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TPS61022: TPS61022 is working as a buffer - not boost at all

Grazyna Murciadis
Prodigy 120 points
Part Number: TPS61022


Hi,

I made a PCB where are used to boost 2.8V to 5V 1A out, however it is not working properly. 

I tested it by providing analog voltage from my laboratory PSU  2V - 4V. The output is always the same, just passing the input voltage to the output, never 5V. In more details if I provide 2V the output is 2V, if provide 3V the output is 3V etc.

I check the schematic 1000 times, also the PCB, looks OK to me.

Can you please check them and comment.

Thank you in advance.

Kind Regards

Ioannis

  • 0 in reply to Grazyna Murciadis
    TI__Mastermind 34231 points

    Hi Grazyna,

    The schematic and layout look good. First please exclude the soldering issue, have you ever tried changing the IC? 

  • 0 in reply to Zack Liu
    Prodigy 120 points

    Hi,

    Thank you for your unbelievable fast answer !!

    Yes, it could be, however I already soldered 2nd IC and behavior n the same way. Do you  have an idea which pin (cold soldering) could produce such effect ?

    This would be the best answer for me

    Stay healthy !!

    My Warmest regards

  • 0 in reply to Grazyna Murciadis
    TI__Mastermind 34231 points

    Hi Grazyna,

    From our experience, it looks like the device has entered into pass-through mode: When Vin is higher than setting Vout (Vout=Vref*(Rfb1/Rfb2+1)), the output voltage follows input voltage, which looks like a buffer. So please check the feedback resistors are soldered correctly. One easy method to check: Use DMM to check Vout and FB pin voltage at the same time. Check if the voltage divider ratio is correct.

    Since you already see a voltage at output. so SW pin, Vout pin, EN pin should be soldered well. 

    Another method to check all pins are soldered correctly: use DMM to measure the diode from GND to other pins separately. Connect the DMM red test pen to GND pin, then connect black test pen to Vin pin, Vout pin, SW pin, FB pin, EN pin, Mode pin. There should be a 0.4V-1.2V voltage drop. 

  • 0 in reply to Zack Liu
    Prodigy 120 points

    Hi,

    It was matter of soldering. I tried to solder about 10 ICs until got the proper placement  (by hand). However now it is powered good, and doing the 5V boosting.

    Thank you very much for your support.

    My Warmest Regards

    Ioannis