Microchip Technology 93AA66A-I/P

Overview

93AA66A-I/P from Microchip Technology Inc. is a 4 Kbit (512 × 8-bit) low-voltage serial EEPROM with Microwire-compatible 3-wire interface, 1.8–5.5 V supply range, industrial temperature rating (−40°C to +85°C), and Pb-free PDIP-8 packaging. It provides nonvolatile memory storage for configuration data in microcontroller-based systems requiring reliable, low-power, byte-serial access.

For engineers reviewing the 93AA66A-I/P datasheet, 93AA66A-I/P pinout, 93AA66A-I/P application, or 93AA66A-I/P equivalent, key selection criteria include its fixed 8-bit organization (no ORG pin), self-timed erase/write cycles (6 ms), Ready/Busy status signaling via DO, and compatibility with legacy Microwire controllers in space-constrained embedded designs.

Technical Context

The 93AA66A-I/P implements a synchronous serial interface using CS, CLK, and DI/DO lines with start-bit detection and opcode-driven command execution. Its internal architecture includes an address decoder, mode decode logic, and output buffer enabling sequential read, individual erase/write, ERAL (Erase All), and WRAL (Write All) operations - all initiated by falling-edge CS (for AA/LC variants) and verified via DO pin polling.

It features built-in power-on/off data protection, automatic erase-before-write, and EWEN/EWDS security commands to prevent accidental writes. The device operates without external timing components and supports clock frequencies up to 3 MHz at VCC ≥ 4.5 V, scaling down to 1 MHz at 1.8 V, ensuring robustness across wide voltage and temperature ranges.

Key Specifications

Pinout & Package

Package: 8-lead PDIP (Plastic Dual In-line Package), Pb-free Matte Tin finish, through-hole mounting, 0.3 inch body width.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 93LC66A-I/P, the 93AA66A-I/P adds 1.8 V operation for ultra-low-power systems; compared with AT25040B-PU, it retains Microwire compatibility for legacy PIC® and 8051 platforms but trades off speed for protocol simplicity and pin count reduction.

Availability

93AA66A-I/P is available at Aetrix Electronics and suitable for smart meter calibration storage, industrial PLC configuration memory, and medical device settings backup requiring stable component supply across extended product lifecycles.

Supply support for 93AA66A-I/P 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 design and manufacturing operations.

The 93XX series EEPROMs were designed specifically for cost-sensitive, low-power embedded systems requiring simple, robust, and long-life nonvolatile storage - particularly in industrial, medical, and consumer applications where Microwire interface compatibility and wide VCC range are essential.

FAQ

What is the memory organization of the 93AA66A-I/P?

The 93AA66A-I/P has a fixed 512 × 8-bit (4 Kbit) organization with no ORG pin - unlike 'C' variants, it does not support configurable word size. This simplifies hardware design by eliminating the need for external logic to drive ORG, and ensures consistent 8-bit data framing in all applications. The 93AA66A-I/P is fully compatible with Microwire protocols expecting x8 memory maps.

Does the 93AA66A-I/P require an external pull-up resistor on the DO pin?

Yes, the 93AA66A-I/P DO pin is open-drain and requires an external pull-up resistor (typically 4.7 kΩ to VCC) to ensure valid logic-high levels during Read and Ready/Busy status reporting. Without it, DO remains undefined or weakly driven, risking communication failure or incorrect busy-state interpretation. This is explicitly required per the datasheet's electrical characteristics and timing diagrams.

How does the 93AA66A-I/P protect against inadvertent writes during power transitions?

The 93AA66A-I/P incorporates dual protection: (1) a power-on reset (POR) circuit that inhibits all write operations until VCC rises above ~1.5 V, and (2) default Erase/Write Disable (EWDS) state at power-up. An explicit EWEN command must precede any ERASE or WRITE instruction. This prevents corruption during brownouts, cold starts, or noisy power-rail conditions - a critical feature confirmed in Section 2.6 and Table 1-1 (D11).

What is the maximum clock frequency supported by the 93AA66A-I/P at 3.3 V operation?

At VCC = 3.3 V, the 93AA66A-I/P supports a maximum clock frequency of 2 MHz, as specified in Table 1-2 (A1). This is derived from the 2.5 V ≤ VCC < 4.5 V condition row, which defines FCLK ≤ 2 MHz. Exceeding this limit risks setup/hold timing violations, especially for TDIS, TDIH, and TCKL parameters, potentially causing opcode misreads or incomplete write cycles.

Can the 93AA66A-I/P be used in place of the 93C66A-I/P?

No - the 93AA66A-I/P is not a functional or pin-compatible replacement for the 93C66A-I/P. While both are 4 Kbit serial EEPROMs in PDIP-8, the 93C66A requires VCC ≥ 4.5 V, uses different timing (2 ms write cycle), and has distinct ERAL/WRAL voltage requirements (≥4.5 V). Substituting them risks failed writes, data corruption, or premature device failure due to incompatible voltage and timing specifications.