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TIOS101: clamping voltage, TVS selection, push pull mode

Ue
Genius 16285 points
Part Number: TIOS101

Hi all

My customer is evaluating the TIOS101 and they have below questions.

Please review and comment.

Best regards

Ueli

---------------------------------

9.2.2.3 Driving Inductive Loads 

The datasheet states: This voltage is clamped internally at about 75 V.

Does this mean the voltage at the OUT pin can be > 50V ?

If we want to use a TVS diode: What voltage should we select ?

What happens if we drive an inductive load push-pull ? ...is demagnetization implemented ?

And do you have detailed functional description for operation with inductive loads (freewheeling) ?

  • +1
    TI__Mastermind 19360 points

    Hello Ueli,

    Ue said:

    The datasheet states: This voltage is clamped internally at about 75 V.

    Does this mean the voltage at the OUT pin can be > 50V ?

    When driving an inductive load, there can be a large kickback voltage when the inductor starts to demagnetize which will cause the voltage on the OUT pin to be greater than 50V.  However, this voltage level will depend on the size of the inductor and the size of the current limiting resistor used in the circuit.  If the voltage exceeds approximately 75V, the device will clamp the voltage to protect the device from damage.

    Ue said:
    What happens if we drive an inductive load push-pull ? ...is demagnetization implemented ?

    In a push-pull configuration, there will always be one active drive transistor to pass the energy from the inductor in addition to the protection diodes depicted in the functional block diagram.  This is not the case in either p-switch or n-switch modes where the output become Hi-Z when disabled and forces the inductor energy to pass through the protection diodes only.

    Ue said:
    And do you have detailed functional description for operation with inductive loads (freewheeling) ?

    We currently do not have any additional information outside of what is in the datasheet.  The TIOS101 internal protection diodes were designed to act as the freewheeling diodes when driving inductive loads. 

    Ue said:
    If we want to use a TVS diode: What voltage should we select ?

    There is no problem using an external TVS diode as well.  As mentioned, the device will internally clamp the voltage to 75V during inductor demagnetization, but otherwise has an abs max voltage rating of 65V for transient pulses less than 100uS.  The value you need would be dependent on your system requirements, but if you didn't want to depend on the TIOS101's internal protection, then a value less than 65V would be needed.

    Regards,

    Jonathan

  • +1
    TI__Genius 16285 points

    Hello Jonathan

    Thank you for the quick reply and the detailed feedback, I appreciate your support.

    Best regards

    Ueli