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LM358 strange behavior !
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michel....@gmail.com
Nov 4, 2012, 4:01:55 AM11/4/12
to
Hello,
Excuse my english, I'm French ...
The LM 358 is a mono-voltage amplifier capable of approaching its negative supply (there is a NPN transistor in the output stage). I had to build a mono-voltage subtractor (a voltage substractor built with a LM358 powered with 0v-12v supply) and with the consent of the electronic simulator ISIS I built (wired) such a subtractor. I was surprised that it could not entirely do the job. For some subtractions, like 2v - 1.8v for example, the substractor said 0.62v instead of 0.2v. But for some other, it answered the right thing, wich was 0.3v (a voltage lower than 0.62v) sometimes. So it was able to go under 0.62v !
Why does a 2v - 1.8v substraction gave 0.62v instead of 0.2v !
Resistors, all identical, were 2.5k one, so I do not suspect bias currents problem. I tried many other chip, it didn't change anything. I changed the 0v suply into a -12v one and the substractor worked well for every input voltage.
Does someone have an explanation?
cdlt.
Michel.
Excuse my english, I'm French ...
The LM 358 is a mono-voltage amplifier capable of approaching its negative supply (there is a NPN transistor in the output stage). I had to build a mono-voltage subtractor (a voltage substractor built with a LM358 powered with 0v-12v supply) and with the consent of the electronic simulator ISIS I built (wired) such a subtractor. I was surprised that it could not entirely do the job. For some subtractions, like 2v - 1.8v for example, the substractor said 0.62v instead of 0.2v. But for some other, it answered the right thing, wich was 0.3v (a voltage lower than 0.62v) sometimes. So it was able to go under 0.62v !
Why does a 2v - 1.8v substraction gave 0.62v instead of 0.2v !
Resistors, all identical, were 2.5k one, so I do not suspect bias currents problem. I tried many other chip, it didn't change anything. I changed the 0v suply into a -12v one and the substractor worked well for every input voltage.
Does someone have an explanation?
cdlt.
Michel.
John Fields
Nov 4, 2012, 5:44:27 AM11/4/12
to
On Sun, 4 Nov 2012 01:01:55 -0800 (PST), michel....@gmail.com
wrote:
---
Can you post a schematic, please?
--
JF
wrote:
Can you post a schematic, please?
--
JF
michel....@gmail.com
Nov 4, 2012, 6:33:05 AM11/4/12
to
http://crteknologies.fr/electronique/cours/ao_soustracteur.gif
In my case, R1=R2=R3=R4=2.5 k, and Us = U2 - U1.
Michel.
>
>
> --
>
> JF
dagmarg...@yahoo.com
Nov 4, 2012, 7:06:54 AM11/4/12
to
output to sink too much current. Close to ground, its
ability is quite limited. See "Output Current Sinking
Characteristics" on page 7 here:
http://www.ti.com/lit/ds/symlink/lm358-n.pdf
The reason for the limitation can be understood easily by
looking at the LM358 schematic on page 20--the output stage
is an emitter follower in parallel with a current sink. Only
12uA is guaranteed at 200mV, Vcc=+15v ("Output Current," pg. 4).
Cures: use larger resistors, or connect a load resistor
or a current sink to the output.
--
Cheers,
James Arthur
Jamie
Nov 4, 2012, 1:53:16 PM11/4/12
to
range. You maybe in the cross over zone and that op-amp does not have
much for shoot-through current.
Jamie
John S
Nov 4, 2012, 2:42:46 PM11/4/12
to
sheer genius.
John S
Nov 4, 2012, 2:46:08 PM11/4/12
to
Arthur's sugesstion as your own is shear genus."
Jamie
Nov 4, 2012, 4:10:49 PM11/4/12
to
James arthur is and I don't give a shit. Maybe you got some infatuation
with him, I don't, who ever he is.
The fact that a 324, 358 having those issues being common knowledge
as it is, leads me to believe that you're just a sit in stooly. Yes,
one that is so full of shit that I smell it all the way over here.
Oh, btw, incase you want to expand that fake no hands on knowledge of
yours, a 358/324 etc can also oscillate if the output is brought down to
or near zero output with no load on it.
What a piece of shit you are. You belong with Phil, down under, the
table, that is.
