SN74CBT3253C: Undershoot Protection of SN74CBT3253C Detailed Operation

Dave Chang

Part Number: SN74CBT3253C
Other Parts Discussed in Thread: SN74CBT3253

Hello support team,

This is FAE Dave. I would like to ask about a question about SN74CBT3253C.

For the substitution, my customer wants to compare the SN74CBT3253 with the C-version, and the difference is at the undershoot protection.

Would you please help to explain about the undershoot protection of SN74CBT3253C more detailed for my customer?

It seems that the figure at page six without the text explanation isn't clear enough.

Many thanks.

Best regards,

Dave

over 2 years ago

+1 Tyler McGuire over 2 years ago

TI__Expert 3515 points

Hi Dave,

We have an application note with sections that go into more detail on the feature: CBT-C, CB3T, and CB3Q Signal Switch Families. Essentially the C version has a clamp that prevents undershoot voltages caused when the gate voltage of the n-channel pass transistors are at ground potential, but a negative voltage on either I/O port with a magnitude greater than the NMOS VT causes the switch to conduct. The C version forces the gate voltage of the NMOS to track the negative input voltage which prevents undershoot voltages up to -2V.

Thanks,
Tyler

0 Dave Chang over 2 years ago in reply to Tyler McGuire

TI__Expert 4015 points

Hello Tyler,

Thanks for the reply here.

I've transferred the information to my customer.

Best Regards,

Dave

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SN74CBT3253C: Undershoot Protection of SN74CBT3253C Detailed Operation