Re: [time-nuts] Power Supply for AD9852 / AD9854

[Charles Steinmetz]

I mentioned the need to be careful with grounding in mixed-signal 
circuits.  This Analog Devices tutorial is a useful introduction to 
the subject, for those interested:


Grounding Data Converters and Solving the Mystery of  "AGND" and "DGND"



Best regards,

Charles


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Re: [time-nuts] Power Supply for AD9852 / AD9854 correction

[EWKehren]

Correction I did put pin 4 on the same regulator as the PIC. Had to have  
one for the PIC so why not use it. Do not know if it made a difference.
Bert
 
 
In a message dated 3/16/2014 3:58:20 P.M. Eastern Daylight Time,  
ewkeh...@aol.com writes:

You have  not said any thing as to what you expect to get out  of the DDS 
and  how important certain parameters are. We recently did a AD 9913  that 
Tom  
tested extensively  http://www.leapsecond.com/pages/ad9913/ using  a  
single 
supply for the DDS. Some may take exception but it works  for us. The AD  
9913 is nice for time nuts applications since it  allows precise offsets 
and we  
use it in applications like Dual Mixer  and what I call the Austron 
circuit, 
a  circuit that is a single  channel digital mixer with ping pong counter 
and  yields 1 E-12 in 1  second. Not ready for release yet.
AD 9913 board is attached.
Bert  Kehren



In a message dated 3/16/2014 12:36:48 P.M. Eastern  Daylight Time,  
t...@patoka.org writes:



I would assume  that using two voltage regulators will  spread the load. 
For the  AD9851 I'am planning to put external radiator  glued on top of  
it.

Regards,

V.P.

> those parts  dissipate a  fair amount of heat, and they're not very big.
> If you turn  on  everything in the 9854 AND run it at 300 MHz clock, it
> draws  about  1.2 Amps (@ 3.3V) which is about 4 Watts.. that's a lot of
>  power to  get out of the part and keep Tj reasonable. Board layout  to
> get the  heat out is very important.  If they get too  hot, they start
> to  act flaky.  You get extra spurs and more  importantly, they don't
>  respond to the programming properly  (e.g. you send the serial stream
>  to program frequency X, and  instead it programs some different
>  frequency).
> 
>  
> "The heat sink of the AD9854ASVZ 80-lead  TQFP package  must
> be soldered to the PCB. "
> 
> "Adequate   dissipation of heat from the AD9854 relies on all
> power and  ground  pins of the device being soldered directly to
> a copper  plane on a PCB.  In addition, the thermally enhanced
> package of  the AD9854ASVZ has an  exposed paddle on the
> bottom of the  package that must be soldered to a  large copper
> plane, which,  for convenience, can be the ground  plane."
--   
WBW,

V.P.
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[time-nuts] Power Supply for AD9852 / AD9854

[EWKehren]

You have not said any thing as to what you expect to get out  of the DDS 
and how important certain parameters are. We recently did a AD 9913  that Tom 
tested extensively  http://www.leapsecond.com/pages/ad9913/ using a  single 
supply for the DDS. Some may take exception but it works for us. The AD  
9913 is nice for time nuts applications since it allows precise offsets and we  
use it in applications like Dual Mixer and what I call the Austron circuit, 
a  circuit that is a single channel digital mixer with ping pong counter 
and  yields 1 E-12 in 1 second. Not ready for release yet.
AD 9913 board is attached.
Bert Kehren



In a message dated 3/16/2014 12:36:48 P.M. Eastern Daylight Time,  
t...@patoka.org writes:



I would assume that using two voltage regulators will  spread the load. 
For the AD9851 I'am planning to put external radiator  glued on top of 
it.

Regards,

V.P.

