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OA47

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Joined: 11/04/2012
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Posted: 03:24am 23 Feb 2023

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I have a project that uses a 4016 connected to a MX170 and it combines a bidirectional 9600 serial link. I have not been able to source the 4016 SMD chips easily so I decided to use the 4066 which is readily available, pin compatible and has lower on resistance.

The problem I have is that I cannot get the 4066 to work using the same MMBasic software.

Could anyone suggest why this is happening?

OA47

TassyJim

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Joined: 07/08/2011
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Posted: 03:35am 23 Feb 2023

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How are you driving the control pins?
Both versions claim 3.5V control when using a 5V supply but maybe the 4066 is fussier than the 4016.

Jim

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phil99

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Posted: 04:26am 23 Feb 2023

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Have used one on a Pico with 3V3 supply and control and it worked ok but the "on" resistance was over 100 ohms.

OA47

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Posted: 06:51am 23 Feb 2023

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Quote Have used one on a Pico with 3V3 supply and control and it worked ok but the "on" resistance was over 100 ohms.

I believe that the 4016 has an ON resistance of 100's of OHMS but the 4066 is supposed to only a few OHMS.

OA47

OA47

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Posted: 07:02am 23 Feb 2023

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Quote How are you driving the control pins?

Here is a rough schematic of the offending circuit.

Serial data coming in is read on Com1 RX and serial data out is bit banged out of pin 30, inverted and increased to 5V pp and let thru to the data line via the 4016.

OA47
Edited 2023-02-23 17:09 by OA47

Martin H.

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Posted: 07:11am 23 Feb 2023

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Maybe 3.3V Control Voltage are a little to low?!

Data Sheet
Edited 2023-02-23 17:12 by Martin H.

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Volhout
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Joined: 05/03/2018
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Posted: 07:37am 23 Feb 2023

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Martin H. said Maybe 3.3V Control Voltage are a little to low?!

Data Sheet

Good thinking..
The ON resistance (when 4066 powered from 5V) is between 470 ohm and 1050 ohm.
At 3.3V the ON resistance could be over 2k ohm (not 100 ohm).

I know the CMOS series (HEF40xx, CD40xx) are promoted as 3V compliant, but this switch does not have any specifications below 5V. Maybe if you connect pin 14 to +5V it may work.

Volhout
Edited 2023-02-23 17:38 by Volhout

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phil99

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Posted: 07:48am 23 Feb 2023

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"Maybe 3.3V Control Voltage are a little to low?"

Yes, that is why the channel resistance was over 100R on the 4066.

OA47 that is where you could start looking. Are you actually getting a 0 - 5v output swing when you set 4016/4066 pin 13 high?

For a static test only a multimeter is needed.

SetPin 30, dout

Pin(30) = 0 'measure pin 30 and 4016/4066 pin 1 & 2, expect 0 and 5V
Pin(30) = 1 'repeat, expect 3V3 and 0

If not you may need a level shifter to drive pin 13 at 5V.
Edited 2023-02-23 17:52 by phil99

OA47

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Posted: 07:51am 23 Feb 2023

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Quote Maybe if you connect pin 14 to +5V it may work.

Certainly worth a try

OA47

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