Need the topology for a current to current SMPS, not voltage tovoltage SMPS

[John S]

The problem is to figure out what your true calling is. Some people
realize that late in life. For example, a top chemical scientist in our
area who some day when he was well in his 50's quit his well-paying job
at Monsanto and started a winery. He said he'd found his true calling.
Or a sccessful surgeon who, late in his 50's, became a pilot (after an
expensive trek through commercial pilot flight schooling) and hired on
with an airline. His income probably went down by 10-15dB but he was happy.

Of course, Joerg. Not everyone has a calling at birth, graduation, or
any other special time in his life. However, when it comes, it is very
hard to resist. If you are enjoying your calling, how much happier can
you be? (Let's not get into salary)

 

[John S]

I'm confused. Why would anyone want to do anything but design
electronics?

It is unimaginable. It has been my calling since 1951. It will never let go.

 

[Jasen Betts]

I don't understand how you can get more current out of the inductor than
it had when the switch opened.

You can't, that's why decreasing the on-time increses the current.

That capacitor on the left that looks like it's doing nothing
is actually essential, you turn on the switch briefly and
the capacitor supplies the bulk of the current to wind the inductor up.

if you want to simulate this arrange the simulation to start with the
switch closed.

 

[Joerg]

I'm confused. Why would anyone want to do anything but design
electronics?

<raises hand>

I'd like to get into beer brewing some day. When I did that last time as
a student in Germany I almost had more fun that when designing
electronics (which I did a lot while studying for my masters). Nowadays,
after designing the umpteenth switch mode converter that can get a bit
old. It's only fun if there is something in the mix where people have
said "it can't be done". That's when my fun level meter goes to 120%.

 

[[email protected]]

<raises hand>

I'd like to get into beer brewing some day. When I did that last time as
a student in Germany I almost had more fun that when designing
electronics (which I did a lot while studying for my masters). Nowadays,
after designing the umpteenth switch mode converter that can get a bit
old. It's only fun if there is something in the mix where people have
said "it can't be done". That's when my fun level meter goes to 120%.

I can imagine that brewing the billionth barrel of beer wouldn't be as
much fun as the first, either. Perhaps you have the hobby and
business right, after all.

 

[John S]

You can't, that's why decreasing the on-time increses the current.

That capacitor on the left that looks like it's doing nothing
is actually essential, you turn on the switch briefly and
the capacitor supplies the bulk of the current to wind the inductor up.

if you want to simulate this arrange the simulation to start with the
switch closed.

Do you have a simulation you can share with us?

 

[Joerg]

I can imagine that brewing the billionth barrel of beer wouldn't be as
much fun as the first, either. Perhaps you have the hobby and
business right, after all.

Hobby brewers and even the small commercial micro brewers don't run a
bland same old same old scheme. They come up with variants and try out
new recipes all the time. Like the chef in a fancy restaurant that is
not tied to a chain, I was told by several that such a job never gets
old. It's just hard not to gain weight (same with brewing).

 

[[email protected]]

Hobby brewers and even the small commercial micro brewers don't run a
bland same old same old scheme. They come up with variants and try out
new recipes all the time. Like the chef in a fancy restaurant that is
not tied to a chain, I was told by several that such a job never gets
old. It's just hard not to gain weight (same with brewing).

I think the same can be said for design engineers. I rarely design
complicated systems with unit logic anymore. ;-)

 

[Joerg]

I think the same can be said for design engineers. I rarely design
complicated systems with unit logic anymore. ;-)

That's because you work on gear that isn't really mass production
oriented. I work for numerous clients who are all in very different
markets. This keeps our jobs interesting. But after talking to
automotive designers I'd be bored stiff if I had to do their job for
more than a year.

 

[[email protected]]

That's because you work on gear that isn't really mass production
oriented.

Really? A couple of million units a year isn't mass production?

I work for numerous clients who are all in very different
markets. This keeps our jobs interesting. But after talking to
automotive designers I'd be bored stiff if I had to do their job for
more than a year.

Perhaps but I think you have a pretty small view of that world.
However, I've been involved in many different markets at many
different levels, over the years. It's a *big* field. There is no
reason to do the same thing for forty years. Impossible, actually.

 

[John S]

<raises hand>

I'd like to get into beer brewing some day. When I did that last time as
a student in Germany I almost had more fun that when designing
electronics (which I did a lot while studying for my masters). Nowadays,
after designing the umpteenth switch mode converter that can get a bit
old. It's only fun if there is something in the mix where people have
said "it can't be done". That's when my fun level meter goes to 120%.

I dunno, Joerg. Isn't brewing sort of like watching paint dry? My desire
is that you poke something and can get an almost immediate response. I
obviously don't have your patience. Which is also my shortcoming.

 

[Joerg]

[email protected] wrote:

[...]

That's because you work on gear that isn't really mass production
oriented. I work for numerous clients who are all in very different
markets. This keeps our jobs interesting. But after talking to
automotive designers I'd be bored stiff if I had to do their job for
more than a year.

Joerg, You're always pinching pennies in your designs.

