5 Test Results With TPS7H4104EVM

To verify this configuration outside of simulation, a TPS7H4104EVM evaluation module was modified to output 0.5V on CH3. Similarly to the previous simulation, the 1.2V output generated by CH2 was used as V_EXT for the CH3 feedback divider. To implement this configuration, four modifications are required to the EVM which are circled in red in Figure 5-1.

• R22 was replaced to set the device switching frequency to approximately 300kHz.
• R17 was depopulated to remove the connection to GND of the feedback divider.
• R33 was populated to be used as R_B1
• V_EXT was connected to R_B1.

Figure 5-1 Modified EVM Schematic

The location of R17 is shown in Figure 5-2.

Figure 5-2 Top-side EVM Board Render

Modifications to the bottom of the EVM are shown in Figure 5-3. When R33 (RB1) is populated, one pad is connected through a via to VSNS3, while the other pad is connected to a trace that leads to R41. Since R41 is not populated, the left-side pad of R41 can be connected through an external wire to VOUT2 (V_EXT), this was done by connecting to the bottom side of the VOUT2 test point. The trace connecting R33 to R41 now provides V_EXT to R_B1, completing the modified feedback circuit.

Figure 5-3 Bottom-Side EVM Board Render

The modified EVM was powered on with the internal sequencer enabled, and the startup was recorded with a 3A load on V_OUT.

Figure 5-4 EVM Startup Result

As expected, the output from the modified EVM matches closely with the simulation results in Figure 4-2, providing a 0.5V output on CH3 using the 1.2V V_EXT generated from CH2.