• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 63 subscribers
  • Views 575 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ25504 Charger Enable - MPPT

Jorge Gomez1
Intellectual 280 points
Other Parts Discussed in Thread: BQ25504

Hi TI Community

I've been working with the bq25504 IC and I have the following issue:

The scope is placed at Vphase (PIN 16)

Once I connect a solar cell, with no storage element at VBAT pint, the harvested energy charges Vstor, when it reaches (V_CHEN=1.8), the main boost starts working. However once the first MPPT sample is taken, the Vphase voltage falls.  It seems that every 16 s a new MPPT sample is taken, but  there is no regulation at VIN_DC.

Surprisingly I have an exact copy of the circuit and it works perfect. So there cause can't be the PCB layout.

Thanks is advance

  • 0
    TI__Guru**** 165866 points

    The capacitor on VREF_SAMP is likely discharging in between MPPT samples.  Residual solder flux can leave parasitic resistors in the 1Mohm range parallel with other components on the board.  In the case of this capacitor, it will cause it to discharge too quickly.  In the case of the voltage regulation resistors, the regulation values may be wrong.