Jamie
Michael A. Terrell
Nov 4, 2012, 5:21:43 PM11/4/12
to
Subject:
Re: LM358 strange behavior !
Date:
Sun, 4 Nov 2012 04:06:54 -0800 (PST)
From:
dagmarg...@yahoo.com
Newsgroups:
sci.electronics.design
References:
1
On Sunday, November 4, 2012 4:01:55 AM UTC-5, michel....@gmail.com
wrote:
> Hello,
>
>
>
> Excuse my english, I'm French ...
>
>
>
> The LM 358 is a mono-voltage amplifier capable of approaching its negative supply (there is a NPN transistor in the output stage). I had to build a
mono-voltage subtractor (a voltage substractor built with a LM358
powered with 0v-12v supply) and with the consent of the electronic
simulator ISIS I
built (wired) such a subtractor. I was surprised that it could not
entirely do the job. For some subtractions, like 2v - 1.8v for example,
the
substractor said 0.62v instead of 0.2v. But for some other, it answered
the right thing, wich was 0.3v (a voltage lower than 0.62v) sometimes.
So it was
able to go under 0.62v !
>
> Why does a 2v - 1.8v substraction gave 0.62v instead of 0.2v !
>
> Resistors, all identical, were 2.5k one, so I do not suspect bias currents problem. I tried many other chip, it didn't change anything. I changed the 0v
suply into a -12v one and the substractor worked well for every input
voltage.
>
> Does someone have an explanation?
>
> cdlt.
>
> Michel.
> Hello,
>
>
>
> Excuse my english, I'm French ...
>
>
>
> The LM 358 is a mono-voltage amplifier capable of approaching its negative supply (there is a NPN transistor in the output stage). I had to build a
mono-voltage subtractor (a voltage substractor built with a LM358
powered with 0v-12v supply) and with the consent of the electronic
simulator ISIS I
built (wired) such a subtractor. I was surprised that it could not
entirely do the job. For some subtractions, like 2v - 1.8v for example,
the
substractor said 0.62v instead of 0.2v. But for some other, it answered
the right thing, wich was 0.3v (a voltage lower than 0.62v) sometimes.
So it was
able to go under 0.62v !
>
> Why does a 2v - 1.8v substraction gave 0.62v instead of 0.2v !
>
> Resistors, all identical, were 2.5k one, so I do not suspect bias currents problem. I tried many other chip, it didn't change anything. I changed the 0v
suply into a -12v one and the substractor worked well for every input
voltage.
>
> Does someone have an explanation?
>
> cdlt.
>
> Michel.
John Fields
Nov 4, 2012, 5:59:58 PM11/4/12
to
Phil's not a bad guy, he just has a hard time suppressing his emotions
when he runs into shit like you, who profess to own knowledge you
don't and can barely use English.
--
JF
Robert Baer
Nov 5, 2012, 2:25:48 AM11/5/12
to
The common mode input voltage, U is equal to 0.5 * U2.
With the negative supply pin of the op-amp being at zero volts, many
common op-amps do not operate with that input.
Also, a number of common op-amps cannot drive the output so close to
its negative supply.
Now..if you use a properly selected rail-to-rail op-amp..
Spehro Pefhany
Nov 5, 2012, 7:29:03 AM11/5/12
to
On Sun, 04 Nov 2012 23:25:48 -0800, the renowned Robert Baer
<rober...@localnet.com> wrote:
>
> Not strange at all.
> The common mode input voltage, U is equal to 0.5 * U2.
> With the negative supply pin of the op-amp being at zero volts, many
>common op-amps do not operate with that input.
The LM358 has an input CM range that is guaranteed to go down to the
<rober...@localnet.com> wrote:
>
> Not strange at all.
> The common mode input voltage, U is equal to 0.5 * U2.
> With the negative supply pin of the op-amp being at zero volts, many
>common op-amps do not operate with that input.
negative rail over the full temperature range. One of the things that
makes it so useful for an extremely cheap and common op-amp (it's half
an LM324). So, it's not that.
> Also, a number of common op-amps cannot drive the output so close to
>its negative supply.
negative rail (5mV typically) over the full temperature range, with a
<=10K load (critically important, but perhaps not obvious from the
data sheet) connected to the negative rail. The subtractor has < 10K
of load but does not have that configuration of loading on the output.