> those parts  dissipate a fair amount of heat, and they're not very big.
> If you turn  on everything in the 9854 AND run it at 300 MHz clock, it
> draws about  1.2 Amps (@ 3.3V) which is about 4 Watts.. that's a lot of
> power to  get out of the part and keep Tj reasonable. Board layout to
> get the  heat out is very important.  If they get too hot, they start
> to  act flaky.  You get extra spurs and more importantly, they don't
>  respond to the programming properly (e.g. you send the serial stream
>  to program frequency X, and instead it programs some different
>  frequency).
> 
> 
> "The heat sink of the AD9854ASVZ 80-lead  TQFP package must
> be soldered to the PCB. "
> 
> "Adequate  dissipation of heat from the AD9854 relies on all
> power and ground  pins of the device being soldered directly to
> a copper plane on a PCB.  In addition, the thermally enhanced
> package of the AD9854ASVZ has an  exposed paddle on the
> bottom of the package that must be soldered to a  large copper
> plane, which, for convenience, can be the ground  plane."
--  
WBW,

V.P.
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AD 9913.pcb
Description: Binary data
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Re: [time-nuts] Power Supply for AD9852 / AD9854

[Graeme Zimmer]

Unless it’s already on a board, this is not a simple chip to use in a home 
environment.


Nevertheless, some of us do manage.

But it's true, the AD9852/AD9854 does run very hot.

It's worth mentioning that the AD9910/AD9912 family runs much cooler.
Mine aren't even warm to the touch. This of course is due to the power 
hungry parts of the chip running on 1.8V instead of 3.3V



. Zim
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Re: [time-nuts] Power Supply for AD9852 / AD9854

[Bob Camp]

Hi

If you use multiple regulators for the same supply and they don’t come up at 
the same time, odd things can happen. On some chips those odd things include 
smoke. In most cases where it fails, the more common effect is the internal 
reset does not work properly and you can’t talk to the chip. 

You really need a multi layer board to heat spread these chips, you also need 
to reflow solder them to get the bottom pad properly connected to the via’s 
under the chip. Unless it’s already on a board, this is not a simple chip to 
use in a home environment. 

Bob


On Mar 16, 2014, at 12:34 PM, d0ct0r  wrote:

> 
> 
> I would assume that using two voltage regulators will spread the load. For 
> the AD9851 I'am planning to put external radiator glued on top of it.
> 
> Regards,
> 
> V.P.
> 
>> those parts dissipate a fair amount of heat, and they're not very big.
>> If you turn on everything in the 9854 AND run it at 300 MHz clock, it
>> draws about 1.2 Amps (@ 3.3V) which is about 4 Watts.. that's a lot of
>> power to get out of the part and keep Tj reasonable. Board layout to
>> get the heat out is very important.  If they get too hot, they start
>> to act flaky.  You get extra spurs and more importantly, they don't
>> respond to the programming properly (e.g. you send the serial stream
>> to program frequency X, and instead it programs some different
>> frequency).
>> "The heat sink of the AD9854ASVZ 80-lead TQFP package must
>> be soldered to the PCB. "
>> "Adequate dissipation of heat from the AD9854 relies on all
>> power and ground pins of the device being soldered directly to
>> a copper plane on a PCB. In addition, the thermally enhanced
>> package of the AD9854ASVZ has an exposed paddle on the
>> bottom of the package that must be soldered to a large copper
>> plane, which, for convenience, can be the ground plane."
> -- 
> WBW,
> 
> V.P.
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Re: [time-nuts] Power Supply for AD9852 / AD9854

[Jim Lux]

On 3/16/14 9:34 AM, d0ct0r wrote:



I would assume that using two voltage regulators will spread the load.
For the AD9851 I'am planning to put external radiator glued on top of it.



It's not the power dissipation of the regulators that's the concern, 
it's the dissipation of the 9854.  A heatsink on top doesn't do much for 
it, since the thermal path is out through the bottom and/or the leads. 
Of course, if your regulators are sharing the thermal path, then 
dissipation in the regulators becomes a concern too.


Read the data sheet and the ap note for details.

The eval board works OK most of the time. I've encountered flaky 
behavior but that could have been from other causes.


The 9854 is the part that was used in the Flex-Radio SDR1000, but most 
of the options were powered off, so the dissipation was in the <1 watt 
range. That particular board would overheat in an enclosure if you 
didn't have a fan blowing on it.

