PIEZO Transformers

[TheDoc]

Hi,

Anyone had any experience with Piezo transformers.. ?
I'm looking for a very efficient way to generate 2000 Volts @ 50uA from a
+5V source

TIA

 

[Joerg]

Anyone had any experience with Piezo transformers.. ?
I'm looking for a very efficient way to generate 2000 Volts @ 50uA from a
+5V source

No "real" transformer in the cards?

Regards, Joerg

http://www.analogconsultants.com

 

[TheDoc]

"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:uMzHe.9126$_%4.907@newssvr14.news.prodigy.com...

Anyone had any experience with Piezo transformers.. ?
I'm looking for a very efficient way to generate 2000 Volts @ 50uA from
a
+5V source

No "real" transformer in the cards?

Regards, Joerg

http://www.analogconsultants.com

No sure I understand your reply.?

 

[Joerg]

Hello,

Can you let us know your first name?

No "real" transformer in the cards?

No sure I understand your reply.?

I just wondered why it has to be a piezo transformer. Couldn't you do a

regular flyback converter? That would be the customary (and probably
cheaper) way to generate such voltages.

Regards, Joerg

http://www.analogconsultants.com

 

[TheDoc]

"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:LAPHe.9299$_%4.1551@newssvr14.news.prodigy.com...

Hello,

Can you let us know your first name?

No "real" transformer in the cards?

No sure I understand your reply.?

I just wondered why it has to be a piezo transformer. Couldn't you do a
regular flyback converter? That would be the customary (and probably
cheaper) way to generate such voltages.

Regards, Joerg

http://www.analogconsultants.com

I have a flyback design, but it's not as efficient as I would like, also
I have been reading about Piezo and it would appear to be more
efficient and perhaps occupy a smaller space.. cost is not an issue,
performance is..

 

[Joerg]

Hello,

I have a flyback design, but it's not as efficient as I would like, also
I have been reading about Piezo and it would appear to be more
efficient and perhaps occupy a smaller space.. cost is not an issue,
performance is..

You should be able to reach an efficiency similar to piezo with flyback.
Anyway, if you are looking for piezo transformers try Fuji-Piezo or
other companies like this one:
http://www.konghong.com/cp-ydtc-e.htm

Regards, Joerg

http://www.analogconsultants.com

 

[Ken Smith]

In article <LfVHe.812$C11.621@newssvr21.news.prodigy.com>,
Joerg <notthisjoergsch@removethispacbell.net> wrote:

Hello,

I have a flyback design, but it's not as efficient as I would like, also
I have been reading about Piezo and it would appear to be more
efficient and perhaps occupy a smaller space.. cost is not an issue,
performance is..

You should be able to reach an efficiency similar to piezo with flyback.
Anyway, if you are looking for piezo transformers try Fuji-Piezo or
other companies like this one:
http://www.konghong.com/cp-ydtc-e.htm

Stray capacitance is the killer. During the switch on part of the cycle
you have to charge the capacitance. This usually leads to a large current
spike just at the turn on time. How about giving this a try:

L1 small V1
------+--)))))----+-----
! ! ! --------
--- ! )(
^ D1 ! )(
! ! )(
+---!!------ )(
! C1 ! ---------
) !!-
) !!- Q1
)L2 !!-
! !
GND GND


When Q1 switches on, the L1 slows the increase in current breifly. The
energy that would normally end up in heat ends up in L1. When the stray
capacitance is charged, the Q1 current decreases. At that time, the L1
inductor flysback doubling the voltage at V1. The energy from L1 gets
divided between going into the transformer and being put back onto the
input power line. At the switch off of Q1, all the remaining energy from
L1 gets put back into the power supply.


You may really be better off with a resonant converter. Stray capacitance
matters a lot less in them.
--
--
kensmith@rahul.net forging knowledge

 

[Joerg]

Hallo Ken,

You may really be better off with a resonant converter. Stray capacitance
matters a lot less in them.

Resonant converters are great. But in low power apps like this one I
fared pretty good with regular converters, mostly made from logic and
some discretes and without specialty PWM chips. Efficiencies of 90% were
not a problem but often that is traded off against a somewhat wimpier
FET for cost reasons.

In this case you almost have to do the discrete thing because PWM chips
will typically either gobble up lots of quiescent power or be pretty
expensive and hard to obtain.

Regards, Joerg

http://www.analogconsultants.com

 

[TheDoc]

"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:LfVHe.812$C11.621@newssvr21.news.prodigy.com...

Hello,

I have a flyback design, but it's not as efficient as I would like, also
I have been reading about Piezo and it would appear to be more
efficient and perhaps occupy a smaller space.. cost is not an issue,
performance is..

