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Microchip Technology 25CS640T-I/Q4B

Name: 25CS640T-I/Q4B
Brand: Microchip Technology
SKU: 25CS640T-I/Q4B
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 25CS640T-I/Q4B

Manufacturer:: Microchip Technology

Category:: Memory

Package:: 8-UFDFN Exposed Pad

Datasheet:: 25CS640T-I/Q4B.pdf

Description:: IC EEPROM 64KBIT SPI 8UDFN

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Product details

Overview

25CS640T-I/Q4B from Microchip Technology Inc. is a 64-Kbit SPI Serial EEPROM with 8,192 × 8-bit organization, 32-byte page size, built-in ECC logic, and AEC-Q100 automotive qualification (I-temp: −40°C to +85°C). It operates across 1.7V–5.5V, supports up to 20 MHz clock at V_CC ≥ 4.5V, and integrates a factory-programmed 128-bit serial number for secure device identification in automotive control modules.

For engineers reviewing the 25CS640T-I/Q4B datasheet, 25CS640T-I/Q4B pinout, 25CS640T-I/Q4B application, or 25CS640T-I/Q4B equivalent, this page delivers verified technical context, real-world timing and protection behavior, SPI Mode 0/3 compatibility, and validated alternatives for automotive-grade nonvolatile memory selection.

Technical Context

The 25CS640T-I/Q4B implements a dual-mode write protection architecture: Legacy mode uses BP[1:0] bits for quarter/half/full array block protection, while Enhanced mode enables four independent memory partitions via MPR0–MPR3 registers, each configurable for software/hardware lock or permanent freeze. Its ECC logic corrects up to one bit error per 4-byte read and reports correction status via the ECS bit in the STATUS register.

It features JEDEC-compliant Manufacturer ID read capability, programmable UVLO threshold (1.4V–4.8V in 32 steps), and HOLD pin support for interrupt-safe SPI pause/resume. The Security register contains 16 bytes of factory-unique 128-bit serial number followed by 32 bytes of user-programmable, lockable ID page - both electrically isolated from main memory.

Key Specifications

Parameter	Value and Actual Design Meaning
Memory Size	64 Kbit (8,192 × 8-bit), organized as 256 pages of 32 bytes - enables efficient firmware patching and parameter storage with minimal page-write overhead.
Write Cycle Time	≤4 ms self-timed internal write - eliminates need for external polling delay; RDY/BUSY bit indicates completion.
Operating Voltage	1.7V to 5.5V - supports direct interface with 1.8V, 3.3V, and 5V microcontrollers without level-shifting.
Max Clock Frequency	20 MHz at V_CC ≥ 4.5V - delivers 2.5 MB/s effective serial throughput for rapid configuration loading.
ECC Capability	Single-bit error correction per 4-byte readout with ECS flag reporting - extends data retention reliability beyond 200 years under industrial conditions.
Endurance	4 million erase/write cycles at +25°C - suitable for high-frequency logging applications such as battery management system event records.
Temperature Range	−40°C to +85°C (Industrial grade) - qualified per AEC-Q100 Rev G for under-hood automotive use including body control modules.

Pinout & Package

25CS640T-I/Q4B is packaged in an 8-pin QFN (UDFN) with wettable flanks, measuring 2 mm × 3 mm × 0.55 mm (JEDEC MO-229WEED), optimized for automated optical inspection and high-density PCB layouts.

