Document 345 SMTPlanarTransformer A9845-AL Coilcraft’s surface mount planar transformers are ideal for applications that require high efficiency in a low-profile package. They are designed to perform in push-pull topologies operating at 200 300 kHz. The auxiliary winding can be used to control input current to PWMs. Planar transformers offer high power densities along with great reliability and repeatability. The A9845-A has a smaller footprint and lower profile than our oth.