That's his problem.
Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
sp...@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
dagmarg...@yahoo.com
Nov 5, 2012, 9:49:47 AM11/5/12
to
On Nov 5, 7:29 am, Spehro Pefhany <speffS...@interlogDOTyou.knowwhat>
wrote:
sink 320uA for his example (Vin+ = 2.0v, Vin- = 1.8v, Vout = 200mV).
R1=R2=100k would go a long way toward fixing that.
--
Cheers,
James Arthur
wrote:
> On Sun, 04 Nov 2012 23:25:48 -0800, the renowned Robert Baer
>
>
> <robertb...@localnet.com> wrote:
>
> > Not strange at all.
> > The common mode input voltage, U is equal to 0.5 * U2.
> > With the negative supply pin of the op-amp being at zero volts, many
> >common op-amps do not operate with that input.
>
> The LM358 has an input CM range that is guaranteed to go down to the
> negative rail over the full temperature range. One of the things that
> makes it so useful for an extremely cheap and common op-amp (it's half
> an LM324). So, it's not that.
>
> > Also, a number of common op-amps cannot drive the output so close to
> >its negative supply.
>
> The LM358 is guaranteed to drive the output within 20mV of the
> negative rail (5mV typically) over the full temperature range, with a
> <=10K load (critically important, but perhaps not obvious from the
> data sheet) connected to the negative rail. The subtractor has < 10K
> of load but does not have that configuration of loading on the output.
> That's his problem.
His R1-R2 combination presents 5k from -Vin to output, so he'd need to
>
> > Not strange at all.
> > The common mode input voltage, U is equal to 0.5 * U2.
> > With the negative supply pin of the op-amp being at zero volts, many
> >common op-amps do not operate with that input.
>
> The LM358 has an input CM range that is guaranteed to go down to the
> negative rail over the full temperature range. One of the things that
> makes it so useful for an extremely cheap and common op-amp (it's half
> an LM324). So, it's not that.
>
> > Also, a number of common op-amps cannot drive the output so close to
> >its negative supply.
>
> The LM358 is guaranteed to drive the output within 20mV of the
> negative rail (5mV typically) over the full temperature range, with a
> <=10K load (critically important, but perhaps not obvious from the
> data sheet) connected to the negative rail. The subtractor has < 10K
> of load but does not have that configuration of loading on the output.
> That's his problem.
sink 320uA for his example (Vin+ = 2.0v, Vin- = 1.8v, Vout = 200mV).
R1=R2=100k would go a long way toward fixing that.
--
Cheers,
James Arthur
Spehro Pefhany
Nov 5, 2012, 5:12:24 PM11/5/12
to
On Mon, 5 Nov 2012 06:49:47 -0800 (PST), dagmarg...@yahoo.com
wrote:
Which overwhelms the 50uA nominal internal sinking capacity.
>R1=R2=100k would go a long way toward fixing that.
Sure, and make the other two 100K as well to kill most of the offset
due to bias current.
I suppose one could do something like this and keep the 2K5 resistors:
|\|
-|-\
| >-----+----
-|+/ |
|/| |
|
|
|
|
1M8 |
___ |/
+12 -|___|--| 2PC4081R
|>
|
|
===
GND
LOL.
wrote:
>R1=R2=100k would go a long way toward fixing that.
due to bias current.
I suppose one could do something like this and keep the 2K5 resistors:
|\|
-|-\
| >-----+----
-|+/ |
|/| |
|
|
|
|
1M8 |
___ |/
+12 -|___|--| 2PC4081R
|>
|
|
===
GND
LOL.
John Larkin
Nov 5, 2012, 5:28:23 PM11/5/12
to
But with a 2:1 beta spread, it's perfectly reasonable.
A depletion mosfet would be fun, too. Or a better opamp. Or a negative
supply for a better opamp.
--
John Larkin Highland Technology, Inc
jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro acquisition and simulation
dagmarg...@yahoo.com
Nov 5, 2012, 6:05:34 PM11/5/12
to
On Nov 5, 5:09 pm, Spehro Pefhany <speffS...@interlogDOTyou.knowwhat>
wrote:
> On Mon, 5 Nov 2012 06:49:47 -0800 (PST), dagmargoodb...@yahoo.com
LOL!
