Microchip Technology 25LC040A-I/MS

Overview

25LC040A-I/MS from Microchip Technology Inc. is a 4 Kbit SPI Serial EEPROM with 512 × 8-bit organization, 16-byte page write capability, and industrial temperature range (−40°C to +85°C). It operates at up to 10 MHz clock frequency, supports hardware write protection via WP pin, and delivers 5 µA standby current at 5.5 V - used for nonvolatile parameter storage in microcontroller-based embedded systems.

For engineers reviewing the 25LC040A-I/MS datasheet, 25LC040A-I/MS pinout, 25LC040A-I/MS application, or 25LC040A-I/MS equivalent, key selection criteria include SPI interface compatibility, 2.5–5.5 V supply range, page-write timing (≤5 ms), block protection granularity (none/¼/½/all), and MSOP-8 package footprint constraints.

Technical Context

The 25LC040A-I/MS implements a standard SPI Mode 0,0/Master-Slave interface with separate SI (data in) and SO (data out) lines, requiring CS, SCK, and HOLD control signals. Its internal architecture includes an 8-bit instruction register, status register (WIP/WEL/BP0/BP1), and page latches enabling atomic 16-byte writes within fixed 16-byte boundaries.

Write operations require explicit WREN instruction followed by CS high-to-low transition to initiate self-timed internal erase/write cycle (max 5 ms); read operations support sequential addressing with automatic address roll-over at 0x1FF. Hardware write protection is enforced via dedicated WP pin and STATUS register BP bits, independent of WEL state per Table 2-4.

Key Specifications

Pinout & Package

25LC040A-I/MS is housed in an 8-lead MSOP (Mini Small Outline Package) with 0.65 mm lead pitch, 3.0 mm × 3.0 mm body, and exposed pad (optional VSS connection). Pin 1 marked by laser dot; pin numbering follows standard MSOP convention.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25AA040A-I/MS, the 25LC040A-I/MS trades 1.8 V operation for tighter VCC min specification (2.5 V), while AT25040B-MAU-1.8 omits HOLD support - making 25LC040A-I/MS optimal for robust 3.3 V/5 V industrial designs needing interrupt-safe SPI pausing.

Availability

25LC040A-I/MS is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, and automotive subsystems requiring stable component supply, long-term data retention, and SPI-compatible nonvolatile memory.

Supply support for 25LC040A-I/MS 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 manufacturing and support infrastructure.

The 25LC040A belongs to Microchip's serial EEPROM product line, designed specifically for reliable, low-power, SPI-based nonvolatile data storage in cost-sensitive and space-constrained embedded applications.

FAQ

What is the maximum clock frequency supported by the 25LC040A-I/MS?

The 25LC040A-I/MS supports a maximum clock frequency of 10 MHz 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 it is further reduced to 3 MHz for 1.8 V ≤ VCC < 2.5 V - though the 25LC040A-I/MS does not operate below 2.5 V. These limits ensure setup/hold timing compliance per Table 1-2 AC characteristics.

Does the 25LC040A-I/MS support page write operations, and what is the page size?

Yes, the 25LC040A-I/MS supports page write mode with a fixed page size of 16 bytes. All bytes written in a single WRITE instruction sequence must reside within the same physical page (addresses ending in 0x00–0x0F, 0x10–0x1F, etc.). Attempting to cross a page boundary causes wraparound to the start of the current page - a behavior explicitly documented in Section 2.3 and Figure 2-3 of the 25LC040A-I/MS datasheet.

How does hardware write protection work on the 25LC040A-I/MS?

Hardware write protection on the 25LC040A-I/MS is implemented via the WP pin (Pin 3): when held low, it disables all writes to memory and STATUS register regardless of WEL or BP bit states. This function is independent of software-controlled protection and takes immediate effect - even during an ongoing write cycle, though that cycle will complete before new writes are blocked. The 25LC040A-I/MS datasheet confirms this behavior in Table 2-4 and Section 3.3.

What is the purpose of the HOLD pin on the 25LC040A-I/MS, and how is it used?

The HOLD pin (Pin 7) on the 25LC040A-I/MS suspends ongoing SPI communication without resetting the internal state, allowing the host microcontroller to service higher-priority interrupts. To activate HOLD, the pin must be driven low while SCK is low; resuming requires bringing HOLD high while SCK remains low. During HOLD, SI/SO/SCK enter high-impedance state - a feature confirmed in Section 3.6 and Figure 1-1 of the 25LC040A-I/MS datasheet.

What package type is used for the 25LC040A-I/MS, and what are its key mechanical features?

The 25LC040A-I/MS uses an 8-lead MSOP (Mini Small Outline Package) with 3.0 mm × 3.0 mm body, 0.65 mm lead pitch, and laser-marked Pin 1 indicator. It includes an exposed thermal pad (optional VSS connection) per Package Drawing YWW-002 in Microchip's DS21827H datasheet. This package provides superior thermal performance and board density versus SOIC, while maintaining compatibility with standard SMT reflow profiles.