MAX6638

Temperature Monitor with Dual Serial Interface

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Overview

Two Independent SMBus/I²C-Compatible Interfaces with Collision Avoidance
High Accuracy ±1.0°C from +85°C to +100°C (Remote)
Remote and Local Temperature Measurements
Three Programmable Output Alarms: Active-Low ALERT1, Active-Low OVERT1, Active-Low ALERT2
Programmable Conversion Rates
11-Bit Low-Noise Integrating ADC
No Calibration Required
Autoscan Conversions

The MAX6638 thermal-management sensor includes internal (local) and external (remote) digital temperature sensors and two independent SMBus™ serial ports. The remote temperature accuracy is ±1.0°C and the local temperature accuracy is ±2°C. The MAX6638 also features extended temperature resolution data available in 0.125°C increments.

The MAX6638 provides three system alarms: channel 1 alert (active-low ALERT1), overtemperature (active-low OVERT1), and channel 2 alert (active-low ALERT2) that contain programmable thresholds set independently by each of the SMBus serial ports (SMBus1 and SMBus2). Each alert output asserts when any of four temperature conditions is violated: local overtemperature, remote overtemperature, local undertemperature, or remote undertemperature. The overtemperature signal asserts when the temperature rises above the value in the overtemperature limit register. Use the active-low OVERT1 output to activate a cooling fan or trigger a system shutdown.

Each of the 2-wire serial-interface ports accepts standard System Management Bus (SMBus) write byte, read byte, send byte, and receive byte commands independently of one another with total collision avoidance handled by the MAX6638. Each SMBus can operate its own unique serial-data rate to access any register in the MAX6638 for data reads or data writes. The MAX6638 manages all dual-port data register access functions providing a seamless, conflict-free, integration into a multimaster architecture for thermal management.

The MAX6638 performs measurements autonomously, at the programmed conversion rate, or in a single-conversion mode. Each SMBus port can set the conversion rate with the higher conversion and update rate dominating the average power-supply current. Single-conversion requests have a maximum delay of two conversion cycles with channel-conversion management and cycling regulated by the dual-port controller.

The MAX6638 operating temperature range is -40°C to +125°C and measures temperatures between 0°C and +145°C. The MAX6638 is available in a 16-pin, 4mm x 4mm TQFN with exposed paddle package.

Applications