John Larkin a écrit :

What do you do with your 24V?

Referencing C68 and C73 to GND will couple less 12V noise to the 24V
output. OK there's the filter and zener, but it's easy and you're not
doing kVs.


--
Thanks,
Fred.

On Fri, 30 Mar 2007 09:42:01 -0700, John Larkin
wrote:

OK. How about -5V out of there at the same time ?:-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

On Fri, 30 Mar 2007 10:29:01 -0700, Jim Thompson
wrote:

On Fri, 30 Mar 2007 09:42:01 -0700, John Larkin
wrote:

OK. How about -5V out of there at the same time ?:-)

...Jim Thompson

We designed this board specifically to need no negative supplies, but
I have done this same trick to go negative. You can also turn the
inductor into a transformer, or center-tap it, as needed.

John

On Fri, 30 Mar 2007 19:10:36 +0200, Fred Bartoli
r_AndThisToo wrote:

John Larkin a écrit :

What do you do with your 24V?

It powers some little logic-level shifters, which I posted about a
couple of weeks ago. They take a 3.3 volt FPGA output and shift it up
about 0.8 volts to drive some 5-volt CMOS logic. Without the shift,
the cmos gadgets have asymmetric prop delays and high static power
dissipation. Current required is only about 50 uA per shifter.


Referencing C68 and C73 to GND will couple less 12V noise to the 24V
output. OK there's the filter and zener, but it's easy and you're not
doing kVs.

But we get a free extra 12 volts out of the C-W this way, which we
need for decent zener regulation. If we grounded the low side, we'd
need another multiplier section.

Some switchers will freak without that R99 thing.

John

Jim Thompson wrote:

On Fri, 30 Mar 2007 09:42:01 -0700, John Larkin
wrote:

OK. How about -5V out of there at the same time ?:-)


And 120V for the margarita mixer...

--
SCNR, Joerg

http://www.analogconsultants.com

John Larkin a écrit :
On Fri, 30 Mar 2007 19:10:36 +0200, Fred Bartoli
r_AndThisToo wrote:

John Larkin a écrit :

What do you do with your 24V?

It powers some little logic-level shifters, which I posted about a
couple of weeks ago. They take a 3.3 volt FPGA output and shift it up
about 0.8 volts to drive some 5-volt CMOS logic. Without the shift,
the cmos gadgets have asymmetric prop delays and high static power
dissipation. Current required is only about 50 uA per shifter.


Ahmm, remember. So the bit of extra noise probably matters not.

Referencing C68 and C73 to GND will couple less 12V noise to the 24V
output. OK there's the filter and zener, but it's easy and you're not
doing kVs.

But we get a free extra 12 volts out of the C-W this way, which we
need for decent zener regulation. If we grounded the low side, we'd
need another multiplier section.


Nope. You don't ground the diodes, just the capacitors. Then you obtain
the same output voltage. C68 and C73 are not flying.

Some switchers will freak without that R99 thing.


Sure. Those with CM feedback and those with switch current limit.


--
Thanks,
Fred.

On Fri, 30 Mar 2007 11:20:49 -0700, John Larkin
wrote:

On Fri, 30 Mar 2007 10:29:01 -0700, Jim Thompson
wrote:

On Fri, 30 Mar 2007 09:42:01 -0700, John Larkin
wrote:

OK. How about -5V out of there at the same time ?:-)

...Jim Thompson

We designed this board specifically to need no negative supplies, but
I have done this same trick to go negative. You can also turn the
inductor into a transformer, or center-tap it, as needed.

John

You don't need a transformer...

http://analog-innovations.com/SED/Ol...tiveOutput.pdf

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

On Fri, 30 Mar 2007 13:28:51 -0700, Jim Thompson
wrote:

On Fri, 30 Mar 2007 11:20:49 -0700, John Larkin
wrote:

On Fri, 30 Mar 2007 10:29:01 -0700, Jim Thompson
wrote:

On Fri, 30 Mar 2007 09:42:01 -0700, John Larkin
wrote:

OK. How about -5V out of there at the same time ?:-)

...Jim Thompson

We designed this board specifically to need no negative supplies, but
I have done this same trick to go negative. You can also turn the
inductor into a transformer, or center-tap it, as needed.

