Hi,

UCC28C43-Q1 or UCC28C53-Q1.

You need to add high voltage startup circuit externally.

There is not single IC which will give me 200 watts output and given input voltage 160 volts and output voltage of 24 volts. And please give me right resources of high voltage startup circuit .And without high voltage my circuit will not work or there is any other way for my forward converter to operate and get 200 watts power. How to design that high voltage startup and please tell me i have to operate my forward converter in CCM or DCM to get desired output and the magnetics that will be designed and the choke that will be  design affect by high voltage startup . What high voltage startup will do as my input voltage is constant nominal 128 volts and input voltage peak is 153 volts. Give all the resources automotive Qualified.

Hi,

I do not see a lot of but what I mentioned particularly for single-ended forward, with automotive graded and with 160V high voltage startup integrated. If you see a lot, can you list a few so I can help to check if they are ok for you?

On how to design an external high voltage startup, a simple way is to tie a resistor from Vin to the IC VDD (UCC28C43-Q1 for example), then charge up the capacitors on VDD to reach its turn on threshold, after switching start, the bias to the IC will be from the auxiliary winding of the transformer.

For how to design a forward converter, please review the below application note.

https://www.ti.com/seclit/ug/slyu036/slyu036.pdf

If you are the designer then the components to use would be part of your design work.

If you want TI to provide a reference design, you need to contact your local TI office.

In regarding CCM or DCM, it looks at light load, a converter may enter DCM but if you use SR (synchronous rectifier) with MOSFET, the operation will be in CCM unless you can add circuit to stop current reverse flowing at light load.

I want the Evaluation Board or Reference design for the forward converter but not getting. Please update me with this point. IC selection and it is possible to make flyback converter of 500 Watt practically and also comment as per my specification that it is possible of getting 200 watt and tell them. I have selected correct topology or with this specification which is better and best topology to go with. 

Hi,

LM5025 EVM can be ordered on ti.com: LM5025AEVAL Evaluation board | TI.com

But if you need a design to meet your specs, you need to make design by yourself or ask your local TI office to request if your business scale is good enough.

A flyback usually is used for up to 150W, 200W maybe ok, already a challenge, so it is better to use a forward converter, if 500W, it is better to use a full bridge converter. 

I understood and according to my specifications forward is the good topology tobe used. But why I am asking for reference design because I want one base as I know reference design is unknown to me who designed it don't know but one confidence that it is the way to proceed that's why please provide me the most reliable reference design so that I can achieve my results as desired. Asit will be used in automotive sector so it should be used cautiously. I will design according to my requirement but I need one proof of concept that this is working so through this I can go and make my design clear and successfully complete. 

Hi,

The EVM from this link is what we have and you can test this EVM after you order to get it:

https://www.ti.com/tool/LM5025AEVAL?keyMatch=LM5025AEVAL&tisearch=universal_search&usecase=hardware

You need to request a reference design to your local TI office if your application scale is good. We do not have a reference design for your application that can provide to you.

I have not got schematic of the EVAL board and if possible please provide other eval board which has schematic and most reliable reference 

Hi,

The schematics is inside the user's guide - did you open the below and have a review yet?

AN-1345 LM5025A Evaluation Board (Rev. B)

The schematics is on page 6 of the above.

I don't want active clamp forward converter as my requirement is of up to 200 watts so single ended forward converter is needed give the solution for that and evaluation board or reference design for that . Please help in this regad.

Hi,

UCC28C43-Q1 or UCC28C53-Q1 can be used. But no 200W design can be found from single ended. This not found an interleaved forward as below. Again, you need to make your own design or ask your local TI office to request a new reference design.

www.ti.com/.../slua312.pdf

I have put my design requirements in webench power designer DC DC converter but it is saying by using the IC UCC28C43-Q1. It is saying that output power greater than 120W is not possible 

Hi,

Yes, that is due to the IC driver current peak 1A not sufficient to over 120W. I think you need to follow this below application note sent to you before for your 200W design with external MOSFET driver - it looks you need 2A MOSFET driver which usually single ended forwardPWM controller does not usually have, as 200W converter usually to use double ended PWM converter or use two phase interleaved PWM converters. 

https://www.ti.com/seclit/ug/slyu036/slyu036.pdf

You can still use Webench to program the IC at 120W then to manually change the power stage from 120W to 200W and add external MOSFET driver.