Pin/Terminal	Circuit Role	Design Meaning
CS	Chip Select Input	Active-low enable; must transition high-to-low to initiate SPI sequence and low-to-high to terminate - controls SO high-impedance state during deselect.
SO	Serial Data Output	Master-out slave-out line; outputs MSb-first on falling SCK edge; enters high-Z when CS high or HOLD active.
WP	Write-Protect Pin	Hardware-enables partition-level write lock in Enhanced mode or BP-based block protection in Legacy mode - pulled high internally if unused.
VSS	Ground Reference	Primary return path for all I/O and core logic; exposed pad (Pin 5) must be connected to PCB ground plane for thermal and EMI performance.
SI	Serial Data Input	Master-in slave-out line; latches MSb-first instruction/address/data on rising SCK edge - requires setup/hold timing compliance per Table 1-2.
SCK	Serial Clock Input	Asynchronous SPI clock; supports Modes 0 and 3 (SCK idle low/high); rise/fall time ≤2 µs required for reliable sampling.
HOLD	Hold Input	Pauses ongoing SPI transfer without resetting internal state; allows host MCU to service higher-priority interrupts - requires 5 ns setup before next SCK edge.
VCC	Supply Voltage	Core power input; undervoltage lockout (UVLO) disables writes below programmable threshold (1.4V–4.8V) to prevent corruption during brownout.

Key Features

Feature	Design Value
Enhanced Write Protection	Four independent memory partitions (MPR0–MPR3), each configurable for unprotected/software/hardware/locked behavior - enables secure OTA update staging and calibration data isolation.
Security Register	Factory-programmed 128-bit globally unique serial number (read-only) + 32-byte user-programmable, software-lockable ID page - eliminates manufacturing serialization and secures device identity.
Built-in ECC Logic	Corrects single-bit errors per 4-byte read and sets ECS flag in STATUS register - reduces uncorrectable error rate by >99.9% versus non-ECC EEPROMs in noisy automotive environments.
JEDEC Manufacturer ID Read	Complies with JEDEC JESD216 standard; returns Microchip's 0x01 Manufacturer ID and device-specific EDI - enables runtime firmware validation and multi-vendor BOM flexibility.
Programmable UVLO Threshold	32-step adjustable lockout voltage (1.4V–4.8V via UVLO register) - prevents partial writes during power ramp-up or supply sag in start-stop vehicle systems.

Applications

Automotive Body Control Module	Industrial PLC Configuration Storage
Use Scenario: Storing seat position presets, mirror angles, and lighting profiles in a vehicle's BCM with over-the-air update capability. IC Role / Device Role / Timing Role: Nonvolatile configuration memory interfaced to an ARM Cortex-M7 MCU via SPI Mode 0 at 10 MHz. Use Value: ECC ensures integrity of safety-critical settings after 15+ years of thermal cycling; 128-bit serial number enables cryptographic binding to vehicle VIN.	Use Scenario: Retaining I/O mapping, PID tuning parameters, and alarm thresholds across power cycles in DIN-rail mounted PLCs. IC Role / Device Role / Timing Role: Parameter EEPROM co-located with RS-485 transceiver and real-time clock on control board. Use Value: 4M write cycles support daily firmware updates over 10-year field life; enhanced partitioning isolates factory-calibrated values from user-modifiable fields.
Medical Infusion Pump Calibration	Smart Energy Meter Firmware Patching
Use Scenario: Storing dose calibration coefficients, motor step counts, and usage logs in Class II medical devices requiring FDA audit trails. IC Role / Device Role / Timing Role: Secure memory element accessed only during maintenance mode via isolated SPI bus. Use Value: Lockable 32-byte ID page stores cryptographic keys and regulatory certification hashes; AEC-Q100 qualification validates robustness against ESD (>4 kV) and temperature stress.	Use Scenario: Hosting delta patches for metrology firmware in ANSI C12.22-compliant smart meters deployed in harsh outdoor substations. IC Role / Device Role / Timing Role: High-reliability boot memory mapped to MCU's XIP-capable SPI flash controller. Use Value: 200-year data retention meets ANSI C12.19 lifetime requirements; 20 MHz operation enables sub-second patch application during scheduled maintenance windows.

Automotive Body Control Module

Industrial PLC Configuration Storage

Use Scenario: Storing seat position presets, mirror angles, and lighting profiles in a vehicle's BCM with over-the-air update capability.

IC Role / Device Role / Timing Role: Nonvolatile configuration memory interfaced to an ARM Cortex-M7 MCU via SPI Mode 0 at 10 MHz.

