Hi all,
I am using an AD5254 (1k version) and an arduino to simulate a pt1000 sensor.
Actually I have a device that use pt1000 for measure temperature and instead plug in the pt1000 sensor I wired my arduino and digital pot like in the attached picture.
I am changing the W0 value every >50ms from arduino.
The issue I have is that at some point (i haven t been able to find a pattern) the AD5254 getting very very hot (2 of them just had smoke out).
Also when is getting hot it doesn't change resistance anymore.
What I am doing wrong?!
Some important info:
Voltage measured without the pt1000 connected (on the device that actually read pt1000) is about 13.3V.
Voltage measured with AD5254 connected like in the picture is around 1.5V.
AD5254 is powered and controlled from arduino mega.
Maximum allowed continues current through AD5254 is 5mA. And PT1000 measurement most likely require higher current. Connect a regular 1K resister or real PT1000 and measure current through it.
alesam:
Maximum allowed continues current through AD5254 is 5mA. And PT1000 measurement most likely require higher current. Connect a regular 1K resister or real PT1000 and measure current through it.
I will do that shortly and get back.
WattsThat:
The 13.8 volts is why they die, no pin on the AD5254 can exceed the applied VDD or VSS.
In addition, could you explain the purpose of the voltage divider on the two output pins of the A5254?
I did that to have a voltage under 5V on AD pins...I saw in datasheed that it supports max 5V.
I redo all the wiring and just play with it like in pictures attached:
I put the 2 capacitors on the power to AD5254.
I put together W0 and B0.
Findings :
If I measure voltage between grey wires W0/A0 i have 0. Is that normal?
I also measured resistance and is moving once I wrote values so it acting normal.
At some point I saw that was again overheated and I unplug it.
Then put back again and till now is cold and is working normal?
What can cause that overheating in that case? Only multimetter was tied to grey wires....I can t reproduced it now.
Hi,
Can you post a complete diagram, showing all your connections including the mega and the AD5254 and the power supply connections and how you have it connected to the device that is expecting the PT1000?
Also the AD5254 pots are not isolated as such and need to be kept in the 5V power supply range.
What device are you simulating the PT1000 for?
Link to specs/data would be a help.
Is one of the connections gnd?
If the device is battery powered, then you may be okay.
Is there a reason for changing the value so fast?
What is the application?
A PT1000 is usually not a fast responsive device, due to its thermal mass?
I use a very small PT100 sensor at my work, it is the size of piano wire and it still takes seconds to respond to any temp change.
