Microchip Technology 24AA1026-I/ST

Overview

24AA1026-I/ST from Microchip Technology is a 128K × 8 (1024 Kbit) I²C-compatible serial EEPROM with 1.7V–5.5V supply range, 400 kHz max clock frequency (100 kHz below 2.5V), and industrial temperature rating (–40°C to +85°C). It features 128-byte page write buffer, hardware write-protection via WP pin, and Schmitt-trigger inputs for noise immunity-used in embedded system configuration storage, sensor calibration data retention, and firmware parameter backup.

For engineers reviewing the 24AA1026-I/ST datasheet, 24AA1026-I/ST pinout, 24AA1026-I/ST application, or 24AA1026-I/ST equivalent, key selection criteria include VCC operating range compatibility, I²C bus timing constraints at target clock speed, page boundary handling in firmware, and hardware write-protect implementation using the WP pin.

Technical Context

The 24AA1026-I/ST implements a two-wire I²C slave interface with fixed 4-bit control code (1010b) and user-configurable A1/A2 address bits enabling up to four devices on one bus. Its internal memory array is split into two 512 Kbit blocks selected by the B0 bit, requiring explicit block addressing for full 1 Mbit access.

It supports byte and page write modes with self-timed erase/write cycles (typ. 3 ms), automatic address pointer incrementing, and acknowledge polling for write completion detection. The device uses open-drain SDA/SCL with external pull-ups and includes slope control and Schmitt-trigger inputs to suppress ground bounce and noise.

Key Specifications

Pinout & Package

24AA1026-I/ST is housed in an 8-lead SOIC package (3.90 mm width), RoHS-compliant, with standard 1.27 mm pitch and gull-wing leads. Pin 1 is marked with a beveled corner or dot.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24LC1026-I/ST, the 24AA1026-I/ST enables lower-voltage operation critical for battery-powered designs, while AT24C1024 offers higher speed at the cost of firmware adaptation and reduced page efficiency.

Availability

24AA1026-I/ST is available at Aetrix Electronics and suitable for industrial sensor nodes, medical device calibration storage, and smart energy metering requiring stable component supply, long-term data retention, and hardware write protection.

Supply support for 24AA1026-I/ST 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 is a U.S.-based semiconductor company specializing in microcontrollers, analog devices, and memory products, with emphasis on reliability, low-power design, and long product lifecycles.

The 24AA1026-I/ST belongs to Microchip's 24XX serial EEPROM family, engineered for robust nonvolatile data storage in resource-constrained embedded systems operating across wide voltage and temperature ranges.

FAQ

What is the minimum VCC voltage supported by the 24AA1026-I/ST?

The 24AA1026-I/ST operates down to 1.7V, making it suitable for single-cell Li-ion, LiFePO₄, or 2-cell alkaline battery systems where supply voltage may sag below 2.5V. This is a key differentiator from the 24LC1026-I/ST, which requires ≥2.5V. The 24AA1026-I/ST maintains full I²C functionality-including 100 kHz operation-at 1.7V, ensuring reliable boot-time configuration loading even under brownout conditions.

How does the WP pin function on the 24AA1026-I/ST?

The WP (Write-Protect) pin on the 24AA1026-I/ST is a hardware-level enable/disable control: when tied to VCC, all write operations (byte and page) are inhibited while read operations remain fully functional. The pin is sampled at the Stop condition of each write command, so toggling WP mid-cycle has no effect. This provides deterministic, glitch-immune protection against accidental or malicious writes-critical for safeguarding calibration data or security keys in the 24AA1026-I/ST.

Can the 24AA1026-I/ST perform sequential reads across its full 1024 Kbit address space?

No. The 24AA1026-I/ST divides its memory into two 512 Kbit blocks (00000h–0FFFFh and 10000h–1FFFFh), and sequential reads automatically roll over within each block but cannot cross the 0FFFFh→10000h boundary. To read the entire array sequentially, firmware must issue separate read commands-one for each block-using the B0 bit in the control byte to select the target segment. This architectural constraint is inherent to the 24AA1026-I/ST's internal addressing logic.

What is the maximum number of 24AA1026-I/ST devices that can share one I²C bus?

Up to four 24AA1026-I/ST devices can be cascaded on a single I²C bus using the A1 and A2 address pins, which configure the two least-significant bits of the 7-bit slave address (1010 A2 A1 B0 R/W). Each device must have a unique A1/A2 combination (00, 01, 10, 11), allowing a total system capacity of 4 Mbit. No additional address decoding logic or bus switches are required-the 24AA1026-I/ST handles multi-device arbitration natively.

Does the 24AA1026-I/ST require external components for I²C operation?

Yes. The 24AA1026-I/ST requires external pull-up resistors on both SDA and SCL lines: 10 kΩ for 100 kHz operation, 2 kΩ for 400 kHz, per Microchip's AC specifications. A 0.1 µF ceramic bypass capacitor is also mandatory between VCC and VSS, placed as close as possible to the 24AA1026-I/ST's power pins to suppress switching noise and ensure stable internal voltage regulation during write cycles.