John

You don't need a transformer...

http://analog-innovations.com/SED/Ol...tiveOutput.pdf

...Jim Thompson


Terrifying. I may not be able to sleep tonight.

John

On Fri, 30 Mar 2007 18:57:37 -0800, John Larkin
wrote:

On Fri, 30 Mar 2007 13:28:51 -0700, Jim Thompson
wrote:

On Fri, 30 Mar 2007 11:20:49 -0700, John Larkin
wrote:

On Fri, 30 Mar 2007 10:29:01 -0700, Jim Thompson
wrote:

On Fri, 30 Mar 2007 09:42:01 -0700, John Larkin
wrote:

OK. How about -5V out of there at the same time ?:-)

...Jim Thompson

We designed this board specifically to need no negative supplies, but
I have done this same trick to go negative. You can also turn the
inductor into a transformer, or center-tap it, as needed.

John

You don't need a transformer...

http://analog-innovations.com/SED/Ol...tiveOutput.pdf

...Jim Thompson


Terrifying. I may not be able to sleep tonight.

John

Sno-o-o-o-ort! Took youngest granddaughter to her birthday dinner at
"My Big Fat Greek Restaurant". The belly dancers were teaching her
their routines and gave her a set of castanets.

N and I did two bottles of Nousa Boutari... we'll sleep well tonight
;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

Jim Thompson wrote:

On Fri, 30 Mar 2007 18:57:37 -0800, John Larkin
wrote:


On Fri, 30 Mar 2007 13:28:51 -0700, Jim Thompson
wrote:


On Fri, 30 Mar 2007 11:20:49 -0700, John Larkin
wrote:


On Fri, 30 Mar 2007 10:29:01 -0700, Jim Thompson
wrote:


On Fri, 30 Mar 2007 09:42:01 -0700, John Larkin
wrote:

OK. How about -5V out of there at the same time ?:-)

...Jim Thompson

We designed this board specifically to need no negative supplies, but
I have done this same trick to go negative. You can also turn the
inductor into a transformer, or center-tap it, as needed.

John

You don't need a transformer...

http://analog-innovations.com/SED/Ol...tiveOutput.pdf

...Jim Thompson


Terrifying. I may not be able to sleep tonight.

John


Sno-o-o-o-ort! Took youngest granddaughter to her birthday dinner at
"My Big Fat Greek Restaurant". The belly dancers were teaching her
their routines and gave her a set of castanets.


Did you ever see the movie "My Big Fat Greek Wedding"? Absolutely worth it.


N and I did two bottles of Nousa Boutari... we'll sleep well tonight
;-)

...Jim Thompson


--
Regards, Joerg

http://www.analogconsultants.com

"Jim Thompson" wrote
in message
On Fri, 30 Mar 2007 11:20:49 -0700, John Larkin
wrote:

On Fri, 30 Mar 2007 10:29:01 -0700, Jim Thompson
wrote:

On Fri, 30 Mar 2007 09:42:01 -0700, John Larkin
wrote:

OK. How about -5V out of there at the same time ?:-)

...Jim Thompson

We designed this board specifically to need no negative supplies, but
I have done this same trick to go negative. You can also turn the
inductor into a transformer, or center-tap it, as needed.

John

You don't need a transformer...


http://analog-innovations.com/SED/Ol...tiveOutput.pdf

Could you show the waveforms for L1 and D1 current?


--

Reply in group, but if emailing add another
zero, and remove the last word.

On Sat, 31 Mar 2007 19:39:03 GMT, Joerg
wrote:

Jim Thompson wrote:

[snip]

Took youngest granddaughter to her birthday dinner at
"My Big Fat Greek Restaurant". The belly dancers were teaching her
their routines and gave her a set of castanets.


Did you ever see the movie "My Big Fat Greek Wedding"? Absolutely worth it.

