DC boost converter max power ?

[bianchi77]

Re: DC boost converter max power ?

Which calculator ? What value did you put ?
I got stable 223V on RL = 7K after I put 2 10 ohm 10W resistors on 5V rail...

[bianchi77]

Re: DC boost converter max power ?

I prefer playing with 555 now another chip will be done later if I have something done with it, I don't want to jump from one to the other and I can't finish both as expected,
making the issue more complicated with two chips to handle..
After I test with good inductor and get 10W 555 I'll move one to other chip either from UCP,MC or MAX everything is good for anyway...

[bianchi77]

Re: DC boost converter max power ?

There are only two explanations for that.

1) The mail in Australia is using actual snails for delivery - highly unlikely

OR

2) The location in your profile is... incorrect (i was tempted to say BS at first).

I don't want to think of a third possibility. Or actually, the "nicer" third possibility would be that you didn't even READ what i wrote in that post.

I'm quite sure you didn't even click on that first result - the seller seems to be based in Croydon, Victoria.

Are you trying to tell me a small envelope with 10 chips takes a whole friggin month to travel from Victoria to Western Australia? Or you really can't spare 5-6$?

did you use that chip for 240V 10W yourself ?

[Khron]

Re: DC boost converter max power ?

Personally, no, but with an external NPN / MOSFET, you should be able to achieve that quite easily.

That is, IF you could be bothered to even look into it...

But hey, if you prefer banging your head against the wall by persisting / insisting on doing this with a 555 instead of a dirt-cheap dedicated (and even "classic") chip... What can i do about it?

I've shown you schematics of finished / tested / proven designs, i've shown you where to get chips locally (so no month-long waits) and cheap (under 1$/pc). What more do you want?!?!?!?

http://schmidt-walter-schaltnetzteil...ww_smps_e.html
http://schmidt-walter-schaltnetzteil...w_hilfe_e.html

[bianchi77]

Re: DC boost converter max power ?

so you think this one is proven work, what's the prove ?
http://translate.google.com/translat...istory_state0=

[Khron]

Re: DC boost converter max power ?

Here it is:

https://translate.googleusercontent....c_FZEw9AqlgNVA

Took a bit of browsing / digging through that same blog, but it's there.

Once again i must ask - what's your excuse?

[bianchi77]

Re: DC boost converter max power ?

ok...here's what I see http://www.nomad.ee/micros/mc34063a/

[Khron]

Re: DC boost converter max power ?

That schematic looks like an inverting converter (to create a negative voltage), by the way. Not to mention, it uses the internal switching transistor as the pass element.

[Khron]

Re: DC boost converter max power ?

https://cdn.badcaps-static.com/pdfs/...dd45f9e3e4.pdf

Boost converter equations start on page 9. As per my earlier recommendations, plug the formulas into an Excel spreadsheet, and play with the "free" values.

https://cdn.badcaps-static.com/pdfs/...18f4bb5c06.pdf

Boost converter (step-up converter) description starts on page 8, right column. Includes real example figures / calculations.

[bianchi77]

Re: DC boost converter max power ?

Ok, I'll buy it,
are the components value right ?
from that circuit, I can not see switching transistor or FET ??
http://www.nomad.ee/micros/mc34063a/

[Khron]

Re: DC boost converter max power ?

Are you intentionally ignoring (some of) my messages?

Post #108: https://www.badcaps.net/forum/showpo...&postcount=108

I quote:
"That schematic looks like an inverting converter (to create a negative voltage), by the way. Not to mention, it uses the internal switching transistor as the pass element."

[bianchi77]

Re: DC boost converter max power ?

Ok, thanks, I bought AP3842CP as well...so can I drive only one FET if I need less current ?

[Khron]

Re: DC boost converter max power ?

"Only one", as opposed to what / how many?

[bianchi77]

Re: DC boost converter max power ?

Is that the right value ?
So I don't need extra switching transistor, but this chip will dissipate a lot of heat
http://www.bobtech.ro/tutoriale/comp...ep-up-inverter

[Khron]

Re: DC boost converter max power ?

I see you insist on doing things your own way, and ignoring information others provide you.

I guess you didn't even check the links in post #104.

http://schmidt-walter-schaltnetzteil...w_hilfe_e.html

Scroll down to the graphs. If your converter goes into discontinuous mode, you'll have the entire output voltage across the internal transistor of the MC34063.

https://cdn.badcaps-static.com/pdfs/...18f4bb5c06.pdf

Scroll down to page 9, to the graphs, and look at the first one. See where the top of the waveform is? I read there "Vout + Vf", ie. output voltage plus forward-bias voltage drop of the diode.

https://cdn.badcaps-static.com/pdfs/...88bb560e37.pdf

Let's go to page 2 of the datasheet. The 5th row says "Switch Collector to Emitter Voltage Vce(switch) 40 Vdc"

You're trying to get over 200v on the output. What do you think will happen? That is, assuming the chip doesn't burn up from the power dissipation alone, before that.

[bianchi77]

Re: DC boost converter max power ?

how can I get 240V then post 105 ? I saw on ST datasheet but there's no value mention on it

[Khron]

Re: DC boost converter max power ?

Saw what on the ST datasheet?

You're not a native Australian, are you? I'm only asking because it "feels" like english isn't your first language.

If you really must ask how to get 240v at the output of the circuit from the link in post #105, that quite clearly indicates you haven't yet understood how feedback works.

http://www.electronics-tutorials.ws/...omparator.html

You really haven't even read through the whole step-up converter design in the application note i linked in post #115, that's quite obvious too.

https://cdn.badcaps-static.com/pdfs/...18f4bb5c06.pdf - page 12, right column, section 9.

[bianchi77]

Re: DC boost converter max power ?

Yes I don't understand MC34063 works, it's maximum 40V output and my target is 240V
ST datasheet page 17


and it's using transformer, making it more complicated, I want to make similar with 555...

I haven't read that yet...too many informations and making the whole point complicated...
I want to make something simple..

https://cdn.badcaps-static.com/pdfs/...18f4bb5c06.pdf - page 12, right column, section 9.
9. The nominal output voltage is programmed by the
R1, R2 divider.
Vout 1.25
1
R2
R1
A standard 5% tolerance, 2.2 k resistor was selected
for R1 so that the divider current is about 500 mA.
R1
1.25
50010–6
2500 , use2.2k
R2 R1
Vout
Then 1.25 1
2200
28
1.251
47, 080 , use47k

[bianchi77]

Re: DC boost converter max power ?

You're not a native Australian, are you? I'm only asking because it "feels" like english isn't your first language.

Why are you asking ?

[Khron]

Re: DC boost converter max power ?

Page 17 in the ST datasheet shows what's called a "flyback converter" and it indeed uses a transformer (or, technically, a coupled inductor).

"too many informations and making the whole point complicated..."

So, you DON'T want EVERY step that's needed to create and calculate the circuit you need, shown and explained to you. But you "want to make something simple", by magic? Just wishing it into reality? Or do you expect any of us to present you with a ready-made circuit?

Or.. you're really too lazy to even look into / use ONE simple equation, to figure out two resistor values? Seriously?..