I nearly suggested a JFET load, Vgs=0v. Bigger resistors was easier
though.
--
Cheers,
James Arthur
wrote:
> On Mon, 5 Nov 2012 06:49:47 -0800 (PST), dagmargoodb...@yahoo.com
I nearly suggested a JFET load, Vgs=0v. Bigger resistors was easier
though.
--
Cheers,
James Arthur
Fred Bartoli
Nov 5, 2012, 6:10:19 PM11/5/12
to
dagmarg...@yahoo.com a �crit :
Hey, a resistor to a negative supply would be nice too :-)
--
Thanks,
Fred.
--
Thanks,
Fred.
dagmarg...@yahoo.com
Nov 5, 2012, 6:17:13 PM11/5/12
to
On Nov 5, 6:10 pm, Fred Bartoli <" "> wrote:
> dagmargoodb...@yahoo.com a écrit :
Sure, if you've got one. (a negative supply, that is.)
Bob Pease did a neat trick--or was it Jim Williams?--using the e-b
junction of a powered optoisolator as a negative current generator.
The phototransistor served as a solar cell, to pull an LM358 output
all the way down. Cute.
--
Cheers,
James Arthur
> dagmargoodb...@yahoo.com a écrit :
Bob Pease did a neat trick--or was it Jim Williams?--using the e-b
junction of a powered optoisolator as a negative current generator.
The phototransistor served as a solar cell, to pull an LM358 output
all the way down. Cute.
--
Cheers,
James Arthur
Fred Bartoli
Nov 5, 2012, 6:24:09 PM11/5/12
to
dagmarg...@yahoo.com a �crit :
Was joking of course. If you have a neg supply then just use it for the
opamp.
> Bob Pease did a neat trick--or was it Jim Williams?--using the e-b
> junction of a powered optoisolator as a negative current generator.
> The phototransistor served as a solar cell, to pull an LM358 output
> all the way down. Cute.
>
I think it was Bob Pease but I doubt this has enough current for an LM358.
--
Thanks,
Fred.
> On Nov 5, 6:10 pm, Fred Bartoli <" "> wrote:
>> dagmargoodb...@yahoo.com a �crit :
opamp.
> Bob Pease did a neat trick--or was it Jim Williams?--using the e-b
> junction of a powered optoisolator as a negative current generator.
> The phototransistor served as a solar cell, to pull an LM358 output
> all the way down. Cute.
>
--
Thanks,
Fred.
dagmarg...@yahoo.com
Nov 5, 2012, 6:39:13 PM11/5/12
to
On Nov 5, 6:24 pm, Fred Bartoli <" "> wrote:
> dagmargoodb...@yahoo.com a écrit :
Missed it--whoosh. I often don't use negative supplies for V- for
other reasons, like, it might be dirty, or to save power, or reduce
loading on V-, etc.
> > Bob Pease did a neat trick--or was it Jim Williams?--using the e-b
> > junction of a powered optoisolator as a negative current generator.
> > The phototransistor served as a solar cell, to pull an LM358 output
> > all the way down. Cute.
>
> I think it was Bob Pease but I doubt this has enough current for an LM358.
Could be. If an ordinary phototransistor isolator has a current
transfer ratio of 20%, and the phototransistor has a hfe of ~100, that
suggests i.b ~= 0.2%. So, 10mA into the IRLED could make 10 or 20uA.
--
Cheers,
James Arthur
> dagmargoodb...@yahoo.com a écrit :
>
>
>
>
>
>
>
>
>
> > On Nov 5, 6:10 pm, Fred Bartoli <" "> wrote:
> >> dagmargoodb...@yahoo.com a écrit :
>
>
>
>
>
>
>
>
> > On Nov 5, 6:10 pm, Fred Bartoli <" "> wrote:
other reasons, like, it might be dirty, or to save power, or reduce
loading on V-, etc.
> > Bob Pease did a neat trick--or was it Jim Williams?--using the e-b
> > junction of a powered optoisolator as a negative current generator.
> > The phototransistor served as a solar cell, to pull an LM358 output
> > all the way down. Cute.
