SN74LVC138A: Regarding abs output voltage

Daisuke Higa

Part Number: SN74LVC138A

Hi support team.

Is there a time limit for the absolute maximum rated voltage?
My customer is experiencing -0.57V / + 4.15V undershoot and overshoot. Is there a problem with this condition?
The notes in the data sheet include the following:
＞ (2) The input and output negative-voltage ratings may be exceeded if the input and output current ratings are observed.

Is it the same on the positive voltage side?

Best regards,

Higa

over 3 years ago

0 Chad Crosby over 3 years ago

TI__Expert 6680 points

Hi Higa,

This part has negative clamp diodes (i.e. voltage on an input may only go so low before the diode starts conducting), but no positive clamp diodes. However this part has overvoltage tolerant inputs, so this overshoot of 4.15V should be no issue.

Thanks!

Chad Crosby

0 Daisuke Higa over 3 years ago

Genius 3475 points

Hi Crosby-san

Thank you for your reply.

I am sorry in the confusing explanation.

-0.57V and 4.15V are under/overshoot peak voltage of output.

It isn't input.

Is there a time limit for the absolute maximum rated voltage?

Best regards,

Higa

0 Clemens Ladisch over 3 years ago in reply to Daisuke Higa

Guru 243180 points

Active LVC outputs have both positive and negative clamping diodes.

The output current absolute maximum rating must not be exceeded, not even for a short time.

Figure 16 of Input and Output Characteristics of Digital Integrated Circuits at 3.3-V Supply Voltage shows that the typical output current at −0.57 V and 4.15 V is about 50 mA and can easily exceed that.

0 Daisuke Higa over 3 years ago in reply to Clemens Ladisch

Genius 3475 points

Hi Ladisch-san

Thank you for your support.

I understand.

Best regards,

Higa

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SN74LVC138A: Regarding abs output voltage