Simulation of a Press-ON-Press-OFF push button

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michcfr

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Hello,
I have created a Proteus model implementing a Press-ON-Press-OFF push button according to the first schematics of this page:

Push Button ON-OFF Toggle Switch and Latching Power Circuit for Microcontrollers

A simple latching high side soft power switch toggles ON and OFF microcontroller based products and instruments, including single board computers and raspberry pi or arduino boards. A short button press applies power, a subsequent press initiates orderly shutdown under control of the...
www.mosaic-industries.com
The Microcontroller is replaced by the LED10 to show Power on/off and SW2 for the I/O pin to reproduce manually the I/O

What I expect:
.short button press of SW1: LED ON
.and another short button press of SW1 toggles it back OFF

What I get:
.short button press of SW1: LED OFF. See the left picture of the attached file. The Probe is at almost 0V
.and another short button press of SW1: LED OFF. See the right picture of the attached file. The Probe is 0.0826V


Can you please help me to debug the Proteus model. Thx

Regards,
Michel
 

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  • Press-ON-Press-OFF.jpg
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Hi,

one problem: never connect a LED directly to a voltage source. Always use any current limiting technique.
--> Simplest way: a series resistor

Diode D3 isn`t a suitable choice. You used a 10A power diode, but the current there is just a couple of 10uA.
This is in the range of the leakage current of the used power diode.
--> Better use a low signal diode specified for milliamperes.

And you have a simulation tool. You are free to use it.
--> Use it to check voltages and currents.

Klaus
 

Thank you Klaus, but is does not help a lot.
Possible to move/duplicate this message in another forum: power electronics or analog circuit design?

thx
 

Hi,

"It doesn´t help" .... means what?
* You didn´t try to modify your circuit?
* you didn´t try to measure voltages and currents?
* or you just did not report any results to us?

***
Dulpicate posting is not allowed. Nor do moderators move posts on request.
(Moving the post will not modify your circuit, nor does it show any voltages / currents to the community)

Klaus
 

I applied your advices: add resistor to the led, modify diode model, add probes. See the picture: before pushing the switch (left) and after (right). nothing is changing.
 

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  • test2.jpg
    328.1 KB · Views: 187

Hi,

Most of the values make no sense.
And - to be honest - it seems you edited the screenshot. I don´t trust edited pictures. Why editing?
--> Do a screenshot and upload it as .PNG. No need to combine two screenshots to a very wide picture.

Example: (left picture)
C3(1) shows V = 0 // so far so good
I (close to this) shows 5uA. This is expecatble because fo 5V/100kOhms.
But for this Q3 needs to be ON. But Q3(G1) - which is V_GS - shows 45uV. With 45uV the MOSFET should be OFF.

If C3(1) is 0V, then V_GS of Q3 is -5V, thus the P-CCh MOSFET should be ON. But it shows 23uV at the drain .. and almost zero current. This can´t be.

Klaus
 

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