Microchip Technology 11AA040T-I/SN

Overview

11AA040T-I/SN from Microchip Technology Inc. is a 4 Kbit (512 × 8) serial EEPROM with UNI/O® single I/O bus interface, operating from 1.8V to 5.5V, featuring 16-byte page write buffer, 1 µA max standby current (I-temp), and Schmitt-trigger SCIO input for noise immunity in space-constrained embedded systems.

For engineers reviewing the 11AA040T-I/SN datasheet, 11AA040T-I/SN pinout, 11AA040T-I/SN application, or 11AA040T-I/SN equivalent, key selection criteria include its 1.8V low-voltage operation, UNI/O® bus timing tolerance (±0.5% frequency drift per byte), built-in block write protection (0%, 25%, 50%, or 100% array), and SOT-23-3 package compatibility with PCB area-limited designs.

Technical Context

The 11AA040T-I/SN implements Manchester-encoded UNI/O® protocol over a single bidirectional SCIO line, eliminating need for separate clock and data lines. It uses internal re-synchronization circuitry that tracks master bit period via start header and adjusts on every MAK edge to tolerate ±0.06 UI input jitter and ±5% cumulative frequency deviation per command.

Its architecture includes a nonvolatile STATUS register with WIP and WEL flags, 16-byte page latches, and HV generator for EEPROM programming. Write operations are self-timed (max 10 ms), with automatic erase before write, and support byte/page writes only within physical 16-byte page boundaries - crossing boundaries causes address wraparound, not multi-page write.

Key Specifications

Pinout & Package

11AA040T-I/SN is packaged in 3-lead SOT-23 (SN suffix), with pin 1 = SCIO (bidirectional serial clock/data), pin 2 = VSS (ground), pin 3 = VCC (supply voltage). No NC pins - all three terminals are functional and electrically defined.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT24C04D-SSHM-T, 11AA040T-I/SN reduces pin count and routing complexity but trades off higher-speed I²C throughput; compared with 11LC040T-I/SN, it enables 1.8V operation at the cost of lacking automotive qualification - making it optimal for cost-sensitive industrial and consumer 1.8V–3.3V designs.

Availability

11AA040T-I/SN is available at Aetrix Electronics and suitable for smart sensor calibration storage, industrial PLC configuration memory, and medical device usage logs requiring stable component supply across multi-year production cycles.

Supply support for 11AA040T-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 U.S.-based semiconductor company specializing in microcontrollers, analog devices, and memory products for embedded control applications.

The 11AA040T-I/SN belongs to Microchip's 11AAxxx UNI/O® EEPROM family, designed specifically for space- and pin-constrained systems needing low-voltage, single-wire nonvolatile storage with robust noise immunity and configurable write protection.

FAQ

What is the UNI/O® interface used by the 11AA040T-I/SN, and how does it differ from I²C or SPI?

The 11AA040T-I/SN uses Microchip's patented UNI/O® bus - a single-wire, Manchester-encoded serial interface where clock and data are combined into one SCIO signal. Unlike I²C (2-wire, open-drain) or SPI (4-wire, separate clock/data), UNI/O® eliminates dedicated clock lines and reduces pin count to one I/O plus power/ground. It requires precise timing synchronization via start headers and supports only master-initiated communication, making it ideal for ultra-low-pin-count microcontrollers.

Does the 11AA040T-I/SN support 1.8V operation, and what are the implications for system design?

Yes, the 11AA040T-I/SN operates from 1.8V to 5.5V, enabling direct interface with 1.8V logic families without level shifting. At 1.8V, DC characteristics specify VIH ≥ 0.36V and VIL ≤ 0.36V, and ICC Read is 1 mA max. This allows integration into battery-powered or energy-harvesting systems where supply voltage may dip below 2.5V, while maintaining full functionality including page writes and status register access.

How does the 11AA040T-I/SN handle write protection, and can it be configured dynamically?

The 11AA040T-I/SN implements dynamic block write protection via BP0/BP1 bits in its nonvolatile STATUS register, set using the WRSR instruction. These bits allow locking 0%, 25%, 50%, or 100% of the memory array - for example, protecting the first 128 bytes (25%) from accidental overwrite. Protection remains active after power cycles and can be reconfigured in-system, provided the write enable latch is set via WREN beforehand.

What is the maximum write speed and timing behavior of the 11AA040T-I/SN during a page write operation?

A page write (up to 16 bytes) in the 11AA040T-I/SN completes in ≤10 ms, as defined by TWC parameter. The device enters a self-timed internal write cycle upon receipt of NoMAK after the final data byte. During this time, the WIP bit in the STATUS register reads '1', and all commands except RDSR are ignored. No external wait states are needed - firmware polls WIP via RDSR until it clears to '0', confirming completion.

Is the 11AA040T-I/SN pin-compatible with other members of the 11AAxxx family, such as the 11AA020T-I/SN or 11AA080T-I/SN?

Yes, the 11AA040T-I/SN shares identical pinout (SCIO/VSS/VCC), package (SOT-23-3), and UNI/O® protocol with all 11AAxxx variants in the same package type, including 11AA020T-I/SN (2Kbit) and 11AA080T-I/SN (8Kbit). Density and page size are identical (16-byte pages), so firmware and hardware are fully interchangeable - only memory map depth differs, requiring no layout or driver changes when scaling capacity.