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Microchip Technology 25LC640A-I/SN
- Part No.:
- 25LC640A-I/SN
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
25LC640A-I/SN.pdf
- Description:
- IC EEPROM 64KBIT SPI 10MHZ 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,638
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Product details
Overview
25LC640A-I/SN from Microchip Technology Inc. is a 64-Kbit SPI Serial EEPROM with 8192 × 8-bit organization, 32-byte page size, and industrial temperature range (–40°C to +85°C). It operates at up to 10 MHz clock frequency with 5 mA read/write current at 5.5 V and supports hardware write protection via WP pin and STATUS register. It is used in microcontroller-based systems for nonvolatile parameter storage, calibration data retention, and firmware configuration.
For engineers reviewing the 25LC640A-I/SN datasheet, 25LC640A-I/SN pinout, 25LC640A-I/SN application, or 25LC640A-I/SN equivalent, key selection criteria include VCC range (2.5–5.5 V), SPI timing compliance (TCSS, TCSH, TWC ≤ 5 ms), block write protection granularity, HOLD functionality for interrupt-safe bus arbitration, and SOIC-8 (SN) package compatibility with legacy PCB layouts.
Technical Context
The 25LC640A-I/SN implements a standard SPI Mode 0,0/Master-Slave interface with separate SI (data-in) and SO (data-out) lines, CS-controlled selection, and SCK-synchronized latching on rising edge (SI) and falling edge (SO). Its internal architecture includes an 8-bit instruction register, page latches, and high-voltage generator for EEPROM programming.
It features dual-layer write protection: volatile WEL latch (set/reset via WREN/WRDI) and nonvolatile BP0/BP1 bits (set via WRSR) enabling 0%, 25%, 50%, or 100% array protection. The HOLD pin suspends ongoing serial transfers without resetting the sequence, allowing host MCU to service higher-priority interrupts while preserving address/data state.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8192 × 8-bit), sufficient for storing bootloader configs, sensor calibration tables, or device identity data in resource-constrained embedded systems. |
| Interface | SPI-compatible serial bus (Mode 0,0), requiring only CS, SCK, SI, SO - minimal GPIO usage and no I²C pull-up dependencies. |
| Max Clock Frequency | 10 MHz at VCC ≥ 4.5 V; enables fast bulk reads/writes (e.g., 32-byte page write in ~5 ms) without demanding high-speed MCU peripherals. |
| Write Cycle Time | ≤ 5 ms internal self-timed erase/write; eliminates need for external polling delay timers in firmware. |
| Endurance & Retention | 1,000,000 erase/write cycles and >200 years data retention at +85°C - suitable for field-deployed equipment with long service life. |
| VCC Range | 2.5 V to 5.5 V - interoperable with both 3.3 V and 5 V logic domains, easing integration into mixed-voltage designs. |
| Operating Temp | –40°C to +85°C (Industrial grade) - validated for use in automotive control modules, industrial PLCs, and outdoor IoT gateways. |
Pinout & Package
25LC640A-I/SN is packaged in an 8-lead narrow-body SOIC (SN), measuring 3.90 mm × 4.90 mm × 1.75 mm, with gull-wing leads and standard JEDEC MS-012AC footprint. Pin 1 is marked by a beveled corner or dot; the package is RoHS-compliant and Pb-free.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS (Pin 1) | Chip Select Input | Active-low enable: pulls device out of standby; rising edge after WRITE initiates internal 5 ms write cycle; must be held low during full SPI transaction. |
| SO (Pin 2) | Serial Data Output | Tri-state open-drain output; data shifted out on SCK falling edge; goes high-Z when CS high or HOLD active - enables multi-device SPI bus sharing. |
| WP (Pin 3) | Write-Protect Control | Hardware lock: when WPEN=1 in STATUS register and WP=low, disables writes to nonvolatile STATUS bits; does not affect memory array if WPEN=0. |
| VSS (Pin 4) | Ground Reference | Primary return path for all internal circuitry; must be low-impedance and decoupled near VCC pin to suppress SPI noise-induced read errors. |
| SI (Pin 5) | Serial Data Input | CMOS input latched on SCK rising edge; accepts 8-bit instructions (READ/WRITE/RDSR/WRSR), 16-bit addresses, and data bytes - MSB-first protocol. |
| SCK (Pin 6) | Serial Clock Input | Asynchronous master clock; defines timing windows (TCSS, TCSH, TSU, THD) - max 10 MHz at 5.5 V; requires monotonic rise/fall times ≤100 ns. |
| HOLD (Pin 7) | Bus Hold Control | Pauses ongoing SPI transfer when pulled low while SCK=low; preserves internal address pointer and state - critical for deterministic interrupt response in real-time systems. |
