Microchip Technology MCP98242T-BE/ST

Overview

MCP98242T-BE/ST from Microchip Technology is a JEDEC JC42.4-compliant digital temperature sensor with integrated 256-byte serial EEPROM, optimized for DDR memory module SPD applications. It delivers ±0.5°C typical accuracy from +75°C to +95°C, operates from 3.0V to 3.6V, draws 200 µA typical active current and 3 µA max shutdown current, and interfaces via I²C/SMBus. It is deployed in DIMM modules for real-time thermal monitoring and vendor data storage.

For engineers reviewing the MCP98242T-BE/ST datasheet, MCP98242T-BE/ST pinout, MCP98242T-BE/ST application, or MCP98242T-BE/ST equivalent, key selection criteria include JEDEC JC42.4 compliance, 0.25°C resolution capability, programmable event boundaries (TUPPER/TLOWER/TCRIT), permanent/software write-protect EEPROM, and open-drain Event output polarity configuration for thermostat or interrupt use.

Technical Context

The MCP98242T-BE/ST integrates a band-gap temperature sensor and ΔΣ ADC with user-programmable registers for boundary hysteresis, shutdown mode, and event output configuration (comparator/interrupt/critical). Its EEPROM is partitioned into permanently or reversibly write-protected lower 128 bytes (00h–7Fh) for SPD data and unprotected upper 128 bytes (80h–FFh) for general storage.

It implements SMBus/I²C Standard Mode timing (10–100 kHz), supports up to eight devices on one bus via A2/A1/A0 address pins, and features a 40 ms serial interface timeout for the temperature sensor (not EEPROM). The Event pin is open-drain with 0.4 V max VOL at 3 mA and 1 µA max IOH.

Key Specifications

Pinout & Package

Package: 8-pin TDFN (2 mm × 3 mm, exposed thermal pad). Pin 9 (EP) is internally connected to GND and must be soldered to PCB ground plane for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar temperature-sensing-with-SPD-EEPROM applications.

Compared with AT30TS74-MA8Y and LM75BIMM/NOPB, the MCP98242T-BE/ST uniquely combines JEDEC JC42.4 compliance, full 256-byte SPD EEPROM with write-protection, and three independent programmable trip thresholds - making it the only single-chip solution qualified for DDR3/DDR4 server and industrial DIMM thermal management.

Availability

MCP98242T-BE/ST is available at Aetrix Electronics and suitable for DIMM modules, server memory subsystems, and industrial embedded memory applications requiring stable component supply, JEDEC-compliant thermal sensing, and SPD EEPROM integration.

Supply support for MCP98242T-BE/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 microcontrollers, analog components, and connectivity solutions, serving automotive, industrial, and computing markets with high-reliability silicon.

The MCP98242 product line was designed specifically for JEDEC JC42.4-compliant memory module thermal monitoring and Serial Presence Detect (SPD) data storage, targeting DDR2/DDR3/DDR4 DIMM manufacturers.

FAQ

What is the primary application domain for the MCP98242T-BE/ST?

The MCP98242T-BE/ST is engineered for DDR memory modules compliant with JEDEC JC42.4 specifications. It serves as both a precision temperature sensor and SPD EEPROM in DIMMs used in laptops, servers, and industrial PCs. Its integrated 256-byte EEPROM stores vendor ID, memory timing parameters, and thermal calibration data, while its ±0.5°C accuracy in the +75°C to +95°C range meets strict thermal monitoring requirements for modern DRAM operation. The MCP98242T-BE/ST is not intended for general-purpose temperature sensing outside SPD-constrained environments.

Does the MCP98242T-BE/ST support I²C Fast Mode or only Standard Mode?

The MCP98242T-BE/ST supports I²C Standard Mode only, with a maximum clock frequency of 100 kHz as specified in its timing diagram. It does not support Fast Mode (400 kHz) or Fast Mode Plus (1 MHz). This limitation aligns with SMBus 2.0 compliance and ensures robust communication in electrically noisy DIMM environments. The device implements a 40 ms serial interface timeout for the temperature sensor block, and its SDA/SCL DC characteristics (VIH = 2.1 V min, VOL = 0.4 V max at 3 mA) are validated for 3.0–3.6 V operation. Using the MCP98242T-BE/ST above 100 kHz may result in unreliable register access or EEPROM writes.

How is EEPROM write protection implemented on the MCP98242T-BE/ST?

The MCP98242T-BE/ST implements two distinct EEPROM write-protection mechanisms: Permanent Write-Protection (PWP) and Software Reversible Write-Protection (SWP), both applicable to the lower 128 bytes (addresses 00h–7Fh). PWP is activated by applying 8–12 V to the A0 pin, which irreversibly locks those bytes. SWP is controlled via internal register bits and can be toggled in-system using standard I²C commands. The upper 128 bytes (80h–FFh) remain fully writable with no protection. This architecture allows DIMM vendors to lock critical SPD fields (e.g., manufacturer ID, memory type) while retaining flexibility for runtime-calibrated thermal offsets or firmware version stamps stored in the upper block - a feature essential for field-upgradable memory modules.

Can the MCP98242T-BE/ST operate outside the 3.0V–3.6V supply range?

No, the MCP98242T-BE/ST is specified and characterized exclusively for 3.0V to 3.6V operation. Its Power-on Reset (POR) threshold is 2.3V for the temperature sensor and 1.6V for the EEPROM, but functional operation below 3.0V is not guaranteed. Electrical characteristics - including accuracy (±0.5°C), conversion time (65–125 ms), and I²C timing - are validated only within the 3.0–3.6V window. Operating the MCP98242T-BE/ST at 2.9V or 3.7V risks degraded accuracy, increased shutdown current, or communication failures. For systems with wider voltage rails, an LDO regulator must be used to deliver a stable 3.3V ±0.3V supply to the MCP98242T-BE/ST's VDD pin.

What thermal response time does the MCP98242T-BE/ST exhibit in its TDFN package?

In its 8-pin TDFN-8 (2 mm × 3 mm) package, the MCP98242T-BE/ST achieves a thermal response time (tRES) of 0.7 seconds to reach 63% of final temperature when transitioning from 25°C air to 125°C oil bath. This value is measured under standardized conditions and reflects the combined thermal mass and conductivity of the die, package, and exposed pad (EP). The EP must be soldered to a PCB ground plane to achieve this spec; omitting EP connection degrades thermal response and increases junction-to-ambient resistance (θJA = 41°C/W with EP, vs. >100°C/W without). This rapid response enables timely detection of thermal transients in high-speed memory subsystems, supporting proactive throttling before DRAM reliability limits are breached.