FS
Frank Stellmach
Thu, Jul 17, 2014 4:40 AM
Randy,
resistor matched in T.C. are extremely expensive, as the manufacturer
(or yourself) would have to select these from a batch of many samples.
reistors with very small T.C. (<1ppm/K) would do the job also, but they
also need to be stable over time, in shelf life opereation mode, i.e.
P<10mW.
That means, you need those hermetically sealed VHP202Z from Vishay, T.C.
is typically < 1ppm/K and they are stable to < 2ppm over 5years. But
they cost already 80€ each, depending on tolerance.
I made a longterm observation of these and found these parameters confirmed.
Frank
Randy,
resistor matched in T.C. are extremely expensive, as the manufacturer
(or yourself) would have to select these from a batch of many samples.
reistors with very small T.C. (<1ppm/K) would do the job also, but they
also need to be stable over time, in shelf life opereation mode, i.e.
P<10mW.
That means, you need those hermetically sealed VHP202Z from Vishay, T.C.
is typically < 1ppm/K and they are stable to < 2ppm over 5years. But
they cost already 80€ each, depending on tolerance.
I made a longterm observation of these and found these parameters confirmed.
Frank
RE
Randy Evans
Thu, Jul 17, 2014 3:26 PM
Frank,
The high cost is my concern, although high performance demands high price
typically. I am trying to double the voltage reference from either an
LM399 or LTZ1000, hence the need for precision matched resistors for a x2
non-inverting amplifier (using a LT1151 precision op amp). An alternative
I am investigating is using the LTC1043 in a voltage doubling circuit as
shown in Linear Technology app note AN 42, page 6, Figure 16. It states
that Vout = 2xVin +/- 5 ppm. I am less concerned about the absolute
accuracy than I am about the long term stability. I assume that a high
quality capacitor is required (low leakage, low ESR, low dielectric
absorbtion, etc.) but the circuit does not appear to be dependent on the
absolute value of the capacitors. I'm not sure if the two 1uF caps need
to be matched. If they do then that would be a show stopper.
Does anyone have any experience using the LTC1043 in such a circuit?
Thanks,
Randy
On Wed, Jul 16, 2014 at 9:40 PM, Frank Stellmach <frank.stellmach@freenet.de
Randy,
resistor matched in T.C. are extremely expensive, as the manufacturer (or
yourself) would have to select these from a batch of many samples.
reistors with very small T.C. (<1ppm/K) would do the job also, but they
also need to be stable over time, in shelf life opereation mode, i.e.
P<10mW.
That means, you need those hermetically sealed VHP202Z from Vishay, T.C.
is typically < 1ppm/K and they are stable to < 2ppm over 5years. But they
cost already 80€ each, depending on tolerance.
I made a longterm observation of these and found these parameters
confirmed.
Frank
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/
mailman/listinfo/volt-nuts
and follow the instructions there.
Frank,
The high cost is my concern, although high performance demands high price
typically. I am trying to double the voltage reference from either an
LM399 or LTZ1000, hence the need for precision matched resistors for a x2
non-inverting amplifier (using a LT1151 precision op amp). An alternative
I am investigating is using the LTC1043 in a voltage doubling circuit as
shown in Linear Technology app note AN 42, page 6, Figure 16. It states
that Vout = 2xVin +/- 5 ppm. I am less concerned about the absolute
accuracy than I am about the long term stability. I assume that a high
quality capacitor is required (low leakage, low ESR, low dielectric
absorbtion, etc.) but the circuit does not appear to be dependent on the
absolute value of the capacitors. I'm not sure if the two 1uF caps need
to be matched. If they do then that would be a show stopper.
Does anyone have any experience using the LTC1043 in such a circuit?
Thanks,
Randy
On Wed, Jul 16, 2014 at 9:40 PM, Frank Stellmach <frank.stellmach@freenet.de
> wrote:
> Randy,
>
> resistor matched in T.C. are extremely expensive, as the manufacturer (or
> yourself) would have to select these from a batch of many samples.
>
> reistors with very small T.C. (<1ppm/K) would do the job also, but they
> also need to be stable over time, in shelf life opereation mode, i.e.
> P<10mW.
>
> That means, you need those hermetically sealed VHP202Z from Vishay, T.C.
> is typically < 1ppm/K and they are stable to < 2ppm over 5years. But they
> cost already 80€ each, depending on tolerance.
>
> I made a longterm observation of these and found these parameters
> confirmed.
>
> Frank
> _______________________________________________
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/volt-nuts
> and follow the instructions there.
>
TM
Todd Micallef
Thu, Jul 17, 2014 10:23 PM
I am not sure if Fluke had matched tempco spare parts, but you can look at
some NOS resistors from Fluke on ebay. They may be a good start and some of
the pricing isn't bad.
Todd
On Thursday, July 17, 2014, Randy Evans wrote:
Frank,
The high cost is my concern, although high performance demands high price
typically. I am trying to double the voltage reference from either an
LM399 or LTZ1000, hence the need for precision matched resistors for a x2
non-inverting amplifier (using a LT1151 precision op amp). An alternative
I am investigating is using the LTC1043 in a voltage doubling circuit as
shown in Linear Technology app note AN 42, page 6, Figure 16. It states
that Vout = 2xVin +/- 5 ppm. I am less concerned about the absolute
accuracy than I am about the long term stability. I assume that a high
quality capacitor is required (low leakage, low ESR, low dielectric
absorbtion, etc.) but the circuit does not appear to be dependent on the
absolute value of the capacitors. I'm not sure if the two 1uF caps need
to be matched. If they do then that would be a show stopper.