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Re: [time-nuts] Power Supply for AD9852 / AD9854

[Graeme Zimmer]

My versions of a DDS using two AD9910 in Quadrature

http://members.wideband.net.au/gzimmer/QuadDDS/default.html


regards ... Zm
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Re: [time-nuts] Power Supply for AD9852 / AD9854

[Graeme Zimmer]

> I would assume that using two voltage regulators will spread the load.
> For the AD9851 I'am planning to put external radiator glued on top of 
> it.


One of my commercial projects used eight x AD9852. During development 
they definitely needed small heat sinks glued on top of each chip.

I discovered that it's quite easy to cook a chip.

In the final version it was possible to switch off many of the internal 
blocks so that the heat sinks were no longer necessary.



.. Zim
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Re: [time-nuts] Power Supply for AD9852 / AD9854

[d0ct0r]

I would assume that using two voltage regulators will spread the load. 
For the AD9851 I'am planning to put external radiator glued on top of 
it.


Regards,

V.P.


those parts dissipate a fair amount of heat, and they're not very big.
If you turn on everything in the 9854 AND run it at 300 MHz clock, it
draws about 1.2 Amps (@ 3.3V) which is about 4 Watts.. that's a lot of
power to get out of the part and keep Tj reasonable. Board layout to
get the heat out is very important.  If they get too hot, they start
to act flaky.  You get extra spurs and more importantly, they don't
respond to the programming properly (e.g. you send the serial stream
to program frequency X, and instead it programs some different
frequency).


"The heat sink of the AD9854ASVZ 80-lead TQFP package must
be soldered to the PCB. "

"Adequate dissipation of heat from the AD9854 relies on all
power and ground pins of the device being soldered directly to
a copper plane on a PCB. In addition, the thermally enhanced
package of the AD9854ASVZ has an exposed paddle on the
bottom of the package that must be soldered to a large copper
plane, which, for convenience, can be the ground plane."

--
WBW,

V.P.
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Re: [time-nuts] Power Supply for AD9852 / AD9854

[Jim Lux]

On 3/16/14 8:13 AM, d0ct0r wrote:


Thanks ! Looks like I am on the right track.
I've attached couple of documents which could be useful. I'am going to
use two separated voltage regulators for VCC/AVDD and DVDD. And use 10
Ohm / 100Mhz  ferrite board and few capacitors to "separate" VCC and AVDD.




those parts dissipate a fair amount of heat, and they're not very big.
If you turn on everything in the 9854 AND run it at 300 MHz clock, it 
draws about 1.2 Amps (@ 3.3V) which is about 4 Watts.. that's a lot of 
power to get out of the part and keep Tj reasonable. Board layout to get 
the heat out is very important.  If they get too hot, they start to act 
flaky.  You get extra spurs and more importantly, they don't respond to 
the programming properly (e.g. you send the serial stream to program 
frequency X, and instead it programs some different frequency).



"The heat sink of the AD9854ASVZ 80-lead TQFP package must
be soldered to the PCB. "

"Adequate dissipation of heat from the AD9854 relies on all
power and ground pins of the device being soldered directly to
a copper plane on a PCB. In addition, the thermally enhanced
package of the AD9854ASVZ has an exposed paddle on the
bottom of the package that must be soldered to a large copper
plane, which, for convenience, can be the ground plane."


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Re: [time-nuts] Power Supply for AD9852 / AD9854

[Tom Knox]