| VCC (Pin 8) | Supply Voltage | 2.5–5.5 V power rail; internal charge pump generates programming voltage; bypass capacitor (0.1 µF ceramic) required between VCC and VSS within 5 mm. |
Key Features
| Feature | Design Value |
|---|---|
| 32-byte page write buffer | Enables burst writes up to 32 bytes within one physical page (0x000–0x01F, 0x020–0x03F, etc.), reducing SPI overhead vs. byte-by-byte writes - improves firmware update efficiency. |
| Four-level block protection | BP1/BP0 bits in STATUS register allow selective write-lock of 0%, 25%, 50%, or 100% of memory (e.g., protect upper 1/4 for factory calibration data while leaving lower 3/4 user-writable). |
| HOLD pin with zero-cycle resume | Halts SPI communication mid-sequence without losing context; resumption occurs on next SCK edge after HOLD returns high - eliminates retransmission logic in host firmware. |
| Power-on write disable | WEL latch resets automatically at power-up, preventing accidental writes during brown-out or reset sequences - enhances system robustness in uncontrolled power environments. |
| ESD tolerance >4 kV HBM | Withstands electrostatic discharge events common during board handling and field servicing - reduces need for external TVS diodes in cost-sensitive consumer applications. |
Applications
| Industrial Sensor Node | Automotive Body Controller |
|---|---|
|
Use Scenario: Storing calibrated offset/gain values for temperature, pressure, and humidity sensors across operating temperature range. IC Role / Device Role / Timing Role: Nonvolatile configuration storage accessed at boot via SPI; retains data through 10+ year field deployment without battery backup. Use Value: Eliminates factory recalibration during repair; enables field-updatable compensation curves using same 25LC640A-I/SN footprint across product variants. |
Use Scenario: Holding seat position memory, mirror angle presets, and lighting configuration profiles in 12 V vehicle electrical systems. IC Role / Device Role / Timing Role: SPI EEPROM interfaced to 8-bit automotive MCU; withstands load-dump transients and –40°C cold cranking conditions. Use Value: AEC-Q100 qualified operation ensures reliability over 15-year vehicle lifecycle; 2.5 V min VCC supports degraded battery operation down to 9 V. |
| Medical Infusion Pump | Smart Energy Meter |
|
Use Scenario: Recording dose history, alarm logs, and maintenance timestamps with tamper-resistant write protection. IC Role / Device Role / Timing Role: Secure parameter storage with WP pin hardwired to ground and WPEN=1 - prevents unauthorized firmware or calibration modification. Use Value: Meets IEC 62304 software safety requirements via hardware-enforced write lock; 1M endurance supports >100,000 dose entries over device lifetime. |
Use Scenario: Storing tariff schedules, metering constants, and cryptographic keys in utility-grade electricity meters. IC Role / Device Role / Timing Role: High-reliability data logger interfaced to metrology SoC; retains data >200 years at 85°C ambient inside sealed meter enclosure. Use Value: Eliminates supercapacitor/battery backup; RoHS-compliant SN package simplifies end-of-life recycling and meets EU WEEE directives. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar SPI EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25AA640A-I/SN | VCC range 1.8–5.5 V; supports 1.8 V logic systems; otherwise identical pinout, timing, and feature set. | Required for 1.8 V microcontrollers (e.g., PIC16F1xxx, STM32L0); not suitable for 2.5 V-only supply rails due to lower VIL thresholds. | Select when interfacing with ultra-low-power MCUs or battery-powered devices where 1.8 V operation is mandatory. |
| AT25DF041A-SHN-T | 4 Mbit density, quad-SPI support, 85 MHz max clock; different instruction set and STATUS register layout; SOIC-8 but not pin-compatible. | Used for firmware code storage (XIP-capable); lacks HOLD pin and hardware write protection granularity of 25LC640A-I/SN. | Choose only when migrating to larger memory or faster read speeds; requires PCB redesign and firmware driver rewrite. |
Compared with 25AA640A-I/SN, the 25LC640A-I/SN offers tighter VCC minimum (2.5 V vs. 1.8 V) but identical packaging, timing, and protection features - making it optimal for 3.3/5 V industrial systems. Versus AT25DF041A-SHN-T, it provides deterministic 5 ms writes and simpler SPI protocol at lower density, reducing firmware complexity and BOM cost.
