Precision SMBus-Compatible Remote/Local Temperature Sensors with Overtemperature Alarms

The MAX6648/MAX6692 are precise, two-channel digital temperature sensors. They accurately measure the temperature of their own die and a remote PN junction, and report the temperature in digital form using a 2-wire serial interface. The remote PN junction is typically the emitter-base junction of a common-collector PNP on a CPU, FPGA, or ASIC.

The 2-wire serial interface accepts standard System Management Bus (SMBus™) write byte, read byte, send byte, and receive byte commands to read the temperature data and to program the alarm thresholds. To enhance system reliability, the MAX6648/MAX6692 include an SMBus timeout. A fault queue prevents the active-low ALERT and active-low OVERT outputs from setting until a fault has been detected one, two, or three consecutive times (programmable).

The MAX6648/MAX6692 provide two system alarms: active-low ALERT and active-low OVERT. Active-low ALERT asserts when any of four temperature conditions are violated: local overtemperature, remote overtemperature, local undertemperature, or remote undertemperature. Active-low OVERT asserts when the temperature rises above the value in either of the two active-low OVERT limit registers. The active-low OVERT output can be used to activate a cooling fan, or to trigger a system shutdown.

Measurements can be done autonomously, with the conversion rate programmed by the user, or in a single-shot mode. The adjustable conversion rate allows the user to optimize supply current and temperature update rate to match system needs.

Remote accuracy is ±0.8°C maximum error between +25°C and +125°C with no calibration needed. The MAX6648/MAX6692 operate from -55°C to +125°C, and measure temperatures between 0°C and +125°C. The MAX6648 is available in an 8-pin µMAX® package, and the MAX6692 is available in 8-pin µMAX and SO packages.

Applications

* Desktop Computers * Multichip Modules * Notebook Computers * Servers * Test and Measurement Equipment * Thin Clients * Workstations

* Dual Channel: Measures Remote and Local Temperature

* 0.125°C Resolution

* High Accuracy: ±0.8°C (max) from +25°C to +125°C (Remote), and ±2°C (max) from +60°C to +100°C (Local)

* Two Alarm Outputs: Active-Low ALERT and Active-Low OVERT

* Two Default Active-Low OVERT Thresholds Available

* MAX6648: +110°C

* MAX6692: +85°C

* Programmable Conversion Rate

* SMBus-Compatible Interface

* SMBus Timeout

* Programmable Under/Overtemperature Alarm Thresholds

* Compatible with 90nm, 65nm, and 45nm Process Technology