LM3478 flyback reference design

I can see where your confusion arises.

What is happening is that TI is re-editing some of the data sheets so that all of the data sheets present the same format, style and information across the whole product line.
Most of the data sheets being re-edited are the old National Semiconductor products which had a slightly different style.

In the case of the LM3478 the older data sheet (SNV085V) has a final section titled "other application circuits" and this contained a quick sketch of a flyback.

The new forma data sheets (SNV085W) do not contain this section.

However the LM3458 can certainly be used in a flyback application.

Hello John,

Thank you for your prompt reply.

I understood LM3478 can be used in a flyback application and I will propose a flyback application circuit with LM3478 to our customer.

Thank you again and best regards,
Kazuya Nakai

Hello John,
Our customer want to genarate 200V/20mA power supply from 15V input with any TI power IC.
I proposed the customer to use LM3478 for the power supply with flyback topology.
But the customer didn't agree to use the device because the solution size would be bigger than
their target size (we don't know what their target size is.).
I found several TI application designs for similar application as the follow.
Do you think whether these solution output wattage can be increased to 4W or not?

PMP10077
www.tij.co.jp/.../PMP10077

PMP8956
www.tij.co.jp/.../PMP8956

PMP8621
www.tij.co.jp/.../PMP8621

PMP7129
www.tij.co.jp/.../PMP7129

And could you tell me any smaller solution circuit for the customer if you have any idea?
Your idea would be appreciated.

Thank you and best regards,
Kazuya Nakai.

Hi Kazuya,
All of these reference designs are non-isolated.
Is this acceptable to the customer ?
The PMP10077 for example is very close to the design requirement that you have and it is about as low cost as you can expect to find and it uses standard off the shelf parts. There is no custom transformer as you would require with a flyback.

Regards,
John

Hi John,

Yes, the customer needs non-isolated solution.
I know PMP10077 solution size is very small, but I concern with step up ratio. The customer target of input and output voltage are 15V and 200V/20mA. So the step up ratio is 13.3. I worry that any problem is happened when the output load current is changed from 0mA to 20mA.
Also could you tell me which parts parmeter should be change for the customer application (Vin=15V, Vo=200V/20mA) if you have any idea?

By the way, how is PMP8621 solution? This application is using Cockroft Walton Multiplier topology. In PMP8621, the on duty is about 30~60%. It is not so high. I think the operation stability of PMP8621 would be higher than PMP10077.

Your reply would be appreciated.

Thank you very much and best regards,
Kazuya Nakai.

Hi John,

Could you please tell me parts parameters value in case of PMP10077 using for the customer application
(Vin=15V, Vout=200V/1A)?

Thank you and best regards,
Kazuya Nakai.