Availability
25LC640A-I/SN is available at Aetrix Electronics and suitable for industrial sensor nodes, automotive body controllers, and medical infusion pumps requiring stable component supply, long-term lifecycle support, and RoHS-compliant manufacturing.
Supply support for 25LC640A-I/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 devices, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.
The 25LC640A belongs to Microchip's serial EEPROM product line, designed specifically for reliable, low-power, SPI-based nonvolatile data storage in industrial, automotive, and medical applications where long data retention and robust write protection are critical.
FAQ
What is the maximum clock frequency supported by the 25LC640A-I/SN?
The 25LC640A-I/SN supports up to 10 MHz clock frequency when VCC is 4.5 V to 5.5 V. At 2.5 V ≤ VCC < 4.5 V, the maximum clock drops to 5 MHz, and at 1.8 V ≤ VCC < 2.5 V, it is limited to 3 MHz. These limits ensure setup/hold timing margins are maintained across voltage and temperature ranges per Table 1-2 in the DS20001830G datasheet. The 25LC640A-I/SN does not support overclocking beyond these specifications.
Does the 25LC640A-I/SN require external pull-up resistors on its SPI lines?
No, the 25LC640A-I/SN does not require external pull-up resistors on SI, SO, or SCK. Its SO pin is internally tri-stated and driven actively, while SI and SCK are CMOS inputs with no pull-up/pull-down requirement. However, CS and WP should be pulled high via 10 kΩ resistors in most designs to ensure defined states during reset or floating conditions - this practice prevents spurious writes or unintended device selection. The 25LC640A-I/SN datasheet specifies no pull-up dependency for functional SPI operation.
How does the HOLD function work on the 25LC640A-I/SN during an active SPI read?
When HOLD is pulled low while SCK is low during an active SPI read, the 25LC640A-I/SN immediately tri-states SO and ignores further transitions on SI, SCK, and CS (except CS deassertion). The internal address pointer and shift register state are preserved. Resuming requires bringing HOLD high while SCK remains low; then normal read continuation occurs from the exact byte where it paused. This behavior is fully documented in Section 2.6 and Figure 1-1 of the 25LC640A-I/SN datasheet and requires no host-side reinitialization.
Can the 25LC640A-I/SN be used in automotive applications?
Yes, the 25LC640A-I/SN is AEC-Q100 qualified for automotive applications and rated for Industrial temperature range (–40°C to +85°C). Its 1,000,000 write endurance, >200-year data retention, and hardware write protection make it suitable for body control modules, infotainment configuration storage, and ADAS sensor calibration memory. The 25LC640A-I/SN part number explicitly denotes the industrial-temp SOIC-8 variant approved for under-hood and cabin-mounted automotive ECUs per Microchip's qualification report.
What is the purpose of the WP pin on the 25LC640A-I/SN, and how is it configured?
The WP (Write-Protect) pin on the 25LC640A-I/SN enables hardware-level write inhibition when combined with the WPEN bit in the STATUS register. When WPEN = 1 and WP = low, writes to nonvolatile STATUS register bits (BP0, BP1, WPEN) are blocked - protecting critical protection settings. If WPEN = 0, the WP pin has no effect. This dual-control scheme allows safe installation in systems with grounded WP pins while retaining full STATUS register programmability until WPEN is set. Configuration is performed via WRSR instruction per Section 3.6 of the 25LC640A-I/SN datasheet.
25LC640A-I/SN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Programmable:
- Verified
- 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:
- 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-SOIC
25LC640A-I/SN FAQ
1.How can I place an order for 25LC640A-I/SN through Aetrix?
Please submit a Request for Quotation (RFQ) for 25LC640A-I/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 25LC640A-I/SN reliable?
The price and inventory of 25LC640A-I/SN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 25LC640A-I/SN is usually 5 days.
3.What payment methods are accepted for 25LC640A-I/SN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25LC640A-I/SN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25LC640A-I/SN?
25LC640A-I/SN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25LC640A-I/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 25LC640A-I/SN?
For technical support, including 25LC640A-I/SN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25LC640A-I/SN requirements.
6.How does Aetrix verify that 25LC640A-I/SN is sourced from the original manufacturer or authorized distributors?
All 25LC640A-I/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 25LC640A-I/SN meets industry standards.
7.What is the process for return or replacement of 25LC640A-I/SN?
All 25LC640A-I/SN units undergo pre-shipment inspection (PSI). If there is an issue with 25LC640A-I/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 25LC640A-I/SN part is unused and in its original packaging.
Return procedure for 25LC640A-I/SN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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