analog switch problem

[air]

now I am using a 8 by 1 analog switch 4051 in my circuit. When I choose X7 port, i.e. ABC = 111 I got a current of 4 ~5 uA from X port where I expect a 0.02 uA coming out from. When I disconnect all connctions from x0 ~x6, I got much better result. I think other channels make some effects on the output. Can any one suggest me what other devices I could choose to replace this 4051 switch.
Thanks!

 

[IanP]

Try very common and popular CD4066 : https://www.fairchildsemi.com/ds/CD/CD4066BC.pdf
Regards,
IanP

 

[echo47]

Is it a plain CD4051B, or some other version?

Typical 4051 leakage is well below one uA. Maybe you have a damaged part or PC board contamination. Or maybe your input voltages are beyond the chip's limits. What are your power supply voltages and input voltages?

 

[air]

Is it a plain CD4051B, or some other version?

Typical 4051 leakage is well below one uA. Maybe you have a damaged part or PC board contamination. Or maybe your input voltages are beyond the chip's limits. What are your power supply voltages and input voltages?

I am routing this circuit on a breadboard. The power is +-8 V for amplifiers and 5 V for MCU and LCD. You gave two reasons "Maybe you have a damaged part or PC board contamination." which, for now, I am concerning most. I am going to check the part, it is JRC NJU4051BD, and see if it is damaged or not. As I mentioned, I disconnected port x0~x6 one by one while monitoring the current change and found that x0 port contribute 2~3 uA current to the output, other ports contribute more or less current but far less than x0 port current. I replaced it using another part with same model before and got same result. I can not rule out the possibility that both of them I tried are damaged due to the incautious store and keeping. I 'll check them again. But for now I have more concerning on the "PC board contamination" problem. I do not know its exact meaning. Could you give me more guide on this topic. I did found something weird happened on this breadboard. For example:
1. Some time when I disconnect the 5v power, the LCD and MCU are still working but not forever.
2. Some time the LCD shows wrong or messy word or has no display at all when +-power is added to the board.
....
I really want to know how to solve and avoid those things happen. Thanks.

 

[Davood Amerion]

check another 4051 from another company.

 

[VVV]

Use MAX4051 from Maxim, or ADG658 from Analog Devices.
www.analog.com/en/prod/0,2877,ADG658,00.html
www.maxim-ic.com/quick_view2.cfm/qv_pk/1352

 

[shalky]

I have a bit experience of 4051. If the input voltage is higher than power voltage, or less than ground, the chip will do some unimaged actions. You may check the input voltage.

 

[10kangstroms]

Can you post a schematic, including all power supplies and signal voltages?