Microchip Technology 11AA161-I/TO

Overview

11AA161-I/TO from Microchip Technology is a 16 Kbit (2,048 × 8) serial EEPROM with single I/O UNI/O® interface, 1.8–5.5 V supply range, and industrial temperature rating (–40°C to +85°C). It features 16-byte page-write buffer, Schmitt-trigger SCIO input, output slope control, and built-in write protection for embedded sensor calibration, firmware parameter storage, and configuration retention in space-constrained systems.

For engineers reviewing the 11AA161-I/TO datasheet, 11AA161-I/TO pinout, 11AA161-I/TO application, or 11AA161-I/TO equivalent, key selection criteria include UNI/O® bus compatibility, TO-92 package footprint, 100 kbps bit rate, 1 µA standby current, and block write protection granularity (none/¼/½/all).

Technical Context

The 11AA161-I/TO implements Manchester-encoded UNI/O® protocol over a single bidirectional SCIO line, eliminating need for separate clock and data lines. Its internal timing recovery circuitry synchronizes to master clock period during start header, tolerating ±0.50% frequency drift per byte and ±0.06 UI edge jitter.

It integrates a status register with WIP and WEL flags, 16-byte page latches, high-voltage generator for EEPROM programming, and current-limited slope-controlled SCIO driver to suppress ground bounce. Block protection is controlled via BP0/BP1 bits in nonvolatile STATUS register.

Key Specifications

Pinout & Package

11AA161-I/TO is housed in a 3-lead TO-92 package (top-down view: Pin 1 = VCC, Pin 2 = VSS, Pin 3 = SCIO). No NC pins are present in this variant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 11LC161-I/TO, the 11AA161-I/TO enables direct 1.8 V operation and lower standby current, while AT24C128-PU offers greater capacity and standard I²C compatibility at the cost of increased pin count and board area.

Availability

11AA161-I/TO is available at Aetrix Electronics and suitable for smart sensor calibration, industrial PLC configuration, and medical device settings requiring stable component supply, long-term obsolescence management, and RoHS-compliant packaging.

Supply support for 11AA161-I/TO 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, and memory products for embedded control applications.

The 11AA161-I/TO belongs to Microchip's 11XX UNI/O® EEPROM family, designed specifically for ultra-low-pin-count systems where minimizing MCU GPIO usage and PCB real estate is critical.

FAQ

What is the UNI/O® interface used by the 11AA161-I/TO?

The 11AA161-I/TO uses Microchip's patented UNI/O® serial bus, which combines clock and data onto a single bidirectional SCIO line using Manchester encoding. This eliminates the need for separate clock and data lines, reducing interconnect complexity and enabling use with any available MCU GPIO. The 11AA161-I/TO fully complies with UNI/O® specification v1.0, supporting up to 100 kbps bit rate and automatic synchronization on each command start header.

Does the 11AA161-I/TO support 1.8 V operation?

Yes, the 11AA161-I/TO supports a VCC range of 1.8–5.5 V, making it compatible with modern low-voltage MCUs and battery-powered systems. This is a key distinction from the pin-compatible 11LC161-I/TO, which requires minimum 2.5 V. The 11AA161-I/TO maintains full functionality-including 100 kbps bit rate, 1 µA standby current, and page-write-across the entire 1.8–5.5 V range.

How does write protection work on the 11AA161-I/TO?

Write protection on the 11AA161-I/TO is implemented via two nonvolatile BP0/BP1 bits in the STATUS register, configurable through the WRSR command. These bits enable hardware-level protection of none, 1/4, 1/2, or all of the 2,048-byte memory array. Protection is active immediately after WRSR execution and persists across power cycles. The 11AA161-I/TO also includes power-on/off data protection circuitry and a write-enable latch that must be set via WREN before any write operation.

What is the maximum write endurance of the 11AA161-I/TO?

The 11AA161-I/TO guarantees 1,000,000 erase/write cycles per memory location under specified conditions (25°C, VCC = 5.5 V). This endurance rating is validated by characterization and supported by Microchip's Total Endurance™ Model. Real-world endurance may vary based on operating voltage, temperature, and write pattern; however, the 11AA161-I/TO is engineered for mission-critical parameter storage in applications requiring frequent field updates over decades.

Can the 11AA161-I/TO be used in place of I²C EEPROMs like the 24AA128?

No, the 11AA161-I/TO cannot be used as a drop-in replacement for I²C EEPROMs such as the 24AA128 because it uses the UNI/O® protocol instead of I²C. The 11AA161-I/TO requires only one I/O line (SCIO) and operates with Manchester-encoded timing, whereas I²C needs two dedicated lines (SDA/SCL) and open-drain drivers with pull-ups. Firmware and hardware changes are required to migrate from I²C to UNI/O®, though both serve similar nonvolatile storage functions.