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Simpler than the World's Simplest Softlatch (re: EEVBLOG #262)

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NeverDie:
Reporting back:  I came across this circuit, which uses just two mosfets:



Source:  http://www.mosaic-industries.com/embedded-systems/microcontroller-projects/electronic-circuits/push-button-switch-turn-on/latching-toggle-power-switch

Aside from using fewer components, it's also easier to understand.

Based on simulation, I found that it can also work with just one transistor and one mosfet (see attached schematic, where I used a Tina time switch to simulate brief button pushes).




So maybe this really is the world's simplest soft latch?  I enjoyed the original video, but maybe it's worth updating the video with these circuits as a fun follow-up.

Keep up the good work!

Fungus:
I ordered a bunch of these modules last week:
https://www.aliexpress.com/wholesale?SearchText=Si4599

I needed some P-channel MOSFETS and these boards were cheap so I figured I could have a stock of "MOSFETS" that can be used in either low or high configuration as needed.

They should be able to implement this circuit easily, too.  :)

NeverDie:
I'd be interested to know how much leakage current there would be in this circuit, since the stated objective is to mimic a physical switch.

NeverDie:
@Fungus Given the seemingly never ending chip shortage I find myself gravitating toward easily substitutable parts that have generic footprints and generic pinouts.  In this case, something like SI2312BDS-T1-E3 and SQ2315ES-T1_GE3 for n-channel and p-channel mosfets.  They also have less leakage and lower threshold voltages, which is a better fit for the general trend toward lower voltage and lower power electronics.  What I like about Vishay parts is that Vishay generally has  easy-to-find p-spice models of their parts.  I don't know of any other manufacture that does as well as Vishay at publishing p-spice models for their parts.  Can anyone here name some?  It seems hit or miss with other manufacturers whenever I've gone looking.

Fungus:

--- Quote from: NeverDie on October 11, 2022, 07:50:51 pm ---@Fungus Given the seemingly never ending chip shortage I find myself gravitating toward easily substitutable parts that have generic footprints and generic pinouts. 

--- End quote ---

"Jellybean" parts.

https://en.wiktionary.org/wiki/jellybean_part

(funnily enough, https://jellybean.parts/ is a site for parts that are anything but jellybean)

My little NP-MOSFET modules just arrived. I might have a go at building that circuit to try one of them out and make sure I haven't been sold duds.

I'll measure the leakage current...

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