Fairchild FAN5350 buck converter and IntelliMAX load switches

I just got a couple press releases from Fairchild. One was for their FPF250X load switches. I wish I had got this in time to include it in my upcoming article about interface ICs in the July 19, 2007 issue of EDN. These high-side switch parts are like intelligent transistors—they work on 4.5 to 20 volts and you can set the current limit from 0.5 to 2 amperes with the FPF2502 (pdf). There are also models with fixed 0.4 or 0.8 amperes current limits. Like TOPFETs and PROFETs, and other high-side smart power switches, these parts have thermal shutdown so they are far more robust than plain old transistors. They come in tiny SOT23 packages and cost is under a buck, in thousands. Well. I will be sure to include them in next years interface article.

The other Fairchild press release that caught my eye was for the FAN5350 synchronous buck converter. The FAN5350 (pdf) datasheet shows an input voltage or 2.7 to 5.5 volts and has a 1.82 volt fixed output What is remarkable about this part is the 16 microampere quiescent current while it operates at 3 MHz. The transient response is 20mV to a 300 mA load step. It is these kind of remarkable specs that make me wonder if the analog folks are going to make life pretty difficult for the digital power crowd. In addition the part can get up to 94% efficiency. Some companies play a game where they spec efficiency with an inductor the size of a fist, but Fairchild mentions that you can still get over 90% efficiency using a 1 uH chip inductor. Bravo.

The new Fairchild FAN5350 synchronous buck converter runs at 3 Mhz with a quiescent current of 16 uA. Wow.