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WEBENCH® Tools/UCC28630: PQ2625 WITH AL 177nH

jayaprakash khodhanpur64
Prodigy 110 points
Part Number: UCC28630

Tool/software: WEBENCH® Design Tools

Short description: AC DC Converter using UCC28630DR
Original details: Using TI Work bench we designed AC-DC Converter for the below specifications:-
VinMin = 160VAC,50Hz
VinMax = 260VAC,50Hz
Vout = 22VDC
Iout = 5ADC

The resulting design: UCC28630DR was generated along with BOM by TI Work bench and this meets our requirement. BOM (Bill of Materials) calls for transformer T1 (PQ2625) with below details, this part is manufactured by wurth elektronik.
Core Part Number=150-2239
Coil Former Part Number=070-5649
LP=269uH
Turns Ratio (Nas) =5:8
Turns Ration (Nps) =39:8
Npri=39.0
Naux=5.0
Naux=8.0

We could get all components expect PQ2625 (Suggested in TI design). Supplier Wurth electronik does not support. We tried with them. Request you to use the core / coil former from popular manufacturer in your design so that part will be available. 

We tried with alternate part and got the equivalent to PQ2625 by the manufacturers TDK / EPCOS / FERROXCUBE etc. Details of wurth and TDK is given below:
Part Wurth Electronik TDK
Core Part Number 150-2239 B65877A
Coil Former Part Number 070-5649 B65878E
Core Material TP4A N97
AL Value 177nH, 4650nH
Npri (Primary Turns) 39, 7


The Al value of wurth is less compared to TDK nearly 20 times. Calculating the primary number turns for TDK, it resulted to 7 which is also less than wurth (39 turns). Hence sec and AUX turns are very less. We are not able to construct the transformer. Please advise us how to carry out further. Project is urgent . Req you to send the solution immediately.

  • 0
    TI__Mastermind 40520 points

    Hello Jayaprakash,

    Thank you for your interest in the UCC28630 controller. 

    I'm sorry that you are having trouble procuring a suitable transformer for your project.

    I believe that the Worth core and the TDK core are essentially equivalent.  The difference is, I believe, that the Wurth core is already pre-gapped at thefactory, so they specify it with the effective Al value of 177nH/T^2.  On the other hand, the TDK core from their catalog is an un-gapped core set, so the Al value is very much higher.

    However, the final transformer will have to have a gap so the final Al value will probably be very close to 177nH/T^2 anyway.  It will require the higher number of primary turns (~39) to achieve the desired inductance with the gap. You can construct the same transformer with a TDK ferrite using the parameters for the Wurth design.  The only difference is that you will have to manually gap the core center legs (or have a magnetics vendor construct it for you) to get the inductance you need.

    Regards,
    Ulrich