CD4502B: CD4502B strange outputs

Qi Liu

Part Number: CD4502B

Hi, support team

My customer has the questions as follow:

I am using a CD4502B IC to invert 4 different signals within a CNC machine, but am having strange outputs. Changing some of the signals seems to enable or disable all, while 1 or 2 will enable the designated output while disabling the rest. I am not using the inhibit or disable pins

for some input channels all outputs go high, while some inputs make the corresponding output high while the rest go low.

I am not sure if it is relevant or not, but I have probed all leads for a potential short, and there is no short. I have 5V to Vdd, GND to Vss, 4 inputs into D1-4, and 4 outputs from Q1-4

Thanks so much.

Best regards,
Yuki

over 4 years ago

0 Andrew F over 4 years ago

Prodigy 10 points

I originally contacted support over this issue. Admittedly, I don't know a whole lot about ICs, and I think what I was looking for was a schmitt trigger inverter, as opposed to the hex inverter/buffer. I won't be using this IC at this point. My guess is I was expecting a different output from the inverter/buffer than what it is supposed to do. Oh well

+1 Clemens Ladisch over 4 years ago in reply to Andrew F

Guru 325050 points

The schematic is missing, and we do not know what input signals you're using. Leaving some inputs floating can have strange effects. And overvoltage could have damageed the device.

0 Sebastian Muriel over 4 years ago in reply to Andrew F

TI__Mastermind 22480 points

Hi,

Can you please provide a schematic so we can further assist you?

Regards,

Sebastian

0 Qi Liu over 3 years ago in reply to Sebastian Muriel

TI__Expert 8835 points

Hi Sebastian,

The customer replied:
"I realized this IC does not suit my application, and I have removed it from the machine, and won't be pursuing this any further. I never had a circuit diagram drawn, so I don't have anything to provide. Another member commented about leaving some inputs floating, which I definitely did. Thanks for all your help!"

Best regards,
Yuki

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CD4502B: CD4502B strange outputs