Hi all,


I’m trying to estimate the power budget for a custom board, but I’ve run into a challenge. Key components like the RTL8211F-CG Ethernet PHY and the STM32MP157FAC1 processor don’t provide clear information on load current consumption in their datasheets.


Without these details, it’s difficult to develop an accurate power budget for the board.


I’d appreciate any guidance on:

• How to approximate missing current values
• Interpreting combined values like total VDD when separate rail data isn’t provided
• Any estimation methods, measurement tips, or design rules of thumb you’ve found helpful in similar situations

Thanks in advance for your insights!
STM32MP157FAC1 current characteristics

 

The table you posted contains the absolute maximum values, which should not been exeeded. This has nothing to do with power consumption.

For such a complex device like STM32xx you cannot simply calculate the power consumtion. It depends on the internal clock frequency, the activated periperals and their clock frequency, the power mode (running, standby) and many otherthings. You should use the CubeMX tool, which can be downloaded at STM's website. This tool calculates a realistic value for the power consumption depending on the device configuration.

 

Hi all,


I’m trying to estimate the power budget for a custom board, but I’ve run into a challenge. Key components like the RTL8211F-CG Ethernet PHY and the STM32MP157FAC1 processor don’t provide clear information on load current consumption in their datasheets.


Without these details, it’s difficult to develop an accurate power budget for the board.


I’d appreciate any guidance on:

• How to approximate missing current values
• Interpreting combined values like total VDD when separate rail data isn’t provided
• Any estimation methods, measurement tips, or design rules of thumb you’ve found helpful in similar situations

Thanks in advance for your insights!
STM32MP157FAC1 current characteristics
View attachment 349314

CMOS parts consume power based on what they are doing. It is literally impractical to try to come up with a reliable estimate. The best you can do is empirical measurements of a system with the application firmware running. Only then can you implement strategies to lower power consumption if that proves necessary.