11AA040T-I/TT

Overview

The Microchip Technology 11AA040T-I/TT is a 4 Kbit (512 x 8) serial electrically erasable programmable read-only memory (EEPROM). It utilizes the UNI/O single I/O bus interface with Manchester encoding for clock and data transmission. The device operates within a supply voltage range of 1.8 V to 5.5 V and supports industrial temperature grades from -40°C to +85°C. It features a maximum bit rate of 100 kbps, a 16-byte page-write buffer, and block write protection capabilities.

Feature Summary

• Supports the patented UNI/O single I/O serial bus protocol using Manchester encoding on the SCIO pin.
• Includes a STATUS register for monitoring write-in-progress status and managing write enable latches.
• Features built-in power-on/off data protection circuitry and self-timed write cycles with auto-erase.
• Provides hardware block write protection allowing selection of none, one-quarter, one-half, or all array segments.

Applications

• Interfacing with microcontrollers requiring discrete I/O line configuration
• ASIC communication systems utilizing the UNI/O protocol
• Low-power embedded storage applications

Procurement Notes

Verify that the ordering suffix 'TT' corresponds to the SOT-23-3 package type as specified in the datasheet. Confirm the 'I' suffix indicates the Industrial temperature range (-40°C to +85°C). Ensure the 'AA' prefix denotes the 1.8V minimum operating voltage requirement rather than the 2.5V variant.

Selection Notes

Select this component when a single-wire serial interface is required to minimize pin count. The 11AA040 offers 4 Kbit capacity suitable for small data logging or configuration storage. Verify system voltage compatibility with the 1.8V to 5.5V operating range and ensure the master controller supports the UNI/O Manchester encoding timing requirements.

Part Context

This part belongs to the 11XX family of serial EEPROMs, which includes densities from 1 Kbit to 16 Kbit. The family shares common architectural features such as the UNI/O interface, Schmitt trigger inputs, and output slope control. The 11AA series specifically supports low-voltage operation down to 1.8V, distinguishing it from the 11LC series which requires a minimum of 2.5V.

Replacement Considerations

The 11AA040T-I/SN serves as a pin-compatible alternative in an SOIC-8 package. For higher density needs within the same interface, the 11AA160T-I/TT provides 16 Kbit capacity in the identical SOT-23-3 package.

FAQ

How does the UNI/O interface handle clock signals?

The UNI/O interface combines clock and data into a single serial bit stream (SCIO) using Manchester encoding techniques. The receiver extracts the clock signal from this stream to correctly decode timing and bit values.

What happens if a page write crosses a physical boundary?

If a page write operation attempts to cross a physical page boundary, the address counter rolls over to the beginning of the current page. Data continues to be written starting from the first byte of that page, potentially overwriting existing data.

Can the STATUS register be read during a write cycle?

Yes, the RDSR instruction allows access to the STATUS register at any time, even while an internal write cycle is executing. This enables the master to monitor the Write-In-Progress (WIP) bit dynamically.