According to you I should go for 2-Switch forward topology and please give me suggestions to use primary side control and also on using secondary side control that many design uses secondary side control by replacing 2 diodes output with 2 active switch and controlling with other IC from secondary side also and optocoupler also with that. But I want simple design and having some doubt at light load or no load of forward converter what will happen it will go to dcm if I use light load or no load in forward converter. Please give the suggestion and suggestions as I am finalizing the IC UCC28C43-Q1 to use . Is it work for my design. 

And the link that you provided previously was taking me to the website but no pdf of application note was downloaded .Please tell me where is the pdf of slyu036.pdf

Hi,

2-switch forward is one that can be used. You can still use UCC28C43 but you need to add external driver to drive 200W associated MOSFETs. As I mentioned, you can still use wenbench to design a 120W or 100W converter with UCC28C43 then manually modify the power stage to 200W.

I do not know why you cannot get that file - did you log in after get that link? Other people were ok to get that file from that link.

External driver means I have to design own gate driver circuit if I use this UCC28C43-Q1 IC . earlier you said that for my input voltage is 100-160 volts so High voltage startup circuit is needed. So please tell in detail and resources of all so that I can design properly. And you are saying to use me configuration of active clamp forward converter. If I want diode in output side then secondary side control is not there? Converter can go to dcm at light load and I have to use optocoupler isolation or no optocoupler is possible by using this IC. Please tell how to design that. 

Hi,

External driver IC is available, such as 

UCC27517A-Q1 Single-Channel High-Speed Low-Side Gate Driver with Negative Input Voltage Capability (with 4-A Peak Source and Sink) datasheet (Rev. B)

For high voltage startup circuit, you can refer to the below application note: section 2.3.8

Automotive 40-V to 1-kV Input Flyback Reference Design (Rev. B)

It would be better to use opto coupler for your feedback control as you are using a forward topology, TI has opto coupler emulator in automotive grade:

ISOM811x-Q1 3.75kVRMS , Automotive Single-Channel Opto-Emulator With Analog Transistor Output datasheet (Rev. C)

I want to ask if I use the IC UCC28C43-Q1 and UCC28C53-Q1,tell me understanding of both that by using this IC I have to use external gate driver if I use active clamp forward topology for my specifications having input voltage (100-150 volts) or it is having internal gate driver circuit so that I can only use MOSFET and external Rg to put. Please tell and if I use Single ended forward topology then will it work for both of these IC or not my output power is 200 watts and output voltage 24 volts.

Hi,

LM5025 integrated driver with driving peak current 2A so it looks ok for 200W driving: But UCC28C43 or C53 driving with peak 1A so you need to add external driver to get 2A for 200W.

I have attached all the 3IC'S Reference design and Evaluation Board and Application circuit LM5025,LM5026 and UCC2879A.I have not understood that I need external Gate driver for the Synchronous rectifier mosfet  present in secondary side but why they are present and why there is needed if I will change them to simple Schottky diodes what will happen and what is double ended center tapped transformer gate drive circuit that is present in each 3 pdf's I shared .Plese tell me in detail and why it is necessary and why there is 2 error amplifier present in LM5026 .Is this is Type1 or Type2 compensation. And You said that UCC2843-Q1 or-53 is not  suitable for my application as it giving 1A peak out current and you said LM5025 is good option as it's peak output current main mosfet is 3A and Clamp mosfet is 1A so how you decide that it is work for 200Watts forward converter .And I also searched LM5026,UCC2879A 2 more IC .please tell me which is good option for my application. Vin(100-160Volts) and Output voltage 24Volts and Out_power=200W.I am going with active forward clamp topology .As I have seen there is current sense transformer present in the application and EVAL board of circuit i have shown above. How to design that and  How this secondary side transformer-based gate driver circuit is designed for synchronous rectification and how that is designed and dead band and all .I have shared all 3 IC CIRCUIT  . Please tell which is good or you know any other then please tell that.  give that and how that type 1 and type 2 feedback compensator designed and how to know that type1 or type2 and I have seen that some IC is feedforward control, and some is current mode. Which is good AND why.

Hi,

You have seen the webench only allows you to design up to 120W, which is from 1A driver. So 2A driver is ok for 200W.

