High voltage and heater PSU from 30V DC

[ilya]

Hello everybody. My first post here. So please don't judge harshly

I'm looking for a solution of the following problem. I have a source of unregulated DC voltage. Let's assume it's 2*35V, but it can be up to 40V. I'm looking for possible solutions of powering a tube preamp from this PSU. I need 300V@20mA HT rail and [email protected] heater.
Now, what I thought was making some custom SMPS based on LM3478 TI chip. It can convert 35-40V into 150V which I can then double up to 300V. TI has a convenient online SMPS builder tool as well.
For a heater supply I thought of using an existing TI power modules. But the problem is how do I sync switching on both rails? Do I have to?
Any thoughts and suggestions welcome.

 

[DonH56]

Doubling can be challenging; be sure to use diode clamps and bleeder resistors across the caps. And follow the TI design and layout guidance closely -- there are some quirks with SMPS and layout is critical. There are also lots of other appropriate B+ supplies in various online and paper articles and books though most focus on AC input and transformers.

For the heater (filament) supply there is no need to synchronize the switching. I'd use a standard buck converter or whatever to drop to 6.3 V, filter it well, and call it done.

 

[ilya]

Don, thanks for advice.
Yes, most HV SMPS are base on chopped mains AC and I don't want to go that route.
My doubler circuit will be like the one in this thread:

I also planned to use this module for heaters. Nice to hear I don't need any synchronization. This makes things a lot less complicated.