Hi all,

since it seems there is a lot of good hardware
designer in this group, I wonder if someone can
provide me little help or point me good reference
(tutorial, book, website, etc) related to the design
of a synchronous boost converter.

I use a LTC3401 with typical reference design and I
have few problems at low temperature (-10oC). This
seem to appear when a higher current is request by the
device (from 120mA to 170mA) and the battery (2 X
Energizer L91 AA 1.5V in parallel) should support this
increase.

Thanks a lot in advance!
Fred


		
__________________________________ 

> I use a LTC3401 with typical reference design and I
> have few problems at low temperature (-10oC). This
> seem to appear when a higher current is request by the
> device (from 120mA to 170mA) and the battery (2 X
> Energizer L91 AA 1.5V in parallel) should support this
> increase.

Can you be more specific about what problem is occuring? Is the output
voltage dropping out? Problems with the switching? Excessive ripple?

Dave

we have similar problem on low temperature - problem was in low base 
current of power bipolar transistor (h21 goes low with 
temperature).regards

I'm working with a RF transceiver Xemics XE1203. When
it is in Rx mode all operate correctly, but when it
turn in Tx mode (which require 50 mA more), the
message  is not sent correctly. The switcher output
voltage seem to take longer to stabilize (1400us
instead of 300us) but the ripple isn't bigger (3mV).

I send you in attachment the output of the switcher at
room temperature, which work correctly, and at low
temperature, where at think there is the problem.

Fred

--- David Rea <dave@dave...> wrote:

> > I use a LTC3401 with typical reference design
and
> I
> > have few problems at low temperature (-10oC). This
> > seem to appear when a higher current is request by
> the
> > device (from 120mA to 170mA) and the battery (2 X
> > Energizer L91 AA 1.5V in parallel) should support
> this
> > increase.
> 
> Can you be more specific about what problem is
> occuring? Is the output
> voltage dropping out? Problems with the switching?
> Excessive ripple?
> 
> Dave
> 
> 


		
__________________________________ 
 

I don't see the voltage scale on those TIFs, but you say the ripple is
only 3mV. Unless you're driving a VCO directly with the output of the
power supply, I don't see how that could possibly cause the transmitter
to glitch. The XE1203 datasheet reports (at a quick glance) that it
works from 2.4 to 3.6VDC, so 3mV ripple in the supply really shouldn't
bother it.

I see that the operating temp of the XE1203 is -40~85.

Here are a few things to consider:

1) Does the circuit exhibit the same behavior when powered by a bench
supply at low temperatures?

2) A can of "Freeze Mist" or other electronics cooling spray can be
helpful in troubleshooting this type of problem - you can spray
refrigerant onto each chip and see which one causes your problem:
http://www.unicornelex.com/newunicorn/subcategory.php?catK04&

Dave

Quoting Frederic Beaulieu <frb78@frb7...>:

> I'm working with a RF transceiver Xemics
XE1203. When
> it is in Rx mode all operate correctly, but when it
> turn in Tx mode (which require 50 mA more), the
> message  is not sent correctly. The switcher output
> voltage seem to take longer to stabilize (1400us
> instead of 300us) but the ripple isn't bigger (3mV).
>
> I send you in attachment the output of the switcher at
> room temperature, which work correctly, and at low
> temperature, where at think there is the problem.
>
> Fred
>
> --- David Rea <dave@dave...> wrote:
>
> > > I use a LTC3401 with typical reference design and
> > I
> > > have few problems at low temperature (-10oC). This
> > > seem to appear when a higher current is request by
> > the
> > > device (from 120mA to 170mA) and the battery (2 X
> > > Energizer L91 AA 1.5V in parallel) should support
> > this
> > > increase.
> >
> > Can you be more specific about what problem is
> > occuring? Is the output
> > voltage dropping out? Problems with the switching?
> > Excessive ripple?
> >
> > Dave
> >
> >
>
>
>
> __________________________________
> 

After few tests, I think it's the battery which cannot
support the current load at lower temperature.
I have put my board (without battery) in a freezer
(~-10oC) for about half a hour then I have inserted
the warm battery in it. All work fine! However, if I
let the device working in the freezer, after 20
minutes, the Tx problem occurs.
Is there a way to solve this problem? Can I put bigger
cap in front of the switcher (input capacity - C67
(see attachement)) and/or after it (output capacity -
C68)? Is there side effect to do that?