>
> I think it was Bob Pease but I doubt this has enough current for an LM358.
transfer ratio of 20%, and the phototransistor has a hfe of ~100, that
suggests i.b ~= 0.2%. So, 10mA into the IRLED could make 10 or 20uA.
--
Cheers,
James Arthur
John Larkin
Nov 5, 2012, 8:22:38 PM11/5/12
to
On Tue, 06 Nov 2012 00:10:19 +0100, Fred Bartoli <" "> wrote:
>dagmarg...@yahoo.com a écrit :
*If* there's no latchup hazard in the opamp. I never pull below ground
any pin on those ancient National designs.
>dagmarg...@yahoo.com a écrit :
any pin on those ancient National designs.
dagmarg...@yahoo.com
Nov 5, 2012, 10:43:40 PM11/5/12
to
On Nov 5, 8:22 pm, John Larkin <jlar...@highlandtechnology.com> wrote:
> On Tue, 06 Nov 2012 00:10:19 +0100, Fred Bartoli <" "> wrote:
> >dagmargoodb...@yahoo.com a crit :
> On Tue, 06 Nov 2012 00:10:19 +0100, Fred Bartoli <" "> wrote:
> >> On Nov 5, 5:09 pm, Spehro Pefhany <speffS...@interlogDOTyou.knowwhat>
> >> wrote:
> >>> I suppose one could do something like this and keep the 2K5 resistors:
>
> >>> |\|
> >>> -|-\
> >>> | >-----+----
> >>> -|+/ |
> >>> |/| |
> >>> |
> >>> |
> >>> |
> >>> |
> >>> 1M8 |
> >>> ___ |/
> >>> +12 -|___|--| 2PC4081R
> >>> |>
> >>> |
> >>> |
> >>> ===
> >>> GND
>
> >>> LOL.
>
> >> LOL!
>
> >> I nearly suggested a JFET load, Vgs=0v. Bigger resistors was easier
> >> though.
>
> >> --
>
> >Hey, a resistor to a negative supply would be nice too :-)
>
> *If* there's no latchup hazard in the opamp. I never pull below ground
> any pin on those ancient National designs.
That's not a hazard, it's a feature--crowbar. LM34, right?
> >> wrote:
> >>> I suppose one could do something like this and keep the 2K5 resistors:
>
> >>> |\|
> >>> -|-\
> >>> | >-----+----
> >>> -|+/ |
> >>> |/| |
> >>> |
> >>> |
> >>> |
> >>> |
> >>> 1M8 |
> >>> ___ |/
> >>> +12 -|___|--| 2PC4081R
> >>> |>
> >>> |
> >>> |
> >>> ===
> >>> GND
>
> >>> LOL.
>
> >> LOL!
>
> >> I nearly suggested a JFET load, Vgs=0v. Bigger resistors was easier
> >> though.
>
> >> --
>
> >Hey, a resistor to a negative supply would be nice too :-)
>
> *If* there's no latchup hazard in the opamp. I never pull below ground
> any pin on those ancient National designs.
Grins,
James
John S
Nov 6, 2012, 2:18:14 PM11/6/12
to
by several orders of magnitude and he communicates it clearly. I have
learned much from him and I suggest Jamie try to do the same.
John S
Nov 6, 2012, 2:53:05 PM11/6/12
to
On 11/4/2012 3:10 PM, Jamie wrote:
>> Oh, good for you! Recommending James Arthur's suggestion as your own
>> is sheer genius.
> I don't know what the fuck you're talking about, I have no idea who
> James arthur is and I don't give a shit.
Well, no wonder that you never learn anything. He is a prolific poster
>> Oh, good for you! Recommending James Arthur's suggestion as your own
>> is sheer genius.
> I don't know what the fuck you're talking about, I have no idea who
> James arthur is and I don't give a shit.
here and provides great information.
Maybe you got some infatuation
> with him, I don't, who ever he is.
> The fact that a 324, 358 having those issues being common knowledge
> as it is, leads me to believe that you're just a sit in stooly. Yes,
> one that is so full of shit that I smell it all the way over here.
anything like that. It must be something with which you are familiar and
I am not.
> Oh, btw, incase you want to expand that fake no hands on knowledge of
> yours, a 358/324 etc can also oscillate if the output is brought down to
> or near zero output with no load on it.
