Analog switching between two sources 5V/1A and 5V/2A

[Dino1400]

Hello everyone,

I'm trying to switch between two sources 5V/1A and 5V/2A based on a decision circuit (a compactor: if high close 5V/1A else close 5V/2A).

can anyone have an idea of how to design these switches (could ne some NPN an PNP).

please see attached picture.

Thank you in advance.

 

[E-design]

Consider doing the switching with P-channel logic level MOSFET devices. The diagram below show the simulation with normal type PMOS.

https://www.fairchildsemi.com/datasheets/FD/FDG332PZ.pdf

 

[barry]

Depends on how fancy you want to be. Do you need to worry about both switches being on momentarily during a switch-over? You could use a P-channel mosfet and drive the gate with your comparator output.

 

[Dino1400]

the first thing that came to my mind is to use either PNP+NPN or N-channel +P-channel but I'm not sure how reliable this idea.
I have attached both approaches please provide me with your though and comment and it there is a better approach i will appreciate your help

- - - Updated - - -

Thank you for your prompt replay. Is AM1 and AM2 connected to the charger box, can you send me some explanation of this circuit looks very interesting.

 

[barry]

Those are a little too simplistic. For one thing, your n-ch fet will always conduct because of its intrinsic diode. Use two p-channels and two complimentary gate drives

 

[Dino1400]

I'm thing about using a part from Texas Instruments
TS5A3157 10-Ω SPDT Analog Switch
I just need to figure out how to use it in my circuit.

Can you provide a drawing for your suggestion or if you have used something before like TS5A3157 or simular part.

Thank you again

 

[E-design]

I used 10 V for the charger since the PMOS needs high level gate drive. You need to use the logic gate types.

 

[schmitt trigger]

10 ohm?
Do the math....how much voltage will you drop at 2 amp current with a 10 ohm switch?

 

[barry]

I'm thing about using a part from Texas Instruments
TS5A3157 10-Ω SPDT Analog Switch
I just need to figure out how to use it in my circuit.

Can you provide a drawing for your suggestion or if you have used something before like TS5A3157 or simular part.

Thank you again

Good luck, you'll be dissipating 40 watts across that sucker.

 

[CataM]

Why post #2 is not good enough for you ?

 

[Dino1400]

post #2 is a good proposal i just needed some more details and explanation.
I also Asked If anyone asked have TI TS5A3157 SPDT Analog Switch or SGM3157YC6 which is based on MOSFET swiching in one IC package.

 

[barry]

post #2 is a good proposal i just needed some more details and explanation.
I also Asked If anyone asked have TI TS5A3157 SPDT Analog Switch or SGM3157YC6 which is View attachment 136988View attachment 136989View attachment 136990based on MOSFET swiching in one IC package.

We've already established that those analog switches can't handle the current.

 

[Dino1400]

Hello all,

I'm posting a circuit that I thinking to use to switch between two power supplies.
Please If you have any comment or better suggestion I will really appreciate that.

Thank you in advance.
Dino

 

[barry]

Hello all,

I'm posting a circuit that I thinking to use to switch between two power supplies.
Please If you have any comment or better suggestion I will really appreciate that.

Thank you in advance.
Dino

View attachment 137057

Sure. Did you give up on trying to design a more reliable, less expensive proper solid-state solution?

 

[Dino1400]

I have not give I just talk to colleague of mine said to keep it simple as you can. I like to use different solution of course I like the proposal from post #2.

I attached here again with a minor modification.

 

[CataM]

Those MOSFETs should be P channel and logic level... if you want it to work. What is the comparator's output voltage ?
The FDG332PZ, P channel mosfets from post #2 looks OK.

 

[Dino1400]

thank you for your response, the comparator's voltage should be 5V.

 

[CataM]

the comparator's voltage should be 5V.

Then this is your circuit.


Currents:


Voltages:


You can thank "E-design" now.

 

[Dino1400]

thank you all
and special thanks to E-design and Catam