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Analog Devices Debuts "dBCOOL" Thermal Systems Sensor, Promoting Quieter PCs

High-performance analog technology reduces noise from continuously running fans, enabling a quieter desktop; also targets high-availability servers and network systems.

The manufacturer says . . .

Chipcenter's Paul O'Shea says . . .

Analog Devices, a provider of high-performance semiconductors for signal processing applications, debuted its first dBCOOL� chip, a complete thermal systems sensor with the ability to monitor and control multiple fans in equipment designed for low noise, such as mobile and desktop PCs. As studies begin to show links between high noise levels and a stressful work environment, corporate executives have begun to recognize that low noise can aid employee health and productivity. ADI's ADM1027 keeps acoustic pollution low, adjusting dynamically to the size of the enclosure in which it is placed and regulating fan usage relative to thermal management needs. Leveraging an international movement toward a healthier work environment, the ADM1027 is compliant with international standards for environmentally-friendly PCs, including Germany's "Blue Angel" ecolabel and Sweden's TCO (the Swedish Confederation of Professional Employees) standard.

A "silent PC" movement has emerged, and PC OEM and motherboard manufacturers are beginning to respond to customer demand for quieter PCs, embedded controllers, high-availability servers, and network systems by producing a range of low-acoustics products. With the ADM1027, Analog Devices provides these manufacturers a complete thermal systems sensor that intelligently monitors and controls both thermal management and noise.

"As users are more and more focused on lower system acoustics, Analog Devices' dBCOOL controllers and Intel Active Monitor offer an intelligent thermal management-fan control solution for Intel Desktop Boards, providing an industry-leading solution for our customers," said Joel Christensen, marketing director of Intel's Desktop Platform Solutions Division.

"With processors in PCs becoming increasingly faster and consuming more power, the heat generated is creating a formidable thermal challenge for many manufacturers," said Mike Britchfield, product line director, Precision Converters, Analog Devices, Inc. "When faced with this challenge, manufacturers often add more fans--that run constantly--to control heat production. The ADM1027 offers an alternative solution: intelligent management of the systems' fans with a hardware-based thermal monitor designed to monitor multiple zones. In an ADM1027-based system, fans do not run constantly or at full speed, thus preserving low noise."

The newest addition to ADI's portfolio of thermal management solutions, the ADM1027 dBCOOL thermal management controller can measure and control the speed of up to four fans--with or without tachometer outputs--allowing them to operate at the lowest possible speed to minimize acoustic noise. The ADM1027 integrates two remote thermal diode monitoring channels and one on-chip temperature sensor. This enables up to three different thermal zones to be monitored. The remote channels can be used to monitor the processor thermal diode or other critical thermal zones, such as the Voltage Regulation Module (VRM), memory or graphics controller zones. The ADM1027 also offers a temperature offset register to remove offset errors due to remote diode-connected series resistance. Featuring the industry's only Pentium� 4 processor Thermal Control Circuit (TCC) monitoring, the ADM1027 also monitors thermal control activity within the CPU itself to ensure no reduction in processor performance. Through TCC monitoring, it allows automatic system setting of the fan control loop, which compensates for thermal design variability, including chassis form factor, fan variation, computer placement, ambient temperature, processor heat sinks and other heat-generating components, such as power supplies, hard-disk drives and video cards. This provides the quietest operation possible. It also determines potential overheating due to fan failure, detects the improper mounting of heat sinks, monitors inadequate air flow in the chassis, and alerts the system if there are inadequate heat sinks or too many high-power peripherals or add-in cards. The ADM1027 can monitor up to five supply voltages. On-chip scaling resistors reduce external component count and cost and allow direct voltage measurement of +12V, +5V, +2.5V CPU supply voltage and its own supply voltage (3.0 to 5.5V). Used in conjunction with ADI's power management solutions, the ADM1027 can monitor current consumed by the processor via Analog Devices' multi-phase synchronous buck regulators, such as the ADP316x family, which are used for converting 5 V or 12 V main supply into the core supply voltage required by the high-performance Intel processor.

Analog Devices, Inc., 804 Woburn Street, Wilmington, MA 01887. Tel: 1/800-ANALOGD (262-5643); Fax: 781-937-1021; http://www.analog.com

The ADM1027 is one in a series of ADM10xx products that Analog Devices has released. Read a review of the ADM1026, done in August of 2000. The 1026 is an integrated device for the server market. The new 1027 is a multichannel, remote thermal diode monitor that oversees up to 2 remote channels. It also has an on-chip temperature sensor and it controls and monitors the speed of up to four fans. It uses ADI's automated control loop for fans which monitors temperature zones and controls the speed of the fans automatically.

