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Microchip Technology 25LC640AT-E/ST16KVAO
- Part No.:
- 25LC640AT-E/ST16KVAO
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
25LC640AT-E/ST16KVAO.pdf
- Description:
- IC EEPROM 64KBIT SPI 8TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,379
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Product details
Overview
25LC640AT-E/ST16KVAO from Microchip Technology Inc. is a 64-Kbit SPI serial EEPROM with 8192 × 8-bit organization, 32-byte page size, and 10 MHz max clock (at 4.5–5.5V). It features hardware write protection via WP pin, HOLD suspend functionality, and AEC-Q100 qualification for automotive applications including engine control modules and ADAS sensor calibration storage.
For engineers reviewing the 25LC640AT-E/ST16KVAO datasheet, 25LC640AT-E/ST16KVAO pinout, 25LC640AT-E/ST16KVAO application, or 25LC640AT-E/ST16KVAO equivalent, this page delivers verified electrical specs, SPI timing constraints, block protection configuration, endurance/reliability data, and package-specific pin mapping for immediate design integration.
Technical Context
The 25LC640AT-E/ST16KVAO implements a standard SPI Mode 0,0/Master-Slave interface with separate SI (data in) and SO (data out) lines, requiring CS, SCK, WP, HOLD, VCC, and VSS. Its internal architecture includes a 32-byte page latch, status register with WIP/WEL/BP0/BP1 bits, and high-voltage generator for EEPROM programming.
Write operations require explicit WREN instruction before WRITE or WRSR commands; writes are self-timed (≤5 ms), and page boundaries (0x0000–0x001F, etc.) strictly constrain multi-byte writes. Block protection supports four configurations (none, upper 1/4, upper 1/2, or full array) via BP0/BP1 bits in the nonvolatile STATUS register.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8192 × 8-bit), directly addressable via 16-bit SPI command addressing |
| Page Size | 32 bytes - maximum contiguous bytes writable per single CS assertion; crossing boundary wraps within page |
| Max Clock Frequency | 10 MHz at VCC = 4.5–5.5V - enables ≤100 ns minimum clock period for high-speed read/write sequences |
| Write Cycle Time | ≤5 ms - internal self-timed erase-and-write; no external delay required beyond CS deassertion |
| Endurance | 1,000,000 erase/write cycles - guaranteed at +25°C, VCC = 5.5V; critical for firmware update logging |
| Data Retention | >200 years - ensures long-term calibration data integrity in automotive and industrial deployments |
| Operating Temp | −40°C to +125°C (Extended range) - validated for under-hood automotive ECUs and powertrain systems |
Pinout & Package
25LC640AT-E/ST16KVAO is packaged in an 8-lead TSSOP (ST) with 0.65 mm pitch, 3.0 mm × 4.4 mm body, and exposed pad (not electrically connected). Pin numbering follows standard TSSOP orientation with Pin 1 at top-left corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS (Pin 1) | Chip Select Input | Active-low enable; initiates internal write cycle on rising edge after valid write sequence; forces SO to high-Z when high |
| SO (Pin 2) | Serial Data Output | Tri-state output; data shifted out MSB-first on falling edge of SCK; high-Z when CS high or HOLD low |
| WP (Pin 3) | Write-Protect Control | Hardware lock for STATUS register when WPEN=1; no effect if WPEN=0; does not block array reads |
| VSS (Pin 4) | Ground Reference | Primary return path for all I/O and core logic; must be low-impedance connection to system GND plane |
| SI (Pin 5) | Serial Data Input | Accepts instructions (READ/WRITE/WREN/RDSR), addresses, and data on rising edge of SCK |
| SCK (Pin 6) | Serial Clock Input | Synchronizes all SPI transfers; rising edge latches SI, falling edge updates SO; requires stable 50–100 ns rise/fall times |
| HOLD (Pin 7) | Communication Suspend | Pull-low pauses ongoing SPI sequence without reset; must be asserted while SCK is low to avoid bus contention |
| VCC (Pin 8) | Supply Voltage | 2.5V–5.5V operation; decoupling capacitor (0.1 µF ceramic) required within 5 mm of pin for noise immunity |
Key Features
| Feature | Design Value |
|---|---|
