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Microchip Technology 93C66BT-I/MC — Memory (DRAM / SRAM / Flash / EEPROM)

Microchip 93C66BT-I/MC 4Kbit Microwire EEPROM, 2 MHz, 8-DFN

MPN93C66BT-I/MC
Active

Microchip 93C66BT-I/MC, 4Kbit EEPROM, Microwire interface, 2 MHz clock, 256 x 16 organization, 4.5V-5.5V supply, -40°C to 85°C, 8-VFDFN Exposed Pad, Tape & Reel.

$0.4650Ref. price · indicative, final on quote
Microchip Technology 93C66BT-I/MC datasheet (PDF)
Packaging8-VFDFN Exposed Pad
RoHSROHS3 Compliant
Independent supplier — new & surplus stockAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

93C66BT-I/MC specifications
ParameterValue
Memory typeNon-Volatile
MountingSurface Mount
Voltage4.5V ~ 5.5V
Frequency2 MHz
Memory interfaceMicrowire
Operating temperature-40°C~85°C(TA)
PackageTape & Reel (TR); Cut Tape (CT)
TechnologyEEPROM
Memory size4Kbit
Memory formatEEPROM
Case8-VFDFN Exposed Pad
Memory organization256 x 16
Write cycle time - word, page2ms

Product details

The Microchip 93C66BT-I/MC is a 4Kbit non-volatile EEPROM that talks over a Microwire serial interface — a three-wire bus (clock, data in, data out) that predates I2C and SPI but still shows up in industrial sensors, legacy PLC I/O modules, and calibration-storage slots where the host controller has a dedicated Microwire port. Organized as 256 x 16 bits, it clocks up to 2 MHz and writes a word or page in 2 ms.

Industrial temp range — field-swap friendly

If you are replacing one in a panel on a cold morning, the part will work at temperature — no warm-up required. The 8-DFN package (2x3 mm) with exposed pad needs a hot-air station for rework; it is not socket-friendly, but with a fine tip and some flux it is a field-swap you can do without a full reflow oven.

The base product number is 93C66B; the -I/MC suffix flags the industrial temp range and the 8-DFN package.

Frequently asked questions

Does the 93C66BT-I/MC work with a 5V supply?

It will not run at 3.3V — do not try to power it from a lower rail without a level translator on the Microwire bus.

What is the closest functional equivalent to the 93C66BT-I/MC?

The 93C66CT-I/MC is a near drop-in: same 4Kbit density, same 8-DFN package, same Microwire interface, but organized as 512 x 8 (byte mode) in addition to 256 x 16, and it clocks at 3 MHz instead of 2 MHz. If your host controller handles the extra clock speed and you need byte-wide access, the 93C66CT-I/MC is worth evaluating as a second source.

How do I program the 93C66BT-I/MC?

Programming uses the Microwire protocol: assert Chip Select (CS), clock in a START bit followed by the opcode (WRITE), address, and data on the DI pin while toggling the SK clock. Each write cycle takes 2 ms (word or page), after which the READY/BUSY status is polled via the DO pin. Standard EEPROM programmers and most MCU Microwire peripherals handle this directly.