Any beefy coil driver chips?

[Joerg]

Jamie wrote:

[...]

Back in the hay days, we used to have dual coil solenoids, one as the
start coil that was in series with a contact on the relay.. It simply
open when pulled in, allowing only the low current coil to stay
energized. But I'm sure this doesn't fit your application.

Not enough room. If that was possible they wouldn't need me

 

[Joerg]

How "fast" a ramp-down?

Around 1/10th of a msec. Twice that would probably be accepted but not a
lot more.

Post your design, when finished. Then I'll post the easy way ;-)

Mine will be the cool way, cool as in no blister when touching

 

[Jim Thompson]

I respectfully disagree

How do you want to hold a coil at 25% current or so without PWM _and_
while dissipating next to nothing?



Not at liberty to do that, I'm afraid.

So why do you ask for help ?

I think you're turning left ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine Sometimes I even put it in the food

 

[Joerg]

Joerg wrote:



It is very handy as the CPU takes care of the soft startup/shutdown,
under/over voltage and the other issues, and you can implement whatever
control algorithm you like.

Most modern PWM chips can do all that. But you are at the mercy of one
manufacturer because other than for the MC34063, the TL494 and some
older Unitrode chips there ain't no 2nd source.

It is possible. The PWM runs at MHz speed, with the resolution imporoved
by the pre-computed noise shaping pattern. The control loop runs much
slower, at 100kHz or so.

The control loop is ok but: Nearly all modern designs use current mode
control and that is a major challenge with a uC. There often is only
25nsec of time between warm & fuzzy and ... phoomp ... *BANG*

Possibly doable with a PSoC but I haven't had time to try that yet.

 

[Jim Thompson]

[snip]

Ok, a bit different here. I must hold it at peak for a while and then at
the hold value for another while (this 2nd hold phase being from very
brief to essentially hours). I am all for analog but you can't do that
analog or you could fry an egg on there after some time.

That's why I bristled at your notion that PWM is for sissies ;-)

It is... at least the way you're approaching the problem.

I respectfully disagree

How do you want to hold a coil at 25% current or so without PWM _and_
while dissipating next to nothing?

Post your design, when finished. Then I'll post the easy way ;-)

Not at liberty to do that, I'm afraid.

I _promise_ not to laugh ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine Sometimes I even put it in the food

 

[Joerg]

So why do you ask for help ?

I was simply asking if anyone knew a nice chip that I might have overlooked.

I think you're turning left ;-)

Me? Never. You should know me better by now

 

[Joerg]

[snip]
Ok, a bit different here. I must hold it at peak for a while and then at
the hold value for another while (this 2nd hold phase being from very
brief to essentially hours). I am all for analog but you can't do that
analog or you could fry an egg on there after some time.

That's why I bristled at your notion that PWM is for sissies ;-)
It is... at least the way you're approaching the problem.

I respectfully disagree

How do you want to hold a coil at 25% current or so without PWM _and_
while dissipating next to nothing?

Post your design, when finished. Then I'll post the easy way ;-)

Not at liberty to do that, I'm afraid.

I _promise_ not to laugh ;-)

In the 90's a client gave me a "Notis to Contrackers: Contracker is
s'posed to be kerrectin' what's drawed wrong and not make fun of da
enginear, or laugh or smile ..." or something like that. I don't have it
anymore and a web search went empty. Anyone know if it's posted anywhere?

 

[Jim Thompson]

Jim Thompson wrote:
[snip]
Ok, a bit different here. I must hold it at peak for a while and then at
the hold value for another while (this 2nd hold phase being from very
brief to essentially hours). I am all for analog but you can't do that
analog or you could fry an egg on there after some time.

That's why I bristled at your notion that PWM is for sissies ;-)
It is... at least the way you're approaching the problem.

I respectfully disagree

How do you want to hold a coil at 25% current or so without PWM _and_
while dissipating next to nothing?


Post your design, when finished. Then I'll post the easy way ;-)

Not at liberty to do that, I'm afraid.

I _promise_ not to laugh ;-)

In the 90's a client gave me a "Notis to Contrackers: Contracker is
s'posed to be kerrectin' what's drawed wrong and not make fun of da
enginear, or laugh or smile ..." or something like that. I don't have it
anymore and a web search went empty. Anyone know if it's posted anywhere?

