Microchip Technology 11AA040-I/SN

Overview

11AA040-I/SN from Microchip Technology 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 11AA040-I/SN datasheet, 11AA040-I/SN pinout, 11AA040-I/SN application, or 11AA040-I/SN equivalent, this device serves as a low-pin-count, low-power nonvolatile memory solution for firmware storage, calibration data retention, and configuration parameter backup in industrial control modules, sensor nodes, and portable medical devices.

Technical Context

The 11AA040-I/SN implements Manchester-encoded UNI/O® protocol over a single bidirectional SCIO line, eliminating need for separate clock and chip-select signals. It uses internal re-synchronization circuitry tolerant to ±0.50% bus frequency drift per byte and ±0.06 UI edge jitter, enabling robust communication with low-cost microcontrollers lacking dedicated serial peripherals.

Its architecture includes a volatile address pointer, nonvolatile STATUS register (WIP/WEL/BP bits), and hardware write protection logic that enforces block-level locking (none/¼/½/all array). Write operations are self-timed with 5–10 ms completion and include auto-erase, while read access supports both random and sequential modes via MAK/NoMAK handshaking.

Key Specifications

Pinout & Package

11AA040-I/SN is packaged in 8-lead SOIC (SN) with standard pinout: Pin 1 = VSS (GND), Pin 2 = NC, Pin 3 = NC, Pin 4 = SCIO (bidirectional serial I/O), Pin 5 = NC, Pin 6 = NC, Pin 7 = NC, Pin 8 = VCC (supply voltage).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT24C04-PU and M95040-WMN6TP, the 11AA040-I/SN delivers lowest pin count and lowest standby current, making it optimal for ultra-compact, battery-sensitive designs where MCU GPIO is constrained and write frequency is low.

Availability

11AA040-I/SN is available at Aetrix Electronics and suitable for industrial control systems, sensor calibration modules, and portable medical devices requiring stable component supply with guaranteed long-term manufacturability.

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

The 11AA040-I/SN belongs to Microchip's UNI/O® serial EEPROM family, designed specifically to reduce pin count and simplify integration in cost-sensitive, space-constrained embedded systems requiring reliable nonvolatile storage.

FAQ

What is the UNI/O® interface used by the 11AA040-I/SN, and how does it differ from I²C or SPI?

The 11AA040-I/SN uses Microchip's patented UNI/O® bus, a single-wire, Manchester-encoded serial interface that combines clock and data on one line (SCIO). Unlike I²C (2-wire) or SPI (4-wire), it eliminates dedicated clock and chip-select signals, reducing MCU pin usage and PCB routing complexity. The 11AA040-I/SN achieves 100 kbps effective throughput with built-in jitter tolerance and re-synchronization-ideal for resource-limited microcontrollers.

Does the 11AA040-I/SN support write protection, and how is it configured?

Yes, the 11AA040-I/SN includes hardware block write protection controlled via BP0/BP1 bits in its nonvolatile STATUS register. These bits can be set using the WRSR command to protect 0%, 25%, 50%, or 100% of the 512-byte array. Protection remains active after power cycles and complements built-in power-on/off write inhibit circuitry-ensuring critical calibration data cannot be overwritten during brown-out conditions.

What is the maximum write speed and page size for the 11AA040-I/SN?

The 11AA040-I/SN supports a maximum serial bus frequency of 100 kHz, resulting in ~100 µs per bit and ~800 µs per byte. Its page size is fixed at 16 bytes, meaning up to 16 contiguous locations can be written in a single self-timed cycle completing in 5–10 ms. Attempting to write across a 16-byte boundary wraps data to the start of the same page-software must enforce alignment to avoid unintended overwrites.

Can the 11AA040-I/SN operate reliably at 1.8V, and what are the implications for current consumption?

Yes, the 11AA040-I/SN is fully specified for 1.8V operation across the industrial temperature range (−40°C to +85°C). At 1.8V, typical active read current is 1 mA and standby current is ≤1 µA-enabling multi-year battery life in always-on sensor nodes. This low-voltage capability is enabled by CMOS process optimization and slope-controlled SCIO driver, distinguishing it from legacy EEPROMs requiring ≥2.5V.

How does the STATUS register in the 11AA040-I/SN assist in system-level firmware development?

The STATUS register in the 11AA040-I/SN provides real-time visibility into device state via two critical bits: Write-In-Progress (WIP) indicates ongoing internal write cycles, allowing host firmware to poll instead of using fixed delays; Write-Enable Latch (WEL) confirms whether write commands will be accepted-preventing accidental writes if WREN was not issued or was cleared by power reset. Both bits are readable at any time, including during active writes.