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YVerm
YVerm
Associate
August 26, 2019
Question

Different return paths for STPM33 ICs?

  • August 26, 2019
  • 2 replies
  • 3056 views

Hello all,

Since i was not able to find thread for Power Monitoring ICs, hence, posting my question here.

I am using STPM33 PM IC for my application and i have below queries:-

  1. As i can see in the datasheet in the application schematic column, two ground references are used: One for Analog ground and the other for digital ground. And also, these two ground paths are shorted. Screenshot below:-

0690X00000AAFwgQAH.png

Kindly let me know the advantages of doing it this way and not having a single ground reference.

  1. Does this STPM33 IC work as a slave or master when configured over SPI?
  2. I am planning to use 8xSTPM33 device configured over SPI on a single SPI bus with different CS lines dedicated for each STPM33 IC. The SPI master is supposed to be STM32L452RCT6 MCU.
  3. Since i am using multiple STPM33 ICs, we need to calibrate them. Thus should i have an extra EEPROM on my board for storing these calibration values? or can i do something like this with my MCU. Kindly direct me towards an application note, if any, about this. I have an SD card provision on my board. Can i do calibration using it? If yes, please let me know for its application note.

Thanks a lot in advance. Waiting for a positive reply.

Have a nice day!

Best Regards,

Yash

This topic has been closed for replies.

2 replies

Danish1
Danish1
Lead III
August 26, 2019

Welcome to the analog world.

A ground (indeed any wire or track or plane on a pcb) is not perfect. There is series resistance and inductance.

You will see both when you switch high currents, particularly if you have inductive loads.

And this will mean that different parts of the pcb that are nominally ground will actually be at measurably different voltages.

Separation of grounds, with them only joined at one point, is a way to keep the high, switched current away from anything that might be disturbed by the voltage differences.

I've no doubt that a good electronic text book that includes this will be able to explain it much better than I can.

Hope this helps,

Danish

YVerm
YVermAuthor
Associate
August 27, 2019

Hi Danish,

Thanks a lot for your answer.

Request you to also answer my last three mentioned questions above.

Thanks a lot again.

Best Regards,

Yash

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