This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

[FAQ] UCC21732-Q1: UCC21739-Q1/UCC21710-Q1/UCC21750 & -Q1/UCC21736-Q1 differences

Part Number: UCC21732-Q1
Other Parts Discussed in Thread: UCC21739-Q1, UCC21710-Q1, UCC21750, UCC21736-Q1

Hello everyone,

I need a high current gate driver and all of these drivers meet my needs. But I need to pick one or two. I went through the datasheets and found no differences between:

UCC21732-Q1
UCC21739-Q1
UCC21710-Q1
UCC21750 & -Q1 version

other than internal or external miller clamp. Even then, 21732-Q1 and 21739-Q1, both, have external miller clamps. Whereas the internal clamp is also available on multiple parts. Furthermore, aside from the AIN pin and its use,

UCC21736-Q1

is also almost the same as these (the max distortion is 25ns as opposed to 30ns for the other parts on my list).

My question, therefore, is this: if I am not using the Miller clamp or the isolated analog input on the AIN pin, are all these drivers equivalent? Can I use any one on the same PCB regardless of which one I design with? My DC bus will not exceed 800 Volts and my inverter does not need to meet any regulatory approvals.

Furthermore, I would like to know the difference between 21732-Q1 and 21739-Q1; and also between 21710-Q1, 21750, and 21750-Q1 aside from the -Q1.

Thanks,

Saurabh

  • Saurabh,

    This is a very good question. We are planning on an FAQ for your exact question.

    The confusion between UCC21732-Q1 and UCC21739-Q1 is understandable. There is an error on UCC21739-Q1 product page, the Isolation ratings are incorrect. We actually noticed that several days ago and are working on pushing the correction to TI.com. Thank you for pointing this out!

    UCC21739-Q1 actually has a lower Isolation rating (basic isolation 3kVrms) and not 5.7kVrms reinforced isolation as in the rest of UCC217xx ICs.

    These are correctly show in the datasheet, so please refer to that for UCC21739-Q1.

    This ISO ratings in the parts of the datasheet:

    Saurabh Tewari said:
    My DC bus will not exceed 800 Volts and my inverter does not need to meet any regulatory approvals.

    Understood. Basic isolation such as offered in UCC21739 should be ok in this case.

    There are some important feature differences between these drivers, the "highlighted ones" are the difference between UCC21732-Q1 and UCC21739-Q1 (Isolation rating)

    Saurabh Tewari said:
    My question, therefore, is this: if I am not using the Miller clamp or the isolated analog input on the AIN pin, are all these drivers equivalent? Can I use any one on the same PCB regardless of which one I design with? .

    Even if you are not using APWM or miller clamp, there are still important differences.

    Tthe PCB layout is extremely similar, just small difference depending on the features.

    Example: if you choose UCC21750, it has DESAT detection, the others have OC detection with series res, which circuit is a bit different, then PCB needs to change slightly.

    Safe shutdown:

    The purpose is to avoid overshoot of VDS/VCE on Short circuit detection. STO with 400mA or 900mA, as well as 2LTO w/ 900mA soft turn-off current differentiate the products. Whether you go with 900mA or 400mA will depend on your system. The 900mA STO current offered in UCC21732-Q1, UCC21736-Q1 and UCC21739-Q1 discharge the gate faster which is appropriate if youre driving a device with quite large gate charge, SiC, e.g in high power level.

    2LTO should benefit SiC mosfets the most, but it is really up to the designer. Both 2LTO and STO effectively reduces the overshoot, so it can be up to the designer preference. Between 900mA STO and 2LTO the only difference is that 2LTO dwells at a voltage for the specified time, but the ramp before and after this is both at 900mA. For IGBT in your inverter, either 2LTO and STO should both be fine.


    Active short circuit:

    Essentially, the ASC is an input on the HV,output-side of the driver that overrides the input and forces the driver to turn the FET/IGBT on. Basically, it FORCES a short circuit to happen. This is a special protection mechanism that is useful only in a few applications where there is control on HV side. It probably wont be very useful for your inverter application. Only UCC21736-Q1 has this feature.


    Shortcircuit detection:

    With the exception of UCC21750 (which uses DESAT detection), All other UCC217xx use a shunt resistor to directly measure the current thru the power switch based on Ohms law.

    DESAT determines when the power switch is "desaturating, " leaving saturation region

    OC detection and DESAT are both effective to detect and protect against short circuit and overshoot. However, DESAT detection is better equipped for IGBTs, while OC detection is best for IGBT and just as effective for IGBTs. The only thing is you need a resistor in series with IGBT to detect the current.

    This has more information on this topic.


    VEE UVLO:

    The goal of UVLO is to keep the gate driver from turning-off if the supply voltage is below a threshold, All of them have UVLO on VDD, but UCC21736 also has it on the VEE to keep the gate driver off if VEE threshold isn't met. This

    I hope this helps to answer your question. If I've answered your question please let me know by clicking the green button.

    And please don't hesistate to let us know if you have more questions or need a further recommendation. You mentioned you don't need all of the features in UCC217xx family of parts. If you even don't need STO, DESAT, let me know.

    Best

    Dimitri

  • Dimitri, this is great information. Thank you.

    Saurabh