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BQ25616EVM: Design Concern of combined TPS61027 and BQ25616

Part Number: BQ25616EVM
Other Parts Discussed in Thread: TPS61027, BQ25616, TCA9548A, INA260

Dear TI,


First of all, thank you very much for your technical supports, especially with my BQ25616EVM and TPS61020EVM. I was able to get the system to work together to charge lithium-ion battery using a bench power supply. 

I currently try to make a PCB to get the two circuits into a smaller form factor for my application, and I wonder if you could give me a quick look if there are something obviously wrong.


The annotation of components for the BQ25616 circuit is identical to the annotation of the BQ25616EVM from TI user manual, so it helps us reference better. I also included two INA260 with JPs for testing the voltage and current monitor to quantify the TPS61027 and BQ25616 combined charging efficiency. t's a very simple charging circuit with the power supply is connected to J4 and the li-ion battery is connected to J5. I have a microcontroller to read voltage and current via SCL and SDA of TCA9548A.


I attached the pdf here for your reference. I do have some questions that I appreciate you could help me.


1. BQ25616 has both PGND and AGND, should the GND of other components (TPS61027, INA260, and TCA9548A) be connected to PGND or AGND?

2. What should I do to simplify the SW output of BQ25616 if I don't use it for load? Can the C7 and J2 be removed?

3. Can the R2 between LBO and VOUT be removed?

4. I do not need to boost the BQ25616 for SW output so can I tie OTG pin to ground and remove R8?

5. The resistors R11 and R21 are chosen such that I could get maximum current output from the BQ25616 module.

6. Are there some other connections I can further remove to make it even simpler? I hope to turn on and off the TPS61027 and BQ25616 via their respective enable pins.

Thank you very much,

Khoi Ly


Charging_System.pdf

  • Hello Khoi Ly,

    1. I assume the boost converter ground would go to power ground, but I would highly recommend opening a thread with the other part numbers asking this question. I am not as familiar with the parts other than the battery charger.

    2. We require minimum 10 uF capacitor on SYS as this is the output of the converter. However if you do not use the load J2 is not needed.

    3. Questions on TPS61027 should form a new thread and be directed towards that device.

    4. Yes please tie OTG pin to GND and remove R8 if not using OTG feature.

    5. Confirm 3 A ICHG and 3 A input current limit.

    6. Please double check your TS connection and make sure it is properly biased. Pulling up STAT would be helpful for debug or external status. The BQ25616 looks pretty minimal. To confirm the other circuits please open separate threads.

    Regards,

    Mike Emanuel

  • Hi Mike,

    Thank you for your detailed supports.

    Regarding 1., what is the main differences between PGND and AGND of BQ25616? Maybe understanding this can help me identify how to tie GND of other components to it.

    Khoi Ly

  • Hi Khoi Ly,

    PGND is where the main power current returns through ground. For example, battery, system, input voltage. AGND is for other signal returns that do not carry as much current and/or not connected to the main power path. For example, VSET, OTG, TS.

    Regards,

    Mike Emanuel

  • Hi Mike,

    I hope you could bare with me with just one last question about BQ25616EVM. On the schematics in Figure 10 page 12, the D3 is connected in parallel with R5, but R5 is 0 Ohm. In this case, is it safe to remove D3 and R5 completely and just make a short wire between them? 

    Thank you very much!

    Khoi Ly

  • Hi Khoi Ly,

    Please test according to your application, but you should be able to connect ACDRV directly to the gate of the OVPFET.

    Regards,

    Mike Emanuel