Microchip Technology 93AA66/SN

Overview

93AA66/SN from Microchip Technology Inc. is a 4K-bit (512 × 8 or 256 × 16) low-voltage serial EEPROM with Microwire interface, ORG-pin configurable memory organization, and 1.8V–5.5V single-supply operation. It delivers 70 µA typical active read current at 1.8V, 2 µA standby current, and supports industrial temperature range (−40°C to +85°C). It is used in embedded system parameter storage where space-constrained SOIC-8 packaging and robust nonvolatile retention (>200 years) are required.

For engineers reviewing the 93AA66/SN datasheet, 93AA66/SN pinout, 93AA66/SN application, or 93AA66/SN equivalent, this page provides verified technical context, real-world timing behavior, validated pin functions, confirmed memory configurations, and cross-referenced alternatives for legacy design continuity and supply chain planning.

Technical Context

The 93AA66/SN implements a synchronous 3-wire Microwire-compatible serial interface with CS, CLK, DI, and DO lines. Its internal architecture includes an address counter, output buffer, data register, and mode decode logic enabling self-timed erase/write cycles-including auto-erase-and automatic ERAL before WRAL execution.

Memory organization is dynamically selected via the ORG pin: tied to VCC for 256 × 16-bit mode (16-bit reads/writes), or to VSS for 512 × 8-bit mode (8-bit reads/writes). The device enters EWDS mode on power-up and requires explicit EWEN instruction prior to any erase or write operation-ensuring immunity to accidental programming during brown-out or noise events.

Key Specifications

Pinout & Package

8-pin SOIC package (JEDEC MS-012, 150 mil body width), marked "/SN" per Microchip's part numbering convention. Pin 1 is CS (Chip Select), pin 2 is CLK (Serial Clock), pin 3 is DI (Data In), pin 4 is DO (Data Out), pin 5 is VSS (Ground), pin 6 is ORG (Memory Organization), pin 7 is VCC (Power Supply), and pin 8 is NU (Not Utilized).

Key Features

Applications

Equivalent & Alternatives

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

Compared with 93AA66C/SN, the 93AA66/SN offers identical functionality but lacks the enhanced ESD rating and newer process node; compared with AT25040B-MAU-1.8, it retains Microwire compatibility and built-in ERAL/WRAL sequencing at the cost of lower maximum clock rate and no SPI daisy-chain capability.

Availability

93AA66/SN is available at Aetrix Electronics and suitable for smart meter calibration storage, industrial PLC configuration memory, and medical sensor module settings requiring stable component supply and long-term obsolescence management.

Supply support for 93AA66/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 microcontroller, analog, and Flash-IP solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 93AAxx family was designed specifically for low-voltage, low-power serial EEPROM applications in space-constrained embedded systems, emphasizing robust data integrity, flexible memory organization, and seamless integration with 8-/16-bit microcontrollers via Microwire.

FAQ

What is the memory organization flexibility of the 93AA66/SN?

The 93AA66/SN supports two memory configurations via the ORG pin: when tied to VCC, it operates as a 256 × 16-bit array; when tied to VSS, it operates as a 512 × 8-bit array. This dual-mode capability allows designers to match data bus width and addressing granularity to their host MCU architecture without changing the physical component. The 93AA66/SN does not support floating ORG above 1 MHz in x16 mode.

How does the 93AA66/SN ensure data integrity during power transitions?

The 93AA66/SN incorporates hardware-level power-on/power-off data protection that inhibits all programming operations until VCC exceeds 1.4V and disables them again when VCC falls below 1.4V. Combined with mandatory EWEN instruction before erase/write and automatic ERAL before WRAL, this ensures no partial writes occur during brown-out or reset conditions. The 93AA66/SN also features 1,000,000 endurance cycles and >200-year data retention to guarantee long-term reliability.

What are the timing requirements for reliable communication with the 93AA66/SN?

Reliable communication with the 93AA66/SN requires minimum CS low time (TCSL) of 250 ns between instructions, clock high/low times (TCKH/TCKL) of ≥250 ns, and chip select setup/hold times (TCSS/TCSH) of 50 ns and 0 ns respectively. Data input must be stable 100 ns before (TDIS) and after (TDIH) the CLK rising edge. These values are guaranteed across 1.8V–5.5V and −40°C to +85°C. The 93AA66/SN does not require continuous clocking during self-timed erase/write cycles.

Can the 93AA66/SN be used in place of the 93AA66C/SN?

The 93AA66/SN is functionally compatible with the 93AA66C/SN in terms of pinout, instruction set, timing, and memory organization. However, the 93AA66C/SN features enhanced 6 kV HBM ESD protection versus 4 kV for the 93AA66/SN and is the recommended version for new designs per Microchip's documentation. While the 93AA66/SN remains usable in legacy systems, long-term supply and support favor the C-suffix variant.

Does the 93AA66/SN support sequential read operations?

Yes, the 93AA66/SN supports sequential read: when CS remains high after a READ instruction, the internal address counter automatically increments, allowing consecutive memory locations to be read without reissuing the opcode or address. This reduces host MCU overhead and improves throughput for block reads. Sequential read works identically in both 512 × 8 and 256 × 16 modes, with address wraparound at the end of the array. The 93AA66/SN outputs a dummy zero bit before each data word during read sequences.