# Electronic – Low Drain-Source MOSFET Leakage

leakage-currentmosfetnmosswitchestransistors

I've been looking at the SM74611 Smart Bypass Diode from Texas Instruments and am very impressed with the reported reverse leakage current (0.3uA at 25C). Considering the device has a N-Channel FET, 0.3uA of Drain-Source leakage current @ 25C is nothing to scoff at considering that most FETs usually have a Drain-Source leakage current of 1uA.

At first I thought this discrepancy could easily be explained by finding the right FET online, but I quickly realized that I would spend days trying to find said part as this parameter is usually not specified in the parametric searches.

Does a sub-1uA Drain-Source leakage current FET exist, or is there some trick to get a smaller leakage current from a typical FET?

There's no guarantee with your device.. it's 300nA at 25C and 3.3uA at high temperature typical. In fact, if the distribution of leakage is Gaussian (a rather big "if"), you'd expect 1uA would be a reasonable guess for the maximum (\$3 \sigma\$).
If you want low typical leakage, you should pick a device that's no bigger (in terms of drain current rating) than you need, and one with a relatively high \$V_{TH}\$ rather than a ginormous MOSFET rated for 1.8V drive. Some small signal MOSFETs are typically 1pA at 25°C, which is 300,000 times better than the SM74611.