Sorry, I forgot to add the link:
http://www.wenzel.com/documents/finesse.html


Thomas Knox



> From: act...@hotmail.com
> To: time-nuts@febo.com
> Date: Sun, 16 Mar 2014 09:46:04 -0600
> Subject: Re: [time-nuts] Power Supply for AD9852 / AD9854
> 
> I do not know if this is of interest or would be applicable. Wenzel uses 
> their Finesse Voltage Regulator in many products which I may be better 
> described as active noise cancelling regulator.
> 
> 
> > From: albertson.ch...@gmail.com
> > Date: Sat, 15 Mar 2014 22:36:23 -0700
> > To: t...@patoka.org; time-nuts@febo.com
> > Subject: Re: [time-nuts] Power Supply for AD9852 / AD9854
> > 
> > On Sat, Mar 15, 2014 at 9:21 PM, d0ct0r  wrote:
> > 
> > >
> > >
> > > Many thanks indeed for detailed answer ! Yes, I will using Evaluation
> > > Board for my project.
> > >
> > 
> > Then it is already done for you.  They have added all the bypass caps
> > already on the board.  Not much left for you to do.  In fact you can't do
> > anything because all the important design work happens within millimeters
> > of the power and ground pins.
> > 
> > -- 
> > 
> > Chris Albertson
> > Redondo Beach, California
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
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> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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> 
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Re: [time-nuts] Power Supply for AD9852 / AD9854

[Tom Knox]

I do not know if this is of interest or would be applicable. Wenzel uses their 
Finesse Voltage Regulator in many products which I may be better described as 
active noise cancelling regulator.


> From: albertson.ch...@gmail.com
> Date: Sat, 15 Mar 2014 22:36:23 -0700
> To: t...@patoka.org; time-nuts@febo.com
> Subject: Re: [time-nuts] Power Supply for AD9852 / AD9854
> 
> On Sat, Mar 15, 2014 at 9:21 PM, d0ct0r  wrote:
> 
> >
> >
> > Many thanks indeed for detailed answer ! Yes, I will using Evaluation
> > Board for my project.
> >
> 
> Then it is already done for you.  They have added all the bypass caps
> already on the board.  Not much left for you to do.  In fact you can't do
> anything because all the important design work happens within millimeters
> of the power and ground pins.
> 
> -- 
> 
> Chris Albertson
> Redondo Beach, California
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Re: [time-nuts] Power Supply for AD9852 / AD9854

[Michael Jensen]

For inspiration you can look on this design we use for many purposes, the
design was mainly a beacon exciter but is now also used in many laboratories
in the developing of laser controlled freq. standards (1x10-18) and also as
a direct programmable freq. source with milli Herz resolution locked to a 10
MHz std. 

http://rudius.net/oz2m/ngnb/dds.htm

In the bottom of the web page is diagrams of both power supply and DDS
design, the DDS is controlled by an ATMEGA 128A, all is open source.

// Michael, OZ2ELA

-Oprindelig meddelelse-
Fra: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] På vegne
af d0ct0r
Sendt: 16. marts 2014 05:22
Til: time-nuts@febo.com
Emne: Re: [time-nuts] Power Supply for AD9852 / AD9854



Many thanks indeed for detailed answer ! Yes, I will using Evaluation Board
for my project.

Regards,

V.P.

On 2014-03-16 00:06, Charles Steinmetz wrote:
>> By design, DDS "stones" like AD9852 from Analog Devices, required 
>> separated power lines for AVDD, DVDD and VCC.  What will is simple 
>> solution for that ?  I am planing to use following approach: +5V from 
>> linear PS, then three LC filters, then three 3.3V voltage regulators
>> (Ex.: MC33269T) connected to each filter. Is it good enough ?  May be 
>> its better solution for this ? Or may be that could be simplified to 
>> join AVDD and VCC (AVDD will be connected to VCC via 100 Ohm).
> 
> Do you have the AD evaluation board, or are you starting with the bare 
> chip?
> 
> If you really want to know how simple you can make it, why not try it 
> yourself, and see what you need?  You will learn a lot more that way 
> than by asking first every time a question occurs to you.
> 
> Follow the evaluation board plan and put a 0.1uF (100nF) monolithic 
> ceramic capacitor right at each power input pin of the IC itself 
> (something like 10 capacitors per supply).
> 
> First, use one 3.3v regulator and feed its output straight to all 
> three circuits, with simply a local bypass cap for each one (plus the 
> per-pin capacitors as noted above).  Run the DDS and see how it 
> performs.
> 
> Then, see how three separate LC filters perform (each LC fed by the 
> regulated 3.3v supply).
> 
> Finally, feed the unregulated supply to the "upstream" side of each of 
> the three LC filters, and use a separate 3.3v regulator on the 
> "downstream" side for each supply.
> 
> In each case, note carefully (at a lot of different output
> frequencies) the general output noise level and the presence of any 
> spurs and birdies in the output, as well as any logic faults you find 
> (wrong frequency, system hangs up, bus errors, etc.).
> 
> It might be more instructive to run those steps backwards -- first, 
> see how it works with the most complex (and presumably best) supply, 
> then try the simpler circuits and see what problems crop up.
> 
> Of course, with either test protocol it is difficult to know whether 
> you have tried every operating state that could cause a problem, so 
> play with it quite a while with each setup and try to use every 
> function and combination.
> 
> As Chris said, you need to be very careful with your grounds.  These 
> chips are intended to be put on boards with four or more layers.  The 
> AD evaluation board has four layers with a common ground plane for the 
> analog and digital circuitry -- it is possible you could do better 
> with more careful attention to grounding.
> 
> Best regards,
> 
> Charles
> 
> 
> 
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> and follow the instructions there.

