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Part Number: LM75A
My customer is adopting LM75A solution and schematic is as attached. Register are all default value. Now there is an issue when doing temperature box experiment. Setting temperature box change rate 25C/hour, so about 0.5C/min. When temperature box shows -30C, however the readback value is -66.5C. I2C waveform is as attached. Register 0X00 is0XBDFF, temp is -66.5C. Could you help comment possible reasons or what i can test to get the reason? Thanks!
In reply to Aaron Heng:
I reviewed your schematic, and don't see anything wrong except the START condition. It look like your firmware brings the SCL and SDA lines to a LOW each time the communciation protocol is ended. Let fix this issue first. Could you please bring SCL and SDA signals to a HIGH so that the device can see the START condition?
Just checking in with you if you have a chance to fix the issue by bringing the SCL and SDA signals to a HIGH before execute the command protocol.
In reply to Vera Mao:
Thank you for providing the update. Could you please ask the customer to capture a scope photo when they read a negative temperature? Please do not use the phone's camera instead save the data file from the oscilloscope. This will allow me to view on my pc in details.
ok! I am wating for customer's ambient chamber ready , once get it I will capture the data. tks a lot!
I have send you email with the plot I captured when issue happens, pls help reply based on the email. thank you very much!
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