Does anyone have any experience using the LTC1043 in such a circuit?
Thanks,
Randy
On Wed, Jul 16, 2014 at 9:40 PM, Frank Stellmach <
frank.stellmach@freenet.de javascript:;
Randy,
resistor matched in T.C. are extremely expensive, as the manufacturer (or
yourself) would have to select these from a batch of many samples.
reistors with very small T.C. (<1ppm/K) would do the job also, but they
also need to be stable over time, in shelf life opereation mode, i.e.
P<10mW.
That means, you need those hermetically sealed VHP202Z from Vishay, T.C.
is typically < 1ppm/K and they are stable to < 2ppm over 5years. But they
cost already 80€ each, depending on tolerance.
I made a longterm observation of these and found these parameters
confirmed.
Frank
volt-nuts mailing list -- volt-nuts@febo.com javascript:;
To unsubscribe, go to https://www.febo.com/cgi-bin/
mailman/listinfo/volt-nuts
and follow the instructions there.
I am not sure if Fluke had matched tempco spare parts, but you can look at
some NOS resistors from Fluke on ebay. They may be a good start and some of
the pricing isn't bad.
Todd
On Thursday, July 17, 2014, Randy Evans wrote:
> Frank,
>
> The high cost is my concern, although high performance demands high price
> typically. I am trying to double the voltage reference from either an
> LM399 or LTZ1000, hence the need for precision matched resistors for a x2
> non-inverting amplifier (using a LT1151 precision op amp). An alternative
> I am investigating is using the LTC1043 in a voltage doubling circuit as
> shown in Linear Technology app note AN 42, page 6, Figure 16. It states
> that Vout = 2xVin +/- 5 ppm. I am less concerned about the absolute
> accuracy than I am about the long term stability. I assume that a high
> quality capacitor is required (low leakage, low ESR, low dielectric
> absorbtion, etc.) but the circuit does not appear to be dependent on the
> absolute value of the capacitors. I'm not sure if the two 1uF caps need
> to be matched. If they do then that would be a show stopper.
>
> Does anyone have any experience using the LTC1043 in such a circuit?
>
> Thanks,
>
> Randy
>
>
> On Wed, Jul 16, 2014 at 9:40 PM, Frank Stellmach <
> frank.stellmach@freenet.de <javascript:;>
> > wrote:
>
> > Randy,
> >
> > resistor matched in T.C. are extremely expensive, as the manufacturer (or
> > yourself) would have to select these from a batch of many samples.
> >
> > reistors with very small T.C. (<1ppm/K) would do the job also, but they
> > also need to be stable over time, in shelf life opereation mode, i.e.
> > P<10mW.
> >
> > That means, you need those hermetically sealed VHP202Z from Vishay, T.C.
> > is typically < 1ppm/K and they are stable to < 2ppm over 5years. But they
> > cost already 80€ each, depending on tolerance.
> >
> > I made a longterm observation of these and found these parameters
> > confirmed.
> >
> > Frank
> > _______________________________________________
> > volt-nuts mailing list -- volt-nuts@febo.com <javascript:;>
> > To unsubscribe, go to https://www.febo.com/cgi-bin/
> > mailman/listinfo/volt-nuts
> > and follow the instructions there.
> >
> _______________________________________________
> volt-nuts mailing list -- volt-nuts@febo.com <javascript:;>
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.
AJ
Andreas Jahn
Fri, Jul 18, 2014 5:37 AM
Hello Randy,
I am using the LTC1043 in 1/2 VIN or 1/3 VIN configuration.
A matching of the caps is not necessary.
In the 1/2 VIN or 1/3 VIN configuration a matching would give
the advantage that the settling time of the cirquit is reduced.
But in 2* VIN or inverting configuration a matching gives no advantage.
So perhaps it is better to put a 1/2 VIN divider into a feedback loop.
The most important point: you will need a low leakage buffer amplifier
at the output.
The caps should be low leakage foil capacitors. (polypropylene would be
best).
The ESR is negligible against the switch resistance of around 1000 Ohms
And dielectric absorption would also affect only settling time.
In 1/2 VIN configuration I am using cheap small mylar capacitors (WIMA
MKS02)
(isolation time constant is given only with >1250 sec (3000 sec typ)).
Buffer amplifier is a LTC1050.
The circuit is very stable over temperature (10 - 40 deg C).
The absolute amplification error is usually some ppm lower than exact
2:1 value.
(depends somewhat on the pinning which is used so I am not shure wether
the pins are mixed up regarding the charge compensation)
So I dont know wether the ±1 ppm is more a stability figure than a
absolute value.
Even polypropylene capacitors do not change the amplification error.
With best regards
Andreas
Am 17.07.2014 17:26, schrieb Randy Evans:
Frank,
The high cost is my concern, although high performance demands high price
typically. I am trying to double the voltage reference from either an
LM399 or LTZ1000, hence the need for precision matched resistors for a x2
non-inverting amplifier (using a LT1151 precision op amp). An
alternative
I am investigating is using the LTC1043 in a voltage doubling circuit as
shown in Linear Technology app note AN 42, page 6, Figure 16. It states
that Vout = 2xVin ± 5 ppm. I am less concerned about the absolute
accuracy than I am about the long term stability. I assume that a high
quality capacitor is required (low leakage, low ESR, low dielectric
absorbtion, etc.) but the circuit does not appear to be dependent on the
absolute value of the capacitors. I'm not sure if the two 1uF caps need
to be matched. If they do then that would be a show stopper.
