Microchip Technology 24AA128-I/P

Overview

24AA128-I/P from Microchip Technology Inc. is a 128 Kbit (16K × 8) I²C-compatible serial EEPROM with industrial temperature range (–40°C to +85°C), 1.7V–5.5V supply operation, and hardware write-protection via the WP pin. It features 64-byte page write buffering, Schmitt-trigger inputs for noise immunity, and supports up to eight devices on a single I²C bus. It is commonly used in embedded system configuration storage, sensor calibration data retention, and firmware parameter backup.

For engineers reviewing the 24AA128-I/P datasheet, 24AA128-I/P pinout, 24AA128-I/P application, or 24AA128-I/P equivalent, this page delivers verified electrical specs, package mapping to 8-lead PDIP, functional pin roles, real-world use cases, and two validated alternative parts with documented technical and application differences.

Technical Context

The 24AA128-I/P implements a two-wire I²C slave interface with fixed 4-bit control code (1010b) and user-configurable 3-bit chip address (A2–A0), enabling up to eight devices on one bus. Its internal architecture includes a 64-byte page latch, HV generator for EEPROM programming, and memory control logic that manages self-timed erase/write cycles.

It supports three read modes-current address, random, and sequential-and uses acknowledge polling to detect write completion. The device samples the WP pin at the Stop bit of each write command to enforce hardware-level write protection across the full 0000h–3FFFh address space.

Key Specifications

Pinout & Package

24AA128-I/P is packaged in an 8-lead plastic dual in-line package (PDIP) with 0.300-inch body width and through-hole mounting. Pin 1 is A0 (chip address input), pin 4 is VSS (ground), pin 5 is SDA (bidirectional open-drain I²C data), pin 6 is SCL (I²C clock input), pin 7 is WP (hardware write-protect), and pin 8 is VCC (power supply). All address pins (A0–A2) must be hardwired to VSS or VCC for device selection.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24AA128-I/P, the 24LC128-I/P offers identical functionality above 2.5V but lacks low-voltage support, while the AT24C128-10PU-2.7 trades 10× lower endurance for faster clocking-making 24AA128-I/P optimal for 1.7V–5.5V systems requiring long-term reliability and frequent updates.

Availability

24AA128-I/P is available at Aetrix Electronics and suitable for smart metering, industrial PLCs, medical diagnostics, and automotive body control modules requiring stable component supply across extended product lifecycles.

Supply support for 24AA128-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 U.S.-based semiconductor manufacturer specializing in microcontrollers, analog devices, and memory products, with global distribution and ISO 9001-certified operations.

The 24AA128-I/P belongs to Microchip's 24XX128 family of I²C EEPROMs, designed specifically for low-power, industrial-grade nonvolatile data storage in embedded systems where voltage flexibility, noise immunity, and long-term data integrity are critical.

FAQ

What is the maximum I²C clock frequency supported by the 24AA128-I/P?

The 24AA128-I/P supports up to 400 kHz when VCC is 2.5V or higher. At VCC < 2.5V (e.g., 1.8V operation), the maximum clock frequency is limited to 100 kHz per its AC specifications. This dual-speed capability ensures interoperability with both standard-mode and low-voltage I²C masters without external clock dividers or protocol translation.

Does the 24AA128-I/P require external pull-up resistors on SDA and SCL lines?

Yes, the 24AA128-I/P requires external pull-up resistors on both SDA and SCL because its I²C interface uses open-drain outputs. Recommended values are 10 kΩ for 100 kHz operation, 2 kΩ for 400 kHz, and ≤1 kΩ for marginal bus capacitance-values must be selected based on bus length, capacitance, and target speed to meet rise-time requirements in Table 1-2.

How does hardware write-protection work on the 24AA128-I/P?

The WP pin on the 24AA128-I/P is sampled at the Stop bit of every write command. When tied to VCC, it disables all write operations-including byte, page, and erase-while permitting unrestricted reads. No software command can override this hardware lock, making it ideal for protecting critical calibration or security data from accidental or malicious overwrite.

Can multiple 24AA128-I/P devices share the same I²C bus?

Yes, up to eight 24AA128-I/P devices can operate on a single I²C bus using unique slave addresses formed by combinations of A0, A1, and A2 pins. Each device must have a distinct A2:A1:A0 setting (e.g., 000, 001, ..., 111), enabling unified addressing and cascaded storage up to 1 Mbit without bus arbitration conflicts.

What is the page write size and how does it affect memory access on the 24AA128-I/P?

The 24AA128-I/P has a 64-byte page write buffer. Writes crossing a 64-byte boundary (e.g., starting at address 0x003E and writing 8 bytes) wrap around within the same physical page instead of advancing to the next page. Therefore, firmware must align page writes to 64-byte boundaries (0x0000, 0x0040, etc.) to avoid unintended data overwrites during bulk programming.