Figure 2-11 shows the power tree consisting of four main power components: the TS7A4501-SP, LMP4050QML-SP, TPS7H2201, and boost circuit.

Figure 2-11 Power Tree and Sequencing

The TPS7A4501-SP is selected to power these rails because of its low noise output to ensure no performance degradation due to injected power noise. There are three TPS7A4501-SP used to power this design. The first TPS7A4501-SP provides a 3.3-V rail used to power the MSP430FR5969-SP. The second TPS7A4501-SP is used to provide the 3.3-V digital voltage rail for the ADC128S102QML-SP. The third device is used to regulate the output of the discrete boost controller to 12 V. The 12 V supplied by the TPS7A4501-SP is optional to the operation of this reference design and an external 12 V can be provided to bypass the boost and LDO circuit.

The LMP4050QML-SP are voltage references to provide a stable voltage at two places in the power tree. The first is the 5-V analog voltage rail for the ADC128S102QML-SP. The second rail is the 2.5-V reference for the integrated ADC in the MSP430FR5969-SP. It is important that this is a clean stable signal, or else it can cause inaccuracies in the measurements taken from the ADC.

The TPS7H2201-SP is a load switch that is used for sequencing and ramp up power safely for the op amps. The main power sequencing in this design is to make sure that the ADC128S102QML-SP analog voltage rail has ramped up first before the digital voltage rails ramps up as Figure 2-12 shows. It is important that the analog voltage rail of the ADC128S102QML-SP is stable at 5 V, because the digital rail must stay at least 0.3 V below the analog voltage rail or else it could cause damage to the ADC128S102QML-SP.

Figure 2-12 ADC128S102-SP Start-up Power Sequence