Sounds like something I want for my wall art ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine Sometimes I even put it in the food

 

[Nico Coesel]

That's the method I'd usually take. And might take on this one as well,
but hard to fit onto the real estate.



Except I have the problem that there is no supply rail. So it would need
to go from zero to "ready for program execution in less than 100usec

Why is that timing so important? Most mechanical stuff is in the msec
range anyway. If its driven by a relay contact timing can't be very
tight.

(considering that the program start itself will require up to 50usec).

I might look into FPGA.

A GAL16V8 or similar? I still think an NE555 solution is the easiest.

 

[Joerg]

Jim Thompson wrote:
[snip]
Ok, a bit different here. I must hold it at peak for a while and then at
the hold value for another while (this 2nd hold phase being from very
brief to essentially hours). I am all for analog but you can't do that
analog or you could fry an egg on there after some time.

That's why I bristled at your notion that PWM is for sissies ;-)
It is... at least the way you're approaching the problem.

I respectfully disagree

How do you want to hold a coil at 25% current or so without PWM _and_
while dissipating next to nothing?


Post your design, when finished. Then I'll post the easy way ;-)

Not at liberty to do that, I'm afraid.
I _promise_ not to laugh ;-)

In the 90's a client gave me a "Notis to Contrackers: Contracker is
s'posed to be kerrectin' what's drawed wrong and not make fun of da
enginear, or laugh or smile ..." or something like that. I don't have it
anymore and a web search went empty. Anyone know if it's posted anywhere?

Sounds like something I want for my wall art ;-)

I think there was more such fun making in electronics in the 90's than
today. Yesterday I needed to look up something on my pulse pattern
generator. Grabbed the service manual, found a cartoon page. This thing
was engineered in Sweden where I'd never have expected that.

 

[Joerg]

Why is that timing so important? Most mechanical stuff is in the msec
range anyway. If its driven by a relay contact timing can't be very
tight.

This one is tight, got to go by the specs given me ;-)

A GAL16V8 or similar? I still think an NE555 solution is the easiest.

Yeah, no gas guzzler devices. A 555 type is nice but there are some buck
and boost chips that have more analog on board and could possibly find
an unorthodox use here.

 

[Jim Thompson]

[snip]

Not at liberty to do that, I'm afraid.
I _promise_ not to laugh ;-)

In the 90's a client gave me a "Notis to Contrackers: Contracker is
s'posed to be kerrectin' what's drawed wrong and not make fun of da
enginear, or laugh or smile ..." or something like that. I don't have it
anymore and a web search went empty. Anyone know if it's posted anywhere?

Sounds like something I want for my wall art ;-)

I think there was more such fun making in electronics in the 90's than
today. Yesterday I needed to look up something on my pulse pattern
generator. Grabbed the service manual, found a cartoon page. This thing
was engineered in Sweden where I'd never have expected that.

Reminds me of a WAI (wild-ass-idea) I have ruminating in my head: What
would it take to record say a 500-bit stream of a data pattern on a
CD, then play it back on an ordinary cheapo CD player modified to
simply spit out 5V logic levels? Use: Poor man's BER tester. How
would you do that?

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine Sometimes I even put it in the food

 

[Joerg]

[snip]
Not at liberty to do that, I'm afraid.
I _promise_ not to laugh ;-)

In the 90's a client gave me a "Notis to Contrackers: Contracker is
s'posed to be kerrectin' what's drawed wrong and not make fun of da
enginear, or laugh or smile ..." or something like that. I don't have it
anymore and a web search went empty. Anyone know if it's posted anywhere?
Sounds like something I want for my wall art ;-)

I think there was more such fun making in electronics in the 90's than
today. Yesterday I needed to look up something on my pulse pattern
generator. Grabbed the service manual, found a cartoon page. This thing
was engineered in Sweden where I'd never have expected that.

Reminds me of a WAI (wild-ass-idea) I have ruminating in my head: What
would it take to record say a 500-bit stream of a data pattern on a
CD, then play it back on an ordinary cheapo CD player modified to
simply spit out 5V logic levels? Use: Poor man's BER tester. How
would you do that?

