This EVM is designed to support different load configurations to maximize flexibility to the user.
MOSFET configurations:
Figure 4-1 shows an application using two back-to-back common source MOSFETs. By connecting the load between terminals SW1-SW2, the user can load the EVM with an AC or a DC load. By using two back-to-back FETs, the body diodes are able to stand off both positive and negative voltages. In addition, an RC snubber can be added for damping the switching oscillations in presence of a highly inductive load.
Figure 4-1 AC/DC Load
Figure 4-2 shows an application using two parallel common source MOSFETs. This action allows the users to achieve lower RDSON. Because one MOSFET cannot block reverse current when off, the recommended load for this configuration is a DC load.
Figure 4-2 DC Load
Figure 4-3 shows a possible load configuration using one MOSFET (Q1) while leaving (Q2) unpopulated. This configuration allows the addition of an RC snubber for when a highly inductive load is connected by shorting terminal SW2 to VSSS terminal.
Figure 4-3 DC Load With RC Snubber
SCR configuration:
Figure 4-4 shows a possible load configuration using an SCR. For this case, TI recommends to use the TPSI3050S-Q1, which allows for a one-shot operation to trigger enable with a pulse to drive an SCR. This action can be useful because a short duration of power can trigger most SCRs.
Figure 4-4 SCR for a DC Load
MOSFET or SCR for highly inductive loads:
Figure 4-5 shows a possible load configuration for a highly inductive load. The setup can be accomplished using a Q1 (MOSFET) or D2 (SCR) for S1 (switching component). This setup has footprints to add D3, which can be used as a clamping diode to provide a connection to ground when S1 switches off the inductive load.