Review this Goofy 555 Based SMPS Design

[D from BC]

I feel like I'm throwing meat into a shark pool.

Specs:
Output: 1.4A, -84VDC across 60ohm load, ~120Watts
Frequency: 100Khz on the simulator

http://www.members.shaw.ca/chainsaw/SED/556Cuk.pdf

Description:
V1 is a dumbed down model of rectified line voltage.

A high side current sense circuit drives a 555 configured as a
hysteretic comparator. This is a startup circuit and becomes inactive
after output settling.

On the flip side, a low side current sense circuit drives another 555
configured as a hysteretic comparator. This regulates the ripple to
control the output current.

Notes:
Q4 maybe excluded.
V4, V3 and V5 from same cct not shown.
C bypassing on IC's not shown.
M3 and D2 haven't been picked yet.

Toughest 555 timer project I've ever done
I plan on building this cct.

Feedback?


D from BC

 

[D from BC]

I'm making changes frequently and updating the schematic.
Best to check link prior to posting...
D from BC

 

[The Real Andy]

I'm making changes frequently and updating the schematic.
Best to check link prior to posting...
D from BC

You need to spend more time at the pub me thinks.

 

[Genome]

I feel like I'm throwing meat into a shark pool.

D from BC

'Hey bub, How they fishing?'

'Well, I have my bait back.'

'Mind if I move your book?'

'No, go ahead.'

'Hmmm. Warhol. Interesting bait you've got their son. Colors are trying but
the bent clock stuff don't fit.'

'But you can see where.....'

'Mind if I flush?'

'No, go ahead.'

'S'OK, see we take your shit out the cistern and we push this here handle
and,
..........
Hey! My shit disappears.'

'Great, I don't suppose you could...'

'No problem son, I'll just put the seat back down and put your book on it,
page 24? There you go. Cistern's filling up so get ready to cast again'.



DNA

 

[D from BC]

Swimming with Sharks
http://www.imdb.com/title/tt0114594/
Good movie
D from BC

 

[D from BC]

Well...I think this post flopped...
Dunno if I should update the file on my site..
I'm still learning the newsgroup culture...so I probably goofed.

I'll take some guesses as to few responses:

*Posting a URL is a security risk
*Large loopy circuits are too much to review
*Not much interest in smps control
*Poor post title
*Circuit is too amateur
*Nothing new ..seen it before..boring..bunch of app notes stuck
together
*The cct is so complicated..I can figure it out myself
*No specific questions posted
* Everybody is out having fun
D from BC

 

[J.A. Legris]

Well...I think this post flopped...
Dunno if I should update the file on my site..
I'm still learning the newsgroup culture...so I probably goofed.

I'll take some guesses as to few responses:

*Posting a URL is a security risk
*Large loopy circuits are too much to review
*Not much interest in smps control
*Poor post title
*Circuit is too amateur
*Nothing new ..seen it before..boring..bunch of app notes stuck
together
*The cct is so complicated..I can figure it out myself
*No specific questions posted
* Everybody is out having fun
D from BC

You forgot: Really ugly schematic: Poor layout. Lousy contrast.
Uninformative explanation of your logic and thinking.

 

[John Popelish]

Well...I think this post flopped...
Dunno if I should update the file on my site..
I'm still learning the newsgroup culture...so I probably goofed.

I'll take some guesses as to few responses:

*Posting a URL is a security risk
*Large loopy circuits are too much to review
*Not much interest in smps control
*Poor post title
*Circuit is too amateur
*Nothing new ..seen it before..boring..bunch of app notes stuck
together
*The cct is so complicated..I can figure it out myself
*No specific questions posted
* Everybody is out having fun
D from BC

You didn't post the text .asc file that we load directly
into LTspice so we could play with the circuit without
rebuilding it from scratch. Why do you think anyone would
invest a couple hours retracing your modeling effort, just
to see that the circuit operates?

 

[D from BC]

You forgot: Really ugly schematic: Poor layout. Lousy contrast.
Uninformative explanation of your logic and thinking.

Wow! Somebody is actually interested .....
Usually I don't focus on schematic neatness when I'm developing a
cct.. Too many changes happening.. I'll try to straighten it out a bit
for presentation.
Lousy contrast? Switch to black background and have white lines?

I'll write up "why" this and that description on the site..
Will be posting updated URL shortly..
Thanks
D from BC

 

[D from BC]

You didn't post the text .asc file that we load directly
into LTspice so we could play with the circuit without
rebuilding it from scratch. Why do you think anyone would
invest a couple hours retracing your modeling effort, just
to see that the circuit operates?