You should be able to reach an efficiency similar to piezo with flyback.
Anyway, if you are looking for piezo transformers try Fuji-Piezo or
other companies like this one:
http://www.konghong.com/cp-ydtc-e.htm

Regards, Joerg

http://www.analogconsultants.com

Thanks for the link..

BTW: I tried TDK and Murata.. but they are not interested unless you
need to place a $1,000,000 order.... sad same old story..

 

[Ken Smith]

In article <2J9Ie.1136$C11.202@newssvr21.news.prodigy.com>,
Joerg <notthisjoergsch@removethispacbell.net> wrote:
[...]

In this case you almost have to do the discrete thing because PWM chips
will typically either gobble up lots of quiescent power or be pretty
expensive and hard to obtain.

You forgot to say "or both".

I'd also include and can be buggy.

At low frequencies, the LM339 makes a faily nice PWM controller, if you
don't want a constant frequency with load.


--
--
kensmith@rahul.net forging knowledge

 

[Joerg]

Hello Ken,

In this case you almost have to do the discrete thing because PWM chips
will typically either gobble up lots of quiescent power or be pretty
expensive and hard to obtain.

You forgot to say "or both".

I'd also include and can be buggy.

Oh yes.

At low frequencies, the LM339 makes a faily nice PWM controller, if you
don't want a constant frequency with load.

Usually I am even cheaper than that. I might toss the converter a few
logic gates. If I feel generous maybe even a flip-flop.

Regards, Joerg

http://www.analogconsultants.com

 

[Joerg]

Hello Doc,

BTW: I tried TDK and Murata.. but they are not interested unless you
need to place a $1,000,000 order.... sad same old story..

With piezo transformers you will most likely not find any low volume
supplier. Unless there is a standard part that somehow ended up in the
low volume distributor chains. Unlikely though.

We usually had the same situation with PZT5-H. Since we didn't need
several containers full of it the solution boiled down to a hefty NRE
charge.

If this was a low volume application and I was the guy tasked to design
it I'd focus on the usual magnetics.

Regards, Joerg

http://www.analogconsultants.com

 

[Chris Jones]

TheDoc wrote:

"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:LfVHe.812$C11.621@newssvr21.news.prodigy.com...
Hello,

I have a flyback design, but it's not as efficient as I would like,
also I have been reading about Piezo and it would appear to be more
efficient and perhaps occupy a smaller space.. cost is not an issue,
performance is..

You should be able to reach an efficiency similar to piezo with flyback.
Anyway, if you are looking for piezo transformers try Fuji-Piezo or
other companies like this one:
http://www.konghong.com/cp-ydtc-e.htm

Regards, Joerg

http://www.analogconsultants.com

Thanks for the link..

BTW: I tried TDK and Murata.. but they are not interested unless you
need to place a $1,000,000 order.... sad same old story..

There is a shop on ebay called steminc selling piezo transformers and other
piezo stuff. I have never dealt with them since it says they only ship to
the US and I am not there.

Chris

 

[TheDoc]

"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
newsNvIe.1776$fJ1.590@newssvr13.news.prodigy.com...

Hello Doc,

BTW: I tried TDK and Murata.. but they are not interested unless you
need to place a $1,000,000 order.... sad same old story..

With piezo transformers you will most likely not find any low volume
supplier. Unless there is a standard part that somehow ended up in the
low volume distributor chains. Unlikely though.

We usually had the same situation with PZT5-H. Since we didn't need
several containers full of it the solution boiled down to a hefty NRE
charge.

If this was a low volume application and I was the guy tasked to design
it I'd focus on the usual magnetics.

Regards, Joerg

http://www.analogconsultants.com

You are probably right.... Piezo looked like an interesting
solution.... I need to take a fresh look at the existing design..


thanks
..

 

[Joerg]

Hello Doc,

You are probably right.... Piezo looked like an interesting
solution.... I need to take a fresh look at the existing design..

There is a lot of information about flyback and other converters in the
app notes in the old Unitrode data book. Now most are available via the
TI web site since they bought them.

Regards, Joerg

http://www.analogconsultants.com

 

[Ken Smith]

In article <qJvIe.9932$_%4.2775@newssvr14.news.prodigy.com>,
Joerg <notthisjoergsch@removethispacbell.net> wrote:
[... me ...]

At low frequencies, the LM339 makes a faily nice PWM controller, if you
don't want a constant frequency with load.

Usually I am even cheaper than that. I might toss the converter a few
logic gates. If I feel generous maybe even a flip-flop.

Last time I checked the LM339 was about as cheap as a logic gate package
and cheaper than two.

Its usually the inductive elements that sets the price of the whole thing.

