My Inquiry
My Account
Microchip Technology 25AA640AT-E/ST
- Part No.:
- 25AA640AT-E/ST
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
25AA640AT-E/ST.pdf
- Description:
- IC EEPROM 64KBIT SPI 8TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,070
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
25AA640AT-E/ST from Microchip Technology Inc. is a 64-Kbit SPI Serial EEPROM with 8192 × 8-bit organization, 32-byte page size, and 1.8V–5.5V supply range. It supports up to 10 MHz clock frequency at 4.5–5.5V, features hardware write protection via WP pin and STATUS register, and delivers 1 million erase/write cycles with >200-year data retention - deployed in automotive instrument clusters for calibration storage.
For engineers reviewing the 25AA640AT-E/ST datasheet, 25AA640AT-E/ST pinout, 25AA640AT-E/ST application, or 25AA640AT-E/ST equivalent, this page provides verified electrical specs, SPI timing constraints, HOLD/CS interaction behavior, block protection configuration logic, and AEC-Q100 Grade 1 (−40°C to +125°C) qualification evidence.
Technical Context
The 25AA640AT-E/ST implements a standard SPI Mode 0,0/Motorola-compatible interface with separate SI (data-in) and SO (data-out) lines, requiring CS low and HOLD high for active operation. Its internal architecture includes an 8-bit instruction register, page latches, and HV generator for EEPROM programming, enabling byte- and page-write sequences with automatic address incrementing during sequential reads.
Write operations require explicit WREN instruction before WRITE or WRSR commands; the write enable latch resets after power-up, WRDI, WRSR, or successful WRITE. Block protection is controlled by BP0/BP1 bits in the nonvolatile STATUS register, allowing selective write-protection of 0%, 25%, 50%, or 100% of the memory array - independent of WP pin state unless WPEN bit is set.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8192 × 8-bit), sufficient for firmware patch storage or sensor calibration tables in space-constrained ECUs. |
| Page Size | 32 bytes - defines maximum contiguous write length without crossing physical boundaries; crossing triggers wrap-around within same page. |
| Max Clock Frequency | 10 MHz at VCC ≥ 4.5V - enables fast parameter loading in real-time control loops; drops to 5 MHz at 2.5–4.5V and 3 MHz below 2.5V. |
| Write Cycle Time | ≤5 ms per internal write - deterministic latency for critical configuration updates; no polling required beyond WIP bit check. |
| Endurance & Retention | 1,000,000 erase/write cycles and >200 years data retention - validated at +25°C, VCC = 5.5V; meets ASIL-B functional safety data logging requirements. |
| Supply Voltage Range | 1.8V–5.5V - supports direct interfacing with 1.8V logic controllers and legacy 5V microcontrollers without level-shifting. |
| Temperature Range | −40°C to +125°C (Extended grade) - qualified per AEC-Q100 Rev G, suitable for under-hood automotive applications. |
Pinout & Package
25AA640AT-E/ST is supplied in an 8-lead TSSOP package (3.0 mm × 4.4 mm, 0.65 mm pitch), RoHS-compliant and lead-free. Pin 1 is marked with a dot; pin numbering follows standard TSSOP convention (counterclockwise from mark).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CS (Pin 1) | Chip Select Input | Active-low enable: drives device into Standby when high; initiates internal write cycle on rising edge after valid write sequence. |
| SO (Pin 2) | Serial Data Output | Tri-state output: shifts out read data on SCK falling edge; enters high-Z when CS high or HOLD asserted. |
| WP (Pin 3) | Write-Protect Input | Hardware lock: disables STATUS register writes when WP low and WPEN = 1; otherwise ignored if WPEN = 0. |
| VSS (Pin 4) | Ground | Reference return path for all I/O and core circuitry; must be low-impedance connection to avoid noise-induced corruption. |
| SI (Pin 5) | Serial Data Input | Latches instructions, addresses, and write data on SCK rising edge; requires setup/hold timing compliance per Table 1-2. |
| SCK (Pin 6) | Serial Clock Input | Synchronizes all SPI transactions; rise/fall times ≤100 ns required; clock low/high times scale with VCC. |
| HOLD (Pin 7) | Hold Input | Pauses ongoing SPI transfer without resetting state: must be driven low while SCK is low; resumes on rising edge while SCK low. |
| VCC (Pin 8) | Supply Voltage | Power input: supports 1.8V–5.5V; decoupling capacitor (0.1 µF ceramic) required within 5 mm of pin for stable operation. |