For SR, you can use diodes to replace MOSFETs.

LM5025 needs type iii compensation. LM5026 and UCC2897A needs type ii compensation, but some designs use type iii to make designs flexible.

Please tell if I use SR in secondary side then how this transformer based gate driver is to design and what is the current sense transformer also please tell both. 

Hi,

If using diodes for SR on the secondary side, then no need to design driver.

If using MOSFETs SR on the secondary side, then like the below:

Current sense transformer, do you know how to use Google to search what you need? This below is from Google search.

Current Sense Transformers & Sensors | Coilcraft

The 3 circuits I have provided above in that how they are driving 2-Secondary side MOSFET in that no BJT is there. That I have not understood.For that secondary side MOSFET how you know how much gate current is sufficient to give 200 Watts output. 

Hi,

The first one drives the secondary SR directly from the transformer - you can check the transformer secondary side winding polarity to find out.

The second one is the same as the first one. The diodes added to gates are for MOSFETs fast turn off in both circuits.

The third one is also the same but without adding the diodes.

These 3 circuits are ok to drive from the transformer windings due to the winding voltage is low from low Vout. Your case Vout = 24V so cannot do like the three circuits since an MOSFET usually its Vgs max <= 20V so need to have the voltage change to a proper level so not able to drive like your three circuits.

Can you share the whole pdf of the above circuit from where you shown that . I have to do similar that driving through bjt and then given that current to MOSFET ? And I have 24 volts so that voltage can't be given to driver so My transformer secondary side will give voltage less than 24 volts ? Or above to obtained 24 volts at output and drives MOSFET properly . 

Hi,

You can get the full schematics from this link:

PMP21318 Schematic

I think you have not read my previous question carefully.I said if I use Synchronous rectification by using MOSFET then I need to use 2 gate driver ic separately for that to drive MOSFET as my output voltage is 24 volts.please correct.e if I am wrong and please give me resources of designing that.and tell the method according to your thought what can be possible in that case . And please give me idea that for compensation type2 is good or type3 indirectly I am asking about the IC  which performs good in hardware current mode control or feed forward voltage mode control. Please tell this. 

My problem is that in the active clamp forward converter duty cycle limits about Dmax<=44-50%. And Switching frequency is limited up to 100-150khz.And in Push pull and Phase Shifted Full bridge. Are having less size of magnetics and switching frequency is also increases 200-250khz and Dmax<=100%. So, what are the advantages I get in Push pull and Full bridge topology so what we get in Forward converter topology in my application case.  Please guide in my automotive application. Please Give me proper reason and validation.  

Hi,

The active clamp forward duty cycle Dmax can be designed to be larger than 50%, such as ok to do 80% or even 90%, switching frequency also can be > 200kHz, or even 400kHz.

Push-pull or full-bridge, duty cycle (combined both drivers) can do close to 98%., frequency can do either as low as 100kHz or as high as 500kHz.

So Dmax and frequency are not the reasons to distinguish them. The active clamp forward is basically a single ended topology so the main MOSFET is to carry all power to conversion. But the push-pull and the full-bridge are double ended topologies, the total power distributed to two or more than two MOSFETs.

You can parallel MOSFETs in single-ended, but this will demand higher current driver.

In automotive, if you need AEC-Q100, then you can use any as long as a design is automotive graded.  Automotive itself does not provide how to select a proper topology but the power does same as above.

I want to know about Cots Power supplies. Is there any available in TI. Please tell of Active clamp Forward converter of my Specifications is available or not. And please guide about difficulty in designing Active clamp forward converter compared to phase shifted full bridge and Push pull and If I operate at less switching frequency 100-150khz in active clamp forward converter any difficulty I see in case of 24 Volts output and tell that my application is automotive so Is there any Protection circuit signal conditioning circuit I needed so that I design that first ten power supply. If Yes Please give me resources of that how and which is needed as I have to give supply to various important components in Automotive inverter, BMS, Motor etc. Please Guide in this regard and Please finally say which is good topology and Dmax<=50% in forward converter recommended in forward converter and if I will take 2 gate diver IC in secondary side and give gate current to mosfet in active lamp forward using pulse transformer then what will happen .Is it Ok .I need any other transformer besides main power transformer for that .How to design that and please give me reference design schematic of using pulse transformer based gate driver doing Synchronous Rectification.