Microchip Technology 11AA040T-I/MS

Overview

11AA040T-I/MS from Microchip Technology is a 4 Kbit (512 × 8) serial EEPROM using the UNI/O® single I/O bus interface. It operates from 1.8V to 5.5V, features 16-byte page-write buffering, Schmitt-trigger SCIO input for noise immunity, and supports up to 100 kbps bit rate. It is used in space-constrained embedded systems requiring nonvolatile storage with minimal pin count, such as sensor calibration data retention in industrial control modules.

For engineers reviewing the 11AA040T-I/MS datasheet, 11AA040T-I/MS pinout, 11AA040T-I/MS application, or 11AA040T-I/MS equivalent, key selection considerations include its 1.8V minimum supply, 1 µA max standby current at I-temp, UNI/O® protocol timing tolerance (±0.5% frequency drift per byte), built-in write protection via STATUS register BP bits, and MSOP-8 package compatibility with automated SMT assembly.

Technical Context

The 11AA040T-I/MS implements Manchester-encoded serial communication over a single bidirectional SCIO line, eliminating separate clock and data lines. Its internal block diagram includes a current-limited slope-controlled SCIO driver, EEPROM array with page latches, STATUS register with WIP/WEL/BP bits, and re-synchronization logic that tracks master clock period via start-header alignment and adjusts on each MAK edge.

It supports four block write-protection modes (none, 1/4, 1/2, or full array) controlled by nonvolatile BP0/BP1 bits in the STATUS register. Write operations require explicit WREN command prior to WRITE or WRSR, and self-timed write cycles complete in ≤10 ms for page writes, with endurance rated at 1,000,000 cycles and data retention >200 years.

Key Specifications

Pinout & Package

11AA040T-I/MS is packaged in an 8-lead MSOP (MS) package with exposed pad (standard JEDEC MO-187AC). Pin 1 is SCIO (bidirectional serial clock/data), Pin 2 is VSS (ground), Pin 3 is NC (no connect), Pin 4 is NC, Pin 5 is NC, Pin 6 is NC, Pin 7 is NC, Pin 8 is VCC (supply voltage). All NC pins must be left unconnected per Microchip's design guidance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 11AA040T-I/MS, 11LC040T-I/MS trades 1.8V compatibility for identical pinout and protocol, while AT24C04C-MAHM-T replaces UNI/O® simplicity with standard I²C but adds address flexibility and faster 1 MHz clock support-making it preferable only where protocol ecosystem outweighs pin-count savings.

Availability

11AA040T-I/MS is available at Aetrix Electronics and suitable for industrial sensor calibration, medical device configuration, automotive body control, smart home actuator tuning, and battery-powered IoT node applications requiring stable component supply and long-term lifecycle assurance.

Supply support for 11AA040T-I/MS 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 for embedded control applications.

The 11AAxxx family was designed specifically for ultra-low-pin-count systems needing reliable, low-voltage serial EEPROM with integrated noise immunity and protocol simplicity-targeting cost-sensitive, space-constrained industrial and consumer electronics.

FAQ

What is the minimum operating voltage for the 11AA040T-I/MS?

The 11AA040T-I/MS operates down to 1.8V, enabling direct connection to 1.8V logic families and low-power microcontrollers without level translation. This specification is validated across the full industrial temperature range (-40°C to +85°C) and is distinct from the 2.5V minimum of the 11LC040 series. Operation below 1.8V is not guaranteed and may result in unreliable read/write behavior or STATUS register corruption.

Does the 11AA040T-I/MS support hardware write protection?

Yes, the 11AA040T-I/MS supports hardware-based block write protection via two nonvolatile BP0 and BP1 bits in its STATUS register. These bits configure protection for none, 1/4, 1/2, or the entire memory array. Protection is enforced independently of software control and remains active after power cycling. The 11AA040T-I/MS does not include a dedicated WP pin; all protection is managed through the UNI/O® interface and WRSR command.

How many bytes can be written in a single operation to the 11AA040T-I/MS?

The 11AA040T-I/MS supports up to 16 bytes per page-write operation, aligned to physical 16-byte boundaries (e.g., addresses 0x00–0x0F, 0x10–0x1F). Writing across a page boundary causes wraparound within the same page rather than spanning pages. To write more than 16 bytes, multiple page-write commands must be issued with appropriate address incrementing and WREN re-arming between operations.

What is the purpose of the NC pins on the 11AA040T-I/MS MSOP package?

Pins 3 through 7 on the 11AA040T-I/MS MSOP-8 package are designated NC (No Connect) and are internally unconnected. They must remain unconnected-no routing, soldering, grounding, or capacitive loading is permitted. Microchip specifies this to prevent parasitic coupling, unintended current paths, or thermal stress that could compromise reliability or violate UNI/O® timing margins. Deviation from NC handling voids warranty and may cause intermittent communication failure.

Can the 11AA040T-I/MS be used in automotive applications?

The 11AA040T-I/MS is rated for Industrial temperature range (-40°C to +85°C) and is not qualified to AEC-Q100 for automotive use. While it may function in benign automotive cabin environments, it lacks automotive-grade screening, extended temperature validation, and failure-in-time (FIT) data required for safety-critical or engine-bay applications. For automotive designs, Microchip recommends the 11LC040T-E/MS (E-temp, -40°C to +125°C) or automotive-qualified alternatives like the BR24G04FJ-WE2.