As form factors of PC's continue to shrink, manufacturers need to be able to remove the heat. The only way you can do that is to put fans on the hot areas, and that creates noise. There is a push among computer manufacturers to lessen the noise factor of computers and one way to do this is automatically control the fans so they aren't always on at full speed. This product recognizes the problems and offers a solution.

Many manufacturers deal with noise and thermal issues with discrete implementations. For example they might have an analog temperature sensor, a transistor-based control circuit and an amplifier. Additionally, they probably leave the fan on full-speed all the time. The 1027 integrates all the fan control functions and provides basic system management monitoring function of multiple system power supplies. It has the standard I2C SMBus interface and has the voltage Identification (VID) for the Pentium processors. When Intel or AMD make a processor they don't know at what voltage the processor will operate best. So they get the motherboard designers to add a complex circuit called the VRM (voltage regulator module) to the motherboard. The 1027 integrates the VID input pins and that info is read and passed onto the SMBus.

The 1027 detects fan speed for fans that use three wires (power, ground and tachometer), or two wires (power and ground) for the fans. The two-wire fans usually have a transistor in series with the fan so it energizes the coils, thus the fans are turning only on or off. This two-wire and three-wire sense mode is important to companies doing thermal management and concerned about the increased cost of a three-wire fan.

The ADM1027 has the ability to control the speed of the fan in a linear fashion and even turn it on and off. It seems reasonable that a fan which turns on and off is potentially at an increased risk of failure due partially to start up currents. However, ADI says that they have investigated that scenario and results indicate that there does not seem to be any significant reliability issues. Additionally, the reliability of the fan is directly proportional to the speed. So by decreasing the fan speed you actually increase the life of the fan.

The ADM1027 was developed with processor-based applications in mind. A new feature ADI added is something they call a proc-hot monitoring function. It ties directly into processors that are doing on-chip thermal management. The 1027 proc-hot feature monitors the thermal management activity of the chip, and can optimize the thermal management control loop by monitoring the processor function and allow clock throttling to reduce the thermal spikes. The Analog Devices' chip lets the CPU run as hot as it possibly can while monitoring the fans, temperatures and thermal control circuit so the processor can runs as hot as it possibly can without impacting performance or reliability. This also makes the system as quiet as possible.

Not just manufacturers of processors are integrating these remote thermal diode monitors. Some network processor manufacturers are adding the remote thermal diode monitors to their processors. The remote thermal diode monitor provides an actual representation of the chip temperature. Many manufacturers are integrating a thermal control circuit that does on-chip clock throttling. The ADM1027 can monitor that function, and optimize the thermal management control loop. It allows you to monitor the temperature and optimize the speed of the fans by monitoring the on-chip thermal loop.

The ADM1027 is sampling now and is priced at $3.75 in 10,000-piece quantities. For more information visit: www.analog.com/temp-sensors

dBCOOL is a trademark of Analog Devices, Inc. All product and company names are trademarks or registered trademarks of their respective holders.

Noise Pollution in the Workplace

Noise pollution is a growing problem in our society. In daily life, we tolerate high levels of noise from a multitude of sources: traffic, factory workplaces, busy shopping centers, television and audio media. The bells and clicks from electronic systems may also be considered a source of noise, but more often, the persistent noise comes from fans running inside these systems. As electronic system form-factors shrink and performance/functionality increases, the burden to remove heat is targeted squarely on the fan. A recent industry report (from Business Communications, Inc) forecast that by the year 2005, more than 800 million fans will be manufactured annually for a variety of electronic devices.

In order to concentrate, however, we need a quiet work environment. Personal computers in the office and at home create noise and can be distracting. According to a study published in the Journal of Applied Psychology ("Stress and Open Office Noise," Vol. 85, No. 5, pp. 779-783, Oct 2000), even low noise levels have large impacts on productivity. These findings go on to suggest that even moderately noisy open offices might contribute to health problems.

As more people become aware of the problems associated with low-intensity noise, they will demand quiet PCs. In the PC, fans and disk drives generate the loudest noise. Blue Angel, one of several international acoustic standard organizations, specifies that a PC be no louder than 48dBA in idle state, i.e. with no hard disk or other drive activity. In the active state--when the hard disk or another drive is being accessed--the machine should be no noisier than 55dBA. Given that a typical conversation is defined at 60dBA, the goal of a truly silent PC is still a long way off.


	Acoustic Power Level Comparison
	Threshold of Hearing		0dBA
	Normal Breathing		10dBA
	Whisper			20dBA
	Standard PC 		35-50dBA
	Typical Conversation		60dBA

If both governments and industry do not take a more aggressive position on noise pollution, we may well be clamping on our noise cancellation headsets twenty-four hours a day, seven days a week.

