Microchip Technology AT21CS11-MCHM10-T

Overview

AT21CS11-MCHM10-T from Microchip Technology is a single-wire, I/O-powered 1-Kbit (128 × 8) serial EEPROM with factory-programmed 64-bit unique serial number, operating from 2.7V to 4.5V VPUP, supporting 125 kbps high-speed mode, and rated for -40°C to +85°C industrial temperature range - used in ink cartridge identification and analog sensor calibration storage.

For engineers reviewing the AT21CS11-MCHM10-T datasheet, AT21CS11-MCHM10-T pinout, AT21CS11-MCHM10-T application, or AT21CS11-MCHM10-T equivalent, this page delivers verified electrical specs, SI/O/GND terminal mapping, ROM zone security features, self-timed 5 ms write cycle, and I²C-emulation protocol behavior - all confirmed for the AT21CS11-MCHM10-T variant.

Technical Context

The AT21CS11-MCHM10-T implements a single-wire bus using open-drain SI/O with internal power harvesting - no VCC pin required. It emulates I²C addressing via 4-bit opcodes (e.g., 0xAh for EEPROM access, 0xEh for high-speed mode), enabling reuse of existing I²C firmware stacks without hardware modification.

It supports four 256-bit ROM zones (permanently lockable), an 8-byte factory-unique serial number in its security register, and discovery response timing compliant with tDACK (8–24 µs) and tMSDR (2–6 µs) - all validated for High-Speed mode only (Standard Speed is not supported on AT21CS11).

Key Specifications

Pinout & Package

AT21CS11-MCHM10-T is packaged in 3-lead SOT23 (JEDEC MO-178AA), with pin 1 = SI/O, pin 2 = GND, pin 3 = NC. Power and bidirectional data share the SI/O pin; GND provides reference; NC is unconnected and must be left floating or grounded per layout best practice.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar single-wire EEPROM applications.

Compared with AT21CS01-MCHM10-T, the AT21CS11-MCHM10-T extends VPUP compatibility to 4.5V and removes Standard Speed mode - simplifying timing design for 125 kbps operation. Against DS2431+T&R, it eliminates VCC dependency and improves throughput, but requires firmware adaptation to Microchip's I²C-emulation protocol.

Availability

AT21CS11-MCHM10-T is available at Aetrix Electronics and suitable for ink cartridge authentication, analog sensor calibration storage, aftermarket automotive module ID, smart cable identification, and consumable lifecycle management requiring stable component supply across industrial and consumer production programs.

Supply support for AT21CS11-MCHM10-T 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 manufacturing and support infrastructure.

The AT21CS11-MCHM10-T belongs to Microchip's single-wire serial EEPROM product line, designed specifically for ultra-low-pin-count, power-harvesting applications in consumables, sensors, and accessories where space, cost, and two-point mechanical connectivity are critical.

FAQ

Does AT21CS11-MCHM10-T require an external VCC supply?

No, AT21CS11-MCHM10-T is fully I/O-powered: it harvests energy from the SI/O line's external pull-up voltage (2.7V–4.5V). No VCC pin exists - only SI/O and GND are electrically active. This enables true 2-pin integration in space-constrained or unpowered attachments like printer cartridges or detachable sensors. The AT21CS11-MCHM10-T draws active current up to 0.5 mA during writes and standby current as low as 0.6 µA.

What is the function of the NC pin on AT21CS11-MCHM10-T?

The NC (No Connect) pin on AT21CS11-MCHM10-T - pin 3 in the 3-lead SOT23 package - is internally unconnected and serves no electrical purpose. It may be left floating or tied to GND for mechanical reinforcement, but must never be driven or used as a signal path. This pin does not affect AT21CS11-MCHM10-T operation, timing, or power harvesting - all functionality resides strictly between SI/O and GND.

Can AT21CS11-MCHM10-T be used alongside AT21CS01 devices on the same bus?

Yes, AT21CS11-MCHM10-T and AT21CS01 devices share identical pinout, command set, and I²C-emulation protocol, allowing coexistence on the same single-wire bus. However, AT21CS11-MCHM10-T defaults to High-Speed mode only, while AT21CS01 supports both Standard and High-Speed modes. Bus timing must be configured for High-Speed (125 kbps) to ensure reliable communication with all devices - AT21CS11-MCHM10-T ignores Standard Speed commands.

How is the 64-bit serial number accessed in AT21CS11-MCHM10-T?

The 64-bit factory-programmed serial number resides in the lower 8 bytes of the 256-bit security register and is read-only. It is accessed via Opcode 0xBh (Security Register Read), starting at offset 0x00. The AT21CS11-MCHM10-T returns these bytes unconditionally - no unlock sequence or password is required. This serial number is globally unique across all Microchip single-wire devices and is laser-trimmed during wafer test.

What happens when a ROM zone is frozen on AT21CS11-MCHM10-T?

When a ROM zone is frozen on AT21CS11-MCHM10-T using Opcode 0x01 (Freeze ROM Zone State), that 256-bit zone becomes permanently read-only: all subsequent write attempts to its address range return NACK and leave memory unchanged. Freezing is irreversible and applies independently per zone (four total). This feature secures calibration data or vendor IDs against accidental or malicious overwrite - even if the AT21CS11-MCHM10-T's security register is unlocked.