How-To/Which passive switch with lowest possible control power

[[email protected]]

Hi

I need to create a passive switch (which means it must not require to
be powered) whose control power is AS LOW AS POSSIBLE (ideally below
the milli Watt range) and the supported power on the secondary circuit
in the multiple milli Watt range.
Which components should I use ? An analog switch (which one), a single
transistor (which one), etc. ?
Does anyone have a sample circuit ? Any link suggestion ?
The most important feature is that the control power is as low as
possible (sorry I say it again).

Thanks in advance
Dave

 

[MooseFET]

Hi

I need to create a passive switch (which means it must not require to
be powered) whose control power is AS LOW AS POSSIBLE (ideally below
the milli Watt range) and the supported power on the secondary circuit

Huh ???? Do you mean that it must only draw power from the control
signal?

Take a look at power MOSFETs. For DC on the gate, they draw nearly no
power.

 

[colin]

Hi

I need to create a passive switch (which means it must not require to
be powered) whose control power is AS LOW AS POSSIBLE (ideally below
the milli Watt range) and the supported power on the secondary circuit
in the multiple milli Watt range.
Which components should I use ? An analog switch (which one), a single
transistor (which one), etc. ?
Does anyone have a sample circuit ? Any link suggestion ?
The most important feature is that the control power is as low as
possible (sorry I say it again).

A latching relay doesnt require power at all,
just a small amount of energy to change its state.

just depends how frequenctly you switch it as to wether this is low enough
power.

or maybe this wasnt what you meant when it must not required to be powered.
a mosfet switch requires power to control it, albeit minuscule.

Colin =^.^=

 

[[email protected]]

A latching relay doesnt require power at all,
just a small amount of energy to change its state.

just depends how frequenctly you switch it as to wether this is low enough
power.

or maybe this wasnt what you meant when it must not required to be powered.
a mosfet switch requires power to control it, albeit minuscule.

Colin =^.^=

Thanks for the answers

a latching relay could be a solution (teoretically the ideal one) if
there is one that can change state with very little power (ideally
much less than 1 mW).

About the solution with the MOSFET, what are the ones with the lowest
DC on the gate (vendor/model) ?

Thanks for any additional tip

 

[colin]

Thanks for the answers

a latching relay could be a solution (teoretically the ideal one) if
there is one that can change state with very little power (ideally
much less than 1 mW).

About the solution with the MOSFET, what are the ones with the lowest
DC on the gate (vendor/model) ?

Thanks for any additional tip

a latching relay isnt specified by power, but by energy,
many battery powered devices use them,
you would need to store up sufficient charge in a moderate size capacitor.
you can get 3v mosfet switches.

not sure of models, digikey probably list both these devices.

Colin =^.^=

 

[[email protected]]

a latching relay isnt specified by power, but by energy,
many battery powered devices use them,
you would need to store up sufficient charge in a moderate size capacitor.
you can get 3v mosfet switches.

not sure of models, digikey probably list both these devices.

Colin =^.^=- Zitierten Text ausblenden -

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Hi Colin

thanks for the answer.
I looked a little around for the MOSFET solution, and I found that the
most "sensible" ones requires on the gate-source still 3 volts and
consume 2 ampere (???) DC to saturate. This makes still 6 watt control
power to switch my passive switch. Isn't there a more "sensible" way
to reach my scope without using an active circuit ?
Sorry for my "beginner" questions, but my understanding of electronic
is quite basic.

Thanks

 

[colin]

Hi Colin

thanks for the answer.
I looked a little around for the MOSFET solution, and I found that the
most "sensible" ones requires on the gate-source still 3 volts and
consume 2 ampere (???) DC to saturate. This makes still 6 watt control
power to switch my passive switch. Isn't there a more "sensible" way
to reach my scope without using an active circuit ?
Sorry for my "beginner" questions, but my understanding of electronic
is quite basic.

they dont require 2A to control,
that probably refers to the maximum current it can switch.
typicaly gate resistance will be megaohms,
so current will be microamps or less.

Colin =^.^=

 

[MooseFET]

Thanks for the answers

a latching relay could be a solution (teoretically the ideal one) if
there is one that can change state with very little power (ideally
much less than 1 mW).

About the solution with the MOSFET, what are the ones with the lowest
DC on the gate (vendor/model) ?

www.supertex.com

TN0604 or TN2501 would need very little energy to switch.