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TPS65132: Input and output capacitor selection

Luke Deng
Prodigy 130 points
Part Number: TPS65132


Hi BU team,

Our customer are considering to change the output caps of VPOS and VNEG from 16V 10uF to 10V 4.7uF, this aims to save cost. They configure the device as tablet mode while the actual current in normal operation is below 20mA. Could you help to give your comments?

 

thanks

Luke

  • 0
    TI__Guru 67150 points

    Hello Luke,

    It is important to have a look at the output capacitance connected to the VREG pin. This is the output of the boost converter. The boost converter is optimized for either 2.2uH/5uF capacitance or 4.7uH/2.2uF capacitance. Please be aware that we are speaking about the output capacitance not the output capacitor.

    So your customer should make sure that on VREG the output capacitance is not going below the above values. It is important especially to check the DC Bias effect. Often this effect is not given in capacitor datasheets, but this one is the worst one for DC converters.

    The capacitors connected to VPOS and VNEG are not such critical. You will observe an increased ripple on VNEG because of the reduced capacitance, but for the VPOS regulator it should be good enough.

    Best regards,
    Brigitte