Temp sensors boost thermal management for 90-nm processors

Hauppauge, NY&#8212SMSC's two new temperature sensor families, the EMC1402, 1403 and 1404 series; and the companion EMC1422, 1423 and 1424 series (pull-up resistor versions), tout benchmark performance for single-chip high-accuracy sensors suited to 90-nm processor platforms while also minimizing diode characterization and time-to- market issues. The sensor technology, also incorporated into the company's new EMC2101 and EMC2102 fan controllers, provide designers with an extra measure of accuracy in forced-air systems.

The new EMC1400-class sensors include all-important resistance error correction, perhaps the most critical system parameter limiting today's temperature sensing systems; automatic beta compensation (to support 90- and 65-mm CPU diodes); and automatic diode type detection to address the CPU and up to three remote temperature measurements for graphical processors, dual-in-line memory modules (DIMM), and wireless cards. “With the launch of these six new temperature sensors, engineers designing for high-end platforms targeting 90 nm and below now have a full-featured solution that delivers flexibility, performance and accuracy for temperature control,” said Mark Beadle, product line director of Analog Products & Technology.

Claiming unmatched performance in a single chip, the devices facilitate &plusmn1 percent temperature accuracy for external diodes and &plusmn2 percent for the system's internal diodes. Anti-parallel diodes minimize the number of board traces required to connect up remote diode transistors for temperature measurement.

Resistance Error Correction
SMSC positions these devices apart from competing sensors, some of which can provide better than average accuracy over the general competition but don't provide compensation for the series resistance in processor diodes and board traces. That resistance, says SMSC, can cause errors of up to 4°C, and it's entirely unacceptable in the more advanced design environments. In this context, SMSC's resistance error correction circuitry cuts overall errors to within &plusmn1°C while at the same time eliminating the often time-consuming process for characterizing system diodes.

The EMC1402 (2 channels—one external, one internal), 1403 (two external, one internal), and 1404 (three external, one internal) devices have interrupt capability. The EMC1422, 1423 and 1424 offer designers the added benefit of setting the system's desired shutdown temperature, at system startup, between 77 and 112°C and without the need for software. Resistance Error Correction and Auto Beta Compensation minimize the need for a temperature offset register to fine-tune measurement accuracy, thus saving hours of engineering time often spent characterizing a system.

Click here to access the EMC1402's datasheet; and here for the EMC1403/1404. The EMC1400 family is available now, with production quantities available in the first quarter of 2007. They will carry a list price of from 60 cents to $1 each in OEM quantities.

Adding fan control
Also announced, SMSC's new EMC2101 and EMC2102 fan controllers incorporate the same same resistance correction and automatic compensation technology to add an extra measure of control in forced-air cooling applications.

“Designers no longer need to sacrifice accuracy to meet certain price points for designs that require sophisticated thermal monitoring and protection from overheating and damage,” says Mark Beadle. The
EMC2101 controller offers engineers a simple and flexible 8-pin option for general-purpose advanced temperature measurement requirements. It maintains fan control with an 8-entry lookup table that relates fan drive to temperature setpoints associated with the remote temperature sensor reading.

The EMC2101 also allows for external temperature overrides to drive the fan. It has an option for loading setpoints from an EEPROM, making it highly suitable for systems lacking a host configuration. These systems now have access to full-featured fan control. The device features a linear fan drive option.

The second device, the EMC2102, integrates linear fan control and four temperature sensors in a small form factor to save space and cost. The device includes shutdown logic and start-up safeguards that are software independent and meet the challenges of critical thermal events. The EMC2102 uses a closed-loop RPM control to operate the fan. It checks the TACH and ensures that the fan set points are met so to avoid resonant points in enclosures and to maintain the right speed in aging fans. The EMC2102 also provides fan power-up flexibility by allowing for a start speed of 0, 60, 75 percent or full speed. The central shutdown feature on the EMC2102 fan controller enables users to operate hardware shutdown from one central location, eliminating additional temperature switches and increasing system savings. The features include inputs for “power good” and an external thermal tripping.

Click here to access the EMC2101's datasheet; and here for the EMC2102. Samples of the EMC2101 and EMC2102 fan controllers are available now with production quantities available in the first quarter of 2007. The pricing for the EMC2101 and the EMC2102 will be 95 cents, and $1.75 cents each, respectively, in OEM quantities.

SMSC , 1-631-435-6000,

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