Simple switching question

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Use a logic-level MOSFET.

https://ec.irf.com/v6/en/US/adirect/ir?cmd=eneNavigation&N=0+4294841672

Or a BJT:

http://www.zetex.com/3.0/3-3-2b.asp?rid=1

or a relay:

http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=1049448;keywords=relay

 

JF

If I use a logic level JFET, the Vgs will be zero for any load within my range if I wire it like so:

Gate: My microcontroller Drain: Load (Load then goes to 0V) Source: 5V

Right?

(Fast switching fortunately isn't a concern, so I should be OK with driving this from a microcontroller, correct?)

2

--- Yes, for a low-side switch, and please bottom-post.

You basically have two choices, depending on whether you want to/have to high-side or low-side switch your load.

Low-side switching is used when one side of the load is permanently connected to its source voltage and the other side of the load is connected to ground through the switch, like this: (View in Courier)

5V>--------+ | [LOAD] | D µCOUT>---G NCH S | GND>-------+

High-side switching is used when one side of the load is permanently connected to ground and the other side of the load is connected to the source voltage through the switch, like this: (View in Courier)

5V>--------+ | S µCOUT>---G PCH D | [LOAD] | GND>-------+

Note that an N-Channel MOSFET is used for the low-side switch, while a P-Channel is used for the high-side switch.

Also, be aware that a high from your µC will turn on the low side switch, while a low will turn on the high side switch.

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--- Depends...

How often are you going to switch it and which device do you want to use?

JF

^^^^ Oops... high

and, Vgs won't be zero, it'll be Rds(on) * Id.

JF

You need a logic power FET ..

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