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TPS61023: How to properly us a Step-Up regulator to power a 5V brushless motor?

Samuele57647
Prodigy 30 points
Part Number: TPS61023
Other Parts Discussed in Thread: DRV11873, BQ24074

Hello,

in my application I have a 5V Brushless motor that is controlled by a DRV11873. This system is powered by a 3.7V  1A Li-ion battery and I use the TPS61023 to get the 5V required to power the motor. 

The motor needs less than 100mA to run and no more than 200mA at startup. The DRV11873 has a current limit resistor of 10k  limiting the current to 660mA.

However the step-up keeps failing for some reason and I'm not sure how to fix this issue. Is that related to the inrush current? 

Thank you,

Sam

  • 0
    TI__Mastermind 34231 points

    Hi Sir,

    May I know which kind of failing are you referring to? Could you share TPS61023 startup waveform? Thank you.

  • 0 in reply to Zack Liu
    Prodigy 30 points

    Hi,

    I don't have the startup waveform but it seems that whenever there is a some sort of friction and the BLDC motor absorb a bit more current the TPS61023 input get shorted to ground and dies. Same issue with the other 5 I had so I exclude a faulty unit. 

    I forgot to mention that I also use a BQ24074 Battery Management before the step-up regulator and not sure if that affects anyhow.

    Should I use a step-up with short-circuit protection and current-limit features instead?

    Thank you,

    Sam

  • 0 in reply to Samuele57647
    TI__Mastermind 34231 points

    Hi Sam,

    Please share the startup waveform and capture TPS61023 Vin, Vout, SW pins waveform so that I can analyze the possible reasons.

    I used to hear feedback from other people that when motor is stopped, it will generate reverse current to charge TPS61023 output capacitors until Vout voltage exceeds TPS61023 absolute maximum Vout voltage rating of 7V. Will it also happen on your boards? 

    To prevent this, you can add a Schottky diode from TPS61023 to Motor driver input.