Use Value: ECC ensures integrity of safety-critical settings after 15+ years of thermal cycling; 128-bit serial number enables cryptographic binding to vehicle VIN.

Use Scenario: Retaining I/O mapping, PID tuning parameters, and alarm thresholds across power cycles in DIN-rail mounted PLCs.

IC Role / Device Role / Timing Role: Parameter EEPROM co-located with RS-485 transceiver and real-time clock on control board.

Use Value: 4M write cycles support daily firmware updates over 10-year field life; enhanced partitioning isolates factory-calibrated values from user-modifiable fields.

Medical Infusion Pump Calibration

Smart Energy Meter Firmware Patching

Use Scenario: Storing dose calibration coefficients, motor step counts, and usage logs in Class II medical devices requiring FDA audit trails.

IC Role / Device Role / Timing Role: Secure memory element accessed only during maintenance mode via isolated SPI bus.

Use Value: Lockable 32-byte ID page stores cryptographic keys and regulatory certification hashes; AEC-Q100 qualification validates robustness against ESD (>4 kV) and temperature stress.

Use Scenario: Hosting delta patches for metrology firmware in ANSI C12.22-compliant smart meters deployed in harsh outdoor substations.

IC Role / Device Role / Timing Role: High-reliability boot memory mapped to MCU's XIP-capable SPI flash controller.

Use Value: 200-year data retention meets ANSI C12.19 lifetime requirements; 20 MHz operation enables sub-second patch application during scheduled maintenance windows.

Equivalent & Alternatives

The following parts are listed as comparable options for similar serial EEPROM applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
AT25DF641A-MAU-T	No built-in ECC; 64 Mbit density; quad-SPI interface; no security register or programmable UVLO.	Better suited for high-speed code shadowing than secure parameter storage; lacks AEC-Q100 qualification.	Select only when raw capacity and quad-I/O speed outweigh ECC, serial number, and automotive reliability needs.
25AA640A-I/SN	Same 64 Kbit density and pinout; no ECC; no security register; legacy-only write protection; max 10 MHz at 2.5V.	Compatible drop-in for cost-sensitive industrial designs where ECC and serialization are not required.	Choose for legacy design refreshes needing identical footprint and basic functionality without enhanced reliability features.

Compared with 25CS640T-I/Q4B, AT25DF641A-MAU-T offers higher density and faster interface but sacrifices ECC, security, and automotive qualification; 25AA640A-I/SN provides pin-compatible backward compatibility but omits ECC, serial number, and programmable UVLO - making 25CS640T-I/Q4B the sole option meeting full AEC-Q100 + ECC + secure ID requirements.

Availability

25CS640T-I/Q4B is available at Aetrix Electronics and suitable for automotive body control modules, industrial PLC configuration storage, medical infusion pump calibration, and smart energy meter firmware patching requiring stable component supply across extended product lifecycles.

Supply support for 25CS640T-I/Q4B 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 microcontroller, analog, FPGA, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 25CS640 series is part of Microchip's automotive-qualified serial EEPROM portfolio, designed specifically for mission-critical nonvolatile storage in safety-aware systems requiring ECC, secure identity, and extended temperature resilience.

FAQ

What is the maximum clock frequency supported by the 25CS640T-I/Q4B and under what voltage condition?

The 25CS640T-I/Q4B supports up to 20 MHz clock frequency when V_CC is ≥4.5V and ambient temperature is ≤+125°C. At V_CC ≥2.5V, maximum frequency drops to 10 MHz, and at V_CC ≥1.7V, it is limited to 5 MHz. These limits are defined in Table 1-2 of the DS20005943D datasheet and ensure reliable setup/hold timing across voltage and temperature ranges. The 25CS640T-I/Q4B maintains full functionality across all three operating points without configuration changes.

Does the 25CS640T-I/Q4B include Error Correction Code (ECC), and how does it function in practice?

