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Microchip Technology 25CS640T-H/ST
- Part No.:
- 25CS640T-H/ST
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
25CS640T-H/ST.pdf
- Description:
- IC EEPROM 64KBIT SPI 8TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,500
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Product details
Overview
25CS640T-H/ST 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 across 2.5V–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/ST datasheet, 25CS640T-H/ST pinout, 25CS640T-H/ST application, or 25CS640T-H/ST equivalent, this device delivers automotive-grade nonvolatile storage with dual write protection modes (Legacy and Enhanced), factory-programmed 128-bit serial number, and programmable undervoltage lockout threshold - critical for robust boot code, calibration data, and configuration retention in harsh-temperature environments.
Technical Context
The 25CS640T-H/ST implements a dedicated SPI client interface with Mode 0 and Mode 3 support, using separate SI (input) and SO (output) lines synchronized to SCK rising/falling edges. Its internal architecture includes a 16-bit STATUS register with volatile/nonvolatile bits, four 8-bit Memory Partition registers (MPR0–MPR3), and an 8-bit UVLO register enabling configurable brown-out protection.
It features two independent memory domains: a 64-Kbit main EEPROM array (0000h–1FFFh) and a 512-bit Security register comprising a read-only 128-bit serial number (0000h–000Fh) plus a user-programmable, software-lockable 32-byte ID page (0020h–003Fh). ECC logic monitors all array reads and reports correction status via the ECS bit.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8,192 × 8-bit), organized in 256 pages of 32 bytes each - enables efficient firmware patching and parameter logging with minimal page erase overhead. |
| Supply Voltage Range | 2.5V to 5.5V - supports direct integration into 3.3V and 5V automotive subsystems without level-shifting. |
| Max Clock Frequency | 20 MHz at VCC ≥ 4.5V - allows high-throughput configuration loading in real-time control systems. |
| Write Cycle Time | ≤ 4 ms self-timed - eliminates external timing dependencies and simplifies host firmware design. |
| Endurance & Retention | 4 million write cycles at +25°C; >200 years data retention at +55°C - ensures long-term reliability in infotainment and ADAS modules. |
| Temperature Range | −40°C to +150°C (H-grade) - qualified per AEC-Q100 Grade 0 for under-hood and powertrain applications. |
| ECC Capability | Corrects up to one bit error per 4-byte readout; ECS flag reports correction event - enhances data integrity without host-side error-handling complexity. |
Pinout & Package
25CS640T-H/ST is supplied in an 8-pin Wettable Flanks VDFN package (3.0 mm × 2.0 mm, 0.5 mm pitch), optimized for automated optical inspection (AOI) and solder joint reliability in automotive reflow profiles.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS | Chip Select Input | Active-low enable signal; must transition high-to-low to initiate SPI command sequence and remain low throughout transaction. |
| SO | Serial Data Output | Push-pull output; data shifted MSb-first on falling edge of SCK; enters high-Z when CS is high or HOLD is asserted. |
| WP | Write-Protect Input | Hardware-enables partition-level write lock in Enhanced mode or BP-bit-based block protection in Legacy mode; latched on rising edge of CS. |
| VSS | Ground Reference | Primary return path for all internal circuitry; exposed pad (Pin 5) must be connected to PCB ground plane for thermal and EMI performance. |
| SI | Serial Data Input | CMOS input; accepts opcodes, addresses, and data MSb-first on rising edge of SCK; ignored when CS is high. |
| SCK | Serial Clock Input | Asynchronous master-generated clock; defines timing for SI sampling (rising edge) and SO output (falling edge); supports Modes 0 and 3 only. |
| HOLD | Communication Pause Input | Active-low; suspends ongoing SPI transfer without resetting internal state - enables host CPU to service higher-priority interrupts. |
| VCC | Supply Voltage | Power rail for core logic and memory array; internal UVLO circuit disables writes if voltage drops below programmable threshold (1.4V–4.8V). |
Key Features
| Feature | Design Value |
|---|---|
| Enhanced Write Protection Mode | Four independent memory partitions configurable via MPR0–MPR3; each supports unprotected, software-write-protected, hardware-locked (WP), or permanently locked behavior - enables secure OTA update staging and calibration zone isolation. |
| Factory-Programmed Security Register | 128-bit globally unique serial number (read-only) + 32-byte user-programmable, software-lockable ID page - eliminates manufacturing serialization steps and secures device identity in fleet management systems. |
| JEDEC® Manufacturer ID Support | Compliant with JEDEC Standard JESD216B; returns Microchip's 0x000020 Manufacturer ID and device-specific EDI - enables runtime identification and firmware compatibility validation in multi-vendor BOMs. |
| Undervoltage Lockout (UVLO) | Configurable 5-bit threshold (32 levels, 1.4V–4.8V) stored in nonvolatile UVLO register - prevents corruption during cold-cranking or battery sag events in automotive power domains. |
| Low-Power Operation | 1.0 µA standby current at 5.5V/+85°C; 5.0 mA active read current at 5.5V/20 MHz - extends battery life in always-on telematics modules and reduces thermal load in dense ECUs. |
Applications
| Automotive Powertrain Control | Industrial Sensor Calibration |
|---|---|
Use Scenario: Storing engine timing maps, fuel trim coefficients, and fault history logs in ECU modules operating under hood temperatures up to +150°C. IC Role / Device Role / Timing Role: Nonvolatile configuration storage with AEC-Q100 H-grade qualification and ECC-protected read access during real-time control loops. Use Value: Guarantees data integrity across 4M+ write cycles and >200-year retention, eliminating recalibration drift and enabling regulatory compliance traceability. |
Use Scenario: Holding factory-calibrated offset/gain values and sensor linearization tables for pressure, temperature, and current sensors in industrial PLC I/O modules. IC Role / Device Role / Timing Role: Secure, tamper-resistant parameter vault with lockable ID page for calibration certificate embedding and revision tracking. Use Value: Prevents unauthorized modification of calibration data via hardware-assisted partition locking and factory-unique serial number binding. |