Your help is very appriciated!
Fred


--- David Rea <dave@dave...> wrote:

> I don't see the voltage scale on those TIFs,
but you
> say the ripple is
> only 3mV. Unless you're driving a VCO directly with
> the output of the
> power supply, I don't see how that could possibly
> cause the transmitter
> to glitch. The XE1203 datasheet reports (at a quick
> glance) that it
> works from 2.4 to 3.6VDC, so 3mV ripple in the
> supply really shouldn't
> bother it.
> 
> I see that the operating temp of the XE1203 is
> -40~85.
> 
> Here are a few things to consider:
> 
> 1) Does the circuit exhibit the same behavior when
> powered by a bench
> supply at low temperatures?
> 
> 2) A can of "Freeze Mist" or other electronics
> cooling spray can be
> helpful in troubleshooting this type of problem -
> you can spray
> refrigerant onto each chip and see which one causes
> your problem:
>
http://www.unicornelex.com/newunicorn/subcategory.php?catK04&
> 
> Dave
> 
> Quoting Frederic Beaulieu <frb78@frb7...>:
> 
> > I'm working with a RF transceiver Xemics XE1203.
> When
> > it is in Rx mode all operate correctly, but when
> it
> > turn in Tx mode (which require 50 mA more), the
> > message  is not sent correctly. The switcher
> output
> > voltage seem to take longer to stabilize (1400us
> > instead of 300us) but the ripple isn't bigger
> (3mV).
> >
> > I send you in attachment the output of the
> switcher at
> > room temperature, which work correctly, and at low
> > temperature, where at think there is the problem.
> >
> > Fred
> >
> > --- David Rea <dave@dave...> wrote:
> >
> > > > I use a LTC3401 with typical reference design
> and
> > > I
> > > > have few problems at low temperature (-10oC).
> This
> > > > seem to appear when a higher current is
> request by
> > > the
> > > > device (from 120mA to 170mA) and the battery
> (2 X
> > > > Energizer L91 AA 1.5V in parallel) should
> support
> > > this
> > > > increase.
> > >
> > > Can you be more specific about what problem is
> > > occuring? Is the output
> > > voltage dropping out? Problems with the
> switching?
> > > Excessive ripple?
> > >
> > > Dave
> > >
> > >
> >
> >
> >
> > __________________________________
> > 
> 
> 


		
__________________________________ 
 
 

I would change to a battery capable of lower temperature operation. 
Li-poly tends to be a lot better than alkaline, and is rechargable. LTC 
is not rechargable but operates down to -40C.

Al

Frederic Beaulieu wrote:

> 
> After few tests, I think it's the battery which cannot
> support the current load at lower temperature.
> I have put my board (without battery) in a freezer
> (~-10oC) for about half a hour then I have inserted
> the warm battery in it. All work fine! However, if I
> let the device working in the freezer, after 20
> minutes, the Tx problem occurs.
> Is there a way to solve this problem? Can I put bigger
> cap in front of the switcher (input capacity - C67
> (see attachement)) and/or after it (output capacity -
> C68)? Is there side effect to do that?
> 
> Your help is very appriciated!
> Fred
> 
> 
> --- David Rea <dave@dave...> wrote:
> 
> 
>>I don't see the voltage scale on those TIFs, but you
>>say the ripple is
>>only 3mV. Unless you're driving a VCO directly with
>>the output of the
>>power supply, I don't see how that could possibly
>>cause the transmitter
>>to glitch. The XE1203 datasheet reports (at a quick
>>glance) that it
>>works from 2.4 to 3.6VDC, so 3mV ripple in the
>>supply really shouldn't
>>bother it.
>>
>>I see that the operating temp of the XE1203 is
>>-40~85.
>>
>>Here are a few things to consider:
>>
>>1) Does the circuit exhibit the same behavior when
>>powered by a bench
>>supply at low temperatures?
>>
>>2) A can of "Freeze Mist" or other electronics
>>cooling spray can be
>>helpful in troubleshooting this type of problem -
>>you can spray
>>refrigerant onto each chip and see which one causes
>>your problem:
>>
> 
> http://www.unicornelex.com/newunicorn/subcategory.php?catK04&
> 
>>Dave
>>
>>Quoting Frederic Beaulieu <frb78@frb7...>:
>>
>>
>>>I'm working with a RF transceiver Xemics XE1203.
>>
>>When
>>
>>>it is in Rx mode all operate correctly, but when
>>
>>it
>>
>>>turn in Tx mode (which require 50 mA more), the
>>>message  is not sent correctly. The switcher
>>
>>output
>>
>>>voltage seem to take longer to stabilize (1400us
>>>instead of 300us) but the ripple isn't bigger
>>
>>(3mV).
>>
>>>I send you in attachment the output of the
>>
>>switcher at
>>
>>>room temperature, which work correctly, and at low
>>>temperature, where at think there is the problem.
>>>
>>>Fred
>>>
>>>--- David Rea <dave@dave...> wrote:
>>>
>>>
>>>>>I use a LTC3401 with typical reference design
>>
>>and
>>
>>>>I
>>>>
>>>>>have few problems at low temperature (-10oC).
>>
>>This
>>
>>>>>seem to appear when a higher current is
>>
>>request by
>>
>>>>the
>>>>
>>>>>device (from 120mA to 170mA) and the battery
>>
>>(2 X
>>
>>>>>Energizer L91 AA 1.5V in parallel) should
>>
>>support
>>
>>>>this
>>>>
>>>>>increase.
>>>>
>>>>Can you be more specific about what problem is
>>>>occuring? Is the output
>>>>voltage dropping out? Problems with the
>>
>>switching?
>>
>>>>Excessive ripple?
>>>>
>>>>Dave
>>>>
>>>>
>>>
>>>
>>>
>>>__________________________________
>>>
>>
>>
> 
> 
> 		
> __________________________________ 
>  
>  
> 
> 
> 
> 
> 
> 
> .
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
> 
> 

