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Ken Inoue
Ken Inoue
Associate III
September 16, 2017
Solved

Maximum output current value of PWM, TIM

  • September 16, 2017
  • 4 replies
  • 1329 views
Posted on September 16, 2017 at 18:18

Sorry for my poor English.

What is the maximum output current value of PWM using TIM? Where can I find it in the data sheet? I am using STM32F334. I am investigating whether the MOSFET can be directly driven by the PWM from the microcomputer without the gate driver.

On page 78/121 of the data sheet of STM32F334x4 STM32F334x6 STM32F334x8, the following description was given

0690X00000608GvQAI.png

Is IIO=8mA, 20mA the PWM maximum output current value? Which is 8 mA or 20 mA?

Best Regards,

Ken Inoue

    This topic has been closed for replies.
    Best answer by Vangelis Fortounas
    Posted on September 16, 2017 at 21:15

    Hi Ken

    >>>I am investigating whether the MOSFET can be directly driven by the PWM

    Driving MOSFETs its not a static condition to make calculations with currents only.  MOSFET's Gate has very high Ohmic resistance. Load Capacitance of Gate, and Frequency are the main factors to decide to drive a MOSFET (also min GateSource threshold voltage must be <VCC)

    In dynamic conditions like you described , the appropriate table of DataSheet to look at, is

    0690X00000608H9QAI.png

    Regards

    vf

    4 replies

    Tesla DeLorean
    Tesla DeLorean
    Guru
    September 16, 2017
    Posted on September 16, 2017 at 18:40

    It's a CONDITION, that impacts the high/low voltage outputs. ie you draw more current the further VOL gets from zero

    Look at the current tables, with max per pin, and max total across all pins.

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    Ken Inoue
    Ken InoueAuthor
    Associate III
    September 18, 2017
    Posted on September 18, 2017 at 03:03

    Dear

    Mr./Ms. 

    Clive One

    Thank you for your reply. 

    You mean that as more current flows, Vol increases. 

    Best Regards,

    Ken Inoue

    Vangelis Fortounas
    Vangelis FortounasBest answer
    Associate II
    September 16, 2017
    Posted on September 16, 2017 at 21:15

    Hi Ken

    >>>I am investigating whether the MOSFET can be directly driven by the PWM

    Driving MOSFETs its not a static condition to make calculations with currents only.  MOSFET's Gate has very high Ohmic resistance. Load Capacitance of Gate, and Frequency are the main factors to decide to drive a MOSFET (also min GateSource threshold voltage must be <VCC)

    In dynamic conditions like you described , the appropriate table of DataSheet to look at, is

    0690X00000608H9QAI.png

    Regards

    vf

    Ken Inoue
    Ken InoueAuthor
    Associate III
    September 18, 2017
    Posted on September 18, 2017 at 03:07

    Dear 

    Mr./Ms. 

    Vangelis Fortounas

    Thank you for your reply. 

    The MOSFET I use can be driven at 2.5 V, Ciss = 15 pF. And I want to operate the MOSFET at around 100 kHz. Therefore it seems possible to drive without gate driver.

    Best Regards,

    Ken Inoue

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