Microchip Technology 93LC56AT-E/OT

Overview

93LC56AT-E/OT from Microchip Technology Inc. is a 2 Kbit (256 × 8-bit) low-voltage serial EEPROM with Microwire-compatible 3-wire interface, 2.5–5.5 V supply range, and automotive-grade temperature operation (−40°C to +125°C). It features self-timed erase/write cycles, automatic ERAL before WRAL, power-on/off data protection, and Ready/Busy status signaling via DO pin - deployed in engine control units for calibration storage.

For engineers reviewing the 93LC56AT-E/OT datasheet, 93LC56AT-E/OT pinout, 93LC56AT-E/OT application, or 93LC56AT-E/OT equivalent, key selection criteria include its SOT-23-6 package, 8-bit fixed organization (no ORG pin), automotive qualification, 1 million erase/write endurance, and 200-year data retention - critical for safety-critical nonvolatile memory in harsh environments.

Technical Context

The 93LC56AT-E/OT implements a synchronous serial Microwire protocol with CS, CLK, and DI/DO signals. It uses a dedicated 8-bit memory array (256 × 8) without ORG pin functionality - distinguishing it from C-variant devices. All instructions (READ, WRITE, ERASE, ERAL, WRAL, EWEN/EWDS) are initiated by a Start bit followed by opcode and address/data on rising CLK edges.

Internal logic enforces power-on write protection: device powers up in EWDS mode, requiring explicit EWEN before any programming. During erase/write, DO pin transitions between High-Z (CS low), Busy (DO = 0), and Ready (DO = 1), enabling polling-based timing control without external delays. VCC detection circuitry inhibits operations below 1.5 V.

Key Specifications

Pinout & Package

93LC56AT-E/OT is housed in a Pb-free 6-lead SOT-23 package (JEDEC MO-178AA), measuring 2.9 mm × 1.6 mm × 1.1 mm, with matte tin (Sn) finish and exposed pad optionally connected to VSS.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 93LC56BT-E/OT and AT25DF021-SSH-T, the 93LC56AT-E/OT provides optimal balance of byte-level write flexibility, automotive qualification, compact SOT-23 footprint, and Microwire compatibility - making it the preferred choice for embedded calibration storage where endurance, reliability, and minimal GPIO usage are prioritized.

Availability

93LC56AT-E/OT is available at Aetrix Electronics and suitable for automotive control modules, industrial sensor nodes, and medical diagnostic equipment requiring stable component supply across extended product lifecycles.

Supply support for 93LC56AT-E/OT 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, mixed-signal, analog, and Flash-IP solutions, serving automotive, industrial, consumer, and communications markets with high-reliability semiconductor products.

The 93LC56A/B/C series was designed specifically for cost-sensitive, low-power serial EEPROM applications in automotive and industrial environments - emphasizing robustness, long-term data integrity, and seamless integration with legacy Microwire controllers.

FAQ

What is the memory organization of the 93LC56AT-E/OT?

The 93LC56AT-E/OT is a fixed 256 × 8-bit (2 Kbit) organization device with no ORG pin - unlike C-variants, it does not support x16 mode. This eliminates external configuration logic and simplifies firmware design for 8-bit data paths. The 93LC56AT-E/OT operates exclusively in x8 mode, delivering one byte per READ instruction with 20 clock cycles required per access.

Does the 93LC56AT-E/OT require an external pull-up resistor on the DO pin?

No, the 93LC56AT-E/OT does not require an external pull-up on DO. Its DO pin is actively driven high/low during READ or Ready/Busy status reporting and enters High-Z when inactive. However, if DI and DO are shorted (shared bus), a current-limiting resistor is recommended to prevent bus conflict when A0 = high during dummy-zero phase - a design consideration specific to the 93LC56AT-E/OT's Microwire protocol implementation.

How is write protection implemented on the 93LC56AT-E/OT?

Write protection on the 93LC56AT-E/OT is implemented through dual hardware/software mechanisms: (1) power-on reset forces EWDS (Erase/Write Disable) mode, blocking all programming until EWEN is issued; and (2) internal VCC detection halts writes below ~1.5 V. These features ensure the 93LC56AT-E/OT remains immune to spurious writes during power ramp-up, brown-out, or noise events - critical for automotive safety compliance.

What is the maximum clock frequency supported by the 93LC56AT-E/OT at 3.3 V?

At VCC = 3.3 V, the 93LC56AT-E/OT supports a maximum clock frequency of 2 MHz (per Table 1-2, A1 parameter). This is derived from the 2.5 V ≤ VCC < 4.5 V condition row, which specifies 2 MHz max. Exceeding this limit risks setup/hold violations (e.g., TDIS, TCKH), leading to opcode misreads or failed writes - a constraint explicitly defined in the 93LC56AT-E/OT's AC characteristics table.

Can the 93LC56AT-E/OT be used in place of the 93LC56CT-E/OT?

No, the 93LC56AT-E/OT cannot substitute for the 93LC56CT-E/OT without hardware and firmware changes. The 93LC56CT-E/OT includes an ORG pin enabling x8/x16 configuration, while the 93LC56AT-E/OT has no ORG pin and is fixed x8. Replacing them requires removing ORG routing, updating address/data framing logic, and verifying timing margins - the 93LC56AT-E/OT is not pin-compatible or functionally equivalent to the C-variant.