TPS65131: Getting Constant 1.42V at the VPOS pin

Md Sadique Hasan

Part Number: TPS65131

Hi,

I am facing a little bit of problem with my boost converter with TPS65131. I am using only the boost converter portion of this chip not the negative converter. I am getting a different voltage at the pin FBP instead of 1.212V according to the datasheet. I am getting constant output voltage 1.42V and when I change the voltage divider resistor ratio the FBP pin voltage changes but the output voltage remains constant. I have checked the input voltage of the chip as 3.24V and the enable voltage and Reference voltages match the voltages as mentioned in the datasheet. Can anyone please let me know what might be wrong I am doing resulting in the constant FBP voltage?

Thanks

over 5 years ago

0 Grant Falkenburg over 5 years ago

TI__Intellectual 1965 points

Hi,

Thank you for your question. Let me contact the expert for this part. You can expect a response by 12/3/19.

Best,

Grant

0 Liaqat Khan over 5 years ago

TI__Mastermind 18550 points

Hello Sadique,

Can you please share schematics of your design? I will review it to see if I can spot something that can result in the behavior you are observing.

Kind Regards,

Liaqat

0 Md Sadique Hasan over 5 years ago in reply to Liaqat Khan

Prodigy 90 points

Hi,

Thank you for your reply. I am attaching a snapshot of my schematic.

0 Liaqat Khan over 5 years ago in reply to Md Sadique Hasan

TI__Mastermind 18550 points

Hello Sadique,

Since you ae not using the inverting buck-boost converter in this device, I suggest to connect pins ENN and PSN to ground instead of leaving them floating and also connect pins INN and INN_2 to +3.3V input supply instead of leaving them floating. This should provide proper operation for the boost converter.

Kind Regards,

Liaqat

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TPS65131: Getting Constant 1.42V at the VPOS pin