Hi team,
My customer found a strange problem while testing CD4051B. Please see the test results as below.
(1) First test
When the selected channel is CH4, CH5 and CH6, the COM output is wrong. The output of COM while selecting CH4 follows CH0, the output of COM while selecting CH5 follows CH1, the output of COM while selecting CH6 follows CH2, and the output of COM while selecting CH7 follows CH3. Therefore, it is suspected that the C pin's voltage level won't affect COM's output. No matter whether C's voltage level is high or low, the chip thinks it as low.
(2) Second test
When the selected channel is CH6, the COM output is wrong. The output of COM while selecting CH4 follows CH0, the output of COM while selecting CH5 follows CH1, the output of COM while selecting CH6 follows CH2, and the output of COM while selecting CH7 follows CH3. Therefore, it is suspected that the C pin's voltage level won't affect COM's output. No matter whether C's voltage level is high or low, the chip thinks it as low.
(3) Third test
When the selected channel is CH4, the COM output is wrong. The output of COM while selecting CH4 follows CH0, the output of COM while selecting CH5 follows CH1, the output of COM while selecting CH6 follows CH2, and the output of COM while selecting CH7 follows CH3. Therefore, it is suspected that the C pin's voltage level won't affect COM's output. No matter whether C's voltage level is high or low, the chip thinks it as low.
(4) Forth test
We changed the part with another new one, and the COM's output is right for different selected channels.
My question is: Can we think the old part fail? Is there other reasons that may cause the problem?
Br,
Nison
