Fully-isolated NLDMOS behavior investigation during reverse recovery of parasitic diodes

The behavior of the fully-isolated laterally diffused MOSFETs (LDMOS) during reverse recovery of parasitic diodes such as buck converter or white light emitting diode (WLED) driver application was presented. The fully-isolated MOSFETs with parasitic diodes have been realized for high power application, but the related reverse recovery charge (Qrr) model fitting accuracy is still an issue for these devices. Generally, only a single model is used to cover all of the applications. However, Qrr behaviors are different between WLED driver and buck converter. In WLED output stage, two parasitic diodes within high-side switch MOS will be turned on. In buck converter application, there is only one parasitic diode within low-side switch MOS during dead time. We performed the measurement with decoupling Qrr extraction method to fit model under high-side and low-side operations. This resulted in significant Qrr model fitting accuracy improvement by 4 times.