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edit approved Nov 13, 2021 at 17:43
Peter Mortensen
edit approved Nov 13, 2021 at 17:43
Peter Mortensen
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Please help me understand What are the fundamentals behind this Pp-Channelchannel MOSFET / driver circuit?

Newbie question here. I'm HavingI have this schemaschematic below. I I have a circuit to switch 8v8 V power using a MOSFET and an NPN transistor with Arduinoan Arduino's 3.3v3 V. The power of the switched side will be around 2A2 A (if this matters somehow).

enter image description hereEnter image description here

I have 2two questions.

  1. What's the value of R55 , how? How is it calculated and is it related to the 2A2 A in any way  ?

  2. When the Arduino pin is in the LOW state, point D measures 8V8 V. When the Arduino pin is in HIGH state, point D measures around 0.3v3 V. According to my understanding, point B is always on 8v8 V, because it get'sgets voltage from the battery in point C. How come that the transistor "breaks" that from point D to B and lowers/overrides that voltage coming from point C  ? I hope I got my question right here:)

Thanks!

Please help me understand the fundamentals behind this P-Channel / driver circuit

Newbie question here. I'm Having this schema. I have a circuit to switch 8v power using a MOSFET and an NPN transistor with Arduino 3.3v The power of the switched side will be around 2A (if this matters somehow).

enter image description here

I have 2 questions.

  1. What's the value of R55 , how is it calculated and is it related to the 2A in any way  ?

  2. When the Arduino pin is in LOW state, point D measures 8V. When the Arduino pin is in HIGH state, point D measures around 0.3v. According to my understanding point B is always on 8v because it get's voltage from the battery in point C. How come that the transistor "breaks" that from point D to B and lowers/overrides that voltage coming from point C  ? I hope I got my question right here:)

Thanks!

What are the fundamentals behind this p-channel MOSFET / driver circuit?

I have this schematic below. I have a circuit to switch 8 V power using a MOSFET and an NPN transistor with an Arduino's 3.3 V. The power of the switched side will be around 2 A (if this matters somehow).

Enter image description here

I have two questions.

  1. What's the value of R55? How is it calculated and is it related to the 2 A in any way?

  2. When the Arduino pin is in the LOW state, point D measures 8 V. When the Arduino pin is in HIGH state, point D measures around 0.3 V. According to my understanding, point B is always on 8 V, because it gets voltage from the battery in point C. How come that the transistor "breaks" that from point D to B and lowers/overrides that voltage coming from point C?

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Jordan Sheinfeld
Jordan Sheinfeld
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Please help me understand the fundamentals behind this P-Channel / driver circuit

Newbie question here. I'm Having this schema. I have a circuit to switch 8v power using a MOSFET and an NPN transistor with Arduino 3.3v The power of the switched side will be around 2A (if this matters somehow).

enter image description here

I have 2 questions.

  1. What's the value of R55 , how is it calculated and is it related to the 2A in any way ?

  2. When the Arduino pin is in LOW state, point D measures 8V. When the Arduino pin is in HIGH state, point D measures around 0.3v. According to my understanding point B is always on 8v because it get's voltage from the battery in point C. How come that the transistor "breaks" that from point D to B and lowers/overrides that voltage coming from point C ? I hope I got my question right here:)

Thanks!