--
--
kensmith@rahul.net forging knowledge

 

[doug dwyer]

I have found Morgan Ceramics in the UK helpful for samples/small
quantities
In message <oNvIe.1776$fJ1.590@newssvr13.news.prodigy.com>, Joerg
<notthisjoergsch@removethispacbell.net> writes

Hello Doc,

BTW: I tried TDK and Murata.. but they are not interested unless you
need to place a $1,000,000 order.... sad same old story..

With piezo transformers you will most likely not find any low volume
supplier. Unless there is a standard part that somehow ended up in the
low volume distributor chains. Unlikely though.

We usually had the same situation with PZT5-H. Since we didn't need
several containers full of it the solution boiled down to a hefty NRE
charge.

If this was a low volume application and I was the guy tasked to design
it I'd focus on the usual magnetics.

Regards, Joerg

http://www.analogconsultants.com

--
dd

 

[Joerg]

Hello Ken,

At low frequencies, the LM339 makes a faily nice PWM controller, if you
don't want a constant frequency with load.

Usually I am even cheaper than that. I might toss the converter a few
logic gates. If I feel generous maybe even a flip-flop.

Last time I checked the LM339 was about as cheap as a logic gate package
and cheaper than two.

Yes, you can have them for about a dime at large qty TSSOP. But the
concern is quiescent current. They draw about a milliamp whereas CMOS
logic goes to zilch when you starve the converter under light or no
load. Cost: If you use Schmitts you usually get a six-pack for less than
10c and only need two or three of them for the converter. The remainder
is "for rent".

Its usually the inductive elements that sets the price of the whole thing.

That's what I thought, too. Until I had to devise a custom inductor for

a switcher in the early 90's and saw a quote on it from Taiwan. Less
than a catalog inductor costs over here.

The usual trick is to find an inductor that is mass produced for some
telco or other consumer app and try to design the switcher around that.
Kind of an odd design flow but if cost is paramount it's the only way.

Regards, Joerg

http://www.analogconsultants.com

 

[Ken Smith]

In article <ma5Je.3071$fJ1.1361@newssvr13.news.prodigy.com>,
Joerg <notthisjoergsch@removethispacbell.net> wrote:

Hello Ken,

[... LM339 ...]
Yes, you can have them for about a dime at large qty TSSOP. But the
concern is quiescent current.

I wasn't thinking of that. Most of my stuff draws way-way more than 1mA
so the chips current really doesn't matter much.

BTW: You can also make a booster with an LM555. If you hook a zener onto
pin-5, you can do it with just the 555 and a transistor no added op-amps
needed. As far as idle power goes, its worse than the LM339.

Its usually the inductive elements that sets the price of the whole thing.
[...]
The usual trick is to find an inductor that is mass produced for some
telco or other consumer app and try to design the switcher around that.
Kind of an odd design flow but if cost is paramount it's the only way.

Don't tell my boss I said this "cost is no object".

Priorities:

1A - will it still be working in 20 years time
1B - will it out perform the other guys
2 - can production actually build them on demand
3 - will we still be able to make one in 10 years time
4 - cost

--
--
kensmith@rahul.net forging knowledge

 

[Joerg]

Hello Ken,

I wasn't thinking of that. Most of my stuff draws way-way more than 1mA
so the chips current really doesn't matter much.

It wouldn't be a concern if it never has to idle. In my case some of the
stuff I design does not have a power switch so things have to drop to a
few uA when not in use. That rules out most classic circuitry.

BTW: You can also make a booster with an LM555. If you hook a zener onto
pin-5, you can do it with just the 555 and a transistor no added op-amps
needed. As far as idle power goes, its worse than the LM339.

So far I have never used a 555. Never really seen an advantage in doing
that since a Hex Schmitt or something like that can do it for less.

Don't tell my boss I said this "cost is no object".

I won't ;-)

Sure he doesn't read usenet? Many of these threads are ported onto sites
on the web. Once I searched up and down the web because I couldn't get
an answer here in the group. The only thing I found was umpteen web
copies of my own post.

Priorities:

1A - will it still be working in 20 years time
1B - will it out perform the other guys
2 - can production actually build them on demand
3 - will we still be able to make one in 10 years time
4 - cost

That all calls for a solution that can live with jelly bean parts. More

than a decade ago a slick sales guy tried to convince me to use "modern
logic". After I balked at the cost he said that my CD4000 logic is going
to be dead in just a few years anyway. I am still designing in CD4000
and the mfgs even ported most of it to newer and smaller TSSOP packages.
They wouldn't ever do this in a situation of declining sales. So, I
guess that sales guys was very wrong.

Regards, Joerg

http://www.analogconsultants.com