I assume you would have to hang a fast comparator (or maybe a Schmitt is
enough) to the output of its RF amp:

http://bani.anime.net/iec958/q_subcode/block.gif

However, I do not really know what the storage format is, where the
Q-codes are hidden and so on. There should be hack sites for that
though. If it is to be spitting out permanently you'd also have to
either record the whole CD full of repeated sequences or mess with the
miror and tracking circuitry. But then I wouldn't know how to record
because your CD writer won't do that.

Why not just use a fast FPGA?

 

[Jim Thompson]

Jamie wrote:

[...]

Back in the hay days, we used to have dual coil solenoids, one as the
start coil that was in series with a contact on the relay.. It simply
open when pulled in, allowing only the low current coil to stay
energized. But I'm sure this doesn't fit your application.

Not enough room. If that was possible they wouldn't need me

I think I can do it with one NAND schmitt trigger section, 2 Rs, 2 Cs,
driving a mosfet.

John

Show us, John ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine Sometimes I even put it in the food

 

[Joerg]

Jamie wrote:

[...]

Back in the hay days, we used to have dual coil solenoids, one as the
start coil that was in series with a contact on the relay.. It simply
open when pulled in, allowing only the low current coil to stay
energized. But I'm sure this doesn't fit your application.

Not enough room. If that was possible they wouldn't need me

I think I can do it with one NAND schmitt trigger section, 2 Rs, 2 Cs,
driving a mosfet.

Seriously, it ain't quite that easy. Just one of the nastier effects:
Such lines can hang, rattle, sizzle, and then you get serious
undervoltage coming in for a while, FET tries its darndest to hang in
there ... *PHUT* ... red lights flash, sirens wail ...

 

[Charlie E.]

This one is tight, got to go by the specs given me ;-)

You have to be careful on what those specs actually represent...

Back when I was working on the 91 Express lanes, we needed a gantry
above the road to hang all the electronics from. My boss had just
used a swag or height +/- 1" on the allowed vertical movement of the
mount points.

The mechanical guy designing the gantry came back, and said the best
he could do was +/- 3", and would that be ok.

So, he comes to me, as the actual engineeer on the thing, and asks me
if that will work. I take a look at the sensors, do a quick calc, and
say "I could actually handle +/- 6"!"

He says "Never tell the mechanical guy that!"

So, if you ever wonder why they have that monster gantry across the
freeway... ;-)

Anyway, moral of story: Sometimes a spec is actually a SWAG, and has
no real bearing on the actual requirements of the system!

Charlie

 

[Fred Bartoli]

Jim Thompson a écrit :

[snip]
Not at liberty to do that, I'm afraid.
I _promise_ not to laugh ;-)

In the 90's a client gave me a "Notis to Contrackers: Contracker is
s'posed to be kerrectin' what's drawed wrong and not make fun of da
enginear, or laugh or smile ..." or something like that. I don't have it
anymore and a web search went empty. Anyone know if it's posted anywhere?
Sounds like something I want for my wall art ;-)

I think there was more such fun making in electronics in the 90's than
today. Yesterday I needed to look up something on my pulse pattern
generator. Grabbed the service manual, found a cartoon page. This thing
was engineered in Sweden where I'd never have expected that.

Reminds me of a WAI (wild-ass-idea) I have ruminating in my head: What
would it take to record say a 500-bit stream of a data pattern on a
CD, then play it back on an ordinary cheapo CD player modified to
simply spit out 5V logic levels? Use: Poor man's BER tester. How
would you do that?

...Jim Thompson

CPLD

 

[Fred Bartoli]

Joerg a écrit :

I respectfully disagree

How do you want to hold a coil at 25% current or so without PWM _and_
while dissipating next to nothing?

Short it.

 

[Joerg]

Joerg a écrit :

Short it.

and then ... phssst ... *BAM*

 

[Fred Bartoli]

Joerg a écrit :

and then ... phssst ... *BAM*

Then it holds, if you're lucky.

Seriously, with a pair of switches you could do that but I just realized
you want hold from brief to, hum, hours...
You could still make your coil supraconducting

Where's your load (coil) attached?
If it's to the supply line, then you could use the ubiquitous 3842/45
Enough pins to coax it to do what you need and I've used it in nearly
the same app.