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REF3330: Working with inverting buffer

Sayan Chakraborty1
Prodigy 10 points
Part Number: REF3330

Dear Sir/Madam,

We need your help on a component, REF3330DBZ that we are using in one of our products.

In the attached picture below, you can see that because of the 5V pull-up resistor before the inverter, current tries to flow towards the 3V reference voltage(REF3330DBZ) through the forward-bias diode. This opposes the 3V reference voltage which is itself trying to drive current. This is why we see a ~13mA increase in current consumption on average for the whole circuit.

This inverter was assembled by mistake by our PCB assembler. Originally, we specified an inverter that did not have those diodes. But, due to this mistake, there are some devices with this wrong inverter on the market. We are now trying to assess the risks that could result because of this wrong component assembly.

My questions to you are:

            1) Will this opposing current on the 3V output, reduce the lifetime of the Voltage Reference IC? If yes, any estimate by how much?

   2) Could we expect a component failure or performance reduction over time?

Also attached is the schematic snapshot of the Voltage Reference IC.

Regards,

Sayan Chakraborty

  • 0
    TI__Mastermind 19370 points
    Hi Sayan,

    I can assist you with this question. The REF3330 can source and sink current to regulate the output. As long as the device is operating with the Recommended Operating Conditions the REF3330 will function as intended.
    In this situation the ROC states that the maximum sink current is 30mA and thus 13mA is still within the specifications.
    Due to the small dropout voltage and such low current, the Tj of both devices are going to be extremely similar and so it is difficult to estimate. I also cannot estimate how much because this is a system and environmentally dependent.

    www.ti.com/.../reliability-testing.html.html

    As long as the device is operating within the ROC I do not see an issue. I would still prefer the device to be sourcing instead of sinking but I do not see this as a concern for lifetime or performance reduction because it is within the ROC.


    -Marcoo