Microchip Technology 93AA66C-I/ST

Overview

93AA66C-I/ST from Microchip Technology is a 4 Kbit low-voltage serial EEPROM with configurable 8-bit or 16-bit word organization selected via the ORG pin, 1.8–5.5 V supply range, industrial temperature rating (–40°C to +85°C), and Microwire-compatible 3-wire serial interface. It delivers 1 million erase/write cycles and >200 years data retention for nonvolatile storage in microcontroller peripherals and power management systems.

For engineers reviewing the 93AA66C-I/ST datasheet, 93AA66C-I/ST pinout, 93AA66C-I/ST application, or 93AA66C-I/ST equivalent, key selection criteria include ORG-pin-configurable word size, self-timed erase/write with ERAL/WRAL support, Ready/Busy status signaling on DO, and compatibility with low-power embedded control buses requiring stable serial memory.

Technical Context

The 93AA66C-I/ST implements a synchronous Microwire-compatible serial interface with CS, CLK, DI, and DO signals plus dedicated ORG input for runtime memory organization selection. Its internal architecture includes an address decoder, mode decode logic, and output buffer enabling sequential read, auto-erase-before-write, and device-status polling.

It supports two distinct memory configurations: when ORG = VSS, it operates as a 512 × 8-bit array; when ORG = VCC, it operates as a 256 × 16-bit array. All programming operations-including ERASE, WRITE, ERAL, and WRAL-are self-timed and initiated by CS falling edge (for 93AA versions), with DO providing real-time Ready/Busy feedback during execution.

Key Specifications

Pinout & Package

93AA66C-I/ST is housed in an 8-lead TSSOP package (ST suffix), with lead pitch of 0.65 mm and body dimensions 4.4 mm × 3.0 mm × 1.2 mm. Pin 1 is marked by laser dot; package is Pb-free and RoHS compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 93LC66C-I/ST, the 93AA66C-I/ST offers lower minimum VCC (1.8 V vs. 2.5 V) for ultra-low-power systems but lacks automotive temperature qualification; versus AT25040B-SSHL-T, it provides ORG-driven flexibility and simpler 3-wire wiring at the cost of non-SPI compatibility.

Availability

93AA66C-I/ST is available at Aetrix Electronics and suitable for industrial sensor calibration, consumer appliance configuration, and automotive body control modules requiring stable component supply, long-term data integrity, and flexible memory organization.

Supply support for 93AA66C-I/ST 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 low-power, space-constrained embedded systems requiring reliable nonvolatile storage with minimal interface overhead and robust data retention across extended lifecycles.

FAQ

What is the function of the ORG pin on the 93AA66C-I/ST?

The ORG pin on the 93AA66C-I/ST selects memory organization: when tied to VSS, it configures the device as 512 × 8-bit; when tied to VCC, it configures as 256 × 16-bit. This allows one 93AA66C-I/ST part to serve dual-host architectures without changing PCB layout or firmware interface logic.

Does the 93AA66C-I/ST require external circuitry to prevent bus conflicts on the DI/DO line?

Yes - when DI and DO are wired together (shared bus), a current-limiting resistor must be placed between them. Without it, a "bus conflict" may occur during the dummy zero preceding read operations if address bit A0 is high, causing undefined voltage levels on DO due to impedance mismatch.

How does the 93AA66C-I/ST protect against accidental writes during power transitions?

The 93AA66C-I/ST incorporates hardware power-on/off protection that inhibits all operations when VCC falls below ~1.5 V. It also powers up in EWDS (Erase/Write Disable) mode, requiring an explicit EWEN command before any erase or write instruction executes - preventing corruption during brown-out or reset sequences.

What is the maximum clock frequency supported by the 93AA66C-I/ST at 3.3 V operation?

At VCC = 3.3 V (within 2.5 V ≤ VCC < 5.5 V range), the 93AA66C-I/ST supports a maximum clock frequency of 2 MHz per Table 1-2 (A1). This defines the upper limit for instruction bit-rate and read throughput in systems using this supply voltage.

Can the 93AA66C-I/ST be used in place of the 93AA66A-I/ST without hardware changes?

No - the 93AA66A-I/ST lacks the ORG pin and is fixed at 512 × 8-bit organization. Replacing it with 93AA66C-I/ST requires connecting the ORG pin to VSS to replicate identical behavior; leaving ORG unconnected or floating violates the requirement that ORG be tied to a valid logic level per Section 3.5.