Does anyone have any experience using the LTC1043 in such a circuit?
Thanks,
Randy
Hello Randy,
I am using the LTC1043 in 1/2 VIN or 1/3 VIN configuration.
A matching of the caps is not necessary.
In the 1/2 VIN or 1/3 VIN configuration a matching would give
the advantage that the settling time of the cirquit is reduced.
But in 2* VIN or inverting configuration a matching gives no advantage.
So perhaps it is better to put a 1/2 VIN divider into a feedback loop.
The most important point: you will need a low leakage buffer amplifier
at the output.
The caps should be low leakage foil capacitors. (polypropylene would be
best).
The ESR is negligible against the switch resistance of around 1000 Ohms
And dielectric absorption would also affect only settling time.
In 1/2 VIN configuration I am using cheap small mylar capacitors (WIMA
MKS02)
(isolation time constant is given only with >1250 sec (3000 sec typ)).
Buffer amplifier is a LTC1050.
The circuit is very stable over temperature (10 - 40 deg C).
The absolute amplification error is usually some ppm lower than exact
2:1 value.
(depends somewhat on the pinning which is used so I am not shure wether
the pins are mixed up regarding the charge compensation)
So I dont know wether the ±1 ppm is more a stability figure than a
absolute value.
Even polypropylene capacitors do not change the amplification error.
With best regards
Andreas
Am 17.07.2014 17:26, schrieb Randy Evans:
> Frank,
>
> The high cost is my concern, although high performance demands high price
> typically. I am trying to double the voltage reference from either an
> LM399 or LTZ1000, hence the need for precision matched resistors for a x2
> non-inverting amplifier (using a LT1151 precision op amp). An
> alternative
> I am investigating is using the LTC1043 in a voltage doubling circuit as
> shown in Linear Technology app note AN 42, page 6, Figure 16. It states
> that Vout = 2xVin ± 5 ppm. I am less concerned about the absolute
> accuracy than I am about the long term stability. I assume that a high
> quality capacitor is required (low leakage, low ESR, low dielectric
> absorbtion, etc.) but the circuit does not appear to be dependent on the
> absolute value of the capacitors. I'm not sure if the two 1uF caps need
> to be matched. If they do then that would be a show stopper.
>
> Does anyone have any experience using the LTC1043 in such a circuit?
>
> Thanks,
>
> Randy
>
A
acbern@gmx.de
Fri, Jul 18, 2014 7:00 AM
randy,
re. vpg: they offer an hermetic divider (vhd) with typ. 0.1ppm tracking of tempco. if you are ok with lowest available abs. accuracy it will be well priced, I remember having asked them for a price and it was below 50€ for standard lead time (which can be very long). it is also fair to assume it would age more homogeneously than two separate resistors, also you dont need to think about how to keep two resistors at the same temp. make sure each resistor is loaded with less than 10mw, otherwise aging may be above what the claim in their collateral.
Gesendet: Donnerstag, 17. Juli 2014 um 04:40 Uhr
Von: "Frank Stellmach" frank.stellmach@freenet.de
An: volt-nuts@febo.com
Betreff: [volt-nuts] Matched resistors
Randy,
resistor matched in T.C. are extremely expensive, as the manufacturer
(or yourself) would have to select these from a batch of many samples.
reistors with very small T.C. (<1ppm/K) would do the job also, but they
also need to be stable over time, in shelf life opereation mode, i.e.
P<10mW.
That means, you need those hermetically sealed VHP202Z from Vishay, T.C.
is typically < 1ppm/K and they are stable to < 2ppm over 5years. But
they cost already 80€ each, depending on tolerance.
I made a longterm observation of these and found these parameters confirmed.
Frank
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
randy,
re. vpg: they offer an hermetic divider (vhd) with typ. 0.1ppm tracking of tempco. if you are ok with lowest available abs. accuracy it will be well priced, I remember having asked them for a price and it was below 50€ for standard lead time (which can be very long). it is also fair to assume it would age more homogeneously than two separate resistors, also you dont need to think about how to keep two resistors at the same temp. make sure each resistor is loaded with less than 10mw, otherwise aging may be above what the claim in their collateral.
> Gesendet: Donnerstag, 17. Juli 2014 um 04:40 Uhr
> Von: "Frank Stellmach" <frank.stellmach@freenet.de>
> An: volt-nuts@febo.com
> Betreff: [volt-nuts] Matched resistors
>
> Randy,
>
> resistor matched in T.C. are extremely expensive, as the manufacturer
> (or yourself) would have to select these from a batch of many samples.
>
> reistors with very small T.C. (<1ppm/K) would do the job also, but they
> also need to be stable over time, in shelf life opereation mode, i.e.
> P<10mW.
>
> That means, you need those hermetically sealed VHP202Z from Vishay, T.C.
> is typically < 1ppm/K and they are stable to < 2ppm over 5years. But
> they cost already 80€ each, depending on tolerance.
>
> I made a longterm observation of these and found these parameters confirmed.
>
> Frank
> _______________________________________________
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.
>
RE
Randy Evans
Sat, Jul 19, 2014 3:57 AM
Andreas,
That is good information, I appreciate it. I have contacted LT application
support but they have yet to get back to me on my questions except they did
recommend to use the LTC6943 instead of the LTC1043. Later generation I
guess.
I think i am going to try both the LTC6943 and the LT5400 resistor array
and characterize them. The LT5400 matching ratio looks pretty good over
temp (0.2ppm/C) but the absolute resistor change over temp is -10 to +25
ppm/C, a little larger than I would like for the circuit I am using.
