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TPS25750EVM: Connecting an External MCU to the Slave I2C of the TPS25750 on the TPS25750 EVM

Part Number: TPS25750EVM
Other Parts Discussed in Thread: BQ25730, TPS25750, BQ25731, BQ25730EVM

Hi there,

Have some questions on the TPS25750EVM

 

I have a customer that wants to use the BQ25730 (for the battery power-path management  since it has the Batt Sys FET) and they would like to use the TPS25750....

They would like to test out the functions on EVMs to save some time while they are designing their board.

 

TPS25750EVM uses the BQ25731.

So we could put the BQ25731 in Hiz (on the TPS25750EVM). We can connect the BQ25730EVM to the TPS25750 EVM  together. We would need to have the TPS25750 and the BQ25730 on the mI2C bus of the TPS25750. We would need to connect the PPHV output & GND from the TPS25750D on TPS25750EVM board to the VIN & PGND of the BQ25730EVM using heavy gauge wire. All this seems okay if we set up the BQ25730 for the right battery setup?

 Now the tough part. How do we connect an external MCU EVM to the TPS25750EVM to control the BQ25730 for the charge termination since the TPS25750 doesn’t handle this function? Since the TM4C (master ) on the TPS25750EVM is connected to the I2C slave port of the TPS25750…is there a way to disable the TM4C or another way to do this? Same question would apply to the TPS25750 EVM as it stands with the BQ25731. Since the TPS25750 doesn’t handle the Charge Termination for that part either, it would need to be done by an external MCU. Trying to look for options!

I believe the MCU is used to program the Patch software, so just programming the EEPROM and disconnecting the MCU I2C would not work?

Also just a generic question, can an External MCU control other I2c slaves through its slave port (TPS25750 master)? So the MCU would control the BQ25730 plus other I2c slaves through the TPS25750...Looks possible?

Thanks for the help!

Cheers,

Mark

 

Thanks for the help!

  • Mark,

    If you are willing to do the modifications that you described to the board, then you can connect the EVMs as described.  As long as you do not plug in the USB microB port, then there will be no impact from the MCU.  

    You will have to wire the I2Cm port over to the 730 EVM and connect the PPHV, VSYS, and GROUND to match your systems needs.  I am not sure that there is an easy way to tristate the 731, so you may have to depopulate it to meet your needs.

    We do support a bridge command in our host interface that allows you to pass commands from our slave I2C interface to our master I2C interface.  They are described TPS25750 Host Interface Technical Reference Manual.  The commands to reference are I2CW and I2CR.

  • Thanks Chuck.

    And just a quick confirm as well that the BQ25730 can be controlled by the TPS25750. 730/731 have pretty much the same register set but a couple extra bits on the Batt FET (reserved on the 731)t that I can see. Again charge termination would need to be taken care of from the Host MCU... Thanks for the help!

  • Mark,

    The TPS25750 can control either the 730 or the 731 to match the Type C/PD  PDO configured.  

    I have look through the configuration, and you will need to control the battery fet and charge current termination with the MCU.

    Chuck

  • Thanks Chuck. I also confirmed that putting the BQ2573x in HiZ mode, will not disable the I2C bus, so you are correct in that the BQ25731 would have to be pulled off the TPS25750EVM, if connecting this board to another BQ2573xEVM.