Have you tried a few different battery brands/chemistries?

Ripple isn't caused as much by the value of the capacitors as it is by
the Equivalent Series Resistance (ESR). You should see if the ESR of
your input capacitors goes up significantly as the caps get colder.

You may need to buy a special low-ESR capacitor for this. I use the TPS
series of low-ESR capacitors from AVX in my power supply designs.

Dave

Quoting Frederic Beaulieu <frb78@frb7...>:

> After few tests, I think it's the battery
which cannot
> support the current load at lower temperature.
> I have put my board (without battery) in a freezer
> (~-10oC) for about half a hour then I have inserted
> the warm battery in it. All work fine! However, if I
> let the device working in the freezer, after 20
> minutes, the Tx problem occurs.
> Is there a way to solve this problem? Can I put bigger
> cap in front of the switcher (input capacity - C67
> (see attachement)) and/or after it (output capacity -
> C68)? Is there side effect to do that?
>
> Your help is very appriciated!
> Fred
>
>
> --- David Rea <dave@dave...> wrote:
>
> > I don't see the voltage scale on those TIFs, but you
> > say the ripple is
> > only 3mV. Unless you're driving a VCO directly with
> > the output of the
> > power supply, I don't see how that could possibly
> > cause the transmitter
> > to glitch. The XE1203 datasheet reports (at a quick
> > glance) that it
> > works from 2.4 to 3.6VDC, so 3mV ripple in the
> > supply really shouldn't
> > bother it.
> >
> > I see that the operating temp of the XE1203 is
> > -40~85.
> >
> > Here are a few things to consider:
> >
> > 1) Does the circuit exhibit the same behavior when
> > powered by a bench
> > supply at low temperatures?
> >
> > 2) A can of "Freeze Mist" or other electronics
> > cooling spray can be
> > helpful in troubleshooting this type of problem -
> > you can spray
> > refrigerant onto each chip and see which one causes
> > your problem:
> >
> http://www.unicornelex.com/newunicorn/subcategory.php?catK04&
> >
> > Dave
> >
> > Quoting Frederic Beaulieu <frb78@frb7...>:
> >
> > > I'm working with a RF transceiver Xemics XE1203.
> > When
> > > it is in Rx mode all operate correctly, but when
> > it
> > > turn in Tx mode (which require 50 mA more), the
> > > message  is not sent correctly. The switcher
> > output
> > > voltage seem to take longer to stabilize (1400us
> > > instead of 300us) but the ripple isn't bigger
> > (3mV).
> > >
> > > I send you in attachment the output of the
> > switcher at
> > > room temperature, which work correctly, and at low
> > > temperature, where at think there is the problem.
> > >
> > > Fred
> > >
> > > --- David Rea <dave@dave...> wrote:
> > >
> > > > > I use a LTC3401 with typical reference design
> > and
> > > > I
> > > > > have few problems at low temperature (-10oC).
> > This
> > > > > seem to appear when a higher current is
> > request by
> > > > the
> > > > > device (from 120mA to 170mA) and the battery
> > (2 X
> > > > > Energizer L91 AA 1.5V in parallel) should
> > support
> > > > this
> > > > > increase.
> > > >
> > > > Can you be more specific about what problem is
> > > > occuring? Is the output
> > > > voltage dropping out? Problems with the
> > switching?
> > > > Excessive ripple?
> > > >
> > > > Dave
> > > >
> > > >
> > >
> > >
> > >
> > > __________________________________
> > > 
> >
> >
>
>
>
> __________________________________
> 
>
>

I used already a Lithium battery, the Energizer L91 AA
1.5V (see attachement), which is supposed to opperate
down to -40oC. The only thing I can see is that the
discharge current at lower temp is too low, but 170mA
is not that high ...