Randy
On Thu, Jul 17, 2014 at 10:37 PM, Andreas Jahn Andreas_-_Jahn@t-online.de
wrote:
Hello Randy,
I am using the LTC1043 in 1/2 VIN or 1/3 VIN configuration.
A matching of the caps is not necessary.
In the 1/2 VIN or 1/3 VIN configuration a matching would give
the advantage that the settling time of the cirquit is reduced.
But in 2* VIN or inverting configuration a matching gives no advantage.
So perhaps it is better to put a 1/2 VIN divider into a feedback loop.
The most important point: you will need a low leakage buffer amplifier at
the output.
The caps should be low leakage foil capacitors. (polypropylene would be
best).
The ESR is negligible against the switch resistance of around 1000 Ohms
And dielectric absorption would also affect only settling time.
In 1/2 VIN configuration I am using cheap small mylar capacitors (WIMA
MKS02)
(isolation time constant is given only with >1250 sec (3000 sec typ)).
Buffer amplifier is a LTC1050.
The circuit is very stable over temperature (10 - 40 deg C).
The absolute amplification error is usually some ppm lower than exact 2:1
value.
(depends somewhat on the pinning which is used so I am not shure wether
the pins are mixed up regarding the charge compensation)
So I dont know wether the ±1 ppm is more a stability figure than a
absolute value.
Even polypropylene capacitors do not change the amplification error.
With best regards
Andreas
Am 17.07.2014 17:26, schrieb Randy Evans:
Frank,
The high cost is my concern, although high performance demands high price
typically. I am trying to double the voltage reference from either an
LM399 or LTZ1000, hence the need for precision matched resistors for a x2
non-inverting amplifier (using a LT1151 precision op amp). An alternative
I am investigating is using the LTC1043 in a voltage doubling circuit as
shown in Linear Technology app note AN 42, page 6, Figure 16. It states
that Vout = 2xVin ± 5 ppm. I am less concerned about the absolute
accuracy than I am about the long term stability. I assume that a high
quality capacitor is required (low leakage, low ESR, low dielectric
absorbtion, etc.) but the circuit does not appear to be dependent on the
absolute value of the capacitors. I'm not sure if the two 1uF caps need
to be matched. If they do then that would be a show stopper.
Does anyone have any experience using the LTC1043 in such a circuit?
Thanks,
Randy
Andreas,
That is good information, I appreciate it. I have contacted LT application
support but they have yet to get back to me on my questions except they did
recommend to use the LTC6943 instead of the LTC1043. Later generation I
guess.
I think i am going to try both the LTC6943 and the LT5400 resistor array
and characterize them. The LT5400 matching ratio looks pretty good over
temp (0.2ppm/C) but the absolute resistor change over temp is -10 to +25
ppm/C, a little larger than I would like for the circuit I am using.
Randy
On Thu, Jul 17, 2014 at 10:37 PM, Andreas Jahn <Andreas_-_Jahn@t-online.de>
wrote:
> Hello Randy,
>
> I am using the LTC1043 in 1/2 VIN or 1/3 VIN configuration.
> A matching of the caps is not necessary.
> In the 1/2 VIN or 1/3 VIN configuration a matching would give
> the advantage that the settling time of the cirquit is reduced.
> But in 2* VIN or inverting configuration a matching gives no advantage.
> So perhaps it is better to put a 1/2 VIN divider into a feedback loop.
>
> The most important point: you will need a low leakage buffer amplifier at
> the output.
> The caps should be low leakage foil capacitors. (polypropylene would be
> best).
> The ESR is negligible against the switch resistance of around 1000 Ohms
> And dielectric absorption would also affect only settling time.
>
> In 1/2 VIN configuration I am using cheap small mylar capacitors (WIMA
> MKS02)
> (isolation time constant is given only with >1250 sec (3000 sec typ)).
> Buffer amplifier is a LTC1050.
> The circuit is very stable over temperature (10 - 40 deg C).
> The absolute amplification error is usually some ppm lower than exact 2:1
> value.
> (depends somewhat on the pinning which is used so I am not shure wether
> the pins are mixed up regarding the charge compensation)
>
> So I dont know wether the ±1 ppm is more a stability figure than a
> absolute value.
> Even polypropylene capacitors do not change the amplification error.
>
> With best regards
>
> Andreas
>
> Am 17.07.2014 17:26, schrieb Randy Evans:
>
>> Frank,
>>
>> The high cost is my concern, although high performance demands high price
>> typically. I am trying to double the voltage reference from either an
>> LM399 or LTZ1000, hence the need for precision matched resistors for a x2
>> non-inverting amplifier (using a LT1151 precision op amp). An alternative
>> I am investigating is using the LTC1043 in a voltage doubling circuit as
>> shown in Linear Technology app note AN 42, page 6, Figure 16. It states
>> that Vout = 2xVin ± 5 ppm. I am less concerned about the absolute
>>
>> accuracy than I am about the long term stability. I assume that a high
>> quality capacitor is required (low leakage, low ESR, low dielectric
>> absorbtion, etc.) but the circuit does not appear to be dependent on the
>> absolute value of the capacitors. I'm not sure if the two 1uF caps need
>> to be matched. If they do then that would be a show stopper.
>>
>> Does anyone have any experience using the LTC1043 in such a circuit?
>>
>> Thanks,
>>
>> Randy
>>
>> _______________________________________________
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/volt-nuts
> and follow the instructions there.