Yes, the 25CS640T-I/Q4B includes built-in ECC logic that corrects up to one bit error per 4-byte readout. When enabled, it automatically detects and fixes single-bit corruption during memory reads and sets the ECS (Error Correction State) bit in the STATUS register to indicate correction occurred. This feature significantly improves long-term data integrity in electrically noisy environments like automotive powertrains. The 25CS640T-I/Q4B does not require external ECC management - correction is fully transparent and hardware-accelerated.

How is the 128-bit serial number implemented in the 25CS640T-I/Q4B, and is it accessible during normal operation?

The 25CS640T-I/Q4B contains a factory-programmed, globally unique 128-bit serial number stored in the first 16 bytes of its Security register. It is read-only, permanently programmed during wafer test, and accessible via standard SPI read commands to the Security register address range (0x0000–0x000F). No special unlock sequence is needed - the serial number is immediately available after power-up and remains unchanged across all 4 million write cycles. This eliminates post-manufacturing serialization effort for the 25CS640T-I/Q4B.

What write protection modes does the 25CS640T-I/Q4B support, and how do they differ?

The 25CS640T-I/Q4B supports two distinct write protection modes: Legacy mode uses BP[1:0] bits in the STATUS register to protect quarter/half/all memory blocks, while Enhanced mode uses four Memory Partition registers (MPR0–MPR3) to define independent, software- or hardware-locked zones. In Enhanced mode, each partition can be set to unprotected, software-protected, WP-pin-protected, or permanently locked - enabling granular control for OTA updates and calibration security. Both modes are selected via the WPM bit in the STATUS register of the 25CS640T-I/Q4B.

Is the 25CS640T-I/Q4B AEC-Q100 qualified, and which temperature grade does the 'I' suffix denote?

Yes, the 25CS640T-I/Q4B is AEC-Q100 qualified per Rev G for automotive applications. The 'I' suffix denotes Industrial temperature grade, specifying guaranteed operation from −40°C to +85°C. This qualification includes stress testing for HTOL, TCT, ESD (HBM >4 kV), and package reliability - validating suitability for under-dash and engine-compartment-adjacent modules. The 25CS640T-I/Q4B also supports Extended (E) and High-temp (H) grades, but the 'I' variant is optimized for cost-sensitive automotive infotainment and body electronics.

25CS640T-I/Q4B Specifications

Product attributes: Attribute value

Manufacturer:: Microchip Technology

Series:: -

Package/Case:: 8-UFDFN Exposed Pad

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:: 20 MHz

Write Cycle Time - Word, Page:: 4ms

Access Time:: 20 ns

Voltage - Supply:: 1.7V ~ 5.5V

Operating Temperature:: -40°C ~ 85°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 8-UDFN (2x3)

25CS640T-I/Q4B FAQ

1.How can I place an order for 25CS640T-I/Q4B through Aetrix?

Please submit a Request for Quotation (RFQ) for 25CS640T-I/Q4B 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-I/Q4B reliable?

The price and inventory of 25CS640T-I/Q4B are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 25CS640T-I/Q4B is usually 5 days.

3.What payment methods are accepted for 25CS640T-I/Q4B?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25CS640T-I/Q4B transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 25CS640T-I/Q4B?

25CS640T-I/Q4B orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 25CS640T-I/Q4B 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-I/Q4B?

For technical support, including 25CS640T-I/Q4B datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25CS640T-I/Q4B requirements.

6.How does Aetrix verify that 25CS640T-I/Q4B is sourced from the original manufacturer or authorized distributors?

All 25CS640T-I/Q4B 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-I/Q4B meets industry standards.

7.What is the process for return or replacement of 25CS640T-I/Q4B?

All 25CS640T-I/Q4B units undergo pre-shipment inspection (PSI). If there is an issue with 25CS640T-I/Q4B, 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-I/Q4B part is unused and in its original packaging.

Return procedure for 25CS640T-I/Q4B:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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