AN603

AN603 Vishay Siliconix Designing With the Si9978DW Configurable H-Bridge Controller Wharton McDaniel Currently, there are a number of fully integrated H-bridges on the market. Both bipolar and MOS technologies have been used to create these parts. However, all of them suffer from problems such as limited current handling capability, large package size, and difficulty of assembly. The Si9978DW addresses these problems with an architecture that allows flexible current handling capability, small size, and ease of assembly. Instead of trying to integrate the power devices with the controller on a single piece of silicon, the Si9978DW approach is to separate the controller from the MOSFETs. The benefit is efficient manufacture of both the controller and the MOSFETs, the flexibility to select the optimum MOSFET for the application, and the ability to use surface-mount parts for both the controller and MOSFETs which makes assembly easier. Altogether this means a low cost H-bridge solution. The Si9978DW is a monolithic controller designed to be used with LITTLE FOOTR power MOSFETs to create an all-n-channel H-bridge or two separate half bridges. In addition to this functional flexibility, the dual function allows standardization of components and reduces inventory costs. The Si9978DW features integral high-side drive circuitry and an internal voltage regulator, which allows operation over a 20to 40-V dc input voltage range. Protection features include cross-conduction protection, cu...