Analog power switch 1A, 20V, control voltage < 3V is it possible to find such Switch?

[levnu]

Analog power switch 1A, 20V, control voltage < 3V is it possible to find such Switch?

Thanks
Arye

 

[alexan_e]

Re: Analog power switch 1A, 20V, control voltage < 3V is it possible to find such Swi

You can use a logic level mosfet or a smart high side switch.

Alex

 

[levnu]

Re: Analog power switch 1A, 20V, control voltage < 3V is it possible to find such Swi

Thanks for your fast response

will it operate well if i control the open/close of this mosfet w 3Vdc & when it in close state it will pass 20Vac@1A?
and in open state it will block 20Vac@1A?
could you please give me some examples cause i looked for and had no findings?

Thanks you very much,

 

[alexan_e]

Re: Analog power switch 1A, 20V, control voltage < 3V is it possible to find such Swi

This is an example for a N-mosfet used as a low side switch (cutting ground side connection)


This was from a different post so ignore the shown voltages, my intension was to give you an example of the device wiring, also the device shown has a max Vds of 20v so it is not a proper one for your application, the resistor values can change too.
Go to any vendor site and select a logic level N mosfet with Vds >20v

If your application requires a high side switch then you have to use a smart high side switch which is a Nmosfet with all the driver circuits needed in one small transistor package

Alex

EDIT: ignore the post, I never noticed the AC requirement that IanP has noted.
Unfortunately you didn't mention that in the original post but you have added it in the second post where I didn't notice it

 

[IanP]

Re: Analog power switch 1A, 20V, control voltage < 3V is it possible to find such Swi

Your quest is about switching AC ..
For that you need a triac driven by, for example, an optocoupler ..
Have a look at the attached picture ..
Circuits like that should work ok with voltages down to roughly 12Vac .

:wink:
IanP

 

[levnu]

Re: Analog power switch 1A, 20V, control voltage < 3V is it possible to find such Swi

Thank you all,
i would like to clarify, i have a load that drawing 5Wdc (current of 1Adc) but in the input to the app there is 25 Volt AC.
i would like to be able to control the load w switch means, i would like sometimes to prevent this power income to the load & sometimes to allow this power to the load
i have only DC control voltage of 3V, is it possible?
Thanks

 

[IanP]

Re: Analog power switch 1A, 20V, control voltage < 3V is it possible to find such Swi

3Vdc control voltage can do a lot of things ..

Can you post a schematic diagram of your circuit ..

:wink:
IanP

 

[levnu]

Re: Analog power switch 1A, 20V, control voltage < 3V is it possible to find such Swi

Yes attached the conceptual schematic:

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---------- Post added at 15:19 ---------- Previous post was at 15:08 ----------

moreover when the control is off around 0Vdc the closed switch should be as open circuit for freqs till 20MHz
is it even possible?
Thanks a lot

 

[FvM]

Re: Analog power switch 1A, 20V, control voltage < 3V is it possible to find such Swi

I think, it's time to post a well-considered full specification. First you told about 20 V, then a 20 V AC, now it's apparently 20 V RF. Please tell about frequency, acceptable signal attenuation (respectively on-resistance) and required isolation. 20 V from 50 ohm source impedance won't draw 1 A, by the way.

 

[levnu]

Re: Analog power switch 1A, 20V, control voltage < 3V is it possible to find such Swi

i'm sorry i just gave a schematic to show the idea of what i want to switch, the 50 ohm is not real here.

i really sorry , it seemed to me a simple case of yes or not answer :-(
but every answer i understand it becomes complicated.

please forget all the power 5W & load: it is confusing and not helping to answer!!

the main characterstic are the ability to block 20V ac from a generator @ freq around 20Mhz
while using AC switch that has a control voltage of 3Vdc

Thanks Again Arye

 

[FvM]

Re: Analog power switch 1A, 20V, control voltage < 3V is it possible to find such Swi

A antiserial MOSFET pair can be basically used as signal switch, but the MOSFET capacitance involves a rather limited isolation at 20 MHz. So it may be necessary to build a L or T switch configuration to improve the isolation. Opto-isolated Photo-MOS switches may be suitable.

Unfortunately, you didn't yet specify isolation.

