STM32U5G9J-DK1: Significance of unusued 1.8 V LDO

[RandomGaurav]

Hello,
 

I was going through the schematic of STM32U5G9J-DK1 where I came across the unused LDO (U19) for generating 1.8 V on this board. I wanted to know the significance of this LDO and what were the reasons to keep it unpopulated?

Also, can I expect to see an improvement in the driving capability of this rail in case I wish to populate U19 with TPS76301? If yes, which orderable part no. of the same would be recommended?

[GET]

Hello ​@RandomGaurav,

“I wanted to know the significance of this LDO and what were the reasons to keep it unpopulated?” :

• no Audio codec populated, no 1.8V LDO was required : lowered BOM. If a very clean power supply such as a LDO is not necessary, using the VDDMCU_SMPS by default on the 1V8 rail (through R62) is ok and recommended, especially if using the default LCD.
• if a power supply with LDO is requested on 1V8 rail for any DSI_V3 or for expansion connectors board (as an analogue power supply for exemple) it is possible to use the TPS76301, but verify the power sequencing is fitting your need and power consumption Vs any peripherals used on DSI_V3 or on expansion board.

“Also, can I expect to see an improvement in the driving capability of this rail in case I wish to populate U19 with TPS76301?”

TPS76301 is only 150 mA. Use U19 only if a very clean power supply is needed for some other perpiherals than the default LCD.

Hope this answers your questions.