>
RE
Randy Evans
Sat, Jul 19, 2014 4:00 AM
I am not familiar with "vpg" or "vhd" terms. I assume the former is a
company (European?) and the latter is a model type? Do you have a URL or
other information to get followup information. The 0.1 ppm tracking is
exactly what I am looking for and I don't need absolute accuracy.
Thanks,
Randy
On Fri, Jul 18, 2014 at 12:00 AM, acbern@gmx.de wrote:
randy,
re. vpg: they offer an hermetic divider (vhd) with typ. 0.1ppm tracking of
tempco. if you are ok with lowest available abs. accuracy it will be well
priced, I remember having asked them for a price and it was below 50€ for
standard lead time (which can be very long). it is also fair to assume it
would age more homogeneously than two separate resistors, also you dont
need to think about how to keep two resistors at the same temp. make sure
each resistor is loaded with less than 10mw, otherwise aging may be above
what the claim in their collateral.
Gesendet: Donnerstag, 17. Juli 2014 um 04:40 Uhr
Von: "Frank Stellmach" frank.stellmach@freenet.de
An: volt-nuts@febo.com
Betreff: [volt-nuts] Matched resistors
Randy,
resistor matched in T.C. are extremely expensive, as the manufacturer
(or yourself) would have to select these from a batch of many samples.
reistors with very small T.C. (<1ppm/K) would do the job also, but they
also need to be stable over time, in shelf life opereation mode, i.e.
P<10mW.
That means, you need those hermetically sealed VHP202Z from Vishay, T.C.
is typically < 1ppm/K and they are stable to < 2ppm over 5years. But
they cost already 80€ each, depending on tolerance.
I made a longterm observation of these and found these parameters
and follow the instructions there.
I am not familiar with "vpg" or "vhd" terms. I assume the former is a
company (European?) and the latter is a model type? Do you have a URL or
other information to get followup information. The 0.1 ppm tracking is
exactly what I am looking for and I don't need absolute accuracy.
Thanks,
Randy
On Fri, Jul 18, 2014 at 12:00 AM, <acbern@gmx.de> wrote:
> randy,
> re. vpg: they offer an hermetic divider (vhd) with typ. 0.1ppm tracking of
> tempco. if you are ok with lowest available abs. accuracy it will be well
> priced, I remember having asked them for a price and it was below 50€ for
> standard lead time (which can be very long). it is also fair to assume it
> would age more homogeneously than two separate resistors, also you dont
> need to think about how to keep two resistors at the same temp. make sure
> each resistor is loaded with less than 10mw, otherwise aging may be above
> what the claim in their collateral.
>
>
>
> > Gesendet: Donnerstag, 17. Juli 2014 um 04:40 Uhr
> > Von: "Frank Stellmach" <frank.stellmach@freenet.de>
> > An: volt-nuts@febo.com
> > Betreff: [volt-nuts] Matched resistors
> >
> > Randy,
> >
> > resistor matched in T.C. are extremely expensive, as the manufacturer
> > (or yourself) would have to select these from a batch of many samples.
> >
> > reistors with very small T.C. (<1ppm/K) would do the job also, but they
> > also need to be stable over time, in shelf life opereation mode, i.e.
> > P<10mW.
> >
> > That means, you need those hermetically sealed VHP202Z from Vishay, T.C.
> > is typically < 1ppm/K and they are stable to < 2ppm over 5years. But
> > they cost already 80€ each, depending on tolerance.
> >
> > I made a longterm observation of these and found these parameters
> confirmed.
> >
> > Frank
> > _______________________________________________
> > volt-nuts mailing list -- volt-nuts@febo.com
> > To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> > and follow the instructions there.
> >
> _______________________________________________
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.
>
RE
Randy Evans
Sat, Jul 19, 2014 4:07 AM
I figured out that VPG is Vishay Precision Group but I have not managed to
identify the vhd hermetic divider. Could you point me to the location on
the Vishay web site?
Thanks,
Randy
On Fri, Jul 18, 2014 at 9:00 PM, Randy Evans randyevans2688@gmail.com
wrote:
I am not familiar with "vpg" or "vhd" terms. I assume the former is a
company (European?) and the latter is a model type? Do you have a URL or
other information to get followup information. The 0.1 ppm tracking is
exactly what I am looking for and I don't need absolute accuracy.
Thanks,
Randy
On Fri, Jul 18, 2014 at 12:00 AM, acbern@gmx.de wrote:
randy,
re. vpg: they offer an hermetic divider (vhd) with typ. 0.1ppm tracking
of tempco. if you are ok with lowest available abs. accuracy it will be
well priced, I remember having asked them for a price and it was below 50€
for standard lead time (which can be very long). it is also fair to assume
it would age more homogeneously than two separate resistors, also you dont
need to think about how to keep two resistors at the same temp. make sure
each resistor is loaded with less than 10mw, otherwise aging may be above
what the claim in their collateral.
Gesendet: Donnerstag, 17. Juli 2014 um 04:40 Uhr
Von: "Frank Stellmach" frank.stellmach@freenet.de
An: volt-nuts@febo.com
Betreff: [volt-nuts] Matched resistors
Randy,
resistor matched in T.C. are extremely expensive, as the manufacturer
(or yourself) would have to select these from a batch of many samples.
reistors with very small T.C. (<1ppm/K) would do the job also, but they
also need to be stable over time, in shelf life opereation mode, i.e.
P<10mW.
That means, you need those hermetically sealed VHP202Z from Vishay, T.C.
is typically < 1ppm/K and they are stable to < 2ppm over 5years. But
they cost already 80€ each, depending on tolerance.
