Microchip Technology 93C46B-I/ST

Overview

93C46B-I/ST from Microchip Technology Inc. is a 1Kbit (64 × 16-bit) low-voltage serial EEPROM with Microwire-compatible 3-wire interface, 4.5–5.5 V supply range, and industrial temperature rating (–40°C to +85°C). It features self-timed erase/write cycles, automatic ERAL before WRAL, Ready/Busy status signaling via DO pin, and RoHS-compliant 8-lead SOIC packaging. Used in embedded system configuration storage where nonvolatile, byte- or word-addressable memory is required.

For engineers reviewing the 93C46B-I/ST datasheet, 93C46B-I/ST pinout, 93C46B-I/ST application, or 93C46B-I/ST equivalent, key selection criteria include its fixed 16-bit organization (no ORG pin), 2 ms write cycle time, 1 million endurance cycles, 200-year data retention, and compatibility with legacy Microwire controllers in space-constrained industrial control modules.

Technical Context

The 93C46B-I/ST implements a synchronous serial Microwire interface with CS, CLK, DI, and DO pins - no ORG pin (dedicated x16 mode). Communication uses start-bit detection followed by opcode, address (6-bit for 64-word array), and 16-bit data, requiring 25 clock cycles for READ/WRITE. The device powers up in EWDS (Erase/Write Disable) state and requires explicit EWEN before programming.

Its internal architecture includes an address decoder, data register, mode decode logic, and output buffer. Erase/write operations are fully self-timed: for 93C versions, the rising edge of CLK on the final data bit initiates auto-erase-and-write; DO transitions to open-drain Ready/Busy status when CS is reasserted after ≥250 ns low time (TCSL).

Key Specifications

Pinout & Package

8-lead SOIC (SOIC-8, package code "ST") with Pb-free Matte Tin finish. Pin 1 marked by laser dot; pin 1 ID corner located at top-left when notch faces up.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 93LC46B-I/ST, the 93C46B-I/ST provides tighter 5 V supply optimization and simpler POR behavior, while AT25010B-SSHL-T trades Microwire compatibility for faster SPI access and broader voltage support - selection depends on host interface capability and system-level voltage architecture.

Availability

93C46B-I/ST is available at Aetrix Electronics and suitable for industrial control systems, medical instrumentation, and automotive body electronics requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for 93C46B-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 microcontroller, analog, and Flash-IP solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 93Cxx series was designed specifically for cost-sensitive, space-constrained embedded systems requiring reliable, low-pin-count serial EEPROM with Microwire compatibility and robust data integrity features.

FAQ

What is the memory organization of the 93C46B-I/ST?

The 93C46B-I/ST has a fixed 64 × 16-bit (1 Kbit) organization - it does not include an ORG pin and operates exclusively in 16-bit word mode. This eliminates external configuration logic and simplifies firmware handling of 16-bit data structures compared to ORG-enabled variants like the 93C46C-I/ST. Each READ or WRITE instruction transfers one full 16-bit word.

Does the 93C46B-I/ST require an external pull-up resistor on the DO pin?

Yes, the 93C46B-I/ST 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 operations and Ready/Busy status polling. Without it, DO remains undriven during High-Z states and cannot reliably signal 'Ready' (high) or support proper Microwire timing margins.

How does the 93C46B-I/ST handle power-up write protection?

The 93C46B-I/ST incorporates hardware power-on reset (POR) circuitry that inhibits all write operations until VCC rises above 3.8 V. Below this threshold, the device remains in EWDS (Erase/Write Disable) state, preventing accidental writes during power ramp or brown-out conditions - a critical safeguard for maintaining configuration integrity in industrial power environments.

Can the 93C46B-I/ST be used with a microcontroller that only supports SPI?

No - the 93C46B-I/ST uses a Microwire-compatible 3-wire interface (CS/CLK/DI/DO) with distinct instruction opcodes, timing, and start-bit protocol; it is not SPI-compatible. Attempting SPI communication will fail due to incompatible clock polarity/phase, frame format, and lack of MISO/MOSI separation. Use SPI EEPROMs like AT25xxx or SST25xxx families instead.

What is the minimum CS low time required between commands on the 93C46B-I/ST?

The 93C46B-I/ST requires a minimum Chip Select low time (TCSL) of 250 ns between consecutive instructions. This ensures internal control logic resets properly and prevents command misinterpretation. Violating this spec may cause skipped instructions, corrupted writes, or unpredictable Ready/Busy status reporting - verified in AC Characteristics Table A6 of the official datasheet.