--- onestone <onestone@ones...> wrote:
> 
> I would change to a battery capable of lower
> temperature operation. 
> Li-poly tends to be a lot better than alkaline, and
> is rechargable. LTC 
> is not rechargable but operates down to -40C.
> 
> Al
> 
> Frederic Beaulieu wrote:
> 
> > 
> > After few tests, I think it's the battery which
> cannot
> > support the current load at lower temperature.
> > I have put my board (without battery) in a freezer
> > (~-10oC) for about half a hour then I have
> inserted
> > the warm battery in it. All work fine! However, if
> I
> > let the device working in the freezer, after 20
> > minutes, the Tx problem occurs.
> > Is there a way to solve this problem? Can I put
> bigger
> > cap in front of the switcher (input capacity - C67
> > (see attachement)) and/or after it (output
> capacity -
> > C68)? Is there side effect to do that?
> > 
> > Your help is very appriciated!
> > Fred
> > 
> > 
> > --- David Rea <dave@dave...> wrote:
> > 
> > 
> >>I don't see the voltage scale on those TIFs, but
> you
> >>say the ripple is
> >>only 3mV. Unless you're driving a VCO directly
> with
> >>the output of the
> >>power supply, I don't see how that could possibly
> >>cause the transmitter
> >>to glitch. The XE1203 datasheet reports (at a
> quick
> >>glance) that it
> >>works from 2.4 to 3.6VDC, so 3mV ripple in the
> >>supply really shouldn't
> >>bother it.
> >>
> >>I see that the operating temp of the XE1203 is
> >>-40~85.
> >>
> >>Here are a few things to consider:
> >>
> >>1) Does the circuit exhibit the same behavior when
> >>powered by a bench
> >>supply at low temperatures?
> >>
> >>2) A can of "Freeze Mist" or other electronics
> >>cooling spray can be
> >>helpful in troubleshooting this type of problem -
> >>you can spray
> >>refrigerant onto each chip and see which one
> causes
> >>your problem:
> >>
> > 
> >
>
http://www.unicornelex.com/newunicorn/subcategory.php?catK04&
> > 
> >>Dave
> >>
> >>Quoting Frederic Beaulieu <frb78@frb7...>:
> >>
> >>
> >>>I'm working with a RF transceiver Xemics XE1203.
> >>
> >>When
> >>
> >>>it is in Rx mode all operate correctly, but when
> >>
> >>it
> >>
> >>>turn in Tx mode (which require 50 mA more), the
> >>>message  is not sent correctly. The switcher
> >>
> >>output
> >>
> >>>voltage seem to take longer to stabilize (1400us
> >>>instead of 300us) but the ripple isn't bigger
> >>
> >>(3mV).
> >>
> >>>I send you in attachment the output of the
> >>
> >>switcher at
> >>
> >>>room temperature, which work correctly, and at
> low
> >>>temperature, where at think there is the problem.
> >>>
> >>>Fred
> >>>
> >>>--- David Rea <dave@dave...> wrote:
> >>>
> >>>
> >>>>>I use a LTC3401 with typical reference design
> >>
> >>and
> >>
> >>>>I
> >>>>
> >>>>>have few problems at low temperature (-10oC).
> >>
> >>This
> >>
> >>>>>seem to appear when a higher current is
> >>
> >>request by
> >>
> >>>>the
> >>>>
> >>>>>device (from 120mA to 170mA) and the battery
> >>
> >>(2 X
> >>
> >>>>>Energizer L91 AA 1.5V in parallel) should
> >>
> >>support
> >>
> >>>>this
> >>>>
> >>>>>increase.
> >>>>
> >>>>Can you be more specific about what problem is
> >>>>occuring? Is the output
> >>>>voltage dropping out? Problems with the
> >>
> >>switching?
> >>
> >>>>Excessive ripple?
> >>>>
> >>>>Dave
> >>>>
> >>>>
> >>>
> >>>
> >>>
> >>>__________________________________
> >>>
> >>
> >>
> > 
> > 
> > 		
> > __________________________________ 
> >  
> >  
> > 
> > 
> > [Non-text portions of this message have been
> removed]
> > 
> > 
> > 
> > .
> > 
> >  
> > Yahoo! Groups Links
> > 
> > 
> > 
> >  
> > 
> > 
> > 
> > 
> 
> 
> 
> .
> 
>  
> Yahoo! Groups Links
> 
> 
>     msp430-unsubscribe@msp4...
> 
>  
> 
> 
> 
> 


		
__________________________________ 
 

CR2032 goes to -40C. VARTA's CRAA (2A/h) goes to -30C.
Caps must be tantalum.