I made a longterm observation of these and found these parameters
and follow the instructions there.
I figured out that VPG is Vishay Precision Group but I have not managed to
identify the vhd hermetic divider. Could you point me to the location on
the Vishay web site?
Thanks,
Randy
On Fri, Jul 18, 2014 at 9:00 PM, Randy Evans <randyevans2688@gmail.com>
wrote:
> I am not familiar with "vpg" or "vhd" terms. I assume the former is a
> company (European?) and the latter is a model type? Do you have a URL or
> other information to get followup information. The 0.1 ppm tracking is
> exactly what I am looking for and I don't need absolute accuracy.
>
> Thanks,
>
> Randy
>
>
> On Fri, Jul 18, 2014 at 12:00 AM, <acbern@gmx.de> wrote:
>
>> randy,
>> re. vpg: they offer an hermetic divider (vhd) with typ. 0.1ppm tracking
>> of tempco. if you are ok with lowest available abs. accuracy it will be
>> well priced, I remember having asked them for a price and it was below 50€
>> for standard lead time (which can be very long). it is also fair to assume
>> it would age more homogeneously than two separate resistors, also you dont
>> need to think about how to keep two resistors at the same temp. make sure
>> each resistor is loaded with less than 10mw, otherwise aging may be above
>> what the claim in their collateral.
>>
>>
>>
>> > Gesendet: Donnerstag, 17. Juli 2014 um 04:40 Uhr
>> > Von: "Frank Stellmach" <frank.stellmach@freenet.de>
>> > An: volt-nuts@febo.com
>> > Betreff: [volt-nuts] Matched resistors
>> >
>> > Randy,
>> >
>> > resistor matched in T.C. are extremely expensive, as the manufacturer
>> > (or yourself) would have to select these from a batch of many samples.
>> >
>> > reistors with very small T.C. (<1ppm/K) would do the job also, but they
>> > also need to be stable over time, in shelf life opereation mode, i.e.
>> > P<10mW.
>> >
>> > That means, you need those hermetically sealed VHP202Z from Vishay, T.C.
>> > is typically < 1ppm/K and they are stable to < 2ppm over 5years. But
>> > they cost already 80€ each, depending on tolerance.
>> >
>> > I made a longterm observation of these and found these parameters
>> confirmed.
>> >
>> > Frank
>> > _______________________________________________
>> > volt-nuts mailing list -- volt-nuts@febo.com
>> > To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
>> > and follow the instructions there.
>> >
>> _______________________________________________
>> volt-nuts mailing list -- volt-nuts@febo.com
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
>> and follow the instructions there.
>>
>
>
AJ
Andreas Jahn
Sat, Jul 19, 2014 4:34 AM
I figured out that VPG is Vishay Precision Group but I have not managed to
identify the vhd hermetic divider. Could you point me to the location on
the Vishay web site?
Thanks,
Randy
On Fri, Jul 18, 2014 at 9:00 PM, Randy Evans randyevans2688@gmail.com
wrote:
I am not familiar with "vpg" or "vhd" terms. I assume the former is a
company (European?) and the latter is a model type? Do you have a URL or
other information to get followup information. The 0.1 ppm tracking is
exactly what I am looking for and I don't need absolute accuracy.
Thanks,
Randy
On Fri, Jul 18, 2014 at 12:00 AM, acbern@gmx.de wrote:
randy,
re. vpg: they offer an hermetic divider (vhd) with typ. 0.1ppm tracking
of tempco. if you are ok with lowest available abs. accuracy it will be
well priced, I remember having asked them for a price and it was below 50€
for standard lead time (which can be very long). it is also fair to assume
it would age more homogeneously than two separate resistors, also you dont
need to think about how to keep two resistors at the same temp. make sure
each resistor is loaded with less than 10mw, otherwise aging may be above
what the claim in their collateral.
Gesendet: Donnerstag, 17. Juli 2014 um 04:40 Uhr
Von: "Frank Stellmach" frank.stellmach@freenet.de
An: volt-nuts@febo.com
Betreff: [volt-nuts] Matched resistors
Randy,
resistor matched in T.C. are extremely expensive, as the manufacturer
(or yourself) would have to select these from a batch of many samples.
reistors with very small T.C. (<1ppm/K) would do the job also, but they
also need to be stable over time, in shelf life opereation mode, i.e.
P<10mW.
That means, you need those hermetically sealed VHP202Z from Vishay, T.C.
is typically < 1ppm/K and they are stable to < 2ppm over 5years. But
they cost already 80€ each, depending on tolerance.
I made a longterm observation of these and found these parameters
and follow the instructions there.
http://www.vishaypg.com/foil-resistors/list/product-63036/
http://www.vishaypg.com/doc?63036
Am 19.07.2014 06:07, schrieb Randy Evans:
> I figured out that VPG is Vishay Precision Group but I have not managed to
> identify the vhd hermetic divider. Could you point me to the location on
> the Vishay web site?
>
> Thanks,
>
> Randy
>
>
> On Fri, Jul 18, 2014 at 9:00 PM, Randy Evans <randyevans2688@gmail.com>
> wrote:
>
>> I am not familiar with "vpg" or "vhd" terms. I assume the former is a
>> company (European?) and the latter is a model type? Do you have a URL or
>> other information to get followup information. The 0.1 ppm tracking is
>> exactly what I am looking for and I don't need absolute accuracy.
