USON is Plastic Ultra-Thin Small Outline No-lead (SON) Package defined by JEDEC, slightly smaller than WSON. It is a surface mounting device (SMD) with 4-16 pins, and the pitch has 0.5mm, 0.65mm (DNP, TI) , and 1.0mm (NLB, TI). Due to underside thermal pad, this kind chip is hard to solder with a soldering iron.