[snip]

Of course. You should know me... I have a copy on DVD ;-)

(It's actually about the same cost to buy a DVD of a movie as it is
for two people to go see it in the theater. And you don't have to put
up with the pair of old biddies behind you that want to talk all thru
the movie :-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

On Sat, 31 Mar 2007 19:58:10 GMT, "Tom Del Rosso"
wrote:

"Jim Thompson" wrote
in message
On Fri, 30 Mar 2007 11:20:49 -0700, John Larkin
wrote:

On Fri, 30 Mar 2007 10:29:01 -0700, Jim Thompson
wrote:

On Fri, 30 Mar 2007 09:42:01 -0700, John Larkin
wrote:

OK. How about -5V out of there at the same time ?:-)

...Jim Thompson

We designed this board specifically to need no negative supplies, but
I have done this same trick to go negative. You can also turn the
inductor into a transformer, or center-tap it, as needed.

John

You don't need a transformer...


http://analog-innovations.com/SED/Ol...tiveOutput.pdf

Could you show the waveforms for L1 and D1 current?

I'll see if I can do that. This was actually built before CAD, and is
in several GenRad portable products... so the controller in the
drawing is actually "fudge" for demo purposes ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

Jim Thompson wrote:

On Sat, 31 Mar 2007 19:39:03 GMT, Joerg
wrote:


Jim Thompson wrote:


[snip]

Took youngest granddaughter to her birthday dinner at
"My Big Fat Greek Restaurant". The belly dancers were teaching her
their routines and gave her a set of castanets.


Did you ever see the movie "My Big Fat Greek Wedding"? Absolutely worth it.


[snip]

Of course. You should know me... I have a copy on DVD ;-)


We have it on, gasp, VCR tape :-)

Our neighbors (she Greek Orthodox, he came into the family as a "xeno")
said their wedding was very similar. Yep, including the baptism.


(It's actually about the same cost to buy a DVD of a movie as it is
for two people to go see it in the theater. And you don't have to put
up with the pair of old biddies behind you that want to talk all thru
the movie :-)


We went once here. Digital screen. Too pixely :-(

--
Regards, Joerg

http://www.analogconsultants.com

On Sat, 31 Mar 2007 19:58:10 GMT, "Tom Del Rosso"
wrote:

"Jim Thompson" wrote
in message
On Fri, 30 Mar 2007 11:20:49 -0700, John Larkin
wrote:

On Fri, 30 Mar 2007 10:29:01 -0700, Jim Thompson
wrote:

On Fri, 30 Mar 2007 09:42:01 -0700, John Larkin
wrote:

OK. How about -5V out of there at the same time ?:-)

...Jim Thompson

We designed this board specifically to need no negative supplies, but
I have done this same trick to go negative. You can also turn the
inductor into a transformer, or center-tap it, as needed.

John

You don't need a transformer...


http://analog-innovations.com/SED/Ol...tiveOutput.pdf

Could you show the waveforms for L1 and D1 current?

Now updated on my website.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

"Jim Thompson" wrote
in message
On Sat, 31 Mar 2007 19:58:10 GMT, "Tom Del Rosso"
wrote:

"Jim Thompson" wrote
in message


http://analog-innovations.com/SED/Ol...tiveOutput.pdf

Could you show the waveforms for L1 and D1 current?

Now updated on my website.

Thanks.


--

Reply in group, but if emailing add another
zero, and remove the last word.

"Jim Thompson" wrote in
message ...


OK. How about -5V out of there at the same time ?:-)

...Jim Thompson

We designed this board specifically to need no negative supplies, but
I have done this same trick to go negative. You can also turn the
inductor into a transformer, or center-tap it, as needed.

John

You don't need a transformer...


http://analog-innovations.com/SED/Ol...tiveOutput.pdf

Could you show the waveforms for L1 and D1 current?

Now updated on my website.

...Jim Thompson


We had a buck step-down from 24V to 7V. I took a charge pump off the
connection between the switch and the inductor. Put a bead in series with
the charge pump capacitor so it does not cause a current spike in the
switch. Gave a decent negative bias supply.
Oppie