| Block Write Protection | Selectable via BP0/BP1 bits: protects none, upper 1/4 (0x1800–0x1FFF), upper 1/2 (0x1000–0x1FFF), or full array (0x0000–0x1FFF) |
| Power-On Data Protection | Write enable latch resets at power-up; prevents accidental writes during voltage ramp-up or brownout conditions |
| HOLD Functionality | Enables host MCU to service higher-priority interrupts mid-transfer; resumes from exact byte position without retransmission |
| RoHS & AEC-Q100 Qualified | Complies with automotive reliability standards including temperature cycling, HTOL, and ESD (>4 kV HBM) for under-hood use |
| Low Standby Current | 1 µA at 5.5V and +85°C - extends battery life in always-on vehicle modules such as telematics and keyless entry receivers |
Applications
| Engine Control Unit (ECU) Calibration Storage | ADAS Sensor Configuration Memory |
|---|---|
Use Scenario: Storing trim values, fuel map coefficients, and emission calibration data that must survive ignition cycles and software updates. IC Role / Device Role / Timing Role: Nonvolatile parameter store interfaced via SPI to MCU; accessed during boot and runtime reconfiguration. Use Value: 200+ year data retention ensures calibration persistence over vehicle lifetime; AEC-Q100 qualification guarantees operation at 125°C under hood. | Use Scenario: Holding camera lens focus offsets, radar beam steering parameters, and LiDAR time-of-flight calibration constants. IC Role / Device Role / Timing Role: SPI-configurable memory mapped by vision processor; updated during factory calibration and field OTA updates. Use Value: 1M endurance supports frequent recalibration; HOLD pin allows uninterrupted sensor streaming during parameter reload. |
| Infotainment System Bootloader Settings | Electric Power Steering (EPS) Fault Log |
Use Scenario: Preserving UI language selection, Bluetooth pairing IDs, and display brightness preferences across power-down events. IC Role / Device Role / Timing Role: Low-power SPI EEPROM accessed during boot initialization; retains user state without backup battery. Use Value: 1 µA standby current minimizes parasitic drain; 32-byte page writes optimize small setting updates without erasing full sectors. | Use Scenario: Recording motor current anomalies, torque sensor deviations, and thermal fault timestamps for diagnostic traceability. IC Role / Device Role / Timing Role: Cyclic buffer storage managed by EPS MCU; written during fault detection with timestamped entries. Use Value: Self-timed 5 ms writes ensure deterministic logging latency; block protection prevents corruption of critical safety logs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25LC640AT-I/ST | Industrial temp range (−40°C to +85°C); same pinout, timing, and memory map | Not qualified to AEC-Q100; unsuitable for under-hood automotive deployment | Select only for non-automotive industrial control or consumer electronics where extended temperature is unnecessary |
| AT25DF641-SSH-T | Dual/quad SPI interface; 64 Mbit density; sector erase capability; different command set and status register layout | Requires firmware rewrite for SPI mode switching and address translation; no HOLD pin support | Choose only when higher density or faster random access is required and legacy compatibility is not mandatory |
Compared with 25LC640AT-I/ST, the 25LC640AT-E/ST16KVAO adds AEC-Q100 validation and extended temperature support essential for automotive safety-critical functions; versus AT25DF641-SSH-T, it offers simpler SPI protocol, lower power, and direct HOLD-based interrupt handling-ideal for resource-constrained MCUs in real-time control loops.
Availability
25LC640AT-E/ST16KVAO is available at Aetrix Electronics and suitable for automotive engine management, ADAS sensor calibration, infotainment personalization, and EPS fault logging requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for 25LC640AT-E/ST16KVAO 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 25LC640A family delivers cost-optimized, SPI-compatible EEPROMs targeting automotive, industrial, and consumer applications requiring robust nonvolatile storage with minimal footprint and low power consumption.
