strange voltages in the charge pump of the TLE9879QXA40

[wph1995]

Hello everyone,

I've been using the TLE9879 shield design for Arduino in my circuit, I made two versions and both work but I've been measuring the voltages at some points, such as the charge pump, the SHx pins and everything related to the power stage, and I noticed that when I connect the same motor to both boards the voltages are similar but between the CP2L and CP2H points there is a difference, in version 1 there is 17.6V and in version 2 there is 23.7 volts, this is between the CP2L and CP2H terminals with the motor off, but when I measure the voltage between CP2H and GND, in both PCB versions there is 34.5V but when I turn on the motor the voltages on both boards are similar, between CP2H and CP2L there is 15.6V and between CP2H and GND there is 34.4V approximately, are these measurements normal? I've been reviewing the datasheet but it only tells me that the charge pump can be configured in a range of voltages but I couldn't find how much the voltage between the CPxL terminals should be, how much should the voltage between the capacitors be? I'm using a 24V power supply in both PCB

[RupakC]

Hello @wph1995 

1. For a rough estimate on the practical values of these voltages that you have mentioned, please check our last reply to your previous thread on https://community.infineon.com/t5/MOTIX-MCU/Temperature-problems-with-the-TLE9879/m-p/378959#M1304. We have provided with some experimental values based on our test results and you could get some guidance from it. 
2. Can you please let me know your exact doubt. Is it about whether the different voltage levels that you are getting on your PCBs at the mentioned test points are correct, or is it about the difference in voltages obtained for the two PCBs you have designed?

Best Regards

[wph1995]

Hi @RupakC ,

Exactly I want to know if the voltage values ​​that I am measuring are correct, could it be possible that the values ​​are correct even though they are so different?

[wph1995]

Check the values ​​of the circuits for a supply voltage of 12V and I got the following values:

Version 1:

CP1H - CP1L : 11.01V

CP2H - CP2L : 15.35V

Version 2:

CP1H - CP1L : 10.8V

CP2H - CP2L : 16.5V

I am not sure if a deviation of approximately 1V is correct in some measurements, I still have doubts about the measurements for a supply voltage of 24V, which is the supply voltage I need, it is possible that you indicate the values ​​of the capacitors with a supply voltage of 24V or is there a way to calculate those values?

[RupakC · Accepted solution]

Hello @wph1995 

I performed some experiments for you, and I am sharing my observations below:

1. At 24V VBAT, for the case when the motor rotates, following are the readings:
   C1 (CCPS1) - around 17V
   C4(CCPS2) - around 17.8V
   C3(CVCP) - around 13.23V
2. At 24V VBAT, for the case when the motor does not rotate, following are the readings:
   C1 (CCPS1) - around 23.13V
   C4 (CCPS2) - around 14.30V
   C3 (CVCP) - around 13.75V

Please note that the capacitors noted as C1, C3 and C4 may be found in the 'Hardware design guidelines' document.
Best Regards

[wph1995]

Hi @RupakC ,

Excellent, it was the information I needed, it seems that I am not that far from the voltages you mention.

Thank you.

[RupakC]

Hello @wph1995 

You may also check the simulation tools on the product page. Go to Design Support > Simulation Tools (7) > Simulate ONLINE - 12V Automotive Motor Control based on Embedded Power Full Bridge Driver TLE986x/TLE987x - Concept Circuit Charge Pump

Running the simulations will help you better understand the way the charge pump operates. 

Best Regards