# +12V source switching (lowest part count, lowest cost)

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#### Jester

##### Full Member level 6
I have done this a few times and the end solution never looks elegant.

I need to switch (control) a 500ma, +12V source ( with 5V logic). The switch must Source not sink.

Please show me your elegant solutions.

Here is a 4 component $0.40 solution #### Rajnaveen ##### Member level 2 Well you are using P channel Mosfet that will not work as I can see. Use NPN BD 139 Transister. #### Jester ##### Full Member level 6 #### yassin.kraouch ##### Advanced Member level 2 I have done this a few times and the end solution never looks elegant. I need to switch (control) a 500ma, +12V source ( with 5V logic). The switch must Source not sink. Please show me your elegant solutions. Here is a 4 component$0.40 solution

View attachment 108620
what is the issue than ? yo uonly need to choose the right component rating, your circuit work perfectly

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#### D.A.(Tony)Stewart

Here is a 1 part SOT-363 165 mOhm $0.09 High Side 1A switch with extra parts for slew rate control. +/- 1.1A KirkMc ### KirkMc Points: 2 Helpful Answer Positive Rating #### Jester ##### Full Member level 6 what is the issue than ? yo uonly need to choose the right component rating, your circuit work perfectly Yes it works, but can it be done with less than 4 components? or with less expensive components or both - - - Updated - - - Here is a 1 part SOT-363 165 mOhm$0.09 High Side 1A switch with extra parts for slew rate control. +/- 1.1A

View attachment 108625

Ding Ding Ding Ding Ding Ding ...... we have a winner

1/2 the parts in a small package for cheap

The +12V output will be connected to the load by the end user (ESD what's ESD?). Any suggestions for protection?

Thank you SunnySkyguy

MrUmunhum

### MrUmunhum

Points: 2
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#### dick_freebird

##### Advanced Member level 5
Depending on some secondary values / concerns, a 5V
reed relay can be a nice simple and fairly reliable option.
Not as high a cycle reliability, but more resilient to some
overstress conditions (and providing isolation between
control and load, if that kind of thing matters).

#### D.A.(Tony)Stewart

##### Advanced Member level 5
Electro-Static-Discharge = ESD . This part has protection with intrinsic diodes.

- - - Updated - - -

This is a half bridge (complementary) emitter follower. THis is equivalent to SPDT between V+ and gnd but with Vce-saturation voltage drops and use where low impedance is but voltage drop is not as important.

#### Jester

##### Full Member level 6
Electro-Static-Discharge = ESD . This part has protection with intrinsic diodes.

- - - Updated - - -

This is a half bridge (complementary) emitter follower. THis is equivalent to SPDT between V+ and gnd but with Vce-saturation voltage drops and use where low impedance is but voltage drop is not as important.

I guess you did not catch my dry humor about ESD, I have had very limited success persuading most end users to take any ESD precautions with electronic equipment.

#### KlausST

##### Super Moderator
Staff member
Hi,

If low side switching is possible, then a single n ch mosfet with low vgth will do.

Klaus

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