TIDUFB1 December 2024
An auxiliary power supply is designed to provide 15V voltage rails. This power supply is controlled by U7 UCC28750 and a high-voltage MOSFET Q8. The 3.3V voltage rails are created with an LDO U11 TLV76133 followed after with a DC/DC buck supply. This setup helps reduce the voltage drop and heat on the LDO, and the LDO also provides a clean and stable 3.3V, which can be used as voltage reference for ADC. Figure 2-10 shows this circuit.
Figure 2-10 Auxiliary Power Supply