Microchip Technology 11AA040-I/MS

Overview

11AA040-I/MS from Microchip Technology is a 4 Kbit (512 × 8) serial EEPROM using the UNI/O® single I/O bus interface, operating from 1.8V to 5.5V with 1 µA max standby current and 1 mA typical active current. It features Manchester-encoded serial communication at up to 100 kbps, 16-byte page-write buffer, and hardware block write protection for industrial temperature range (–40°C to +85°C). It is commonly used in space-constrained embedded systems for parameter storage, calibration data retention, and firmware configuration.

For engineers reviewing the 11AA040-I/MS datasheet, 11AA040-I/MS pinout, 11AA040-I/MS application, or 11AA040-I/MS equivalent, key selection considerations include its 1.8V minimum supply, SOT-23-3 package footprint, UNI/O® protocol timing tolerance (±0.5% frequency drift per byte), STATUS register accessibility during writes, and compatibility with microcontroller GPIO-based bit-banged masters.

Technical Context

The 11AA040-I/MS implements a Manchester-encoded, master-controlled UNI/O® bus where clock and data share the SCIO line; timing synchronization occurs via start-header detection and dynamic re-synchronization on every MAK bit. Its internal architecture includes a 16-byte page latch, nonvolatile STATUS register with WIP/WEL/BP bits, and current-limited slope-controlled SCIO driver to suppress ground bounce.

It supports four block-protection modes (none, 1/4, 1/2, or full array), self-timed write cycles (5–10 ms), and Schmitt-trigger inputs for noise immunity. The device enters Standby mode after NoMAK+SAK or a TSTBY ≥600 µs high pulse on SCIO, and Idle mode upon invalid address/command or missed edge transitions.

Key Specifications

Pinout & Package

11AA040-I/MS is packaged in an 8-lead MSOP (MS) package with exposed pad, measuring 3.0 mm × 3.0 mm × 1.0 mm. Pin 1 is SCIO, Pin 2 is VSS, Pin 3 is VCC, and Pins 4–8 are no-connect (NC).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT24C04C-SSHM-T and BR24G04FJ-3GE2, the 11AA040-I/MS uniquely combines industrial temperature rating, Schmitt-trigger noise suppression, STATUS register accessibility during writes, and hardware block protection - making it optimal for mission-critical embedded systems where pin count, power, and robustness are jointly constrained.

Availability

11AA040-I/MS is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, and automotive body electronics requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for 11AA040-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 leading provider of microcontrollers, analog devices, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 11AA040-I/MS belongs to Microchip's 11XX family of UNI/O® serial EEPROMs, designed specifically for ultra-low-pin-count, low-power embedded systems where MCU GPIO resources are limited and board space is at a premium.

FAQ

What is the minimum supply voltage required for reliable operation of the 11AA040-I/MS?

The 11AA040-I/MS operates reliably down to 1.8V across its full industrial temperature range (–40°C to +85°C), as specified in the DC Characteristics table. Below 1.8V, functionality is not guaranteed - this enables direct integration with 1.8V logic families and battery-powered systems without voltage translation circuitry. The 11AA040-I/MS maintains full read/write capability and STATUS register access at 1.8V.

Can the 11AA040-I/MS be used with a microcontroller that lacks dedicated UNI/O® hardware support?

Yes - the 11AA040-I/MS is fully compatible with bit-banged GPIO implementations. Its Manchester-encoded protocol and defined timing tolerances (e.g., ±0.5% frequency drift per byte, ±0.06 UI input jitter) allow robust software-driven communication on standard MCU pins. Reference firmware examples for PIC® and ARM Cortex-M devices are available in Microchip Application Note AN1248, confirming functional interoperability of the 11AA040-I/MS in GPIO-based systems.

How does the STATUS register of the 11AA040-I/MS behave during an active write cycle?

The STATUS register of the 11AA040-I/MS remains readable during internal write operations: the WIP bit reflects real-time write progress ('1' = busy, '0' = complete), and the WEL bit retains its state. This allows non-blocking polling without halting bus activity. The 11AA040-I/MS guarantees atomic reads - even if the STATUS register itself is being updated, the returned value corresponds to a consistent snapshot of BP0, BP1, WEL, and WIP bits.

What package variants are available for the 11AA040-I/MS, and which is used in the -I/MS suffix?

The 11AA040-I/MS is specifically the 8-lead MSOP (Mini Small Outline Package) variant, with dimensions 3.0 mm × 3.0 mm × 1.0 mm and exposed thermal pad. Other package options for the 11AA040 include PDIP (P), SOIC (SN), TDFN (MN), SOT-23 (TT), TO-92 (TO), and Chip Scale (CS). The "MS" suffix explicitly denotes the MSOP package per Microchip's ordering code convention in DS22067J.

Does the 11AA040-I/MS support write protection of individual memory pages?

No - the 11AA040-I/MS implements only block-level write protection via BP0/BP1 bits in the STATUS register, enabling protection of 0%, 25%, 50%, or 100% of the 512-byte array. It does not support per-page or byte-level locking. Protection granularity is fixed to quarter-array boundaries (128 bytes), aligned to physical memory blocks - this simplifies firmware implementation while providing sufficient security for most configuration storage use cases.