TI's new RES60A makes high-voltage attenuation easy! - Page 1
Forum section: electronics / general

author: laichh
author_rank: Regular Contributor
timestamp: October 22, 2024, 03:25:25 am
content: An alternative to Caddock, Vishay, & VPG divider.https://www.ti.com/product/RES60A-Q1

author: mendip_discovery
author_rank: Super Contributor
timestamp: October 22, 2024, 05:32:41 pm
content: Tempting solution for an issue I have of measuring output of some Hipot testers, it states it is happy up to 4k for 60 seconds. I wonder if it could be pushed to 5kV without long term issues.

author: HalFoster
author_rank: Frequent Contributor
timestamp: October 22, 2024, 05:47:16 pm
content: Very nice! And they have a related low voltage part with dual matched dividers as well:https://www.ti.com/product/RES11AHal

author: razvan784
author_rank: Regular Contributor
timestamp: October 22, 2024, 07:19:54 pm
content: Tracking TC 1 ppm/K typ., 5 ppm/K max.Voltage Coeff. 2 ppm/V typ.Very nice.I see one slight drawback, the 15% absolute tolerance, which does allow you to claim >10M input resistance, but not 10M precisely.Long-term drift and humidity sensitivity might be some other issues.

author: laichh
author_rank: Regular Contributor
timestamp: October 23, 2024, 02:53:51 am
content: Quote from: razvan784 on October 22, 2024, 07:19:54 pmVoltage coefficient of 2 ppm/V could be an issue! Imagine up to ±2 V of measurement error when measuring a 1000 V source, that is between 998 V ~ 1002 V, or 3½ digit resolution limited just by the voltage coefficient alone.In contrast, the similar 10 MΩ voltage divider from Vishay & Caddock has a voltage coefficient of less than 0.02 ppm/V.https://www.vishay.com/docs/60043/cns471.pdfhttps://www.caddock.com/online_catalog/mrktg_lit/TypeHVD.pdfhttps://www.caddock.com/online_catalog/mrktg_lit/TypeUSVD.pdf

author: Kleinstein
author_rank: Super Contributor
timestamp: October 23, 2024, 07:07:41 am
content: The voltage coefficient would be a problem. However the main nonlinearity is usually more a thermal thing and thus more a square law, not a linear part as implied by giving ppm/V. The thermal effect is a principle limitation for such a small case - for improved accuracy some better DMMs use additional heating to compensate. For the thermal effect it also make a difference which voltage is assumed (e.g. 500 V , 1000 V or maybe 1700 V). The RES11 data-sheet shows using a rather high voltage used for the test of the voltage coeffcient.For the Vishay and Caddock resistors the voltage coeffient given in the data-sheets may be just the the linear part, so excluding the direct thermal effect on the TCR. A linear effect is possible from uneven heating and thermal EMF. So the numbers may not be comparable.A problem with the high voltage dividers from Ti is there ESD rating - when used for a DMM input, they would need extra ESD protection ! Once damages by ESD the resistor may no longer be able to withstand a high voltage. So the dividers are really made to be used in a more fixed circuit, like a high voltage power supply or checking on the high voltage battery.After all the divider is a rel. small and cheap part ($2 range), not really made for highest performance. The plastic case also makes it possibly sensitive to humidity effects. For high performance applications the divider ratio is also a bit large - one would like more 1:100 and I would even like 1:50.It is still nice to see a new source for precision resistor arrays. The lower resistance versions like RES11 are mor something for high precision, though these are missing doubled pins (4 wire connections) at the ends.