Analog Devices Inc./Maxim Integrated MAX6687AU40H

Overview

MAX6687AU40H from Maxim Integrated is a dual local/remote temperature switch IC with open-drain active-low outputs, factory-programmed +125°C remote trip threshold, pin-selectable local trip range of +40°C to +80°C in 5°C increments, ±1.5°C accuracy over -40°C to +125°C, and 215µA average supply current. It monitors CPU/FPGA die temperature via external P-N junction and board temperature simultaneously for system shutdown or fan control.

For engineers reviewing the MAX6687AU40H datasheet, MAX6687AU40H pinout, MAX6687AU40H application, or MAX6687AU40H equivalent, this device supports precise thermal protection in space-constrained embedded systems where reliable overtemperature detection without false triggers during power-up or transients is critical.

Technical Context

The MAX6687AU40H integrates two independent thermal comparators: one senses remote junction temperature using DXP/DXN inputs with factory-trimmed +125°C threshold, and the other senses local die temperature with threshold set by S1/S2 logic states at power-on. Both feature 5°C hysteresis and noise-immune oversampling.

It operates from 3.0V to 5.5V, samples temperature every 0.5s (typ), and uses BiCMOS process with 7765 transistors. The device asserts TREMOTE and TLOCAL only after stable thermal measurement-no assertion occurs on power-up or single-sample faults, ensuring robust system-level thermal management.

Key Specifications

Pinout & Package

Package: 8-pin µMAX (3mm × 3mm, 21-0036J drawing), RoHS-compliant variant available as MAX6687AU40H+; lead-free option uses same mechanical outline.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar temperature switch applications.

Compared with MAX6687AU40H, MAX6687AU40L offers earlier remote shutdown at +120°C for tighter thermal margins, while MAX6688AU40H replaces open-drain outputs with CMOS push-pull-enabling direct MCU interface but removing wired-OR capability.

Availability

MAX6687AU40H is available at Aetrix Electronics and suitable for CPU thermal protection, FPGA board monitoring, and industrial temperature alarm systems requiring stable component supply across extended temperature ranges (-40°C to +125°C).

Supply support for MAX6687AU40H 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

Maxim Integrated (now part of Analog Devices) designs precision analog and mixed-signal ICs for industrial, communications, and computing applications, with emphasis on reliability and integration.

The MAX6687/MAX6688 product line delivers highly accurate, dual-sensor thermal switches optimized for real-time CPU/FPGA die and PCB temperature monitoring in space-constrained systems.

FAQ

What is the remote temperature trip threshold for MAX6687AU40H?

The MAX6687AU40H has a factory-programmed remote temperature trip threshold of +125°C. This value is fixed and cannot be adjusted; it triggers the TREMOTE output low when the external P-N junction (e.g., CPU substrate transistor) exceeds +125°C. The 'H' suffix in MAX6687AU40H explicitly denotes the +125°C remote trip version, distinguishing it from the 'L' variant with +120°C.

How do I configure the local temperature trip point on MAX6687AU40H?

The local temperature trip point on MAX6687AU40H is set by connecting pins S1 and S2 to GND, VDD, or leaving them floating-before applying power to VDD. For the AU40H variant, this selects a value between +40°C and +80°C in 5°C increments (e.g., S1=GND, S2=FLOAT yields +45°C). The setting is latched at power-on and remains fixed until next power cycle.

Does MAX6687AU40H assert its outputs immediately after power-up?

No, MAX6687AU40H does not assert TREMOTE or TLOCAL on power-up. It waits for the first complete temperature conversion (~0.3s) and validates the reading before enabling outputs. This prevents false shutdowns during system initialization-a key design feature confirmed in the datasheet's "Detailed Description" section.

What external components are required for reliable operation of MAX6687AU40H?

MAX6687AU40H requires three mandatory external components: a 0.1µF ceramic capacitor from VDD to GND, a 2200pF capacitor across DXP and DXN, and pullup resistors (typically 10kΩ) on TREMOTE and TLOCAL outputs. The DXP/DXN capacitor is critical-deviations beyond ±50% cause measurable trip error (±1°C), per Typical Operating Characteristics Figure 3.

Can MAX6687AU40H monitor both CPU die and motherboard temperature simultaneously?

Yes, MAX6687AU40H simultaneously monitors remote temperature via DXP/DXN (e.g., CPU die's substrate PNP) and local temperature via its own die (mounted on the PCB). The local measurement reflects board temperature due to thermal conduction through package leads, while the remote channel reads the CPU junction-enabling coordinated thermal management with two independent thresholds.