| Medical Device Configuration | Smart Energy Metering |
Use Scenario: Retaining user-defined therapy parameters, audit logs, and device serial binding in portable infusion pumps and diagnostic handhelds. IC Role / Device Role / Timing Role: Safety-critical nonvolatile memory with ECC correction and software reset (SRST) for deterministic recovery after brown-out events. Use Value: Meets IEC 62304 Class C requirements through guaranteed write endurance, data retention, and deterministic power-up default state. |
Use Scenario: Storing tariff schedules, metering constants, and firmware update metadata in ANSI C12.22-compliant smart meters deployed in outdoor utility cabinets. IC Role / Device Role / Timing Role: High-reliability EEPROM with programmable UVLO and extended temperature operation (−40°C to +125°C) for unregulated AC mains environments. Use Value: Ensures accurate billing data persistence during grid voltage sags and thermal cycling, reducing field failure rates and warranty claims. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar SPI EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT25DF641A-MAU-T | 64-Mbit NOR Flash (not EEPROM); no built-in ECC; requires sector erase before write; lacks security register and UVLO configuration. | Targeted at firmware storage, not frequent parameter updates; unsuitable for calibration data requiring byte-level writes and 4M-cycle endurance. | Select only if code storage dominates over configuration logging and ECC is handled externally. |
| 25AA640A-I/MS | Legacy Microchip 64-Kbit EEPROM; no ECC, no security register, no enhanced write protection; max 10 MHz at 2.5V; only Industrial temp (−40°C to +85°C). | Lacks automotive qualification, serial number, and partitioned protection - insufficient for Tier-1 ECU or medical device certification. | Acceptable for cost-sensitive consumer products where AEC-Q100, ECC, and security are non-mandatory. |
Compared with AT25DF641A-MAU-T and 25AA640A-I/MS, the 25CS640T-H/ST uniquely combines AEC-Q100 H-grade operation, factory-serialized security, ECC-enabled reliability, and software-configurable UVLO - making it the only choice for safety-critical, high-endurance, and identity-aware automotive and industrial applications.
Availability
25CS640T-H/ST is available at Aetrix Electronics and suitable for automotive powertrain control, industrial sensor calibration, medical device configuration, and smart energy metering requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for 25CS640T-H/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 communications markets with vertically integrated silicon and development tools.
The 25CS640 series was designed specifically for automotive and high-reliability embedded systems requiring secure, long-life nonvolatile storage with advanced data integrity features - including ECC, programmable UVLO, and factory-serialized identity.
FAQ
What is the operating temperature range for the 25CS640T-H/ST?
The 25CS640T-H/ST is rated for −40°C to +150°C and qualified per AEC-Q100 Grade 0. This H-grade specification ensures reliable operation in under-hood automotive environments, such as engine control units and transmission control modules, where ambient temperatures exceed +125°C during peak load conditions.
Does the 25CS640T-H/ST support SPI Mode 1 or Mode 2?
No, the 25CS640T-H/ST supports only SPI Mode 0 (CPOL = 0, CPHA = 0) and Mode 3 (CPOL = 1, CPHA = 0). Data are always latched on the rising edge of SCK and output on the falling edge. Modes 1 and 2 are not implemented and will result in communication failure.
How is the 128-bit serial number accessed in the 25CS640T-H/ST?
The 128-bit serial number resides in the read-only portion of the Security register (addresses 0000h–000Fh) and is accessed via standard READ instruction (03h) with address 0000h. It is factory-programmed, globally unique across all CS-series EEPROMs, and cannot be altered or erased.
Can the UVLO threshold be changed after programming the 25CS640T-H/ST?
Yes, the UVLO threshold is stored in the nonvolatile 8-bit UVLO register and can be reprogrammed using the WRSR instruction. The threshold is selectable across 32 levels (1.4V–4.8V in 0.1V steps), allowing system designers to align lockout behavior precisely with their power supply rail characteristics.
What happens to the STATUS register after a power cycle of the 25CS640T-H/ST?
Upon power-up, the 25CS640T-H/ST resets volatile bits in the STATUS register (WEL, RDY/BUSY, ECS, PREL, WLS) to 0, while nonvolatile bits (WPEN, BP[1:0], WPM, FMPC, PABP) retain their last programmed values. This ensures predictable startup behavior and preserves write protection settings across power cycles.
25CS640T-H/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:
- -
- 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-TSSOP
25CS640T-H/ST FAQ
1.How can I place an order for 25CS640T-H/ST through Aetrix?
Please submit a Request for Quotation (RFQ) for 25CS640T-H/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 25CS640T-H/ST reliable?
The price and inventory of 25CS640T-H/ST 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/ST is usually 5 days.
3.What payment methods are accepted for 25CS640T-H/ST?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25CS640T-H/ST transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25CS640T-H/ST?
25CS640T-H/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25CS640T-H/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 25CS640T-H/ST?
For technical support, including 25CS640T-H/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25CS640T-H/ST requirements.
6.How does Aetrix verify that 25CS640T-H/ST is sourced from the original manufacturer or authorized distributors?
All 25CS640T-H/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 25CS640T-H/ST meets industry standards.
7.What is the process for return or replacement of 25CS640T-H/ST?
All 25CS640T-H/ST units undergo pre-shipment inspection (PSI). If there is an issue with 25CS640T-H/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 25CS640T-H/ST part is unused and in its original packaging.
Return procedure for 25CS640T-H/ST:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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