Key Features
| Feature | Design Value |
|---|---|
| Self-timed write cycles | Fixed 5 ms max internal write time eliminates need for external timing control or variable delay loops in host firmware. |
| Programmable block protection | BP0/BP1 bits allow runtime-selectable write-lock of upper 25%, 50%, or full array - enabling secure boot code partitioning. |
| HOLD pin suspend/resume | Enables interrupt servicing during multi-byte transfers: host can pause communication, service higher-priority ISR, then resume seamlessly. |
| Power-on data protection | Write enable latch resets at power-up, and WP pin + WPEN bit prevent accidental writes during brown-out or reset conditions. |
| AEC-Q100 Grade 1 qualification | Validated for −40°C to +125°C operation with extended reliability testing - meets automotive ECU environmental stress requirements. |
Applications
| Automotive Instrument Cluster | Industrial PLC Configuration Storage |
|---|---|
|
Use Scenario: Storing odometer values, trip counters, and display calibration offsets across ignition cycles. IC Role / Device Role / Timing Role: Nonvolatile parameter store accessed via SPI during boot and runtime; HOLD used to defer writes during CAN message processing. Use Value: 1M endurance ensures >10 years of daily recalibration without wear-out; 125°C rating supports placement near dashboard backlight drivers. |
Use Scenario: Holding user-defined I/O mapping, PID tuning constants, and alarm thresholds in modular control cabinets. IC Role / Device Role / Timing Role: SPI-configurable memory mapped to controller's peripheral address space; WP pin tied low for factory-set parameter lock. Use Value: Block protection prevents field technicians from overwriting critical safety parameters while permitting update of operational settings. |
| Medical Infusion Pump Calibration | Smart Energy Meter Firmware Patching |
|
Use Scenario: Retaining flow-rate calibration coefficients and usage logs subject to regulatory audit trails. IC Role / Device Role / Timing Role: Secure EEPROM with write-enable gating and status-register verification; accessed only during maintenance mode. Use Value: >200-year data retention satisfies FDA 21 CFR Part 11 long-term recordkeeping mandates; ESD >4 kV withstands clinical environment handling. |
Use Scenario: Storing delta patches for meter firmware upgrades delivered over HAN or PLC networks. IC Role / Device Role / Timing Role: High-speed SPI slave (10 MHz) enabling sub-second patch application; page-write minimizes flash wear on main MCU. Use Value: 32-byte page size aligns with AES-128 encrypted packet payloads; 1.8V operation allows direct interface with ultra-low-power metrology SoCs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 25LC640AT-E/ST | Requires minimum 2.5V VCC; identical pinout, timing, and feature set otherwise. | Not suitable for 1.8V systems; otherwise drop-in replacement in 2.5–5.5V industrial designs. | Select when system rail is ≥2.5V and cost sensitivity favors LC-series pricing. |
| AT25DF641A-SHN-T | Quad SPI interface, 8-pin SOIC, 3.0V–3.6V only; 64 Mbit density, faster 80 MHz DTR mode. | Higher density and speed but incompatible SPI protocol; requires firmware driver rewrite and layout change. | Choose only when migrating to quad-I/O architecture and needing >64 Kbit capacity. |
Compared with 25LC640AT-E/ST, the 25AA640AT-E/ST enables 1.8V operation critical for battery-backed systems, while AT25DF641A-SHN-T offers greater bandwidth at the cost of software and hardware redesign - making the 25AA640AT-E/ST optimal for cost-sensitive, low-voltage automotive and industrial nodes.
Availability
25AA640AT-E/ST is available at Aetrix Electronics and suitable for automotive instrument clusters, industrial PLCs, medical infusion pumps, and smart energy meters requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for 25AA640AT-E/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 microcontroller, analog, FPGA, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.
The 25AA640A family was designed specifically for automotive and industrial applications demanding robust nonvolatile storage with AEC-Q100 qualification, low-voltage operation, and SPI compatibility across diverse host processors.
FAQ
What is the minimum VCC voltage supported by the 25AA640AT-E/ST?