-----Mensagem original-----
De: onestone [mailto:onestone@ones...] 
Enviada em: sexta-feira, 10 de dezembro de 2004 16:24
Para: msp430@msp4...
Assunto: Re: [msp430] DC-DC converter design




I would change to a battery capable of lower temperature operation. 
Li-poly tends to be a lot better than alkaline, and is rechargable. LTC 
is not rechargable but operates down to -40C.

Al

Frederic Beaulieu wrote:

> 
> After few tests, I think it's the battery which cannot support the 
> current load at lower temperature. I have put my board (without 
> battery) in a freezer
> (~-10oC) for about half a hour then I have inserted
> the warm battery in it. All work fine! However, if I
> let the device working in the freezer, after 20
> minutes, the Tx problem occurs.
> Is there a way to solve this problem? Can I put bigger
> cap in front of the switcher (input capacity - C67
> (see attachement)) and/or after it (output capacity -
> C68)? Is there side effect to do that?
> 
> Your help is very appriciated!
> Fred
> 
> 
> --- David Rea <dave@dave...> wrote:
> 
> 
>>I don't see the voltage scale on those TIFs, but you
>>say the ripple is
>>only 3mV. Unless you're driving a VCO directly with
>>the output of the
>>power supply, I don't see how that could possibly
>>cause the transmitter
>>to glitch. The XE1203 datasheet reports (at a quick
>>glance) that it
>>works from 2.4 to 3.6VDC, so 3mV ripple in the
>>supply really shouldn't
>>bother it.
>>
>>I see that the operating temp of the XE1203 is
>>-40~85.
>>
>>Here are a few things to consider:
>>
>>1) Does the circuit exhibit the same behavior when
>>powered by a bench
>>supply at low temperatures?
>>
>>2) A can of "Freeze Mist" or other electronics
>>cooling spray can be
>>helpful in troubleshooting this type of problem -
>>you can spray
>>refrigerant onto each chip and see which one causes
>>your problem:
>>
> 
> http://www.unicornelex.com/newunicorn/subcategory.php?catK04&
> 
>>Dave
>>
>>Quoting Frederic Beaulieu <frb78@frb7...>:
>>
>>
>>>I'm working with a RF transceiver Xemics XE1203.
>>
>>When
>>
>>>it is in Rx mode all operate correctly, but when
>>
>>it
>>
>>>turn in Tx mode (which require 50 mA more), the
>>>message  is not sent correctly. The switcher
>>
>>output
>>
>>>voltage seem to take longer to stabilize (1400us
>>>instead of 300us) but the ripple isn't bigger
>>
>>(3mV).
>>
>>>I send you in attachment the output of the
>>
>>switcher at
>>
>>>room temperature, which work correctly, and at low temperature,
where 
>>>at think there is the problem.
>>>
>>>Fred
>>>
>>>--- David Rea <dave@dave...> wrote:
>>>
>>>
>>>>>I use a LTC3401 with typical reference design
>>
>>and
>>
>>>>I
>>>>
>>>>>have few problems at low temperature (-10oC).
>>
>>This
>>
>>>>>seem to appear when a higher current is
>>
>>request by
>>
>>>>the
>>>>
>>>>>device (from 120mA to 170mA) and the battery
>>
>>(2 X
>>
>>>>>Energizer L91 AA 1.5V in parallel) should
>>
>>support
>>
>>>>this
>>>>
>>>>>increase.
>>>>
>>>>Can you be more specific about what problem is
>>>>occuring? Is the output
>>>>voltage dropping out? Problems with the
>>
>>switching?
>>
>>>>Excessive ripple?
>>>>
>>>>Dave
>>>>
>>>>
>>>
>>>
>>>
>>>__________________________________
>>>
>>
>>
> 
> 
> 		
> __________________________________
>  
>  
> 
> 
> 
> 
> 
> 
> .
> 
>  
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
> 
> 



.

 
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