ATM90E26 Calibration method question - Page 1
Forum section: electronics / general

author: pepesanches
author_rank: Newbie
timestamp: March 03, 2021, 02:23:31 pm
content: Hello, I'm fairly new to this forum, my name is PepeI am having troubles trying to calibrate the ATM90E26 IC, wich is an AC voltage-current metering IC with pulse output for active and reactive energy from Atmel (Microchip).This question is from a complete amateur side in regards to calibration methods: The calibration should be done in a control circuit (like a special scenario)? or it can be done on the run (like while using the IC in any circuit)?The thing is, after a few attempts at calibrating, when powering down or reseting the IC the calibration parameters are lost. This means that the calibration parametes have to be set on site or save in an external memory so I can use them each time it's needed. Is this a correct approach?At the moment, I'm calibrating the IC in a custom board that operates a street light power supply (on-off, dimmer 1-10V). AC voltage is 230V (I'm handling this in a secure manner of course, having the right precautions) and maximun current drawn by the light is 0.7A.The circuit for measuring current consist on a 22mOhms shunt resistor, and for voltage sampling a series of 4 x 220kOhms resistors. The rest is exactly as the application note describes in the circuit :http://ww1.microchip.com/downloads/en/AppNotes/Atmel-46102-SE-M90E26-ApplicationNote.pdfMicrocontroller is a SAMR35 from Microchip. The uC is no isolated from the metering IC as the circuit will not be near any contact with people.Continuing with another question, in datasheet says : "Calibrate gain at unity power factor;" and "Calibrate phase angle compensation at 0.5 inductive power factor."How can I achieve this power factors in reality?Does this two sentences mean that I can't make the calibrations "on the run", and it need to be done in control circuit?Thank you for your time in advance, and sorry for bad english (I hope the questions were understandable)

author: pepesanches
author_rank: Newbie
timestamp: March 05, 2021, 08:58:54 pm
content: Continuing the previous post;I have read that in order to achieve a load that makes a power factor equal to 1, this load has to be resistive. So I'm going to connect a few old lamps, the ones with a resistance inside (don't know the name in english sorry), and with this achieve 1A of current approximately.I have also read that to achieve a power factor of 0.5 the circuit has to include some kind of inductive load. This is where I get a bit lost.How can I achieve an inductive load to test this, and what kind of equipment should I get to corroborate the results?Does the inductive load has to consume the same amount of current as the resistive one?Sadly my resources are a bit limited and I can't afford important lab equipment to measure with great accuracy, at the moment all I have got (in terms of lab equipment) is an oscilloscope, a DC variable power supply (max 30V-5A), and 2 different multimeters (one being an amp-meter clamp).I can get a bit crafty, in a way, and try some crazy homemade solution (if is not too crazy tho xD )Thanks for your time!