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
Today’s contenders. From left to right; Fluke 789, Fluke 12, Extech EX330 and Pro-Test 03-150K.

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Changing HTU21D Temperature and Humidity Resolution

By default the HTU21D sets the temperature and humidity sensor resolutions are set at their highest. These default values are, humidity = 12bit and temperature = 14bit. This is all well and good for most situations when you are trying to get the best performance from your device. However, a higher resolution comes at the expense of increased measuring time. Consequently, a longer measuring time will increase the current consumption too.

To demonstrate, I’ve tabulated the maximum measuring times for the different sensor resolution modes from the HTU21D_datasheet.

Resolution Humidity Temperature
14bit NA 50ms
13bit NA 25ms
12bit 16ms 13ms
11bit 8ms 7ms
10bit 5ms NA
08bit 3ms NA

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