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DRV8835: Output Configuration with four independent Resistive Loads

Colin Campbell1
Prodigy 40 points
Other Parts Discussed in Thread: DRV8835, DRV8835EVM

Hi TI,

I'm planning to use the DVR8835 to drive an output configuration consisting of four independent resistive loads, each connected from a single Output pin to the common Ground reference (GND). Hence in this configuration, all four Output Bridges would operate independently - there is no load connected between a pair of Outputs (e.g. AOUT1 to AOUT2). The Data Sheet infers that this is a legal configuration with the state of each Output being independently set by its associated Input (with consideration for the MODE pin setting). Could you please confirm that this configuration is practical for use of the DRV8835? Many thanks for your assistance.

Best regards,
Colin Campbell

  • 0
    TI__Guru** 114905 points
    Hi Colin,

    The configuration described should work, although you may not get the same amount of current out of the system. The reason is that the high side RDSon is usually a higher than the low side. This may lead into thermal issues at higher currents.

    What value is VM and the resistive load?
  • 0 in reply to Rick Duncan
    Prodigy 40 points
    Hi Rick,

    Thanks for the quick follow up, and feedback on the MOSFET Rdson. For one application, we will be running a VM supply of 5 Vdc with a nominal 20 mA resistive load (250R); our second application has a VM supply of 10 Vdc, with the same nominal 20 mA resistive load (500R). We do not anticipate any issues with a low current load of this nature? Thank you for your confirmation and guidance on any issues we need to be aware of with this configuration. Many thanks.

    Best regards,
    Colin Campbell
  • 0 in reply to Colin Campbell1
    TI__Guru** 114905 points
    Hi Colin,

    At these current levels, there should be no problems.

    One question on the VM = 10V. What is the tolerance and maximum VM? How close will it be to the 12V Absolute maximum?

    There is a DRV8835EVM available for evaluation.
  • 0 in reply to Rick Duncan
    Prodigy 190 points
    Hi Rick,

    Thank you for the confirmation on our configuration. Our maximum VM Level is specified as 10.5 Vdc, so we will be within the DRV8835 spec. We will follow up the EVM - that is a good idea. Many thanks for your assistance.

    Best regards,
    Colin Campbell