Microchip Technology AT24CS04-XHM-B

Overview

AT24CS04-XHM-B from Microchip Technology is a 4-Kbit I²C-compatible serial EEPROM with factory-programmed 128-bit unique serial number, 1.7V–5.5V operation, and hardware write protection via WP pin-used for secure device identification and configuration storage in industrial sensors and embedded controllers.

For engineers reviewing the AT24CS04-XHM-B datasheet, AT24CS04-XHM-B pinout, AT24CS04-XHM-B application, or AT24CS04-XHM-B equivalent, key selection criteria include its guaranteed-unique serial number, 16-byte page write capability, industrial temperature range (−40°C to +85°C), and support for I²C Fast Mode Plus (1 MHz) at VCC ≥ 2.5V.

Technical Context

The AT24CS04-XHM-B implements a two-wire I²C slave interface with Schmitt-trigger inputs and noise-filtered SCL/SDA lines, enabling robust communication in electrically noisy environments. It uses internal address latching and automatic page wrap during sequential writes across its 512 × 8-bit memory array.

Its hardware write protection is controlled solely by the WP pin state (GND = enabled, VCC = full-array locked), independent of software commands. The 128-bit serial number resides in a dedicated, read-only memory region outside the user-accessible EEPROM array and is permanently programmed during wafer test.

Key Specifications

Pinout & Package

AT24CS04-XHM-B is supplied in an 8-lead TSSOP package (3.0 mm × 4.4 mm, 0.65 mm pitch) with exposed pad for thermal enhancement and optional GND connection.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT24CS04-SSHM-B, the AT24CS04-XHM-B offers identical memory, serial number, and interface features in a smaller, lower-profile TSSOP package-ideal for space-constrained PCBs. Versus M95M04-DRMN6TP/K, it provides guaranteed unique identification and I²C compatibility but at lower density and different protocol stack requirements.

Availability

AT24CS04-XHM-B is available at Aetrix Electronics and suitable for industrial sensor calibration, secure firmware authentication, and smart meter asset tracking requiring stable component supply, long-term lifecycle support, and RoHS-compliant green packaging.

Supply support for AT24CS04-XHM-B 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 U.S.-based semiconductor manufacturer specializing in microcontrollers, analog devices, and nonvolatile memory solutions for industrial, automotive, and communications markets.

The AT24CS04-XHM-B belongs to Microchip's CS-series Serial EEPROM product line, designed specifically to deliver factory-assigned uniqueness and enhanced reliability for secure device identity and configuration storage in mission-critical embedded systems.

FAQ

What is the function of the A1 and A2 pins on the AT24CS04-XHM-B?

The A1 and A2 pins on the AT24CS04-XHM-B are hardware device address inputs that allow up to four AT24CS04 devices to share a single I²C bus. They are hard-wired to GND or VCC to set the device's 7-bit I²C slave address. If left unconnected, both pins are internally pulled down to GND-though Microchip recommends explicit biasing to avoid noise-induced misaddressing. These pins have no effect on the 128-bit serial number or memory operation.

Does the AT24CS04-XHM-B support 1 MHz I²C communication?

Yes, the AT24CS04-XHM-B supports I²C Fast Mode Plus at 1 MHz-but only when VCC is between 2.5V and 5.5V. At lower supply voltages (1.7V–2.5V), it operates in standard (100 kHz) or fast (400 kHz) mode. The 1 MHz capability enables faster configuration loading in time-sensitive applications such as real-time sensor initialization or bootloader parameter fetch.

How is the 128-bit serial number accessed on the AT24CS04-XHM-B?

The 128-bit serial number on the AT24CS04-XHM-B is accessed via a dedicated I²C read sequence starting at memory address 0x00FA (hex). It occupies eight consecutive bytes (0x00FA–0x00FF) and is read-only-no write command can modify it. This region lies outside the main 512-byte user EEPROM array and is permanently programmed during Microchip's wafer-level test process.

What happens when the WP pin is left floating on the AT24CS04-XHM-B?

When the WP pin is left floating on the AT24CS04-XHM-B, it is internally pulled down to GND, enabling normal write operations. However, due to capacitive coupling risks in noisy environments, Microchip explicitly recommends connecting WP to a defined logic level (GND for write-enable, VCC for full-array lock) using ≤10 kΩ resistors-never leaving it floating in production designs.

Is the AT24CS04-XHM-B pin-compatible with other AT24CS04 variants like AT24CS04-SSHM-B?

Yes-the AT24CS04-XHM-B shares identical pinout, signal definitions, and electrical characteristics with other AT24CS04 variants including AT24CS04-SSHM-B. The only difference is package type: XHM-B denotes 8-lead TSSOP, while SSHM-B denotes 8-lead SOIC. Both use the same 8-pin mapping (A1, A2, GND, VCC, WP, SCL, SDA, NC), enabling direct PCB footprint substitution where mechanical constraints allow.