Low power PWM controller, possibly the 555 (flame war coming)

[josephkk]

Well that was easy. You really are a terrible troll, you know that? ^^^^ sleazy

Tim

Misspelling notice above^

?-)

 

[Klaus Kragelund]

We use zillions of SMJ-140B. The SHJ series has better insulation, I

think.



http://www.talema.net/en/products/pdf/So Single Trafo Oct-07.pdf



Nice little parts. They might manage 100 mw in flyback mode. We push

watts through them, into isolated DAC channels, with push-pull/forward

drive, a couple of 2N7002's driving a center-tapped primary.

Wow, have been searching for a part with isolated windings, not just center tapped, for weeks. You just made my day

Thanks

Klaus

 

[josephkk]

Our little ISDN transformers, from Talema,

are good for EN60590, whatever that means.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Why do i find this altitude sooo typical of Larkin?

 

[Tim Williams]

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Why do i find this altitude sooo typical of Larkin?

Because he doesn't need standards. Meanwhile, life goes on for those of
us who connect to the AC line, blissfully unaware of his ignorance.

Tim

 

[[email protected]]

You are only supposed to save the test samples (and report?) for 3 years. But good thing to hang on to it.

Regards

Klaus

 

[josephkk]

How about you contribute something to the technical issue here?

PKB

?-)

 

[josephkk]

Do you have a copy of that spec handy?

Not in my personal collection, maybe i have a copy that my PPoE provided.
The two blocks are on the order of $8000 each.

?-)

 

[John Devereux]

And you expect me to have those handy?

Isn't it 60950?

 

[josephkk]

Check my posts. I've been talking about dc/dc converters and ISDN
transformers, while you and your clutch of hens/lurkers/old ladies
have been my-o-my'ing about personalities and whining about spelling
errors and writing ghastly *poetry*

Man up. Wuss down. Do some electronics. This isn't some retirement
home sewing circle.

The problem is that OP told that your posts did not contribute to a
solution. You seem to have forgotten that.

?-/

 

[josephkk]

Keerection i think; $800 each. A simple search will tell.

And you expect me to have those handy?

Since you are manufacturing for world wide distribution, YES!

 

[josephkk]

Isn't it 60950?

Probably, 60590 seems to deal with aromatic hydrocarbons. Ask Larkin, it
is from his post.

?-)

 

[Klaus Kragelund]

The problem is that OP told that your posts did not contribute to a

solution. You seem to have forgotten that.

Well, I am the OP and from my perspective John did contribute a lot, actually the most I think....

SED is filled with people attacking each other, why not just talk electronics and leave the other with you wife or whoever wants to go down that road?

Cheers

Klaus

 

[legg]

Hi

I am working on a small 100mW forward converter and I need a very low power PWM control.

So the 555 comes up, along with some ultra low power opamps. But, isn't there a PWM chips out there with low operating current. Sofar I found the TPS5110 with sub mA current consumption:

http://www.ti.com/lit/ds/symlink/tps5110.pdf

Anyone used one with lower current?

Thanks

Klaus

UCC3805 is a simpler part, possibly with lower part count and
quiescent current. It could also has an output stage that could drive
a transformer directly, at low power.

It has the same low voltage 3-5V operating range as TPS5110. Other
versions are available for 8, 12 and 15V.

http://www.ti.com/lit/ds/symlink/ucc3805.pdf

Otherwise, a couple of nand gates and a bipolar transistor will be
about the most basic, lowest power, hard-switching controller.
Typified by the drawing on page three here:

http://itee.uq.edu.au/~aupec/aupec99/walker299.pdf

You'd modulate it by biasing the bipolar tansistor, directly through a
simple zener or isolated with optocoupler. You might use a transformer
in the feedback, but that's a hard sell at most power levels,
nowadays.

These guys sure get off-topic, fast, don't they.

RL