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TPS61032: TPS61032 boost converter can't boost to 5V at lower battery volts

Prabhu R
Prodigy 30 points
Part Number: TPS61032

We are using TPS61032 boost converter for boosting 3.7V to 5V from li-pol battery to power the PCB, we are using Senseair S8 LP sensor to measure the Co2 gas the sensor operates at 50mA average and 300mA at peak. In 3.3V the converter can't boost the voltage to 5v the controller gets restart. In datasheet mentioned the boost converter has 1.8V to boost 5V output.

  • 0
    TI__Guru 62635 points

    Hello Prabhu,

    Can you please check the input voltage with an oscilloscope when the converter gets restarted?

    In the layout, it seems that the connection to VBAT is vary small. So please measures VBAT close to the IC.

    Best regards,
    Brigitte

  • 0 in reply to Brigitte
    Prodigy 30 points

    Hi Brigitte thanks for your response. I have used RPS instead of battery and set 2.7V input and getting the oscillation in the input supply. I attached the picture of it. The mentioned VBAT pin is EN pin and i think that not an issues here.

  • 0 in reply to Prabhu R
    TI__Expert 6845 points

    Hi Prabhu,

    The input ring problem is most likely caused by not sufficient input cap:

    MLCC has a DC bias effect which means its capacitance will reduce when DC voltage is applied. Please go to the webpage of the manufacturer and check the effective capacity of Cin and Cout.

    Taking this Murata GRM188R61A226ME15 as an example, its capacitance will reduce by 74.7% at 5V voltage, which mean this 22uF cap only has 5.5uF effective capacitance under 5V voltage.

    When not enough Cin is applied, the parasite inductance on the wires will cause an oscillation on the input supply. Such oscillation will affect the output. Please add more capacitors on the input and add extra tantalum Cap as Cin if the power supply is connected by long wire over 10cm.

    Also, connection between Cin and Vcc should be close and wide:

    Best Regards,

    Travis