Microchip Technology 25LC128-I/SN

Overview

25LC128-I/SN from Microchip Technology is a 128 Kbit SPI Serial EEPROM with 16,384 × 8-bit organization, 64-byte page size, and industrial temperature range (−40°C to +85°C). It operates at up to 10 MHz clock frequency with 5 mA read/write current at 5.5 V and supports hardware write protection via WP pin and STATUS register. It is widely used in microcontroller-based systems for firmware parameter storage, calibration data retention, and boot configuration.

For engineers reviewing the 25LC128-I/SN datasheet, 25LC128-I/SN pinout, 25LC128-I/SN application, or 25LC128-I/SN equivalent, key selection considerations include V_CC range (2.5–5.5 V), page-write timing (≤5 ms), HOLD functionality for interrupt-safe SPI pausing, and block-level write protection granularity (none/¼/½/all array).

Technical Context

The 25LC128-I/SN implements a standard SPI Mode 0,0 interface with separate SI (data-in) and SO (data-out) lines, requiring CS, SCK, SI, SO, WP, HOLD, VCC, and VSS. Its internal architecture includes a 64-byte page latch, HV generator for EEPROM programming, and status register with WIP, WEL, BP0/BP1, and WPEN bits.

It supports sequential read across address boundaries with automatic rollover, byte/page write with CS-high termination, and hardware-assisted write protection that combines WP pin state and nonvolatile WPEN bit. The HOLD pin suspends ongoing SPI transfers without resetting the sequence, enabling deterministic interrupt handling in real-time embedded systems.

Key Specifications

Pinout & Package

25LC128-I/SN is packaged in an 8-lead narrow SOIC (SN) with 150-mil body width, JEDEC MS-012AC compliant, footprint dimensions 4.90 mm × 3.90 mm × 1.75 mm (L × W × H), and recommended land pattern per Microchip Drawing C04-2057-SN Rev B.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25AA128-I/SN and AT25128B-SSHL-T, the 25LC128-I/SN provides optimal balance of industrial temperature support, proven AEC-Q100 qualification, and seamless integration with Microchip MCU ecosystems-making it preferred for cost-sensitive, temperature-stable embedded control where 10 MHz bandwidth suffices.

Availability

25LC128-I/SN 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, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for 25LC128-I/SN 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 design and manufacturing operations.

The 25LC128 belongs to Microchip's serial EEPROM product line, designed specifically for reliable, low-power, SPI-based nonvolatile data storage in industrial, automotive, and consumer embedded systems where pin count, board space, and firmware simplicity are critical.

FAQ

What is the maximum clock frequency supported by the 25LC128-I/SN?

The 25LC128-I/SN supports up to 10 MHz clock frequency when V_CC is between 4.5 V and 5.5 V. At lower supply voltages (2.5 V ≤ V_CC < 4.5 V), the maximum clock drops to 5 MHz, and at 1.8 V ≤ V_CC < 2.5 V, it is limited to 3 MHz. These limits ensure reliable setup/hold timing across voltage and temperature ranges as specified in Table 1-2 of DS20001831F.

Does the 25LC128-I/SN require external pull-up resistors on its SPI lines?

The 25LC128-I/SN SO pin is open-drain and requires an external pull-up resistor (typically 4.7 kΩ) to V_CC. CS, SI, SCK, WP, and HOLD are CMOS inputs with internal clamping diodes but no internal pull-ups; external pull-ups/downs may be needed for robust noise immunity in noisy environments. VSS and VCC must be decoupled with 0.1 µF ceramic capacitors.

How does the HOLD function work in the 25LC128-I/SN during an active SPI read?

When HOLD is pulled low while SCK is low during an active SPI read, the 25LC128-I/SN pauses transmission: SO goes high-impedance, and SI/SCK inputs are ignored. The internal address pointer and shift register state are preserved. Resuming requires bringing HOLD high while SCK remains low-then communication continues from the exact bit position where it paused, eliminating re-synchronization overhead.

Can the 25LC128-I/SN be used in automotive applications?

Yes-the 25LC128-I/SN is explicitly AEC-Q100 qualified for automotive applications and rated for the industrial temperature range (−40°C to +85°C). Its 1,000,000 write cycles, >200-year data retention, and >4 kV ESD protection meet stringent automotive reliability requirements for body electronics, infotainment, and ADAS subsystems.

What happens if a page write crosses a 64-byte boundary in the 25LC128-I/SN?

If a page write command attempts to cross a 64-byte boundary (e.g., writing 10 bytes starting at address 0x003E), the 25LC128-I/SN wraps the excess bytes to the start of the same page instead of advancing to the next page. This overwrites earlier data in the page. Application firmware must enforce page alignment-checking address & 0xFC00 before initiating multi-byte writes-to prevent unintended data corruption.