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TPS61023: TPS61023 Output current

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Replies: 41

Views: 203

Part Number: TPS61023

Hallo,

I am using TPS61023 to control motor using DRV8837. TPS61023 parameters: Vin=3V, Vout=3.3V, max. output current for motor=700mA

But the device resets sometimes when the motor is turned ON.

Is there any changes required in the design? What is the max.output current of TPS61023 when Vin is 3V?

I am using 1uH inductor (74479787210B) for TPS61023. Is it fine? or are resets because of need of higher value capacitors?

Thanks in advance

  • Hi Jain,

    The chosen inductor saturation current level is only 1.15A. Please change to a higher Isat inductor and try again.

    TPS61023 switch valley current limit minimum spec is 2.7A. For 3Vin-3.3Vout application, the estimated maximum output current is around 2A.

    Regards,
    Zack Liu
    Boost Converter Solution

  • In reply to Zack Liu:

    Hello,

    But my application requires max. 700mA. Does TPS61023 still require higher inductor saturation current?

  • In reply to Jain Priyank Jagadish:

    Hi Jain,

    700mA is the output current. You need to calculate the inductor peak current, then a suitable inductor could be selected.

    Regards,
    Zack Liu
    Boost Converter Solution

  • In reply to Zack Liu:

    Hello,

    Thanks. I have replaced the inductor with a higher saturation current.

    I have connected now a second boost converter TPS61020 which has output voltage of 3V (VCC) which supplies power to microcontroller as it has regulator mode and then TPS61023 for motor-Vcc (3.3V). There is a voltage drop at VCC whenever the motor is ON and it leads to reset.

    What should be the delay for soft startup for both the converters?   Currently, I have 5ms delay after TPS61020 Enable high and then again 5ms delay after TPS61023 Enable high.

    Or is there any other solution which avoids resets or voltage drop?

    Thanks

  • In reply to Jain Priyank Jagadish:

    Hi Jain,

    TPS61020 typical start up time is around 4ms and TPS61023 startup time is around 1ms. It's better to wait for the device finished startup time then apply a load to VCC, So I think you have to keep the 5ms delay time. 

    Regards,
    Zack Liu
    Boost Converter Solution

  • In reply to Zack Liu:

    Hello,

    but even with 5ms delay for both the converters, the device resets.

    What is the max. output current for TPS61020 at Vin=2.8V & Vin=3V and Vout=3V?

  • In reply to Jain Priyank Jagadish:

    Hi Jain,

    Per datasheet, the maximum output current at Vin=2.8V, Vout=3.3V is around 1A. The maximum output current at Vin=3V, Vout=3.3V is around 1.1A.

    Regards,
    Zack Liu
    Boost Converter Solution

  • In reply to Zack Liu:

    Hello,

    I am still having issues of resets when motor is turned ON using both boost converters.

    I have noticed that when TPS61020 is turned OFF during motor operation i.e current is supplied directly from pass-transistor T105 to TPS61023 then it works fine 

    OR when TPS61020 output is connected directly to DRV8837 motor bridge then also it works fine.

    There seems to be problem when I have both boost converter active for motor operation.

    Is there any mistake or changes required in schematic? I need max. 600mA output current for motor operation.

    Thanks

      

  • In reply to Jain Priyank Jagadish:

    Hi Jani,

    Could you capture the waveform of VCC_BAT, VCC, MOTOR_VCC nets waveform when Motor is on? I need to check the waveform first and see what's the voltage drop of TPS61020. 

    BTW, you mentioned TPS61020 output 3V to supply microcontroller. Do you know how much current will the microcontroller draw during working? And are you sure the motor driver DRV8837 is drawing 600mA from MOTOR_VCC? I mean is there a huge inrush current when motor is turned on. If the inrush current is high, the TPS61020 output voltage will drop quickly and cause the reset. So it's better to capture the three net voltage and motor driver inrush current waveform.  

    Regards,
    Zack Liu
    Boost Converter Solution

  • In reply to Zack Liu:

    Hello,

    Blue w/f - VCC_BAT (3.2V)

    Pink w/f - VCC (3V)

    Green w/f - Motor_VCC (3.3V)

    The waveform below had TPS61020 OFF and VCC directly from transistor. Here we see, there is a small spike in Motor_VCC after motor is OFF.

    In below w/f there was no reset and both boost converters are active.

    In w/f below, reset occurs and there is spike at Motor_VCC.