Kindly help! high side mosfet switch high power

[ZincBear]

high side mosfet switch high power

Hi all,

I am looking for a high power switch (5V, 1.5A or 2A will suffice) that can be controlled by a digital signal of 00, 01, 10 and 11 to switch between powering up 4 devices. Pls see the attached picture.

Each device is identical and requires a fixed 5V, and about 1A to 1.5A of current. My power supply is homemade and is fixed at 5V and max current of 7A. Now, i need to solve the interface between them.

I have tried looking for multiplexers or demultiplexers from TI and analog devices. However MUX and deMUX are usually for digital signals, hence, only low load currents are permitted. 1A is definitely out of the question.

Kindly help!

 

[banjo]

n channel mosfet switch

How about switching the ground return of each device? Then you could use an N-Channel MOSFET. If you really need to switch the high side, then P-Channel MOSFETs are required. The P-Channel MOSFET usually has a higher On Resistance, so N-Channel is the preferred method.

By choosing the right MOSFET the control can be just a 0 to 5 V digital signal. (Look for logic level MOSFETS.

 

[ZincBear]

switch high power

I was hoping to have an elegant single IC kind of solution. Is it possible with the N-channel Mosfet/Logic Level Mosfet?

 

[banjo]

decoder high power switch

Since your control signals are binary encoded, you will need a 2 to 4 decoder to provide four unique MOSFET gate drives. These are then followed by the MOSFETs. You can find some dual MOSFET packages, which would reduce your parts count from four MOSFET packages to two. Unfortunately, the 74139 decoder is active low output. Therefore, you would have to follow that IC with an inverter to get the active high outputs you need. (Active low outputs are what you need for P-Channel high side MOSFETs, so an inverter is not needed there.)

When looking at the MOSFET datasheets, search for small Rds(on) at approximately 4.5V. These are the logic level parts that can easily be driven by 5V digital logic. You want a maximum drain current of at least 3A or more.