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Author Topic: High stability shunt resistor  (Read 2337 times)

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Offline ivonenandTopic starter

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High stability shunt resistor
« on: October 31, 2016, 07:03:13 am »
Hi Guys,
I'm doing a modular electronic load design and I need help with choosing a good shunt resistor. I need the shunt to handle 10A and I would like to have at least 100mV of sensing voltage, so that makes a 0.01 Ohm resistor. The module would be quite small and the heatsink would only need to dissipate 50W max, but still the PCB will heat up. So I'm looking for a high temperature stability resistors. The best ones I can find in Mouser of Farnell are 3W SMD are 50ppm/C, which seems quite high, as I'll be using a reference voltage that has 8ppm/C. Anyone has any recommendations?

Regards,
Ivo
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Offline bktemp

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Re: High stability shunt resistor
« Reply #1 on: October 31, 2016, 07:11:54 am »
Vishay/powertron has some nice current shunt resistors down to 1ppm/°C, but they are not small:
http://www.vishaypg.com/powertron/

SPR 4-T220 seems to be the smallest one suitable for your requirements.
« Last Edit: October 31, 2016, 02:55:34 pm by bktemp »
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Offline T3sl4co1l

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Re: High stability shunt resistor
« Reply #2 on: October 31, 2016, 01:56:21 pm »
Yeah Vishay Foil Products Division is the way to go, but you're going to pay for it, too.

Tim
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Offline bktemp

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Re: High stability shunt resistor
« Reply #3 on: October 31, 2016, 03:03:01 pm »
Quote from: T3sl4co1l on October 31, 2016, 01:56:21 pm
Yeah Vishay Foil Products Division is the way to go, but you're going to pay for it, too.
Yes, they are really expensive, but worth the money, because you get what you pay for.
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Offline RobK_NL

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Re: High stability shunt resistor
« Reply #4 on: October 31, 2016, 03:03:40 pm »
TT Electronics OARS series might meet your needs at 20 ppm/°C. Far cheaper than those Vishays, in any case.
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Offline bktemp

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Re: High stability shunt resistor
« Reply #5 on: October 31, 2016, 03:15:51 pm »
Quote from: RobK_NL on October 31, 2016, 03:03:40 pm
TT Electronics OARS series might meet your needs at 20 ppm/°C. Far cheaper than those Vishays, in any case.
The specified 20ppm/°C is misleading. It says "Element TCR ±20ppm/°C" So the total TCR isn't 20ppm/°C, especially for the lower values. Further down in the datasheet it guarantees only 40ppm/°C.
I have used the older OAR through hole version, and it is really bad. Maybe it is a problem with the stand-off affecting the temperature coefficient, but I avoid them for anything where the thermal coefficient is important.
They are cheap. That sums it up.

Isabellenhuette also has some nice precision resistors:
http://www.isabellenhuette.de/en/precision-and-power-resistors/
I have used their SMT series several times. They are specified at only 50ppm/°C max, but their typical coefficient is much better.
http://www.isabellenhuette.de/fileadmin/content/praezisions-leistungswiderstaende/SMT.PDF
« Last Edit: October 31, 2016, 03:21:52 pm by bktemp »
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