--
WBW,

V.P.
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Re: [time-nuts] Power Supply for AD9852 / AD9854

[Chris Albertson]

On Sat, Mar 15, 2014 at 9:21 PM, d0ct0r  wrote:

>
>
> Many thanks indeed for detailed answer ! Yes, I will using Evaluation
> Board for my project.
>

Then it is already done for you.  They have added all the bypass caps
already on the board.  Not much left for you to do.  In fact you can't do
anything because all the important design work happens within millimeters
of the power and ground pins.

-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Power Supply for AD9852 / AD9854

[d0ct0r]

Many thanks indeed for detailed answer ! Yes, I will using Evaluation 
Board for my project.


Regards,

V.P.

On 2014-03-16 00:06, Charles Steinmetz wrote:
By design, DDS "stones" like AD9852 from Analog Devices, required 
separated power lines for AVDD, DVDD and VCC.  What will is simple 
solution for that ?  I am planing to use following approach: +5V from 
linear PS, then three LC filters, then three 3.3V voltage regulators 
(Ex.: MC33269T) connected to each filter. Is it good enough ?  May be 
its better solution for this ? Or may be that could be simplified to 
join AVDD and VCC (AVDD will be connected to VCC via 100 Ohm).


Do you have the AD evaluation board, or are you starting with the bare 
chip?


If you really want to know how simple you can make it, why not try it
yourself, and see what you need?  You will learn a lot more that way
than by asking first every time a question occurs to you.

Follow the evaluation board plan and put a 0.1uF (100nF) monolithic
ceramic capacitor right at each power input pin of the IC itself
(something like 10 capacitors per supply).

First, use one 3.3v regulator and feed its output straight to all
three circuits, with simply a local bypass cap for each one (plus the
per-pin capacitors as noted above).  Run the DDS and see how it
performs.

Then, see how three separate LC filters perform (each LC fed by the
regulated 3.3v supply).

Finally, feed the unregulated supply to the "upstream" side of each of
the three LC filters, and use a separate 3.3v regulator on the
"downstream" side for each supply.

In each case, note carefully (at a lot of different output
frequencies) the general output noise level and the presence of any
spurs and birdies in the output, as well as any logic faults you find
(wrong frequency, system hangs up, bus errors, etc.).

It might be more instructive to run those steps backwards -- first,
see how it works with the most complex (and presumably best) supply,
then try the simpler circuits and see what problems crop up.

Of course, with either test protocol it is difficult to know whether
you have tried every operating state that could cause a problem, so
play with it quite a while with each setup and try to use every
function and combination.

As Chris said, you need to be very careful with your grounds.  These
chips are intended to be put on boards with four or more layers.  The
AD evaluation board has four layers with a common ground plane for the
analog and digital circuitry -- it is possible you could do better
with more careful attention to grounding.

Best regards,

Charles



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and follow the instructions there.


