Microchip Technology 25LC256-I/SM

Overview

25LC256-I/SM from Microchip Technology Inc. is a 256 Kbit SPI Serial EEPROM with 32,768 × 8-bit organization, 64-byte page size, and industrial temperature range (–40°C to +85°C). It operates from 2.5V to 5.5V, supports up to 10 MHz clock frequency, and delivers 5 mA max write current at 5.5V - used for nonvolatile configuration storage in microcontroller-based embedded systems.

For engineers reviewing the 25LC256-I/SM datasheet, 25LC256-I/SM pinout, 25LC256-I/SM application, or 25LC256-I/SM equivalent, key selection criteria include SPI interface compatibility, hardware write protection via WP pin, block-level array protection (BP0/BP1), and guaranteed 1 million erase/write cycles with >200-year data retention.

Technical Context

The 25LC256-I/SM implements a standard SPI Mode 0,0 or Mode 1,1 interface with separate SI (data in) and SO (data out) lines, controlled by CS, SCK, and optional HOLD for transaction suspension. Its internal architecture includes an 8-bit instruction register, status register with WIP/WEL/BP0/BP1 bits, and page latches enabling up to 64-byte page writes within aligned 64-byte boundaries.

Write operations require explicit WREN instruction followed by CS high-to-low transition to initiate self-timed internal write cycle (≤5 ms). Built-in power-on reset, write-enable latch auto-clear, and hardware/software write protection (WP pin + WPEN bit) ensure robust data integrity during brown-out or interrupt-driven host operation.

Key Specifications

Pinout & Package

25LC256-I/SM uses an 8-lead SOIC package (SN designation), 3.90 mm body width, with standard pin 1 marking and JEDEC-compliant lead pitch (1.27 mm).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT25SF041-SSHD-B, 25LC256-I/SM enables true byte-level random writes without erase overhead, critical for real-time parameter logging; versus 25AA256-I/SM, it trades 1.8V support for tighter VCC min (2.5V), simplifying power design in 3.3V/5V-only systems.

Availability

25LC256-I/SM is available at Aetrix Electronics and suitable for industrial sensor nodes, automotive body control modules, medical infusion pumps, and smart energy meters requiring stable component supply across extended product lifecycles.

Supply support for 25LC256-I/SM 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 components, and memory solutions, headquartered in Chandler, Arizona, with global manufacturing and support infrastructure.

The 25LC256 belongs to Microchip's serial EEPROM product line, designed specifically for reliable, low-power, SPI-based nonvolatile data storage in cost-sensitive, space-constrained embedded applications.

FAQ

What is the maximum clock frequency supported by the 25LC256-I/SM?

The 25LC256-I/SM supports up to 10 MHz clock frequency when VCC is 4.5V to 5.5V. At 2.5V to 4.5V, the maximum is 5 MHz, and at 1.8V to 2.5V it drops to 3 MHz. These limits are defined in Table 1-2 AC Characteristics and ensure setup/hold timing compliance across voltage and temperature ranges. The 25LC256-I/SM does not operate below 2.5V, so the 1.8V specification applies only to the 25AA256 variant.

Does the 25LC256-I/SM require external pull-up resistors on its SPI lines?

No, the 25LC256-I/SM does not require external pull-up resistors on SI, SO, SCK, or CS. Its inputs meet standard CMOS thresholds (VIH ≥ 0.7×VCC, VIL ≤ 0.3×VCC), and SO is actively driven or tri-stated - not open-drain. Pull-ups may be added only if bus contention or noise immunity is a concern in long-trace or multi-drop configurations, but they are not specified in the 25LC256-I/SM datasheet.

How does the HOLD pin function during an active SPI transaction on the 25LC256-I/SM?

The HOLD pin suspends an ongoing SPI transaction (e.g., mid-read or mid-write command) when pulled low while SCK is low. All inputs (SI, SCK, CS) are ignored except CS, and SO enters high-impedance. To resume, HOLD must be returned high while SCK remains low - then communication continues from the exact bit position where it paused. This behavior is confirmed in Section 2.1 and Figure 1-1 of the 25LC256-I/SM datasheet.

Can the 25LC256-I/SM be used in automotive applications?

Yes, the 25LC256-I/SM is AEC-Q100 qualified for automotive use and rated for the industrial temperature range (–40°C to +85°C). Its 1 million endurance cycles, >200-year data retention, and ESD protection (>4000V HBM) meet baseline requirements for body electronics and infotainment subsystems. However, for under-hood applications requiring extended temperature (–40°C to +125°C), the 25LC256-E/SM variant should be selected instead.

What happens if a page write crosses a 64-byte boundary on the 25LC256-I/SM?

If a page write command attempts to cross a 64-byte boundary (e.g., writing 10 bytes starting at address 0x003E), the 25LC256-I/SM wraps the excess bytes to the start of the same page (0x0000–0x003F), overwriting previously written data in that page. This behavior is explicitly documented in Section 2.3 and prevents unintended writes to adjacent pages - firmware must validate address alignment before initiating page writes.