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BQ25570EVM-206 - Programming Via Resistors & PCB Design

Phillip Do1
Prodigy 20 points
Other Parts Discussed in Thread: BQ25570EVM-206, BQ25570

Hi,

There are two power sources in my system; solar panels, and Thermoelectric Generators (TEGs). My objective is to use the BQ25570EVM-206 to boost the TEG voltage, and buck the solar panel's output voltage, with the goal of charging a super capacitor.

I have looked at the data sheets, and I have done some testing with the EVM. I was able to get the super capacitor to charge, but I am confused about how to reprogram the EVM's settings (buck, boost, etc.).

In terms of modelling the system, I've been trying out LTspice; would this program be compatible with the PSpice models of the BQ25570?

Also, I was hoping someone could point me into the right direction in designing a PCB for the BQ25570. This is to reduce size, and costs, as I would require two BQ25570's (one for solar panels, one for TEGs).

Thanks!

  • 0
    TI__Guru**** 167196 points

    The bq25570 boost output (VSTOR) is the input to the buck converter. So you cannot tie the TEG to VIN_DC and solar panel to VSTOR of the same bq25570.

    The design spreadsheet

    http://www.ti.com/lit/zip/sluc484

    should help you properly size the resistors.  Please read the explanation in the applications section of the datasheet regarding removing solder flux residue when installing new resistors. 

    Regarding PCB design help, attached are the gerbers for the EVM.  Following the EVM layout should lead an acceptable design.  Placing the VSTOR capacitors as close to IC VSTOR and GND pin as done on the EVM is key.  In addition, not pouring ground around the voltage setting resistors and the capacitor on VREF_SAMP is important as the applications LAYOUT section explains.

    PWR206A_gerbers.zip