UCC21710-Q1: OC and DESAT pin difference

Reza Asrar Ghaderloo

Part Number: UCC21710-Q1
Other Parts Discussed in Thread: UCC21710

This is Reza. I am a Ph.D student at University of Maryland at College Park. I do have following design questions about the TI's impressive gate drivers UCC21710, UCC21717 and UCC21755.

1- I want to design an isolated gate driver block for SiC switch and I intend to have effective short circuit protection. The UCC21710 (and UCC21717) has OC pin with 0.7V threshold voltage, while, the UCC21755 has DESAT pin with 5V threshold voltage. I was thinking that potentially the UCC21710 is proper for SiC short circuit protection and UCC21755 can be used for IGBT short circuit protection, hence, the UCC21755 may not have effective short circuit protection in my application. Is that correct? What is the difference in general between OC and DESAT pins?

2- The UCC21710 and UCC21717 looks pretty similar based on the data provided in their datasheets. The only difference is about their suggested application. I would like to ask if there is any major difference between these gate drivers? Can I use both of them effectively for the solar connected inverters?

Best regards

Reza Asrar

7 months ago

0 Sean Cashin 7 months ago

TI__Genius 15186 points

Hi Reza,

You are right. In general, IGBTs have a higher normal conduction voltage than SiC. That means the overcurrent voltage setting of the gate driver must be higher than 0.7V, such as 5V.

The function is otherwise the same.

Best regards,

Sean

0 Reza Asrar Ghaderloo 7 months ago in reply to Sean Cashin

Prodigy 10 points

Hi Sean

Thank you so much for the quick response.

Just for confirmation, the UCC21755 with 5V threshold voltage may not have effective short circuit protection for SiC switch, right?

Best regards

Reza

0 Sean Cashin 7 months ago in reply to Reza Asrar Ghaderloo

TI__Genius 15186 points

Hi Reza,

To trip 5V instead of 0.7V, the short circuit current would have to get 7x higher. What type of solar project are you working on? I think IGBTs are the cheapest option for high voltage, low frequency.

Best regards,

Sean

0 Reza Asrar Ghaderloo 7 months ago in reply to Sean Cashin

Prodigy 10 points

The solar inverter we are working on that is research based and will have high switching frequency, hence, SiC is proper for our case. BTW, thank you so much for your response and support.

Regards

Reza

0 Sasikala Thangam 7 months ago in reply to Reza Asrar Ghaderloo

TI__Expert 5570 points

Hi Reza,

OC is to sense the overcurrent/SC current - by measuring voltage across the sense resistor and DESAT threshold is measure the desaturation voltage across the power module (typically for IGBT). As Sean highlighted OC with 0.7V threshold by measuring voltage across sense resistor will give faster protection.

Here is an article about SC protection of SiC modules.

https://www.ti.com/lit/an/slua863c/slua863c.pdf?ts=1702497307388&ref_url=https%253A%252F%252Fwww.google.com%252F

Thanks

Sasi

0 Reza Asrar Ghaderloo 7 months ago in reply to Sasikala Thangam

Prodigy 10 points

Hi Sasikala

Got you. Thank you for the detailed description. I will go through the document.

Best regards

Reza

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UCC21710-Q1: OC and DESAT pin difference