Analog Devices Inc. ADT7481ARMZ-R7-AD

Overview

ADT7481ARMZ-R7-AD from onsemi is a dual remote + local digital temperature sensor IC with SMBus interface, ±1°C accuracy on all channels, 0.25°C remote resolution, programmable over/undertemperature limits, and dual open-drain THERM outputs for thermal management in PCs and embedded systems.

For engineers reviewing the ADT7481ARMZ-R7-AD datasheet, ADT7481ARMZ-R7-AD pinout, ADT7481ARMZ-R7-AD application, or ADT7481ARMZ-R7-AD equivalent, key selection criteria include remote diode sensing capability, dual THERM output configurability, SMBus address 0x4C, MSOP-10 package compatibility, and extended −64°C to +191°C measurement range support.

Technical Context

The ADT7481ARMZ-R7-AD integrates an 11-bit ADC, analog multiplexer, and digital register bank to alternately sample on-chip ambient temperature and two external thermal diodes (e.g., CPU/GPU substrate transistors). It uses delta-V_BE measurement at two current levels to reject device-to-device V_BE variation and achieve ±1°C accuracy.

Its SMBus interface supports ALERT interrupt signaling and reconfigurable Pin 8 (ALERT/THERM2), while internal limit comparators drive THERM outputs directly-enabling fan control or CPU throttling without host intervention. Conversion rate (0.0625–64 Hz) and channel selection are software-programmable via Configuration Register 1 and Conversion Rate Register.

Key Specifications

Pinout & Package

ADT7481ARMZ-R7-AD is housed in a Pb-free 10-lead MSOP package (Case 846AC), with exposed pad for thermal dissipation. Pin 1 is VDD; pins 2/3 and 6/7 are differential remote sensor inputs; pins 4 and 8 are open-drain THERM outputs; pins 9 and 10 are SMBus I/O.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual remote temperature sensor applications.

Compared with ADM1032ARQZ, ADT7481ARMZ-R7-AD adds a second remote channel and extended temperature range-critical for multi-core platforms. Versus LM95235CIMMX, it offers tighter ±1°C accuracy at lower cost and SMBus-native integration, though with reduced resolution.

Availability

ADT7481ARMZ-R7-AD is available at Aetrix Electronics and suitable for desktop PC thermal management, industrial PLC controllers, and automotive infotainment systems requiring stable component supply and long-term lifecycle support.

Supply support for ADT7481ARMZ-R7-AD 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and IoT applications.

The ADT7481ARMZ-R7-AD belongs to onsemi's precision thermal monitoring product line, designed specifically for PC platform management, server thermal control, and embedded systems requiring dual remote diode sensing with SMBus integration.

FAQ

What is the SMBus address of the ADT7481ARMZ-R7-AD?

The ADT7481ARMZ-R7-AD has a fixed SMBus address of 0x4C. This is hardwired and cannot be changed via hardware pins. A variant, ADT7481-1, uses 0x4B. The address is used for all register reads and writes over the SMBus interface, and multiple ADT7481ARMZ-R7-AD devices can coexist on the same bus only if different addresses are assigned-requiring use of the alternate part number.

Can the ADT7481ARMZ-R7-AD measure temperatures below 0°C?

Yes, the ADT7481ARMZ-R7-AD supports measurements down to −64°C when configured for extended range mode (bit 2 of Configuration Register 1 = 1). In default mode, readings below 0°C return 0x00 (binary scale). The extended mode uses offset binary format, where −55°C maps to 0x09. Accuracy remains ±1°C from 0°C to +70°C ambient, but degrades slightly outside that range per datasheet specifications.

How does the ADT7481ARMZ-R7-AD handle remote diode open-circuit detection?

The ADT7481ARMZ-R7-AD continuously monitors D1+–D1− and D2+–D2− voltage differentials. If either pair shows >1.4 V or <0.1 V, the corresponding D1 OPEN or D2 OPEN flag (Status Register 1 Bit 2 or Status Register 2 Bit 2) is set. These flags remain latched until the status register is read and the fault condition clears-enabling robust diagnostics in unattended systems using ADT7481ARMZ-R7-AD.

Is the ADT7481ARMZ-R7-AD pin-compatible with the ADM1032?

No, the ADT7481ARMZ-R7-AD is not pin-compatible with the ADM1032. While both share the same SMBus address (0x4C) and target PC thermal management, ADT7481ARMZ-R7-AD has 10 pins with dual remote inputs (D1+/D1−, D2+/D2−) and dual THERM outputs (THERM, ALERT/THERM2), whereas ADM1032 uses 16-pin QSOP with only one remote pair and no second THERM output. Layout redesign is required for migration.

What is the maximum conversion rate supported by the ADT7481ARMZ-R7-AD?

The ADT7481ARMZ-R7-AD supports up to 64 conversions per second on all three channels (local + remote 1 + remote 2) when averaging is disabled. At this rate, conversion time is 11–14 ms per full cycle. Slower rates (e.g., 0.0625 Hz) extend measurement intervals to 16 seconds and reduce average current to 3 mA-optimizing power in battery-backed or thermally stable environments using ADT7481ARMZ-R7-AD.