Chandler, Ariz. - Fan-manager ICs reflect the increasing sophistication of fan controllers and cooling strategies not only for high-end PCs, but also for routers, basestations and other communications equipment. Even as some OEMs focus on low-cost solutions, others are striving to minimize power requirements, suppress fan noise and prolong battery life to enable 24/7 reliability. As a result, vendors like Microchip Technology, Analog Devices, National Semiconductor and Maxim Integrated Products are broadening their lines.
Microchip, here, says its TC654, 655, 664 and 665 are the first fan managers to offer the combination of a thermistor input, two-wire fan-speed control and circuitry to detect unconnected, stalled or open fans and to help predict future malfunctions. And Analog and National are promising significant announcements within 60 days.
Microchip's ICs use a pulse-width modulation (PWM) scheme for precise control and low power dissipation. They drive 5-, 12-, 24- and 48-volt fans rated up to 1 amp, and adjust fan speed according to temperature, cutting down on noise and extending system life. The required fan speed can be programmed by the output of the remote thermistor or by SMBus-based commands. This dual operation increases design flexibility, Microchip said, while the two-wire design is said to cut costs over three-wire systems.
TC6xx-series ICs detect a fan's condition by measuring the number of fan pulses. "With the ability to read rpm data and detect when a fan wears out, the TC6xx family enables designers to replace fans prior to malfunction, eliminating thermal issues that can impact a system's performance and reliability," said product-marketing manager George Paparrizos. The Microchip family offers complete thermal protection in a variety of temperature-monitoring options, freeing system processors from fan-control duties and thus saving cost and maximizing system efficiency.
The TC654/5 monitors two fans simultaneously, and the TC664/5 targets single-fan applications. The TC655 and 665 devices also assert an overtemperature signal, eliminating the need for an additional temperature-detection IC.
Housed in 10-pin MSOPs, the ICs operate over 3 to 5.5 V at -40 degrees C to 85 degrees C. Pricing in lots of 1,000 is from $1.51 to $1.79. Samples are available now, with volumes due in the third quarter.
Analog Devices Inc. (Norwood, Mass.) earlier this year introduced a thermal-systems sensor called dBCool that can monitor and control multiple fans in equipment designed for low noise, such as mobile and desktop PCs. Its ADM1027 is said to adjust dynamically to the size of the enclosure and to regulate fan usage relative to thermal-management needs. Paul Errico, thermal and systems management marketing manager, said ADI is working to overcome reliability issues related to PWM technology, and is expanding the number of protocols supported.
National Semiconductor Corp. (Santa Clara, Calif.) has three new thermal-management entries: the LM86, a remote-diode temperature sensor accurate to less than 1 degrees ; LM85, a hardware-monitoring chip with one local and two remote-diode temperature sensors; and LM90, a local- and remote-diode temperature sensor. Zaryab Hamavand, marketing manager for thermal solutions, said the company is developing a chip that will give system designers maximum fan-control flexibility.
Maxim Integrated Products (Sunnyvale, Calif.) offers the MAX6680 and MAX6681 CPU temperature monitors for notebooks, desktops, servers and workstations. They measure the temperature both of a remote-diode-connected transistor and of their own dice.
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