Schematic Review for BQ24650

Hi Pradhan,

The schematic for bq24650 looks good, you may want to increase C4 voltage rating for better effective capacitance on the filter.

If I find something on the layout I will reply back.

Regards,
Steven

Dear Steven

Thanks for your below suggestion. i am discussing it with Customer and will revert back if any query.

In the mean time please help to give your valuable inputs on layout also.

Thanks and best regards

Pradhan

Dear Steven

Can you please help to give your valuable feedback on the battery charger layout portion. Need a final confirmation from you to proceed further for PCB fabrication.

Thanks and awaiting for your kind confirmation.

Regards
Pradhan

Hi Pradhan,

Sorry for the delayed response. It looks good overall. You can try to get C12 and C13 a little closer to R14 sense resistor.

Just in case you want to optimize your power loop even more, look at the following, you want to reduce power loops in order to reduce noise and ringing on your switching waveform:

Regards,

Steven

Dear Steven

Thanks for your most valuable feedback.

Have a nice day.

Reagards

Pradhan

Dear Steven

We are working on agriculture automation project. Recently coming up with one issue , BQ24650 is suspended charging during Noon(12.30pm to 4pm) due to hot temperature.

Kindly consider below inputs on your Suggestions:

• Charge is disabled (MPPSET < 75 mV). If the voltage on MPPSET is pulled down below 75 mV, charge is disabled. Charge resumes if the voltage on MPPSET goes back above 175 mV.

  [Teksun-1]: MPPSET voltage is constant 1.25V when the battery is charging through solar panel. MPPSET voltage is 1.4V when charge is suspended during 12.00 noon to 4.00pm.

 

• Adapter is removed, causing the device to enter VCCLOWV or SLEEP mode

  [Teksun-2]: we use Solar panel(6V-1000mA) as input source so in that case solar panel is constantly on.

 

• Adapter voltage is less than 100 mV above battery

 [Teksun-3]: we use Solar panel(6V-1000mA) as input source.

 

• Adapter is over voltage

  [Teksun-4]: We already taken care about that. We put diode D3 and D4 in our schematic for over voltage protection.

 

• REGN or VREF LDO voltage is not valid

   [Teksun-5]: REGN : 5.45V in normal mode REGN: 4V when Charge is suspended. VREF Voltage is 3.2V. Voltage at LODRV pin 0.439 and HIDRV pin 7.81V in normal mode.

 

• TSHUT IC temperature threshold is reached

   [Teksun-6]: As per Datasheet the threshold temperature is 145°C. We have not any thermal scanner or any other equipment to measure IC’s temperature. We have on board Temperature sensor and the atmosphere temperature is neat to 35°C.

                     As per the discussion with Tie2e person battery temperature is not affect on the charging mechanism.

 

• TS voltage goes out of range indicating the battery temperature is too hot or too cold.

    [Teksun-7]: We already check this scenario. Voltage at TS pin is 1.9V in normal mode. As per our voltage divider at TS pin in working condition we are getting 49.95%(As per image in previous mail) and 84.86% or 43.692% when charging is suspended.

Attached is the schematic for your reference.

Thanks and regards

Pradhan

Hi Pradhan,

It looks like the problem here is the TS voltage. Why would it go to 85%? How is it getting too cold?

Also, going down to 44% means the battery is getting hot. Why is the battery getting too hot? Make sure that the battery gets enough room to breath if that is the case. Since this will be outdoors, place the battery in the shade and far from hot surfaces if possible.

Regards,

Steven