Microchip Technology 11AA040-I/TO

Overview

11AA040-I/TO 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 a 16-byte page-write buffer, Schmitt-trigger SCIO input for noise immunity, and built-in write protection including power-on/off circuitry and STATUS register control. It is used in space-constrained industrial sensor nodes for nonvolatile parameter storage.

For engineers reviewing the 11AA040-I/TO datasheet, 11AA040-I/TO pinout, 11AA040-I/TO application, or 11AA040-I/TO equivalent, key selection criteria include its 1.8V minimum VCC, TO-92 3-lead package, UNI/O® protocol compatibility, 100 kbps bit rate, and block-level write protection configuration via STATUS register.

Technical Context

The 11AA040-I/TO implements Manchester-encoded serial communication over a single SCIO line, extracting clock and data from one bidirectional signal. Its internal architecture includes a 16-byte page latch, STATUS register with WIP/WEL/BP bits, and HV generator for EEPROM programming.

It supports only master-initiated commands (READ, WRITE, WREN, RDSR, etc.) with strict timing requirements: THDR ≤ 5 µs, TSS ≥ 10 µs, and ±0.06 UI input jitter tolerance. Standby mode is entered after NoMAK+SAK or a TSTBY ≥ 600 µs high pulse on SCIO.

Key Specifications

Pinout & Package

11AA040-I/TO is housed in a 3-lead TO-92 package (top-down view: Pin 1 = VCC, Pin 2 = VSS, Pin 3 = SCIO). The package is through-hole compatible, RoHS-compliant, and rated for industrial temperature operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 11LC040-I/TO, the 11AA040-I/TO enables lower-voltage operation but shares identical timing, command set, and packaging; versus 24AA04T-I/OT, it trades I²C compatibility for reduced pin count and superior noise immunity in harsh environments.

Availability

11AA040-I/TO is available at Aetrix Electronics and suitable for industrial sensor calibration, energy meter firmware patching, and medical device usage logging requiring stable component supply across extended product lifecycles.

Supply support for 11AA040-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 devices, and memory products for industrial, automotive, and consumer applications.

The 11AA040-I/TO belongs to Microchip's UNI/O® serial EEPROM family, designed specifically for ultra-low-pin-count, low-power embedded systems where board space and GPIO resources are severely constrained.

FAQ

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

The 11AA040-I/TO operates reliably down to 1.8V across its full industrial temperature range (–40°C to +85°C). Below 2.5V, DC characteristics such as VIL and VOL shift per datasheet Table 1-1; operation at 1.8V is fully specified and validated, enabling direct integration with modern ultra-low-power MCUs without level-shifting circuitry. This specification is unique to the "AA" variant - the 11LC040-I/TO requires ≥2.5V.

How does the UNI/O® interface of the 11AA040-I/TO differ from standard I²C or SPI interfaces?

The 11AA040-I/TO uses a patented single-wire UNI/O® bus with Manchester encoding, combining clock and data into one SCIO signal - unlike I²C (2-wire) or SPI (3–4 wires). It requires no dedicated clock line, no address pins, and no chip-select signals. Communication is strictly master-initiated with defined start headers, ACK sequences (MAK/SAK), and standby pulses. This reduces host GPIO usage to one pin and eliminates bus arbitration complexity.

Can the 11AA040-I/TO be written to across page boundaries, and what happens if it is attempted?

No - the 11AA040-I/TO's 16-byte page buffer wraps around within the same physical page. If a WRITE command transmits more than 16 bytes or crosses a 16-byte boundary (e.g., writing from address 0x0F to 0x10), data overwrites from the start of the current page (0x00), not the next. This behavior is documented in Section 4.3 and requires firmware to enforce page-aligned writes. Attempting cross-boundary writes corrupts data silently; no error flag is generated.

What protection mechanisms prevent accidental writes to the 11AA040-I/TO during power-up or brownout conditions?

The 11AA040-I/TO incorporates three hardware protections: (1) Power-on/off data protection circuitry that disables writes until VCC stabilizes, (2) a volatile write-enable latch (WEL bit) reset on every power cycle and after each successful WRITE/WRSR/ERAL/SETAL command, and (3) nonvolatile block protection (BP0/BP1) bits that persist through power loss. These ensure no unintended writes occur during supply ramp-up, dropout, or reset sequences.

Is the TO-92 package of the 11AA040-I/TO compatible with automated through-hole assembly processes?

Yes - the 11AA040-I/TO in TO-92 package (suffix "TO") is designed for standard through-hole reflow and wave soldering per Microchip's packaging specifications. Lead finish is matte tin, compliant with J-STD-020 moisture sensitivity level 1 (unlimited floor life at ≤30°C/85% RH), and the body dimensions match JEDEC TO-92 outline. Pin 1 (VCC) orientation is marked by a flat side on the package body per datasheet Figure "TO-92".