Author Topic: Discuss improvements in the design of a latching switch?  (Read 390 times)

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Offline CrsusTopic starter

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Discuss improvements in the design of a latching switch?
« on: January 15, 2025, 01:08:42 pm »
In the design of my latching switch, I've noticed that the drive current is relatively low, and I want to increase the power output. What improvements can be made in the design?

To increase the drive power of your latching switch design, you can consider improvements in the following areas:

Voltage rating: 3.7V to 24V

1.Can the power be increased by paralleling two MOSFETs?
2.Can improvements be made in the structure and heat dissipation?
3.Should an additional transistor stage be added when the MCU directly drives a MOSFET?
 

Offline inse

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Re: Discuss improvements in the design of a latching switch?
« Reply #1 on: January 15, 2025, 01:25:36 pm »
Please don’t overcharge us with too much details of your design as well as resolution.
If “drive current is relatively low“, what current level are you talking about?
Compare the MOSFET gate voltage to the datasheet value first.
P.S. How do you get your MCU programmed without ICSP pads?
« Last Edit: January 15, 2025, 03:51:27 pm by inse »
 

Offline Konkedout

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Re: Discuss improvements in the design of a latching switch?
« Reply #2 on: January 16, 2025, 04:31:28 am »
What is the desired behavior of your "latching switch"?  What are the voltage and current levels?  How does it turn off?

Maybe you can just use an SCR?

These listings are somewhat whack-o.  An SCR should have 3 terminals.  It is easy to get one rated for several amps and 100's of volts.  But...once it turns on it stays on until the current drops down below the holding current which is normally quite low.

https://www.mouser.com/c/semiconductors/discrete-semiconductors/thyristors/scrs/?instock=y&sort=pricing
« Last Edit: January 16, 2025, 04:38:20 am by Konkedout »
 

Online WattsThat

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Re: Discuss improvements in the design of a latching switch?
« Reply #3 on: January 16, 2025, 04:48:43 am »
My magic crystal ball is broken today, you’re asking for physic abilities from us to come up with the multitude of pertinent details you’ve omitted from the post such as:

Why did you use a non-logic level mosfet driven by an unknown voltage MCU?
Why not a gate driver?
What are the load characteristics? Voltage? Current?

Do you really expect people to research the parts you used without links?

 

Offline CrsusTopic starter

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Re: Discuss improvements in the design of a latching switch?
« Reply #4 on: January 16, 2025, 12:12:13 pm »
"This is a contactless switch that uses an MCU to drive a MOSFET.
The MCU has been directly programmed without leaving an ICSP interface for in-circuit serial programming.
I have limited proficiency in English, which may lead to some unclear or imprecise descriptions on my part.
 

Offline inse

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Re: Discuss improvements in the design of a latching switch?
« Reply #5 on: January 16, 2025, 12:36:50 pm »
Ah, it’s doing capacitive sensing via TP5, then whats the switch for?
The supplied schematic is barely readable.
What current is being switched?
What did you measure yet?
What supply voltage is the MCU run with?
Don’t just give the minimal information if you want answers
 


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