Reg: SN74LVC1G08DCKR AND Gate Issue

Marimuthu P

Hi,

We are using SN74LVC1G08DCKR AND gate in our design. Our products are installed in customer premises. Suddenly one product stopped working and when we checked it, we have found that the AND gate input (PIN 2) is always low even though there is a 10K pull-up t0 3.3V. And in PIN 2, there is no other signals except the pull up resistor. Can you please tell me whether any problem happened to the AND gate? Is the GATE damaged? Please give your feedback ASAP. I have a detailed picture which explains the issue more clear. If you need it I can send it to you.

BR Muthu

over 14 years ago

0 Chris Cockrill over 14 years ago

TI__Mastermind 46480 points

It sounds like the part has been damaged.

0 Marimuthu P over 14 years ago in reply to Chris Cockrill

Prodigy 40 points

Hi Chris,

Thanks for your quick reply.

Can you please tell me the possible reasons for the AND gate damage?

Actually in our design we didn't provide 0.1uF decoupling capacitor for the VCC pin. Will this a be a possible reason for the gate damage?

Is there any other possible reasons for the AND gate damage?

BR
Muthu

0 Marimuthu P over 14 years ago in reply to Chris Cockrill

Prodigy 40 points

Hi Chris,

Is there any other way to find out whether the chip is damaged or not?

For example by checking the resistance between input and output? Will this be useful to verify whether the gate is damaged or not?

Muthu

0 Chris Cockrill over 14 years ago in reply to Marimuthu P

TI__Mastermind 46480 points

If the input is being pulled to gnd then you can probably measure a lower resistance between the pin and gnd.

0 Marimuthu P over 14 years ago in reply to Chris Cockrill

Prodigy 40 points

Hi Chris,

Thanks for your quick reply.

Can you please tell me the possible reasons for the AND gate damage?

Actually in our design we didn't provide 0.1uF decoupling capacitor for the VCC pin. Will this a be a possible reason for the gate damage?

Is there any other possible reasons for the AND gate damage?

BR
Muthu

0 Chris Cockrill over 14 years ago in reply to Marimuthu P

TI__Mastermind 46480 points

Damage is usually caused by over voltage or ESD. Do any of the pins go to a connector or are there any spikes on the signals that might violate the absolut max limits.

A bypass caps prevents the Vcc and Gnd fromm beeing jerked around. without a bypass you could more succeptable to oscillation. excessive oscillation can cause a lot of current which could cause damage. not likely the cause but a possibility.

The best way to look for the cause is to put a scope on the pins and look for signals that violate spec or oscillates.

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Reg: SN74LVC1G08DCKR AND Gate Issue