In automotive designs you're pinching _tenths_ of cents... which can
really tax your imagination on how to get a job done.

I've done that kind of job as well. Where we had to ease resistor
tolerance to 10% and for some to 20% (non-trimmed). Can be fun but it
does get old.

 

[Joerg]

Really? A couple of million units a year isn't mass production?

Oops, I probably mixed you up with someone else. I thought it was stage
electronics for rock bands and stuff.

Perhaps but I think you have a pretty small view of that world.

Nope. Medical devices for hospitals, low cost medical devices for
consumers (over-the-counter), aircraft electronics, spacecraft stuff,
chemical pump controllers, power generation, oil/gas exploration
electronics, NDT, commercial automotive (trucks), and so on.

However, I've been involved in many different markets at many
different levels, over the years. It's a *big* field. There is no
reason to do the same thing for forty years. Impossible, actually.

Not impossible. I met people who worked in one particular field such as
engine control units for over 30 years. I'd have a hard time doing that,
after being a consultant for this long.

 

[Joerg]

On 10/19/2013 6:36 PM, Joerg wrote:
[...]

I'd like to get into beer brewing some day. When I did that last time as
a student in Germany I almost had more fun that when designing
electronics (which I did a lot while studying for my masters). Nowadays,
after designing the umpteenth switch mode converter that can get a bit
old. It's only fun if there is something in the mix where people have
said "it can't be done". That's when my fun level meter goes to 120%.

I dunno, Joerg. Isn't brewing sort of like watching paint dry? My desire
is that you poke something and can get an almost immediate response. I
obviously don't have your patience. Which is also my shortcoming.

For brewing one must have patience. Occasionally stuff has to just sit
there for a couple of weeks, your gear must be squeaky clean and
sterilized, you can't cut corners. Else you might ruin a day's worth of
work in minutes. When we brewed beer back in my university days we were
rather busy for a whole day and then again when it was time to bottle.
But we made sure there was a crate left over from last time and that
none of us had to drive that evening.

 

[John S]

On 10/19/2013 6:36 PM, Joerg wrote:
[...]

I'd like to get into beer brewing some day. When I did that last time as
a student in Germany I almost had more fun that when designing
electronics (which I did a lot while studying for my masters). Nowadays,
after designing the umpteenth switch mode converter that can get a bit
old. It's only fun if there is something in the mix where people have
said "it can't be done". That's when my fun level meter goes to 120%.

I dunno, Joerg. Isn't brewing sort of like watching paint dry? My desire
is that you poke something and can get an almost immediate response. I
obviously don't have your patience. Which is also my shortcoming.

For brewing one must have patience. Occasionally stuff has to just sit
there for a couple of weeks, your gear must be squeaky clean and
sterilized, you can't cut corners. Else you might ruin a day's worth of
work in minutes. When we brewed beer back in my university days we were
rather busy for a whole day and then again when it was time to bottle.
But we made sure there was a crate left over from last time and that
none of us had to drive that evening.

Yeah, I know. But, I can't sit still for a day let alone a couple of
weeks. I would die from boredom. I'm just not up to it. Others see it as
a challenge. It is why we are so diverse. Thanks, Momma (Nature), for that.

 

[[email protected]]

Oops, I probably mixed you up with someone else. I thought it was stage
electronics for rock bands and stuff.

That was the last job. ;-) I've done a few career changes in the
last 10 years. Before that, one employer, oneish (perhaps two)
markets, but very different jobs every five to eight years.

Nope. Medical devices for hospitals, low cost medical devices for
consumers (over-the-counter), aircraft electronics, spacecraft stuff,
chemical pump controllers, power generation, oil/gas exploration
electronics, NDT, commercial automotive (trucks), and so on.

You have a very small view of the automotive market. That is for
sure.

Not impossible. I met people who worked in one particular field such as
engine control units for over 30 years. I'd have a hard time doing that,
after being a consultant for this long.

ECUs have changed more than a little in 30 years. They will change
drastically, again, over the next ten. Hell, you'd have a hard time
showing up for work with your pants on, after being a consultant that
long. ;-)

 

[George Herold]

Do you have a simulation you can share with us?

I was going to say it looked a bit like what I drew for a current boost. But I had the diode and inductor switched around.

+----+--FET--+-LLL--+
| | | |
^ C _ R
I C ^ R
| | | |
+----+-------+------+

Something like that,

George H.

 

[Jasen Betts]

Do you have a simulation you can share with us?

lt-spice crashed before I coiuld save it.

when I had it start with the switch open it'd put 15GV on the
capacitor

 

[John S]

I was going to say it looked a bit like what I drew for a current boost. But I had the diode and inductor switched around.

+----+--FET--+-LLL--+
| | | |
^ C _ R
I C ^ R
| | | |
+----+-------+------+

Something like that,

George H.

Thanks, George. It believe this is a standard buck switcher without the
output filter capacitor.

 

[John S]

lt-spice crashed before I coiuld save it.

when I had it start with the switch open it'd put 15GV on the
capacitor

No matter what you do, you will never get more current out of the
circuit than the amount of peak current in the inductor at the moment
your FET switch opens.