Other Parts Discussed in Thread: UCC2897A, LM5002
Hello everyone,
Is it possible to implement an LM51581 to build up a forward converter?
Thank you,
Davide
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Hi Davide,
Thanks for using the e2e forum.
I have not seen any designs with LM51581 in forward converter topology.
From experience, parts from other product families are commonly used for this, like UCC2897A for example:
https://www.ti.com/product/de-de/UCC2897A
A design example can be found here:
https://www.ti.com/lit/ug/sluu192a/sluu192a.pdf
Are there specific input specs given for the application? (Vin, Vout, Iout)
Best regards,
Niklas
Hi Niklas,
I am looking for a forward converter with Vin=24V, Vout=15V, Iout=200mA. I initially found the LM5002, but on his webpage, it is suggested a newer component version, the LM51581. To me, the components are working the same, so they both could be ok to design a forward topology.
What do you think about it?
Davide
Hi Davide,
Thanks for the specification.
Is there are reason why a forward converter is chosen for this application?
Forward converters commonly are alternatives to flyback converters if higher output power is required.
For 200mA of load, I would recommend a flyback solution instead, which is less complex.
Best regards,
Niklas
I think that for my application the forward is smaller than the flyback due to the dimensions of the transformer. If I use a Flyback I have to use a planar transformer that occupies more PCB area than a traditional one.
Davide
Hi Davide,
Thanks for the feedback and the explanation.
If LM5002 was a suitable part you found, I agree with the page recommendation to use LM5158x instead.
LM51581 runs in newest process and has better availability, features and pricing than LM5002.
If you want to select a Boost controller for this design, LM51581 would be the best choice.
Best regards,
Niklas
If you want to select a Boost controller for this design, LM51581 would be the best choice.
So it is a good choice also for a forward converter, isn't it?
Davide
Hi Davide,
Yes, in theory, it is possible to use LM51581 for this forward converter.
However, please note that you need to avoid a duty cycle above 50%, as this is required to de-magnetize the inductor during the off-time.
To make sure this is not violated, it would be preferable to choose a PWM controller with fixed max duty cycle limit.
Best regards,
Niklas