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UCC27322-Q1: Recommended low-side motor driver for automotive fans ~120A @ 12V

James Weaver
Prodigy 30 points
Part Number: UCC27322-Q1
Other Parts Discussed in Thread: LM5134,

Hi,  I'm looking at one of the UCC2732x products to PWM modulate dual automotive fans (each Fan =700W).    I am also looking at  LM5134. 

(1) Can someone recommend which is better for this application?

(2) Is it better to run the fans in parallel or individually (I'm concerned about being able to dissipate heat and also the size of PCB conductor needed if I go with parallel- that's about 120A).  

(3)  Also, is it common to monitor temperature of the power MOSFETs or the driver chip?  

I think this should be posted to motor controller forum, but no choice was given.

  • 0
    TI__Guru**** 189399 points
    Hi James,

    Welcome to e2e, and thanks for your interest in our products!

    I would recommend UCC27322-Q1 for the following reasons:
    1. It's automotive qualified (I assume this is a requirement)
    2. It's got higher gate drive current capability
    3. You don't need to add a second external pull-down FET like the LM5134 allows

    As for your other questions, if you can explain a little more about your application, I can see if one of my colleagues in the motor drive group can elaborate.
  • 0 in reply to Don Dapkus
    Prodigy 30 points
    Don,
    I didn't realize these parts were specified differently for temperature. The UCC part says: "Device Temperature Grade 1: –40°C to 125°C Ambient Operating Temperature Range", but the LM5134 specifies "junction temperature range". Can you tell me why the LM5134 does not specify ambient temperature range?
    Also I see the the LM5134 has a VCC max of 12.6 V which will be a problem for automotive applications.

    Also you mentioned (3) about not needing an external FET for the LM5134, as if that added FET is a disadvantage, whereas it looks like the option to dampen oscillations is a nice advantage, without having to tune optimally with a series resistor or adding a ferrite bead.
    And if it is not an advantage, then why produce the LM5134 in the first place?

    As for my application, its simply to control the power delivered to these fans using PWM. I'm not trying to precisely control RPMs.
    And I'm not sure which approach is better- to drive the fans independently thereby reducing current, or parallel them and save on parts count. I've never hear of a PCB trace handling in excess of 120 A ! How to other designers deal with such large currents when trying to interface MOSFETs on the PCB with a connector going to the load?

    Thanks very much for your advice
  • 0 in reply to Don Dapkus
    Prodigy 30 points
    Don,
    I didn't realize these parts were specified differently for temperature. The UCC part says: "Device Temperature Grade 1: –40°C to 125°C Ambient Operating Temperature Range", but the LM5134 specifies "junction temperature range". Can you tell me why the LM5134 does not specify ambient temperature range?
    Also I see the the LM5134 has a VCC max of 12.6 V which will be a problem for automotive applications.

    Also you mentioned (3) about not needing an external FET for the LM5134, as if that added FET is a disadvantage, whereas it looks like the option to dampen oscillations is a nice advantage, without having to tune optimally with a series resistor or adding a ferrite bead.
    And if it is not an advantage, then why produce the LM5134 in the first place?

    As for my application, its simply to control the power delivered to these fans using PWM. I'm not trying to precisely control RPMs.
    And I'm not sure which approach is better- to drive the fans independently thereby reducing current, or parallel them and save on parts count. I've never hear of a PCB trace handling in excess of 120 A ! How to other designers deal with such large currents when trying to interface MOSFETs on the PCB with a connector going to the load?

    Thanks very much for your advice
  • 0 in reply to James Weaver
    TI__Guru**** 189399 points
    Hi James,

    The LM5134 was released a few years ago, and we weren't careful with including ambient temperature range. For commercial applications, the max ambient operating temp is usually controlled by the power dissipation capability of the package to keep the junction temperature within specified limits.

    I think either approach is valid - use a single output, and use parallel wires/connector pins to carry the 120A, or split it up. I assume the number of wires/connector pins will be the same either way, as it's determined by your load current.