Evolution of a Quiet PC Movement

People's concept of noise has changed over time: "It is only within the last 60 years that the noise of a fan has been perceived to be a nuisance--a concept strange to our forebears of the 19th century. Then just as a chimney belching black smoke indicated wealth creation, a noisy fan proved that it was doing useful work." W.T.W. Cory (source: Fan Noise: An International INCE Symposium, CETIM, 1992)

It is also somewhat culturally specific: Northern European countries--which have been at the forefront of the Quiet PC movement--have developed expectations for a silent PC that are relative to the ambient noise levels.

While the Europeans have been leading the way on this issue, American companies, such as Intel, Hewlett-Packard, Compaq, and Apple, and Asian companies such as Asus, Toshiba and Via, have all promoted low-acoustic products of one type or another.

Responding to demand from PC OEMs and integrators who want to provide low-acoustics PCs--and other hardware devices--to their customers, Analog Devices has joined the Quiet PC movement by launching its newest thermal systems sensor, the ADM1027, the company's first dBCOOL IC.

About the dBCOOL Thermal Systems Controller for Low-acoustics PCs

Existing thermal management solutions range from systems that run the fan continuously to systems that monitor temperature with hardware sensors. The advantages of using the dBCOOL IC vs. other existing hardware-controlled solutions lie in acoustic reduction, increased reliability and higher system performance.

Acoustic Reduction - A dBCOOL solution can reduce acoustic power by 15 dBA over systems that continuously run fans at full speed, a significant improvement considering a standard PC can produce up to 50dBA (see figure 1 below). The dBCOOL chip alleviates the problem of continuously cycling fans in a PC by intelligently monitoring and controlling fan operation. By integrating a filtering feature that reduces the annoying noise of a fan cycling, the dBCOOL chip ensures that fans will not respond immediately to fast thermal events and will gracefully increase or decrease speed as required (see figure 2 below.)

Figure 1
Fan Noise Always On vs. dBCOOL Control Plotted vs. Increasing CPU Temperature

Figure 2
Rapid Thermal Event and dBCOOL Fan Ramp Control Profile

Increased Reliability - the dBCOOL IC is a hardware-controlled, closed-loop solution that promotes higher reliability through several means: 1) a hardware solution eliminates bus communication or software-related problems; 2) running fans at lower speeds improves Mean Time Between Failures (MTBF); 3) using dBCOOL-based solutions can track fan speed degradation, and thus can be used to alert the user or network administrator to take action such as cleaning the fan filter.

Higher System Performance - The dBCOOL autocalibration loop optimizes system performance by detecting processor thermal throttling activity and by adjusting the fan speed limits automatically. Therefore, as the system configuration or surrounding environmental conditions change, the dBCOOL IC intelligently detects and optimizes the fan control loop. For example, if a user adds a graphics card that slightly inhibits airflow within the chassis--and thus increases the ambient temperature near the processor--the dBCOOL IC's control loop will detect and increase fan speed to maximize performance.

Analog Devices and Intel: Collaborating for a Quieter Desktop

The silent PC is a panacea that most will not achieve, because as performance continues to climb and form factors continue to be reduced, thermals are becoming much more of an issue than they have been in the past. In order to deal with these new thermal challenges, designers are required to add more fans, which increase acoustics. These new thermal/acoustic problems that the industry faces are not only being tackled by Analog Devices, but also by Intel in their latest Pentium� 4 processor.

To ease the burden on cooling solutions, Intel has integrated a new thermal monitor feature into the silicon of the Pentium 4 processor. By taking advantage of this feature, system designers and integrators may decrease the cooling system costs and reduce acoustics, while maintaining processor reliability and performance goals. Other options within the thermal management logic allow end user-controlled software (provided by Intel) to monitor and control the thermal and acoustic characteristics of the system.

About Analog Devices Thermal and System Management Group

Analog Devices, Inc. (ADI) is the worldwide market leader in both data converters and high-performance amplifiers. The Thermal and System Management (TSM) team within ADI has leveraged those internal core competencies to rapidly gain market share in the PC thermal and system management segment. In the five years since TSM has entered the market, the group has expanded its portfolio from integrated circuits that simply monitor the processor temperature to highly integrated solutions. These solutions include: processor thermal monitoring, processor power monitoring (with ADI's power management solutions), and monitoring thermally active zones (such as disk drives, graphics cards, power supplies and memory).

Sources

Hewlett-Packward white paper: "HP PCs and Acoustic Noise"

The SilentPC Web site: http://home.swipnet.se/tr/silence.html

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