supply across extended product lifecycles.
Supply support for 25CS640T-H/SN 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, serving automotive, industrial, and consumer markets with vertically integrated silicon and software platforms.
The 25CS640 series is designed specifically for automotive applications demanding AEC-Q100 qualification, enhanced data integrity, and secure nonvolatile storage - addressing ECU configuration, sensor calibration, and firmware update requirements in harsh environments.
FAQ
What is the operating temperature range for the 25CS640T-H/SN?
The 25CS640T-H/SN is rated for –40°C to +150°C and qualified to AEC-Q100 Grade 0. This H-grade specification ensures reliable operation in under-hood and powertrain applications where ambient temperatures exceed +125°C, unlike standard industrial or extended-grade variants.
Does the 25CS640T-H/SN support SPI Mode 1 or Mode 2?
No, the 25CS640T-H/SN supports only SPI Modes 0 and 3. In both modes, data are latched on the rising edge of SCK and output on the falling edge. Mode 0 uses low-idle SCK; Mode 3 uses high-idle SCK. Modes 1 and 2 are not implemented and will not function correctly with the 25CS640T-H/SN.
How does the built-in ECC work in the 25CS640T-H/SN?
The 25CS640T-H/SN applies ECC across every 4-byte read, correcting up to one flipped bit per group. The STATUS register's ECS bit flags whether correction occurred. This protects against single-event upsets in automotive environments without requiring host-side error-handling logic - a key differentiator from standard EEPROMs like the 25AA640A-I/SN.
Can the 128-bit serial number in the 25CS640T-H/SN be overwritten?
No, the 128-bit serial number in the 25CS640T-H/SN is factory-programmed, read-only, and globally unique across the entire CS-series EEPROM family. It resides in the lower 16 bytes of the Security register and cannot be altered, erased, or reprogrammed - ensuring permanent device identity for traceability and anti-counterfeiting.
What is the difference between Legacy and Enhanced Write Protection modes in the 25CS640T-H/SN?
Legacy mode uses BP[1:0] bits in the STATUS register to protect quarter/half/full memory blocks. Enhanced mode uses four independent Memory Partition registers to define custom, software- or WP-pin-protected zones - enabling granular control for multi-tier firmware architectures. The 25CS640T-H/SN defaults to Legacy mode but can be switched via the WPM bit.
25CS640T-H/SN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Programmable:
- -
- Memory Type:
- Non-Volatile
- Memory Format:
- EEPROM
- Technology:
- EEPROM
- Memory Size:
- 64Kbit
- Memory Organization:
- 8K x 8
- Memory Interface:
- SPI
- Clock Frequency:
- 10 MHz
- Write Cycle Time - Word, Page:
- 4ms
- Access Time:
- 40 ns
- Voltage - Supply:
- 2.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 150°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
25CS640T-H/SN FAQ
1.How can I place an order for 25CS640T-H/SN through Aetrix?
Please submit a Request for Quotation (RFQ) for 25CS640T-H/SN 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 25CS640T-H/SN reliable?
The price and inventory of 25CS640T-H/SN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 25CS640T-H/SN is usually 5 days.
3.What payment methods are accepted for 25CS640T-H/SN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25CS640T-H/SN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25CS640T-H/SN?
25CS640T-H/SN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25CS640T-H/SN 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 25CS640T-H/SN?
For technical support, including 25CS640T-H/SN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25CS640T-H/SN requirements.
6.How does Aetrix verify that 25CS640T-H/SN is sourced from the original manufacturer or authorized distributors?
All 25CS640T-H/SN 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 25CS640T-H/SN meets industry standards.
7.What is the process for return or replacement of 25CS640T-H/SN?
All 25CS640T-H/SN units undergo pre-shipment inspection (PSI). If there is an issue with 25CS640T-H/SN, 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 25CS640T-H/SN part is unused and in its original packaging.
Return procedure for 25CS640T-H/SN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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