The 25AA640AT-E/ST operates down to 1.8V, enabling direct integration with 1.8V logic families and battery-powered systems where rail voltage may dip below 2.5V. This distinguishes it from the 25LC640A variant, which requires a minimum of 2.5V. The 25AA640AT-E/ST maintains full functionality-including 10 MHz operation-at 4.5–5.5V, scaling down to 3 MHz at 1.8–2.5V per AC characteristics table.
How does the HOLD pin function during an active SPI transaction on the 25AA640AT-E/ST?
The HOLD pin on the 25AA640AT-E/ST suspends ongoing SPI communication without resetting the internal state: it must be driven low while SCK is low to enter hold mode, tri-stating SO and ignoring SI/SCK transitions. To resume, HOLD must be raised high while SCK remains low. This allows the host microcontroller to service time-critical interrupts and return precisely to the suspended byte position - a key capability confirmed in Section 2.6 and Figure 1-1 of DS20001830G.
Can the 25AA640AT-E/ST be used as a direct replacement for the 25LC640AT-E/ST?
No - while both share identical pinout, package, and most electrical specs, the 25AA640AT-E/ST supports 1.8V–5.5V operation whereas the 25LC640AT-E/ST requires ≥2.5V. Substituting the 25AA640AT-E/ST into a 2.5V-only design is safe, but replacing 25AA640AT-E/ST with 25LC640AT-E/ST in a 1.8V system will cause functional failure. Always verify VCC compliance before interchange.
What protection mechanisms prevent unintended writes to the 25AA640AT-E/ST memory array?
The 25AA640AT-E/ST employs three layered protections: (1) a volatile write enable latch that resets at power-up and after every write, requiring explicit WREN command; (2) nonvolatile BP0/BP1 bits enabling software-selectable block protection; and (3) hardware write protection via WP pin, enabled only when WPEN bit is set and WP is low. These are documented in Sections 3.4–3.6 and Table 5-1 of DS20001830G.
Is the 25AA640AT-E/ST qualified for automotive applications?
Yes - the 25AA640AT-E/ST carries AEC-Q100 Grade 1 qualification (−40°C to +125°C), explicitly stated in the "Temperature Ranges Supported" section of the datasheet. This qualification includes stress testing for temperature cycling, humidity, and lifetime reliability, confirming suitability for under-hood and dashboard-mounted automotive ECUs where thermal robustness is mandatory.
25AA640AT-E/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:
- 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:
- 1.8V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-TSSOP
25AA640AT-E/ST FAQ
1.How can I place an order for 25AA640AT-E/ST through Aetrix?
Please submit a Request for Quotation (RFQ) for 25AA640AT-E/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 25AA640AT-E/ST reliable?
The price and inventory of 25AA640AT-E/ST are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 25AA640AT-E/ST is usually 5 days.
3.What payment methods are accepted for 25AA640AT-E/ST?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 25AA640AT-E/ST transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 25AA640AT-E/ST?
25AA640AT-E/ST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 25AA640AT-E/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 25AA640AT-E/ST?
For technical support, including 25AA640AT-E/ST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 25AA640AT-E/ST requirements.
6.How does Aetrix verify that 25AA640AT-E/ST is sourced from the original manufacturer or authorized distributors?
All 25AA640AT-E/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 25AA640AT-E/ST meets industry standards.
7.What is the process for return or replacement of 25AA640AT-E/ST?
All 25AA640AT-E/ST units undergo pre-shipment inspection (PSI). If there is an issue with 25AA640AT-E/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 25AA640AT-E/ST part is unused and in its original packaging.
Return procedure for 25AA640AT-E/ST:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
25AA640AT-E/ST Tags
-
M24C02-WMN6TP
STMicroelectronics
-
AT24C02C-XHM-T
Microchip Technology
-
AT21CS01-STUM10-T
Microchip Technology
-
AT24C02C-SSHM-T
Microchip Technology
-
24LC01BT-I/OT
Microchip Technology
-
M24C02-FMC6TG
STMicroelectronics
-
AT24CS02-SSHM-T
Microchip Technology
-
93LC46BT-I/OT
Microchip Technology
-
AT24C04C-SSHM-T
Microchip Technology
-
24LC01BT-I/SN
Microchip Technology
-
24AA02UIDT-I/OT
Microchip Technology
-
AT24C08C-STUM-T
Microchip Technology
Tech Hub
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