> What a piece of shit you are. You belong with Phil, down under, the
> table, that is.
your junk.
John Fields
Nov 6, 2012, 7:14:52 PM11/6/12
to
On Mon, 05 Nov 2012 17:22:38 -0800, John Larkin
<jla...@highlandtechnology.com> wrote:
I never pull below ground any pin on those ancient National designs.
More's the pity.
<jla...@highlandtechnology.com> wrote:
I never pull below ground any pin on those ancient National designs.
--
JF
John Larkin
Nov 6, 2012, 8:30:06 PM11/6/12
to
If you're not 100% sure where substrate current is going to go,
pulling pins below ground is hazardous. LM324, LM339, 4000A cmos,
LM35, lots of ADCs and DACS, were notorious. Lots of new designs still
have latchup problems; it must be very hard to fix, since so many
designs have this hazard.
When you put hundreds, sometimes 1000+ parts on a board, you've got to
be paranoid about risk, or it will never work.
John Larkin
Nov 6, 2012, 8:36:02 PM11/6/12
to
On Mon, 5 Nov 2012 19:43:40 -0800 (PST), dagmarg...@yahoo.com
wrote:
Yes. Read the tiny footnotes, and never power them from more than 5
volts.
We're using LM50's lately, because you can pull down to ground safely
and still measure -40C.
wrote:
volts.
We're using LM50's lately, because you can pull down to ground safely
and still measure -40C.
John Fields
Nov 7, 2012, 9:29:09 AM11/7/12
to
On Tue, 06 Nov 2012 17:30:06 -0800, John Larkin
Whoosh!!!
. +--------+
. | +V |
. | | [R]
.Vin>---[R]--+--|-\ |
. | >--+-->-Vin
. +---|+/
. | |
. GND -V <--- Below ground
"I never pull below ground any pin on those ancient National designs."
;)
--
JF
<jla...@highlandtechnology.com> wrote:
>On Tue, 06 Nov 2012 18:14:52 -0600, John Fields
><jfi...@austininstruments.com> wrote:
>
>>On Mon, 05 Nov 2012 17:22:38 -0800, John Larkin
>><jla...@highlandtechnology.com> wrote:
>>
>>
>>I never pull below ground any pin on those ancient National designs.
>>
>>More's the pity.
>
>Why? Do you enjoy chips doing weird things, latching up?
>
>If you're not 100% sure where substrate current is going to go,
>pulling pins below ground is hazardous. LM324, LM339, 4000A cmos,
>LM35, lots of ADCs and DACS, were notorious. Lots of new designs still
>have latchup problems; it must be very hard to fix, since so many
>designs have this hazard.
>
>When you put hundreds, sometimes 1000+ parts on a board, you've got to
>be paranoid about risk, or it will never work.
---
>On Tue, 06 Nov 2012 18:14:52 -0600, John Fields
><jfi...@austininstruments.com> wrote:
>
>>On Mon, 05 Nov 2012 17:22:38 -0800, John Larkin
>><jla...@highlandtechnology.com> wrote:
>>
>>
>>I never pull below ground any pin on those ancient National designs.
>>
>>More's the pity.
>
>Why? Do you enjoy chips doing weird things, latching up?
>
>If you're not 100% sure where substrate current is going to go,
>pulling pins below ground is hazardous. LM324, LM339, 4000A cmos,
>LM35, lots of ADCs and DACS, were notorious. Lots of new designs still
>have latchup problems; it must be very hard to fix, since so many
>designs have this hazard.
>
>When you put hundreds, sometimes 1000+ parts on a board, you've got to
>be paranoid about risk, or it will never work.
Whoosh!!!
. +--------+
. | +V |
. | | [R]
.Vin>---[R]--+--|-\ |
. | >--+-->-Vin
. +---|+/
. | |
. GND -V <--- Below ground
"I never pull below ground any pin on those ancient National designs."
--
JF
John Larkin
Nov 7, 2012, 2:07:34 PM11/7/12
to
On Wed, 07 Nov 2012 08:29:09 -0600, John Fields
I meant, obviously, pulling a signal pin of a single-supply chip below
its substrate ground.
its substrate ground.
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