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TPS55332-Q1: Large input current

Dice-K
Mastermind 7470 points
Part Number: TPS55332-Q1

Hi support team,

The motor driver is driven by TPS55332-Q1.
If the motor is driven with the VIN of TPS55332-Q1 lowered, a large input current flows into TPS553321-Q1.

tps55332-q1_wave2.pdf

I am thinking about countermeasures.
Is it possible to avoid it by increasing the amount of SS capacitor?
Now it is 0.47μF.

I want to be a friend and send the schematic with a private message.

Regards,
Dice-K

  • 0
    Mastermind 7470 points

    Hi support team,
    This is supplementary information.

    The problem behavior does not occur at startup of TPS55332-Q1.
    The problem occurs when the motor starts running in steady state after the TPS55332-Q1 has started.
    The problem occurs when the input voltage is low.

    It does not improve even if the following part constants are changed.
     - RT Resistor
     - COMP Capacitor
     - Inductor
     - SS Capacitor
     - Input Capacitor

    Is this behavior a characteristic of the product?
    Is there a countermeasure?

    Regards,
    Dice-K

  • 0 in reply to Dice-K
    Mastermind 7470 points

    Hi support team,
    Can anyone reply?

    Regards,
    Dice-K

  • 0 in reply to Dice-K
    TI__Guru* 78070 points

    Hi Dice-K,

    Sorry I thought I already replied yesterday, and seemingly it did not go through.  Yes increasing the SS capacitor should help reduce the inrush current at startup.

    Thanks,

    Youhao Xi, Applications Engineering

  • 0 in reply to Youhao Xi
    Mastermind 7470 points

    Hi Youhao,
    Thank you for your reply.

    I'm glad to meet you again.

    As I wrote in the supplementary information, the problem does not occur at startup, but after startup.
    Changing the SS capacitor capacity does not improve it.

    I send you the schematic in a private message later.

    Best regards,
    Dice-K

  • 0 in reply to Dice-K
    TI__Guru* 78070 points

    Hi Dice-K,

    Sorry I thought it was the TPS55332's start up current.  I took a look of the schematic and so far I haven't see anything apparently wrong.  Could you also show the Motor Driver current, namely the load current of the TPS55332 dc-dc stage?  I am afraid the high input current is just a natural response to the surge current when motor starts.  Its better to show the following waveforms on the same scope picture.

    1. TPS55332's input current

    2. TPS55332's output current

    3. TPS5532's output rail voltage

    4. TPS55332's input rail voltage.

    Thanks,

    Youhao