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OPT4001: Fragility and possible sources of damage

Keyanna Coghlan
Prodigy 60 points
Part Number: OPT4001

We have been working with the OPT4001 sensor for many months, and something that seems to repeatedly happen is that the I2C communication will simply stop working. The device is getting the proper power, but when attempting to communicate over I2C with it, the controller doesn't ever receive an ACK or any other meaningful signal. 

The sensors are being powered by a desktop power supply at 3.3V, and the highest voltage they could receive even accidentally is 5V. There is never any visible damage on the PCB it is mounted on. We have 5Kohm pullup resistors connected to the SDA and SCL lines, and these have been working fine. They are stored in a normal room at about 22.5C with low humidity.

Is there anything that this sensor might be sensitive to and is repeatedly causing multiple sensors to spontaneously fail? I notice in the datasheet it recommends a 100uF capacitor between VDD and GND, could the lack of that capacitor be causing our sensors to fail?

Thanks,

Keyanna

  • 0
    TI__Mastermind 25815 points

    Hi Keyanna,

    Yes, decap is recommended. Without it it is possible for device voltage to drop and if this happened during i2c device could be unresponsive. Besides that, this behavior would not be expected.

    You may also want to put a scope on to the i2c lines to inspect the waveform. This would help confirm if any issues on the i2c side.

    Best,

    Alex

  • +1 in reply to Alex Bhandari-Young
    Prodigy 60 points

    Thank you for your reply.

    We scoped the I2C lines and confirmed that there was no signal coming from the device. Additionally 2 of the non-functioning chips were drawing way more current then they should be when functioning properly, (25mA and 80mA!) so our current assumption is that an occurred error in our system (external to the chip) which caused an overvoltage and then shorted something in the chip and broke it.