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DRV8872-Q1: Rds_on vs Iout worst characteristics

Tomoaki Yoshida
Expert 2200 points
Part Number: DRV8872-Q1


Hi support team,

In order to identify the worst conditions under their use conditions, out customer would like the following data.

1. Rds_on vs Iout Graph worst condition

2. RDS(on) vs Tj worst condition

3. VTRIP vs Tj worst condition

For the number 2 and 3 above, there was a typical conditionand ambient temperature in the data sheet.

Although the design must be established under the worst condition in their use conditions, the worst condition of the electrical characteristics of the data sheet is more stringent than their condition.

Is there no way to calculate the worst value under usage conditions with simulation etc. even if there is no graph?

Best regards,

Tomoaki Yoshida

  • 0
    TI__Guru** 114905 points
    Hi Yoshida-san,


    For number 2 and 3, the typical number is at 25C and 24V.

    For number 2, the maximum is across temperature and voltage.
    For number 3, the maximum is across temperature with Iout=1A.

    Please note the statement at the top of the Electrical Characteristics:

    Over recommended operating conditions unless otherwise noted. Typical limits apply for TA = 25°C and VVM = 24 V

    We do not have data for number 1. What current and voltage does the customer intend to use?
  • 0 in reply to Rick Duncan
    Expert 2200 points
    Hi Rick-san,

    Thank you for your support.

    Rds_on is described in the data sheet, but the condition is for output current 1A.
    They are thinking maximum output current is up to 1.5A and Vm is from 7V to 16V.
    Since ambient temperature can not be assumed yet, it is good for them a graph of temperature vs Rds like above number 2.
    Or can I know the worst Rds_on at Ta_max or Tj_max?

    Best regards,
    Tomoaki Yoshida
  • 0 in reply to Tomoaki Yoshida
    Expert 2200 points
    Hi Rick-san,

    Any update on this issue?
    Can I know the maximum Rds_on at output current is 1.5A?

    Best regards,
    Tomoaki Yoshida
  • 0 in reply to Tomoaki Yoshida
    Genius 5255 points
    Hi team,

    Under our assumed conditions, is there a possibility that it will be larger than the maximum Rds_on of the datasheet?
    Vm is from 7V to 16V.
    Output current is 1.5A.
    Ambient temperature is up to 125℃.

    Best regards,
    Tomoaki Yoshida
  • 0 in reply to Tomoaki Yoshida91
    TI__Guru** 114905 points
    Hi Yoshida-san,

    Sorry for the delay.

    A rough estimate is the RDSon will be ~15% more at 1.5A. More power in the FETs contributes to more heat and higher RDSon.
  • 0 in reply to Rick Duncan
    Genius 5255 points

    Hi Rick-san,

    Thank you for your support.

    Do you mean that we can think 15% up of the maximum Rds(on) of the following data as MAX at Iout =1.5A?

    Since the maximum ambient temperature and load current are not yet determined in their system, it is pleasing if there is a graph how the maximum of Rds changes depending on temperature and load current.

    Is there such data?

    Best regards,

    Tomoaki Yoshida

  • 0 in reply to Tomoaki Yoshida91
    TI__Guru** 114905 points
    Hi Yoshida-san,

    "Do you mean that we can think 15% up of the maximum Rds(on) of the following data as MAX at Iout =1.5A?"

    Yes, that is correct.

    "Since the maximum ambient temperature and load current are not yet determined in their system, it is pleasing if there is a graph how the maximum of Rds changes depending on temperature and load current.

    Is there such data?"

    No, there is no such data.