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DRV8412: High current condition

Part Number: DRV8412
Other Parts Discussed in Thread: DRV8842, DRV8842EVM

Hi all

We are looking for the motor driver which be able to be filled with following conditions;

Motor type : BDC
H bridge : 2
Mode : Forward, Reverse, Brake
VM : DC11.5V~12.0V
Peak cuurent : 5.8Apeak wiht 500msec ~1sec
Normal current : 2.4A
OCP : more than 6.0A

Is it possible to use DRV8412 with above conditions?
We assume that current peak is difficult to be filled with following conditions.

Kind regards,

Hirotaka Matsumoto

  • Hi Matsumoto-san,

    What is the ambient temperature?

    The DRV8412 could be used in these conditions. It is recommended to configure the device in parallel full bridge mode for optimal performance.

    Thermal considerations will be important. Please be sure to have a large ground plane for proper thermals.
  • Rick san

    Thank you for your reply!

    What is the ambient temperature?
    ->Ta=40C

    It is recommended to configure the device in parallel full bridge mode for optimal performance.
    ->OK, we got it is recommended to configure the device in parallel full bridge mode for optimal performance for one motor.
        If the system is dual 6A configuration(dual motor), is it impossible to construct from point of view of thermal?


    Kind regards,

    Hirotaka Matsumoto

  • Hi Matsumoto-san,

    The device should be able to handle 6A if only one motor is operating at peak current. The DRV8412EVM is available for evaluation.
  • Rick san

    We would like to confirm one point.

    Is DRV8842 with paralle output setting possible to be satisfied with the customer's condition?

    <The customer's condition>
    Motor type : BDC, one motor
    H bridge : 2
    Ta=45C~50C
    Mode : Forward, Reverse, Brake
    VM : DC11.5V~12.0V
    Peak cuurent : 5.8Apeak within 500msec ~1sec
    Normal current : 2.4A
    OCP : more than 6.0A

    It depends on the heat radiation pattern, we assume that DRV8842 with paralle output setting is fitable for the customer's condition.

    PD=I^2 × Rds × 2(paralle)=3.6A
    ->3.6A×31.6(θja)=113.3C, 113.3C+45~50C(Ta)>150C, even though 5.8Apeak is within 500msec ~1sec, however is it difficult to realize with DRV8842 with paralle output setting?

    Kind regards,

    Hirotaka Matsumoto

  • Hi Matsumoto-san,

    It may be possible. Please remember θja is based on a standard JEDEC board, and the actual θja may vary based on the board.

    The DRV8842EVM is available for evaluation. The DRV8842EVM has very large planes to dissipate the heat from the device.
  • Rick san

    Thank you for your reply!

    We have two additional questions as follows;

    <Question1>
    There is the discription "Peak motor drive output current, t < 1 μS" on Absolute Maximum Ratings.
    Does it mean OCP's deglitch time?

    <Question2>
    Does DRV8842 have two H-Bridge internally? or one H-Bridge?
    If one H-Bridge, PD=I^2 × Rds × 1 = 6A×6A×0.2=7.2W
    7.2W×31.6(θja)=226.6C
    It will be theremal shut down threshold immediately.

    Kind regards,

    Hirotaka Matsumoto

  • Hi Matsumoto-san,

    <Question1>
    There is the discription "Peak motor drive output current, t < 1 μS" on Absolute Maximum Ratings.
    Does it mean OCP's deglitch time?

    This is referring to section 7.3.6.1 of the datasheet:
    An analog current limit circuit on each FET limits the current through the FET by removing the gate drive.

    This circuit limits the current during the blanking time (tblank) to protect the FETs from current much higher than the OCP trip.

    <Question2>
    Does DRV8842 have two H-Bridge internally? or one H-Bridge?
    If one H-Bridge, PD=I^2 × Rds × 1 = 6A×6A×0.2=7.2W
    7.2W×31.6(θja)=226.6C
    It will be theremal shut down threshold immediately.

    The DRV8842 has one-Hbridge.
    As previously mentioned, "θja is based on a standard JEDEC board, and the actual θja may vary based on the board.
    The DRV8842EVM is available for evaluation. The DRV8842EVM has very large planes to dissipate the heat from the device."
  • Rick san

    Thank you for your cooperation always!

    We would like to confirm one point.

    On the 7.3.6.1 of DRV8842's datasheet, there is the description "OCP time".
    Does it mean tBLANK(Current sense blanking time)?

    And then, is "Absolue Peak motor drive output current, t < 1us" different from OCP time, right?
    As the conclusion, we recognize follows;
    -OCP time = tBLANK
    -It should keep 6Apeak within 1us at Absolute maximum rating.
    If our understanding is not correct, could you give us the advice?

    Kind regards,

    Hirotaka Matsumoto

  • Hi Matsumoto-san,

    "On the 7.3.6.1 of DRV8842's datasheet, there is the description "OCP time".
    Does it mean tBLANK(Current sense blanking time)?"

    The OCP time is typically the same as the tBLANK time. The OCP circuit is active any time the outputs are enabled.

    Please see the end of post: e2e.ti.com/.../344499 for details.

    "And then, is "Absolue Peak motor drive output current, t < 1us" different from OCP time, right?
    As the conclusion, we recognize follows;
    -OCP time = tBLANK
    -It should keep 6Apeak within 1us at Absolute maximum rating.
    If our understanding is not correct, could you give us the advice?"

    If a short is present, the current can rise well above 6A. The peak current is reduced by an internal circuit to prevent damage to the FETs. The peak current will remain above 6A until the overcurrent protection is activated.
  • Rick san

    Thank you so much for your reply.

    If a short is present, the current can rise well above 6A.
    The peak current is reduced by an internal circuit to prevent damage to the FETs.
    The peak current will remain above 6A until the overcurrent protection is activated.
    ->As the conclusion, if the current is more than 6A with 1us,  does the device damage or not?
       If the device damages with 6A@1us, before OCP function operates, we assume that the device will damage.

    Kind regards,

    Hirotaka Matsumoto

  • Hi Matsumoto-san,

    ->As the conclusion, if the current is more than 6A with 1us,  does the device damage or not?

    The device should not suffer damage is the short circuit current is more than 6A.

  • Rick san

    OK, thank you so much for your reply!

    Kind regards,

    Hirotaka Matsumoto