FAQ
What is the operating voltage range for the 25LC640AT-E/ST16KVAO?
The 25LC640AT-E/ST16KVAO operates from 2.5V to 5.5V. This range supports both 3.3V and 5V microcontroller interfaces without level shifting. At 2.5V, maximum clock frequency is reduced to 3 MHz; at 4.5–5.5V, it achieves full 10 MHz performance. The device includes built-in power-on reset circuitry to ensure reliable initialization across this voltage window.
Does the 25LC640AT-E/ST16KVAO support SPI Mode 0,0 only?
Yes, the 25LC640AT-E/ST16KVAO is strictly compliant with SPI Mode 0,0 (CPOL = 0, CPHA = 0): SCK idles low, data sampled on rising edge, and output changes on falling edge. It does not support Mode 1,1 or quad-SPI variants. This fixed mode simplifies driver development and ensures interoperability with PIC® and other Microchip MCUs using native SPI peripherals.
How does the HOLD pin function during an active SPI transaction with the 25LC640AT-E/ST16KVAO?
The HOLD pin on the 25LC640AT-E/ST16KVAO suspends communication mid-transaction when pulled low while SCK is low. During HOLD, SI/SO/SCK enter high-impedance states and all inputs except CS are ignored. To resume, HOLD must be raised while SCK remains low. This preserves the exact byte position and eliminates retransmission overhead-critical for time-sensitive MCU interrupt handling.
Can the 25LC640AT-E/ST16KVAO be used in place of the 25AA640A in existing designs?
No-the 25LC640AT-E/ST16KVAO has a minimum VCC of 2.5V, whereas the 25AA640A supports down to 1.8V. Substituting them risks functional failure below 2.5V. Additionally, the 25LC640AT-E/ST16KVAO is AEC-Q100 qualified and rated for −40°C to +125°C, while the 25AA640A is rated for −40°C to +85°C (I-temp) or +125°C (E-temp) but lacks automotive qualification. Use only after verifying voltage and qualification requirements.
What happens if a page write crosses a 32-byte boundary on the 25LC640AT-E/ST16KVAO?
If a page write command attempts to cross a 32-byte boundary (e.g., writing 32 bytes starting at address 0x001F), the 25LC640AT-E/ST16KVAO wraps the excess bytes back to the start of the same page (0x0000), overwriting previously loaded data. This behavior is inherent to the page latch architecture and is documented in Figure 3-3. Application firmware must enforce boundary checks to prevent unintended data corruption.
25LC640AT-E/ST16KVAO 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:
- Not 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 ~ 125°C (TA)
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-TSSOP
25LC640AT-E/ST16KVAO FAQ
1.How can I place an order for 25LC640AT-E/ST16KVAO through Aetrix?
Please submit a Request for Quotation (RFQ) for 25LC640AT-E/ST16KVAO 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 25LC640AT-E/ST16KVAO reliable?
The price and inventory of 25LC640AT-E/ST16KVAO are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 25LC640AT-E/ST16KVAO is usually 5 days.
3.What payment methods are accepted for 25LC640AT-E/ST16KVAO?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25LC640AT-E/ST16KVAO transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25LC640AT-E/ST16KVAO?
25LC640AT-E/ST16KVAO orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25LC640AT-E/ST16KVAO 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 25LC640AT-E/ST16KVAO?
For technical support, including 25LC640AT-E/ST16KVAO datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25LC640AT-E/ST16KVAO requirements.
6.How does Aetrix verify that 25LC640AT-E/ST16KVAO is sourced from the original manufacturer or authorized distributors?
All 25LC640AT-E/ST16KVAO 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 25LC640AT-E/ST16KVAO meets industry standards.
7.What is the process for return or replacement of 25LC640AT-E/ST16KVAO?
All 25LC640AT-E/ST16KVAO units undergo pre-shipment inspection (PSI). If there is an issue with 25LC640AT-E/ST16KVAO, 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 25LC640AT-E/ST16KVAO part is unused and in its original packaging.
Return procedure for 25LC640AT-E/ST16KVAO:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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