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Tool/software:
Battery Voltage is - 4s - 16.8V
Charge current is ~ 4A Default
Input Voltage is - 20V adapter
High Side Mosfer is getting Hot after 20-30 Seconds
I Tried Below. but Heating issue still there.
1. Removed RC snubber For both mosfets
2. Changed Inductor to 6.8uH from 4.7uH.
3. Tried adding series 4.7Ohm gate resistance to High side Mosfet.
4.Resistance R1(150Ohm) changed to 75 Ohms and even tried with 4.7Ohms and Zero Ohms.
5. Shorted B1, Removed R35.
6. Diode D2 Changed to BAT54.
Please find the below schematics
PH Waveform
PH + LODRV (Yellow is PH, Blue is LODRV)
LAYOUT
HIDRV and LODRV Trace
Hello Sadhish,
The switching FETs and inductor are the components with highest power loss. Allow enough copper area for heat dissipation. Multiple thermal vias can be used to connect more copper layers together and dissipate more heat.
Best Regards,
Christian.
Hi,
Thanks. But my BQ24610 is also getting hot and toggles STATUS line after some time. I suspect the issye might be related to the mosfet switching or deadtime, but i am unsure if thats’s the root cause. Could the highside/lowside mosfet switching behavior or deadtime responsible for this heating issue?
I am not sure this much heat can be dissipated by increasing the number of vias and copper areas. please suggest what can be done to reduce the heating issues.
Hello Sadhish,
Have you tried adding a schottky diode across R37?
Best Regards,
Christian.
Hi Christian,
Thanks, we will try this and let you know the result tomorrow at the earliest. we tried reducing the charge current to 1.5A and we observed that the temperature of the BQ24610 Is reduced to 70deg celcius. We provided maximum number of vias to the thermal pad of the BQ24610 and which is connected to the Ground plane on Layer-2. We will add Schottkey diode across R13 and we will let you know the result.
Value of the Resistance R13 is Zero Ohm jumper right?
Hi Christian,
We added a Schottky diode in parallel with the high-side zero-ohm gate resistor, but unfortunately, it did not improve the situation. As mentioned earlier, we reduced the charging current to 1.5A, which resulted in the BQ24610 and the high-side MOSFET stabilizing at around 70-75°C. We are planning to modify the layout to increase the copper area for better thermal dissipation around the high-side MOSFET. However, we would appreciate any advice on additional steps we could take to further reduce the temperature of the BQ24610.
Please suggest How to reduce the temperature for BQ24610?
Hi Christian,
Adding to my previous message,
We have modified the layout to increase the copper area for the high-side MOSFET with thermal vias. Please let me know how I can personally share the Altium project file for your review. As we are moving into mass production, I kindly request you to verify the modified PCB layout to ensure everything is correct.
Hello Sadhish,
You can provide the altium file on this thread, or send it to my email. c-moyer@ti.com
Best Regards,
Christian.
Hi Christian,
I shared the Altium project file via email. Kindly review and let us know your feedback. your timely input will be very helpful.
Email Subject : NB_OOKA_LOUNGE_DVT2 || LAYOUT_REVIEW
Hello Sadhish,
I'm reviewing your layout file, I will provide feedback by EOD Wednesday.
Best Regards,
Christian.
Hello Sadhish,
The layout on the Q1 looks better, another design consideration is to switchout the High side fet with the FDS8477, this is the Fet that we use on the BQ24610 EVM.
Best Regards,
Christian.
Hi christian,
We've observed a difference in the footprint of the FDS8477 part currently in use, and we’ve already purchased this component in bulk for production. Could you advise if there are any specific modifications we should implement to optimize heat dissipation and reduce the temperature during operation?
Additionally, if you have any comments on potential layout improvements to further reduce the temperature, please let us know.
Hello Sadhish,
The previous change that you made to add more vias on the highside fet should help to optimize heat dissipation and reduce the temperature during operation, other than that I don't see any other obvious layout changes.
I just recommend following our layout guildlines:Layout Guidelines and Example (4).pdf
Best Regards,
Christian.