Ahhh...I guess LTspice graphics are easy to spot...
k....I'll include .asc download link on site..
Also, any missing models.
Will be updating site soon..look for post later on..
Thanks
D from BC

 

[John Popelish]

Ahhh...I guess LTspice graphics are easy to spot...
k....I'll include .asc download link on site..
Also, any missing models.
Will be updating site soon..look for post later on..
Thanks

The main advantages of providing the .asc file is that not
only can we see exactly what you can see about how every
part of your circuit operates (or is modeled to operate) we
can give back working examples of suggestions for changes in
the circuit and even the layout of the schematic that you
can instantly use. You might also join the Yahoo discussion
group dedicated to LTspice, where there is a lot of LTspice
expertise on line.
http://tech.groups.yahoo.com/group/LTspice/

 

[J.A. Legris]

Wow! Somebody is actually interested .....
Usually I don't focus on schematic neatness when I'm developing a
cct.. Too many changes happening.. I'll try to straighten it out a bit
for presentation.
Lousy contrast? Switch to black background and have white lines?

No, it's something else - I'm using a Mac and your PDF comes out as
very pale grey lines on a white background. How are you generating the
schematic?

 

[D from BC]

D from BC wrote: [snip]

Lousy contrast? Switch to black background and have white lines?

No, it's something else - I'm using a Mac and your PDF comes out as
very pale grey lines on a white background. How are you generating the
schematic?

Looks great at my end.. I'm using Adobe to create PDF's.
I'll be uploading JPEG and SwitcherCADIII files sometime today..
D from BC

 

[Genome]

Swimming with Sharks
http://www.imdb.com/title/tt0114594/
Good movie
D from BC

Looks Bad in the sense that Bad does not mean Good. However, not an excuse
to stereotype the atypical. I give you 'Species' and the part when her titty
nipples descend to strangle the 'hero' of the filum.

DNA

 

[D from BC]

The ironic thing is LTSpice SwitchercadIII was probably made to sell
LT controllers but I'm controlling with cheapo 555's instead.

Links:
JPG schematic on:
http://www.members.shaw.ca/chainsaw/SED/Cuk2graphic.jpg

ASC. SwitcherCADIII file on:
http://www.members.shaw.ca/chainsaw/SED/556BasedCuk.asc

PDF on:
http://www.members.shaw.ca/chainsaw/SED/556BasedCuk.pdf
I've included notes for many parts in the PDF. Might be reader version
dependent.

This is my current project that I'm improving and developing.
I'll be interested in any comments, helpful tips and design
improvements.

D from BC

 

[D from BC]

Note:
FMMT596 transistor model info is in the PDF file. Put mouse on note
icon. Cut and paste in SwitcherCADIII standard.bjt file..
Or sub in a good 200V rated xsistor for simulation.

Currently thinking about:
*Selecting a good MOS for M3 and catch diode for D2.
*I don't trust that high side current sensing cct... don't know
why..however looks good on sim.
* Limit bandwidth on U2 op amp?
D from BC

 

[[email protected]]

I feel like I'm throwing meat into a shark pool.

Specs:
Output: 1.4A, -84VDC across 60ohm load, ~120Watts
Frequency: 100Khz on the simulator

http://www.members.shaw.ca/chainsaw/SED/556Cuk.pdf

Description:
V1 is a dumbed down model of rectified line voltage.

A high side current sense circuit drives a 555 configured as a
hysteretic comparator. This is a startup circuit and becomes inactive
after output settling.

On the flip side, a low side current sense circuit drives another 555
configured as a hysteretic comparator. This regulates the ripple to
control the output current.

Notes:
Q4 maybe excluded.
V4, V3 and V5 from same cct not shown.
C bypassing on IC's not shown.
M3 and D2 haven't been picked yet.

Toughest 555 timer project I've ever done
I plan on building this cct.

Feedback?


D from BC

Dell used to roll their own Dc/DC converters with 555s. Well, the key
phrase is "used to."

 

[D from BC]

Dell used to roll their own Dc/DC converters with 555s. Well, the key
phrase is "used to."

Do you know if it was hysteretic or PWM?
I recall seeing an app note one time for turning the 555 into a PWM.
D from BC

 

[Terry Given]

Do you know if it was hysteretic or PWM?
I recall seeing an app note one time for turning the 555 into a PWM.
D from BC

I reverse engineered the smps from a nintendo gameboy once. very cute
buck converter based around an HC14 (which is now my preferred PWM
contoller)

Cheers
Terry

 

[D from BC]

I reverse engineered the smps from a nintendo gameboy once. very cute
buck converter based around an HC14 (which is now my preferred PWM
contoller)

Cheers
Terry

Neat... Guess all to keep costs down..
That's the schmitt inverter...right?

I picked CMOS 555..just because it had that cool parallel processing
look to it.
Also.... it's one of the most ancient IC's and a text book item. Using
it in the cct. has an artistic quality.

D from BC