--
WBW,

V.P.
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Re: [time-nuts] Power Supply for AD9852 / AD9854

[Charles Steinmetz]

By design, DDS "stones" like AD9852 from Analog Devices, required 
separated power lines for AVDD, DVDD and VCC.  What will is simple 
solution for that ?  I am planing to use following approach: +5V 
from linear PS, then three LC filters, then three 3.3V voltage 
regulators (Ex.: MC33269T) connected to each filter. Is it good 
enough ?  May be its better solution for this ? Or may be that could 
be simplified to join AVDD and VCC (AVDD will be connected to VCC via 100 Ohm).


Do you have the AD evaluation board, or are you starting with the bare chip?

If you really want to know how simple you can make it, why not try it 
yourself, and see what you need?  You will learn a lot more that way 
than by asking first every time a question occurs to you.


Follow the evaluation board plan and put a 0.1uF (100nF) monolithic 
ceramic capacitor right at each power input pin of the IC itself 
(something like 10 capacitors per supply).


First, use one 3.3v regulator and feed its output straight to all 
three circuits, with simply a local bypass cap for each one (plus the 
per-pin capacitors as noted above).  Run the DDS and see how it performs.


Then, see how three separate LC filters perform (each LC fed by the 
regulated 3.3v supply).


Finally, feed the unregulated supply to the "upstream" side of each 
of the three LC filters, and use a separate 3.3v regulator on the 
"downstream" side for each supply.


In each case, note carefully (at a lot of different output 
frequencies) the general output noise level and the presence of any 
spurs and birdies in the output, as well as any logic faults you find 
(wrong frequency, system hangs up, bus errors, etc.).


It might be more instructive to run those steps backwards -- first, 
see how it works with the most complex (and presumably best) supply, 
then try the simpler circuits and see what problems crop up.


Of course, with either test protocol it is difficult to know whether 
you have tried every operating state that could cause a problem, so 
play with it quite a while with each setup and try to use every 
function and combination.


As Chris said, you need to be very careful with your grounds.  These 
chips are intended to be put on boards with four or more layers.  The 
AD evaluation board has four layers with a common ground plane for 
the analog and digital circuitry -- it is possible you could do 
better with more careful attention to grounding.


Best regards,

Charles



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Re: [time-nuts] Power Supply for AD9852 / AD9854

[Chris Albertson]

I think most people use just one regular and then use bypass caps that are
physically close to the power pins.  Being really close is likely the most
important point.

What matters as much or even more is the design of the ground system. The
Vcc pins are actually easier to take care of, I think, because you can just
bypass them. but you obviously can't use a bypass can in a ground pin.  On
the ground side you have to think about inductance of the traces.


On Sat, Mar 15, 2014 at 6:10 PM, d0ct0r  wrote:

>
> Hello,
>
> By design, DDS "stones" like AD9852 from Analog Devices, required
> separated power lines for AVDD, DVDD and VCC.
> What will is simple solution for that ?  I am planing to use following
> approach: +5V from linear PS, then three LC filters, then three 3.3V
> voltage regulators (Ex.: MC33269T) connected to each filter. Is it good
> enough ?
>
>
> May be its better solution for this ? Or may be that could be simplified
> to join AVDD and VCC (AVDD will be connected to VCC via 100 Ohm). Thanks in
> advance !
>
> --
> WBW,
>
> V.P.
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> time-nuts mailing list -- time-nuts@febo.com
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>



-- 

Chris Albertson
Redondo Beach, California
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[time-nuts] Power Supply for AD9852 / AD9854

[d0ct0r]

Hello,

By design, DDS "stones" like AD9852 from Analog Devices, required 
separated power lines for AVDD, DVDD and VCC.
What will is simple solution for that ?  I am planing to use following 
approach: +5V from linear PS, then three LC filters, then three 3.3V 
voltage regulators (Ex.: MC33269T) connected to each filter. Is it good 
enough ?



May be its better solution for this ? Or may be that could be simplified 
to join AVDD and VCC (AVDD will be connected to VCC via 100 Ohm). Thanks 
in advance !


--
WBW,

V.P.<>___
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