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129 points hasheddan | 2 comments | | HN request time: 0.762s | source
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SOLAR_FIELDS ◴[] No.44367397[source]
Nordic makes some good products. When I was doing hardware design for a product that uses a battery my options for power profiling were either not to do it or spend some eye watering amount of money. Then I discovered Nordic makes the PPKII, a cost effective, highly accurate profiler with quite good software. I detect good things in store for the company just based on the quality of stuff they have been putting out.
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Neywiny ◴[] No.44367526[source]
Looks like it switches different ranges. ST makes something similar that has similar dynamic range without switching. They use analog circuitry (op amps and junk) to compensate for the resistor drop, so the path is uninterrupted. I've had systems where the auto-ranging on a bench meter is enough to cause it to reset. I can't find a schematic for the PPKII (haven't looked too hard though) but if it's actually switching the supply, that can cause issues to devices downstream. Especially if that switching causes a voltage drop change.
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1. readmodifywrite ◴[] No.44367661[source]
It switches the detection range, but not the actual power supply. You can ramp from <5 uA up to 500 mA and back all you want. I haven't noticed any glitching on the actual supply.

Schematics: https://www.nordicsemi.com/Products/Development-hardware/Pow...

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2. dragontamer ◴[] No.44370442[source]
With the onset of cheap 16-bit, 18-bit or even 24-bit sigma delta ADCs, it isn't a very hard circuit to shove a 1 Ohm sense resistor, 2.048V reference and have sensing down to 31uA (16-bit), 8uA (18-bit) or less for 24-bit ADC.

SigmaDelta gets pricy if you want higher speeds though. But it's possible.