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Hi Team,
My customer is using CD4051B for current sensing MUX, shown as below. it works normally when there has no high transient spikes.
But if high transient spikes appears, sometimes the CD4051 can be heated to very hot (but not damaged even after 30mins). If power it again, it can go back to normal work (CD4051B is not damaged).
Then, we tried to add a resistor suck as 1k, CD4051B doesn't become hot anymore even transient spikes appears.
Based on above experiments, we guess there may exist surge current to CD4051B when transient spikes appears, but we don't understand why CD4051 can be heated to very hot and not damaged. it looks like "latch-up effect“ is activated when transient spikes appears. Do you have any comments on this issue? Could you share some knowledge of MUX input structure which can help us understanding this issue and solve it?
thanks.
Best regards,
Yang
This indeed sounds like a latch-up. The device gets hot because the power supply gets shorted inside the device. See the Latch-Up White Paper.
A latch-up can happen only if you violate the absolute maximum ratings. The series resistor helps because it limits the current through the clamping diodes.
Consider a latch-up-immune multiplexer like the TMUX7208 or TMUX7308F.
Hello Yang,
I agree with Clemens and if this issue concerns you please look into our latch up immune multiplexers.
Here are some great resources for you to understand more about latch up immunity.
https://www.ti.com/video/6136185233001?keyMatch=
Thank you and Regards,
Kameron