New Industry Products

2-Coil Fan Drivers now in SOT25 Straight Lead Package to Support Automated Production

December 12, 2018 by Paul Shepard

Melexis announced a new package variant of its popular and highly integrated US90A and US91A 2-coil fan drivers. Based on Melexis' patented No-VDD technology and manufactured on its advanced CMOS process, the US90A and US91A 2-coil fan drivers integrate dual low-side open-drain output drivers with a high sensitivity Hall-effect sensor.

The output drivers can handle peak currents up to 500 mA (250 mA continuous) and offer locked rotor protection and auto-restart. The No-VDD fan driver design has been very successful over the past 10 years in standard 4-pins Single In Line (packages), such as VA and VK, and it is now available in the ZE 5-pin SOT25 package.

Melexis' No-VDD products do not require a separate supply voltage, instead they are powered by the fan's supply, which provides inherent protection against reverse polarity. In addition, the output driver channels are fully protected against switching transients, removing the need for an external protection diode.

As no supply is required, the fourth pin can be used to provide a diagnostic output. In the US90A, the FG (Frequency Generator) pin indicates the fan's speed, while the RD (fan ReaDy) output, available in the US91A, indicates the fan's rotation. Both pins are open-drain.

Commenting on the new product release Dirk Leman, Product Line Manager Fan drivers said: "The US90A and US91A have been market-leading products in Melexis' fan driver portfolio for many years. With the recent introduction of the straight leads SOT package for the MLX90411 latest generation 1-coil fan driver, we optimized these reference products in a low-cost SMD package.

The fan market is moving gradually away from manually soldered SIP packages and is embracing Surface Mount assembly more and more, in order to further improve quality levels even for the older generation of 2-coil fans," Leman observed.

Both devices are available in tape-and-reel, and operate from -40°C to +125°C.