Issue with INA214

Owais;

It was necessary to use a magnifier to read your schematic but unless I am mistaken, you show the INA214 supply pin (V+, pin 3) connected to +1V. According to the data sheet, the INA214 minimum supply voltage is +2.7V.

Hi,

I'm sorry about the image.  No, the pin 3 is actually connected to 5VDC_CD, which is nominally 5VDC.

I wasn't able to qualify exactly when the failure occurred.  I'm going to replace it again and then do a more controlled bring-up to see.  I'm also going to take a look at changing the TVS to a a more conservative range keeping it below 24VDC.  I am surprised if it is transients because as I mentioned I am using a bench-top power supply.  Maybe at power-up there is a surge that goes over 26VDC.  I'll try to quantify this surge.  One thing that I do know is the 24VDC and the 5VDC may not occur simultaneously and that there might be a period of time when either the 5VDC is present with no 24VDC or vice-versa, i.e. 24VDC present when the part is de-powered.  Is there any harm to the device if this occurs?

Thanks for the suggestions and help!

Owais

Owais;

Thank you for correcting me on the supply voltage.

According to the INA214 data sheet, it can have the inputs connected to a sense voltage without being powered up so your power-up sequence should not be a problem.

I did notice an inductor in the 24_SAFE line-- could it be creating a voltage spike due to Lenz's Law? E = - I dV/dt.

Hi

I wanted to update you on my investigation on the INA214 failure.  For my testing, I am using a BK Precision 9130 power supply that has a a master power button in addition to the local on/off output button that turns off power to the local outputs.  I hooked my scope up directly to the 24VDC output of this power supply and looked at the waveforms and saw massive transients when the master power button was used (see scope capture below). 

The capture shows the nominal 24VDC with transients that go > 20volts above and below.  I believe these transients were killing the INA214.  The transients occur when the power supply is turned-off using the master power switch.  I saw no appreciable transients when turning the local output on/off buttons.  After replacing the components, I powered and de-powered the INA214 using the local output on/off buttons and now the INA214 seems to be operating correctly every time.

What is surprising is that the TVS I have on the 24VDC line (I mentioned this a few posts ago) did little to remove the transients.  Here is a scope capture after the TVS:

As you can see, the peak TVS values have dropped somewhat but still not appreciably. 

So, my conclusion is that this is a self-inflicted damage to the INA214 due to the test-equipment, but the vulnerability it has exposed means that my circuit should indeed include some additional transient-suppression to prevent damage to this chip.  I am wondering if there is a version of this chip that has a higher operating voltage designed to operate at 24VDC....it seems 26VDC limitation is too close.  Am I using the wrong chip that needs to operate at 24VDC?

If the INA214 is the best chip for my application, then I should get the demo kit and play with different arrangements of zeners, etc until it is able to withstand these type of transients.

As a side-note, the inductor on the 24V line is actually a ferrite-bead.

Thanks to you two for helping me get here.

Warm Regards!