 

[levnu]

Re: Analog power switch 1A, 20V, control voltage < 3V is it possible to find such Swi

Thanks,
This is exectly what happened in one of my tries the Fets like becoming a short circuit in 20Mhz,

what is L or T configuration i need to study it, same opto isolated Photo, i never heard about it.
where can i study or see example of it?

About isolation as i define it:
when swith close Rds on is very little like maximum 500mOhm
when switch is open it should have the effect of 10KOhm

thanks again

---------- Post added at 20:49 ---------- Previous post was at 20:43 ----------

by the way what about some Galium Arsenaid Transistors? they short circuit too in high freq?
arn't there transistors or switch that working in high freqs?
cell phones having switchs in 900MHz arn't they?
for me 2 fets or ready switch is the best solution,
yet i will study about your other suggestions

 

[FvM]

Re: Analog power switch 1A, 20V, control voltage < 3V is it possible to find such Swi

10 kohm translates to 0.8 pF @ 20 MHz, that won't be achived even with a single GaAs switch. I also assume for the time beeing, that GaAs switches can't handle the intended voltage level. But I'm not sure due to the unclear specification. It should be clarified if 20 Vac (or even 25 V) means Vrms, Vp or Vpp and if the switch must be DC capable. GaAs RF swiches are mostly used with AC coupling, please refer to vendor data sheets, e.g. from Hittite or RFMD.

L or T configuration means that you have a combination of series and shunt switches to improve the isolation. You'll find it as a usual solution for RF switches with higher isolation requirement. But I suppose, you are able to figure out their operation yourself.

 

[levnu]

Re: Analog power switch 1A, 20V, control voltage < 3V is it possible to find such Swi

Thanks
i now study the antiserel Mosfets as you mentioned.
the signal is 20Vac pp. (the RF circuit makes somehow 5W of power from this signal as mention in pic above)

it is not DC capable, just this AC signal i mentioned which i want to be able to stop w 3V dc control signal.
is the ac current that passes w the 20Vac importent? cause i don't have this info yet? should i measure it?


so i guess my plan to slove this should focus first on L or T
than antiseriel. (even thought you mention Mosfet won't handle the 20MHz freq and become short circuit between drain source)
and than on the opto mos
after on GaAs

i hope there is a possibility to solve this ac switch issue cause it becoming a complicated thing for me
(i love to study)

Thanks a lot for your help

 

[poorchava]

Re: Analog power switch 1A, 20V, control voltage < 3V is it possible to find such Swi

You can use a relay. There are ones with nominal coil voltage of 3V

 

[levnu]

Re: Analog power switch 1A, 20V, control voltage < 3V is it possible to find such Swi

relay isnt it w high loses when closed? i need it to be like open circuit in 20MHz & closed circuit at around 500KHz w Rds on like till 200 mOhms and passing 20Vac signal w as much as possible losses.
and the closing control signal is 3Vdc
Tnx

 

[FvM]

Re: Analog power switch 1A, 20V, control voltage < 3V is it possible to find such Swi

You can use a relay. There are ones with nominal coil voltage of 3V.

You can expect about 0.1 to 0.2 pF open contact capacitance with small reed relays. 200 mohm is feasible, too.

 

[levnu]

Re: Analog power switch 1A, 20V, control voltage < 3V is it possible to find such Swi

Thanks
FvM is the order of study as i mentioned for solution is ok:

1 focus first on L or T
2 than antiseriel. (even thought you mention Mosfet won't handle the 20MHz freq and become short circuit between drain source)
3 the opto mos
4 GaAs switches
5 Relays

i'm asking because it is hard to focus
&
this one won't help due to high freq cap ?
http://www.irf.com/product-info/datasheets/data/irf540n.pdf

Thanks
Arye

 

[levnu]

Re: Analog power switch 1A, 20V, control voltage < 3V is it possible to find such Swi

What do you think about this next part can it be a solution?
https://www.analog.com/static/imported-files/Data_Sheets/ADG901_902.pdf
i mean
- can it block 20Vac pp & 50mA @ 10MHz at RF1-RF2 ports(see in pg 1 the RF1 & RF2)?
- can it pasa 20Vac pp & 300mA @ 500KHz at RF1-RF2 ports?
and just by using Vdd or Vctrl of 3Vdc control?

if yes it would great,
btw the forum here is great

BR
Arye

 

[FvM]

Re: Analog power switch 1A, 20V, control voltage < 3V is it possible to find such Swi

Maximum input voltage of ADG901 is about 1 Vrms.