>>
>> Thanks,
>>
>> Randy
>>
>>
>> On Fri, Jul 18, 2014 at 12:00 AM, <acbern@gmx.de> wrote:
>>
>>> randy,
>>> re. vpg: they offer an hermetic divider (vhd) with typ. 0.1ppm tracking
>>> of tempco. if you are ok with lowest available abs. accuracy it will be
>>> well priced, I remember having asked them for a price and it was below 50€
>>> for standard lead time (which can be very long). it is also fair to assume
>>> it would age more homogeneously than two separate resistors, also you dont
>>> need to think about how to keep two resistors at the same temp. make sure
>>> each resistor is loaded with less than 10mw, otherwise aging may be above
>>> what the claim in their collateral.
>>>
>>>
>>>
>>>> Gesendet: Donnerstag, 17. Juli 2014 um 04:40 Uhr
>>>> Von: "Frank Stellmach" <frank.stellmach@freenet.de>
>>>> An: volt-nuts@febo.com
>>>> Betreff: [volt-nuts] Matched resistors
>>>>
>>>> Randy,
>>>>
>>>> resistor matched in T.C. are extremely expensive, as the manufacturer
>>>> (or yourself) would have to select these from a batch of many samples.
>>>>
>>>> reistors with very small T.C. (<1ppm/K) would do the job also, but they
>>>> also need to be stable over time, in shelf life opereation mode, i.e.
>>>> P<10mW.
>>>>
>>>> That means, you need those hermetically sealed VHP202Z from Vishay, T.C.
>>>> is typically < 1ppm/K and they are stable to < 2ppm over 5years. But
>>>> they cost already 80€ each, depending on tolerance.
>>>>
>>>> I made a longterm observation of these and found these parameters
>>> confirmed.
>>>> Frank
>>>> _______________________________________________
>>>> volt-nuts mailing list -- volt-nuts@febo.com
>>>> To unsubscribe, go to
>>> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
>>>> and follow the instructions there.
>>>>
>>> _______________________________________________
>>> volt-nuts mailing list -- volt-nuts@febo.com
>>> To unsubscribe, go to
>>> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
>>> and follow the instructions there.
>>>
>>
> _______________________________________________
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.
AJ
Andreas Jahn
Sat, Jul 19, 2014 5:11 AM
Hello Randy,
I think the only difference is in oscillator section (and thus power
consumption)
and of cause the TSSOP-package.
The LTC1043 is easily available from stock e.g. from digikey.
The LTC6943 is more difficult to get.
Within the Keithley 2002 LTC1043 is used.
http://www.eevblog.com/forum/testgear/keithley-2002-8-5-digit-dmm-review-and-teardown/
http://dev.xdevs.com/projects/kei2002/repository/entry/photos/K1/small/K2002_1-2251.jpg
I have added a drift chart with longterm drift data.
Note: the drift is for the whole measurement arrangement.
It consists of 3 7V references (2 LTZ1000A and 1 LM399)
measured via a LTC1043 divider with a 24 bit LTC2400 ADC with
temperature compensated voltage reference AD586LQ.
So most of the drift is related to the AD586LQ reference.
(X-axis is in days, Y-axis in ppm)
I get around 2 ppm drift for the LTZ1000A over 1 year
which I guess is mostly humidity related
from the ADC printed cirquit board + AD586 reference drift
and usually below 0.25 ppm standard deviation over 1000 hours. (42 days).
All at unstabilized room temperature.
I guess with resistors you will need ovenized temperature stabilisation
to achieve this.
with best regards
Andreas
Am 19.07.2014 05:57, schrieb Randy Evans:
Andreas,
That is good information, I appreciate it. I have contacted LT application
support but they have yet to get back to me on my questions except they did
recommend to use the LTC6943 instead of the LTC1043. Later generation I
guess.
I think i am going to try both the LTC6943 and the LT5400 resistor array
and characterize them. The LT5400 matching ratio looks pretty good over
temp (0.2ppm/C) but the absolute resistor change over temp is -10 to +25
ppm/C, a little larger than I would like for the circuit I am using.
Randy
On Thu, Jul 17, 2014 at 10:37 PM, Andreas Jahn Andreas_-_Jahn@t-online.de
wrote:
Hello Randy,
I am using the LTC1043 in 1/2 VIN or 1/3 VIN configuration.
A matching of the caps is not necessary.
In the 1/2 VIN or 1/3 VIN configuration a matching would give
the advantage that the settling time of the cirquit is reduced.
But in 2* VIN or inverting configuration a matching gives no advantage.
So perhaps it is better to put a 1/2 VIN divider into a feedback loop.
The most important point: you will need a low leakage buffer amplifier at
the output.
The caps should be low leakage foil capacitors. (polypropylene would be
best).
The ESR is negligible against the switch resistance of around 1000 Ohms
And dielectric absorption would also affect only settling time.
In 1/2 VIN configuration I am using cheap small mylar capacitors (WIMA
MKS02)
(isolation time constant is given only with >1250 sec (3000 sec typ)).
Buffer amplifier is a LTC1050.
The circuit is very stable over temperature (10 - 40 deg C).
The absolute amplification error is usually some ppm lower than exact 2:1
value.
(depends somewhat on the pinning which is used so I am not shure wether
the pins are mixed up regarding the charge compensation)
So I dont know wether the ±1 ppm is more a stability figure than a
absolute value.
Even polypropylene capacitors do not change the amplification error.
