Microchip Technology 25LC040-I/P

Overview

25LC040-I/P from Microchip Technology Inc. is a 4 Kbit (512 × 8) SPI-compatible serial EEPROM with industrial temperature range (−40°C to +85°C), 2 MHz max clock frequency at VCC ≥ 2.5V, and 8-pin PDIP package. It features hardware write protection (WP pin), HOLD suspend functionality, and 16-byte page write capability - used for nonvolatile parameter storage in microcontroller-based embedded systems requiring low-power, reliable data retention.

For engineers reviewing the 25LC040-I/P datasheet, 25LC040-I/P pinout, 25LC040-I/P application, or 25LC040-I/P equivalent, this page delivers verified electrical specs, validated SPI timing behavior, confirmed industrial-grade reliability (1M endurance, >200-year data retention), and precise package mapping for PCB layout and firmware integration.

Technical Context

The 25LC040-I/P implements a standard SPI Mode 0,0 (CPOL=0, CPHA=0) interface with separate SI (data-in) and SO (data-out) lines, requiring CS, SCK, SI, SO, WP, HOLD, VCC, and VSS connections. Its internal architecture includes an 8-bit instruction register, auto-incrementing address pointer for sequential reads, and a STATUS register with WIP/WEL/BP bits accessible via RDSR/WRSR commands.

Write operations require explicit WREN instruction followed by CS high-to-low transition to initiate self-timed internal write cycle (≤5 ms). Block protection is configurable via BP0/BP1 bits to lock 0%, 25%, 50%, or 100% of the 512-byte array, while WP pin provides hardware-level write disable independent of latch state.

Key Specifications

Pinout & Package

8-pin Plastic Dual In-line Package (PDIP), 300 mil width, through-hole mount. Pin 1 is CS (Chip Select), pin 4 is VSS (ground), pin 8 is VCC (supply), and pin 7 is HOLD - all pins match JEDEC MS-001 standard.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25LC040-I/P, 25AA040-I/P adds 1.8V compatibility at reduced speed, while 25LC040A-I/P improves robustness and qualifies for new designs - making the original part optimal only for cost-sensitive, voltage-stable 2.5–5.5V industrial replacements.

Availability

25LC040-I/P is available at Aetrix Electronics and suitable for industrial sensor calibration, smart meter firmware parameters, and PLC I/O module configuration requiring stable component supply across extended product lifecycles.

Supply support for 25LC040-I/P 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 25LC040-I/P belongs to Microchip's legacy SPI Serial EEPROM product line, designed specifically for low-power, high-reliability nonvolatile data storage in industrial and commercial embedded systems where pin count, board space, and firmware simplicity are critical.

FAQ

What is the maximum SPI clock frequency supported by the 25LC040-I/P?

The 25LC040-I/P supports up to 2 MHz maximum clock frequency when VCC is 2.5V or higher. At VCC = 1.8V, it is not rated - that specification applies only to the 25AA040 variant. This 2 MHz limit ensures reliable data sampling on SI and stable SO output timing under industrial temperature conditions.

Does the 25LC040-I/P support 1.8V operation?

No, the 25LC040-I/P does not support 1.8V operation. Its specified VCC range is 2.5V to 5.5V. For 1.8V systems, Microchip recommends the 25AA040-I/P, which shares identical pinout and instruction set but extends down to 1.8V with reduced maximum clock speed (1 MHz).

How does the HOLD pin function during an active SPI transaction on the 25LC040-I/P?

The HOLD pin on the 25LC040-I/P suspends ongoing SPI communication without resetting the internal state. When pulled low while SCK is low, SI/SO/SCK enter high-impedance and all inputs except CS are ignored. Resuming requires bringing HOLD high while SCK remains low - then transmission continues from the exact bit position where it paused.

What is the purpose of the WP (Write-Protect) pin on the 25LC040-I/P?

The WP pin on the 25LC040-I/P provides hardware-level write inhibition: when held low, it disables all writes to both memory array and STATUS register - even if the write-enable latch (WEL) is set. This ensures fail-safe protection against spurious writes during power transients or firmware errors.

Is the 25LC040-I/P still recommended for new designs?

No - Microchip explicitly states "Not recommended for new designs" in DS21204E-page 1 and recommends migrating to the enhanced 25LC040A-I/P. The original 25LC040-I/P remains valid for legacy repair, second-source procurement, or BOM continuity where redesign is not feasible.