UCC256304: Diode Inquiry

Cedrick

Part Number: UCC256304

Hi,

Good day.

Our customer is using the UCC256304 in their project. They noticed that the EVM uses the MURA160T3G in HV pin. It is aultrafast rectifier and they want to know if it is necessary to use such a fast diode on HV. pin.

Looking forward to your inputs. Thank you.

Regards,

Cedrick

over 2 years ago

0 Eric Reicher over 2 years ago

TI__Expert 7900 points

Hi Cedrick,

You can try Webench designer to enter your application parameters (Vin, Vout, etc) and generate a schematic.

See what Webench recommends for that diode:

https://webench.ti.com/wb5/TISearch/panel.html?p=UCC256304&origin=ODS__UCC256304

Regards,

Eric

0 Manikanta Pallantla over 2 years ago

TI__Genius 12875 points

Hi Cedrick,

Ultra-fast diodes are not must for the HV pin. That’s because, mostly HV JFET which is inside the controller will be ON only during the startup. Once the VCC is charged to sufficient threshold, controller voltage will be supplied by bias winding in which case these diodes won’t be ON.

Also, while selecting the standard diodes, care must be taken as each diode needs to carry both HV pin current and reverse recovery current of opposite diode.

Regards

Manikanta P

0 Cedrick over 2 years ago in reply to Manikanta Pallantla

TI__Expert 8270 points

Hi Manikanta,

Good day. Thank you for your response.

Our customer has a followup inquiry;

HV pin also discharges X cap. So diode speed can be important at that time? And on the data sheet i see that HV pin has AC zero cross detection. Can this be a concern ?Can you confirm if i can use S1J-13-F ?https://www.diodes.com/assets/Datasheets/ds16003.pdf

I hope you could help us further. Thank you.

Regards,

Cedrick

0 Manikanta Pallantla over 2 years ago in reply to Cedrick

TI__Genius 12875 points

Hi Cedrick,

After comparing the device data sheet (DS16003) with the MURA160T3G, it should be okay to use the device as most of the parameters are same except reverse recovery time (which is obvious because it's a standard diode) which is in micro seconds. Where as X-cap discharge time is in the range of milli seconds which is way higher. So, shouldn't be a problem.

Regards

Manikanta P

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UCC256304: Diode Inquiry