With best regards
Andreas
Am 17.07.2014 17:26, schrieb Randy Evans:
Frank,
The high cost is my concern, although high performance demands high price
typically. I am trying to double the voltage reference from either an
LM399 or LTZ1000, hence the need for precision matched resistors for a x2
non-inverting amplifier (using a LT1151 precision op amp). An alternative
I am investigating is using the LTC1043 in a voltage doubling circuit as
shown in Linear Technology app note AN 42, page 6, Figure 16. It states
that Vout = 2xVin ± 5 ppm. I am less concerned about the absolute
accuracy than I am about the long term stability. I assume that a high
quality capacitor is required (low leakage, low ESR, low dielectric
absorbtion, etc.) but the circuit does not appear to be dependent on the
absolute value of the capacitors. I'm not sure if the two 1uF caps need
to be matched. If they do then that would be a show stopper.
Does anyone have any experience using the LTC1043 in such a circuit?
Thanks,
Randy
Hello Randy,
I think the only difference is in oscillator section (and thus power
consumption)
and of cause the TSSOP-package.
The LTC1043 is easily available from stock e.g. from digikey.
The LTC6943 is more difficult to get.
Within the Keithley 2002 LTC1043 is used.
http://www.eevblog.com/forum/testgear/keithley-2002-8-5-digit-dmm-review-and-teardown/
http://dev.xdevs.com/projects/kei2002/repository/entry/photos/K1/small/K2002_1-2251.jpg
I have added a drift chart with longterm drift data.
Note: the drift is for the whole measurement arrangement.
It consists of 3 7V references (2 LTZ1000A and 1 LM399)
measured via a LTC1043 divider with a 24 bit LTC2400 ADC with
temperature compensated voltage reference AD586LQ.
So most of the drift is related to the AD586LQ reference.
(X-axis is in days, Y-axis in ppm)
I get around 2 ppm drift for the LTZ1000A over 1 year
which I guess is mostly humidity related
from the ADC printed cirquit board + AD586 reference drift
and usually below 0.25 ppm standard deviation over 1000 hours. (42 days).
All at unstabilized room temperature.
I guess with resistors you will need ovenized temperature stabilisation
to achieve this.
with best regards
Andreas
Am 19.07.2014 05:57, schrieb Randy Evans:
> Andreas,
>
> That is good information, I appreciate it. I have contacted LT application
> support but they have yet to get back to me on my questions except they did
> recommend to use the LTC6943 instead of the LTC1043. Later generation I
> guess.
>
> I think i am going to try both the LTC6943 and the LT5400 resistor array
> and characterize them. The LT5400 matching ratio looks pretty good over
> temp (0.2ppm/C) but the absolute resistor change over temp is -10 to +25
> ppm/C, a little larger than I would like for the circuit I am using.
>
> Randy
>
>
> On Thu, Jul 17, 2014 at 10:37 PM, Andreas Jahn <Andreas_-_Jahn@t-online.de>
> wrote:
>
>> Hello Randy,
>>
>> I am using the LTC1043 in 1/2 VIN or 1/3 VIN configuration.
>> A matching of the caps is not necessary.
>> In the 1/2 VIN or 1/3 VIN configuration a matching would give
>> the advantage that the settling time of the cirquit is reduced.
>> But in 2* VIN or inverting configuration a matching gives no advantage.
>> So perhaps it is better to put a 1/2 VIN divider into a feedback loop.
>>
>> The most important point: you will need a low leakage buffer amplifier at
>> the output.
>> The caps should be low leakage foil capacitors. (polypropylene would be
>> best).
>> The ESR is negligible against the switch resistance of around 1000 Ohms
>> And dielectric absorption would also affect only settling time.
>>
>> In 1/2 VIN configuration I am using cheap small mylar capacitors (WIMA
>> MKS02)
>> (isolation time constant is given only with >1250 sec (3000 sec typ)).
>> Buffer amplifier is a LTC1050.
>> The circuit is very stable over temperature (10 - 40 deg C).
>> The absolute amplification error is usually some ppm lower than exact 2:1
>> value.
>> (depends somewhat on the pinning which is used so I am not shure wether
>> the pins are mixed up regarding the charge compensation)
>>
>> So I dont know wether the ±1 ppm is more a stability figure than a
>> absolute value.
>> Even polypropylene capacitors do not change the amplification error.
>>
>> With best regards
>>
>> Andreas
>>
>> Am 17.07.2014 17:26, schrieb Randy Evans:
>>
>>> Frank,
>>>
>>> The high cost is my concern, although high performance demands high price
>>> typically. I am trying to double the voltage reference from either an
>>> LM399 or LTZ1000, hence the need for precision matched resistors for a x2
>>> non-inverting amplifier (using a LT1151 precision op amp). An alternative
>>> I am investigating is using the LTC1043 in a voltage doubling circuit as
>>> shown in Linear Technology app note AN 42, page 6, Figure 16. It states
>>> that Vout = 2xVin ± 5 ppm. I am less concerned about the absolute
>>>
>>> accuracy than I am about the long term stability. I assume that a high
>>> quality capacitor is required (low leakage, low ESR, low dielectric
>>> absorbtion, etc.) but the circuit does not appear to be dependent on the
>>> absolute value of the capacitors. I'm not sure if the two 1uF caps need
>>> to be matched. If they do then that would be a show stopper.
>>>
>>> Does anyone have any experience using the LTC1043 in such a circuit?
>>>
>>> Thanks,
>>>
>>> Randy
>>>
>>> _______________________________________________
>> volt-nuts mailing list -- volt-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/
>> mailman/listinfo/volt-nuts
>> and follow the instructions there.
>>
> _______________________________________________
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.
