TA3020 vs. TK2350

[nominis]

on the transformers board here someone told me to look at the data page of TA3020 to find out what transformers could be used and how the quote from 41Hz Truepath page:

"10V gate voltage, 200mA, referenced to the negative rail (10V above the negative voltage)"

are to be implemented. So I looked at http://www.tripath.com/pb3020.htm which says

"This product is not recommended for new designs.
Please check the recommended product, TK2350"

does it mean I'd better wait for Truepath TK2350?

[Jan]

Hi,

My guess is that TK3020 went out for two non-technical reasons:
- It was more expensinve to produce than the TK2350 chipset
- Major manufacturers are avoiding hole mount components

If you look at TK2350 it also says "Not recomended for new designs", because Tripath cut down on all products they could, to cut costs.
According to Tripath, the modulator section in TA3020 and TA2001 (input chip of the TK2350 chipset), is the same.

As you pointed out, there is one difference between the two, in that the TK3020 has a small SMPS for the VN10 voltage in the chip, while TK3020 does not have this.

I am very pleased to have the Trupepath and the TK3020 chip available, as these have a very good reputation. There is no TK2350 Truepath planned.

[nominis]

> VN10 voltage

ok, but how can this part of the PSU be implemented?

or if the corresponding instructions are part of the TP kit, what additional components are needed to produce the VN10?

[Jan]

The VN10 is more or less identical to how you implement +5V, except the VN10 has its positive side at ground and the negative side at the negative rail. Instead of a voltage 5V above ground, you get a voltage 10V above negative rail, which is how it needs to be. At startup and shutdown, or any PS fluctuations, the VN10 should follow the negative rail, but 10V above.

You could have a small two winding transformer with two rectifiers and one 7810 regulators for VN10 and one 7805 5V, or some more sofisticated regulator for 5V. The VN10 voltage does not need a sofisticated regulator.

Or you could have two positive high voltage regulators in a similar way.

[andrewbee]

Hello Jan,

Are you going to post a suggested Power Supply schematic for the Truepath or is the suggested power supply included in the kit documentation?
I want to see what is involved before I purchase a kit.

Thanks

Andrew

[chris4916]

Hi,

My feeling is that both +5V and VN10 power supply are quite easy to build.

One debate could be to go for either CRC+LM317 or cascaded LM317s for +5V. From my point of view, designing cascaded LM317s is easier (plus smaller PCB) but to be honest, I don't have the right skill level to understand the potential pitfalls of such design ;) I assume that correct decoupling (10uF + 100nF) at each stage will do the job.

For VN10, this could be done directly with 7810 from VNN or, as explaine dby Jan, using another transformer.

The use of one unique "two windings" transformer is interesting.

In case of new transformer for VN10 (or use of second winding) - compared to VN10 from VNN - is there any potential issue with phase when connecting ground from VN10 supply to VNN ?

Did you had a look at this link ?
http://www.acoustica.org.uk/t/3pin_reg_notes1.html

Christian

[andrewbee]

hi Christian,

nice link, it appears I have yet to implement the 317 / 337 properly!
I saw Jan's response and think I understand what he is saying but as the expression goes "a picture is worth a thousand words"
It is much easier for me to see a picture, that way there is no misunderstanding. I believe a complete power supply schematic would be very helpful to builders.

Andrew

[chris4916]

I'll try to draw it.
Anyway, I cannot escape as I need at least one for me now (since I've purchased a couple of Truepath board) ;)

Christian