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PSoC™ 5, 3 & 1 Forum Discussions

joel_4789771
Level 2
Level 2
5 sign-ins Welcome! First solution authored

I am trying to implement an analog DeMutiplexer on PSOC 5lp -059 kit,  as I have a single power supply (5v) which needs to feed different transducers ( in different moments in time) . I was not able to find a DEMUX component, but  the existing AMUX component datasheet shows that it is "bidirectional". If I understand right this, does it mean that the classic digital DEMUX function can be implemented by a AMUX component?. If so, what is the max voltage/current that the AMUX component can drive?.

If the idea can not be implemented through the above references options, is there any advice to make it ( application note,...)?

Thanks for the help

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1 Solution

joel,

You don't need mux for that. Please read my updated post above. Just power PSoC from the energy harvesting device, and power sensors from various Digital pins. For 10mA source gang 2-3 pins together. If sensor can be used with Pin in sink mode (floating), single GPIO Pin can carry up to 8 mA, and SIO Pins can carry up to 20mA in sink mode. PSoC itself consumes very small power in low-power mode, and can serve both as interface and power source.

/odissey1

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odissey1
Level 9
Level 9
First comment on KBA 1000 replies posted 750 replies posted

joel,

It is not clear why you want to use analog mux, when transducers only need 5V "enable" signal? It seems that digital demux should do. The driving current is limited by the Pin (4mA source, 8mA sink).

The AMUX is bidirectional, that is it can pass voltage both ways. I believe that analog pins can handle up to 20 mA.

It is my understanding, that you want to power several external sensors one at a time, sourcing power from PSoC pins. If current is small (4ma), you can set some Pin High. For higher current (up to 100 mA) you can gang several pins together.

Overall, PSoC should not be used as a power source for external components.

/odissey1

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Good afternoon.

The reason why I propose to deliver power supply to the transducers in different moments in time, is because the available power is very limited, as this is coming from havesting energy. Supply 10 mA to every transducer ( 5 off, so 50 mA), makes a significant portion of my power budget, so the idea was to supply 10 mA in different moments in time, in order to avoid the current addition. The obvious cost from this proposal is that I have to wait some time from the application of the power supply to every transducer to its output value…for every transducer…I suppose that the final solution will be a compromise between current supply and waiting time ( reading confirmation time)…but I would like to make some trade off…

Thanks for the help.

De: BoTa_264741 <community-manager@cypress.com>

Enviado el: miércoles, 2 de diciembre de 2020 15:47

Para: Elias Algaba, Jose Felix <elias.albaga@itpaero.com>

Asunto: Re: - AMUX component questions (Psoc Creator 4.4)

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Cypress Developer Community <https://community.cypress.com/?et=watches.email.thread>

AMUX component questions (Psoc Creator 4.4)

reply from BoTa_264741<https://community.cypress.com/people/BoTa_264741?et=watches.email.thread> in Community Information - View the full discussion<https://community.cypress.com/message/268019?et=watches.email.thread#268019>

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joel,

You don't need mux for that. Please read my updated post above. Just power PSoC from the energy harvesting device, and power sensors from various Digital pins. For 10mA source gang 2-3 pins together. If sensor can be used with Pin in sink mode (floating), single GPIO Pin can carry up to 8 mA, and SIO Pins can carry up to 20mA in sink mode. PSoC itself consumes very small power in low-power mode, and can serve both as interface and power source.

/odissey1

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Len_CONSULTRON
Level 9
Level 9
500 solutions authored 1000 replies posted 750 replies posted

joel,

AMUXes are just switch settings in the analog routing system.  To implement a DEMUX, flip the AMUX.

There is NO buffer drivers implemented in the Amux.  Just switches.  The analog system is designed to be a fairly high HiZ.   The series resistance of the switches to input components (such as comparators, ADCs, opamps, etc) is dependent on the analog routing.  Combined series resistance can be as high as 4K ohms.  However if the input resistance of the analog component is >1M ohms then this series resistance is relatively insignificant.

You can use a DEMUX to output from analog components (VDACs, IDACs, opamps, Vrefs, etc).  The output current will be maximum limited by the component.   However series routing resistance (up to 4K) to the GPIO output can be significant.

Len

Len
"Engineering is an Art. The Art of Compromise."
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