Multimeter Accuracy and AD587 Performance

Having built a small, portable 10.000V reference using the Analog Devices AD587 reference chip, now is a good time to evaluate its performance with a bunch of multimeters.

However, I have a feeling that the AD587 with its 10.000V ±5mV @25ºC is going to be the better performer than some of the multimeters being tested. In today’s performance shootout, ranked in order of their pedigree we have:

  • Fluke 789 Processmeter
  • Fluke 12 Multimeter
  • Extech EX330
  • Pro-Tester 03-150K
10Vref_meters
Today’s contenders. From left to right; Fluke 789, Fluke 12, Extech EX330 and Pro-Test 03-150K.

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AD587 Battery Powered 10V Reference Tutorial

Following on from a previous post discussing the Analog Devices AD587 precision 10.000V voltage reference, I built a portable device to utilise the chip.

Some requirements of the project were:

  • 10.000V ±5mV output
  • 10mA output
  • Battery operated device
  • Visual, low battery indication
  • Small, aluminium housing
  • Clear front panel
  • Low cost (under $50), readily available components

A low battery indication was a desired feature to prevent the device being used in an important test and the battery level drops low and compromises the AD587’s performance. A simple green LED will suffice. Output performance of 10.000V (± 5mV) couldn’t be compromised so there is no protection to prevent high current draw from the chip, I’ll just have to be sensible.

Battery powered AD587 10V reference.
Battery powered AD587 10V reference.

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Analog Devices AD587 10V Reference

Voltage references are a humble piece of hardware, their sole function is to provide a stable, known voltage. This constant, known value of voltage can then be used as a reference for ADCs and DACs as well as provide a precision current source.

I recently got hold of an Analog Devices AD587KN high precision 10.000V reference chip.

10Vref_AD587
AD587KN 10V precision reference

This model of chip has an output value of 10.000V ± 5mV (that is, an output value of 9.995V to 10.005V) straight out of the factory. A voltage drift of 10ppm/°C at 25°C meaning that the output voltage will drift by 10μV for each 1°C the chip is exposed to. Additionally, the chip has a voltage trim input, so if you have access to a precision voltmeter, the chip’s output value can be adjusted even closer to 10.000V.

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