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Electronics => Beginners => Topic started by: x4ce on August 17, 2024, 06:04:16 am

Title: Schematic Review of Solenoid Control through multiple channels
Post by: x4ce on August 17, 2024, 06:04:16 am

Hi,

Please if someone can review the attached schematic. I am trying to control solenoid (12, 15W) from 2 channels of MCU.

1. P0.16 will permanently turn on the solenoid using NMOS from 12V.
2. P0.18 will turn on the NMOS but the solenoid will be driven by a PWM source through another NMOS.

I have selected SI4214DDY-T1-GE3 as a logic level FET and as such added 100 Ohm resistor for current protection along with a pull-down to avoid floating of NMOS. Whereas, the gate of STN3NF06L will be driven by VGS >10V.

Please review the schematic for any potential issues and any further suggestion in its improving.

Thanks

Title: Re: Schematic Review of Solenoid Control through multiple channels
Post by: squadchannel on August 17, 2024, 07:48:46 am

I don't think P16 is a problem.
I don't see the point of using two FETs for P18, is there any reason why the gate of P18 FET cannot be directly PWM controlled?

If it were me, I would not use P16 and put P18 through an AND gate to combine P18 control and PWM control. no need for STN.

Title: Re: Schematic Review of Solenoid Control through multiple channels
Post by: x4ce on August 17, 2024, 09:08:07 am

Quote from: squadchannel on August 17, 2024, 07:48:46 am

I don't think P16 is a problem.
I don't see the point of using two FETs for P18, is there any reason why the gate of P18 FET cannot be directly PWM controlled?

If it were me, I would not use P16 and put P18 through an AND gate to combine P18 control and PWM control. no need for STN.

Thanks for responding.

These two FET are be turned ON under two different conditions through MCU. In one condition, P16 turns ON the solenoid and P18 remains OFF. In second condition, P16 is off then P18 turns ON and here 3rd (bottom) FET is driven by external PWM source. So, the purpose is to drive the solenoid from external source under 2nd condition.

Thanks

Title: Re: Schematic Review of Solenoid Control through multiple channels
Post by: PGPG on August 17, 2024, 09:47:09 am

Quote from: x4ce on August 17, 2024, 09:08:07 am

So, the purpose is to drive the solenoid from external source under 2nd condition.

You are making AND (External with P18) and then OR of it with P16 at high output current.
After converting external signal into your logic level you can do all that at signal level reducing the use of high current output transistors to 1.