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Re: RESET circuit tweaks

Posted: Mon Nov 12, 2018 7:03 am
by Icky
exxos wrote:
Mon Nov 12, 2018 12:27 am
http://www.ti.com/product/TPS3808/technicaldocuments

Looks good.. But output drive seems a bit wimpy :roll:

I guess a small MOSFET could be used to beaf it up.. Still smaller than a TTL chip..
Did you look at these https://www.st.com/en/reset-and-supervi ... m1816.html

Re: RESET circuit tweaks

Posted: Mon Nov 12, 2018 1:21 pm
by exxos
Icky wrote:
Mon Nov 12, 2018 7:03 am
Did you look at these https://www.st.com/en/reset-and-supervi ... m1816.html
That looks cool as well. I only had a quick look at TI so far..

I am thinking though that a programmable delay time might be better as I don't actually know what the reset time is of the ST... 0.2s might be fine, though I was thinking of more like 0.5 second.

Re: RESET circuit tweaks

Posted: Mon Nov 12, 2018 2:08 pm
by exxos
https://www.mouser.co.uk/datasheet/2/38 ... 250874.pdf


https://www.mouser.co.uk/ProductDetail/ ... 2bx6HAI%3d

MIC6315 - cheapest one in mouser... 200ms delay, manual reset, 20mA seems about as good as anything gets...

This wouldn't technically need the external buffers, my only slight concern is that there is RESET & HALT which are actually two different signals which need to be driven independently.. This could be done with 2 diodes.. Or I guess use 2 logic level MOSFETs to do the actual switching independently... Or we could just use two of these chips..

Logic level MOSFETs would have been my first choice, but the problem is this is a additional part... If we were going to have additional parts anyway, it would make sense to just use two of these chips then it is only actually one part, and buying more one part generally gets better price breaks.

It would have been nice just to have done this all in one part, but it does do away with the external buffering, so it wouldn't really be any more expensive in using two chips, but the footprint is obviously a lot smaller and of course is just one single part..

I will have a look and see if there is anything else, there are chips which have multiple monitoring inputs, so one of those might be better suited....

EDIT:

I'd say this one is the best candidate to try next...

https://uk.farnell.com/microchip/mic631 ... st=MIC6315

Even though I detest evil bay....

https://www.ebay.co.uk/itm/5pcs-SOT-143 ... :rk:1:pf:0

It would be far quicker to obtain these than wait for them to come from a pcb fab house for a month...

Re: RESET circuit tweaks

Posted: Mon Nov 12, 2018 7:19 pm
by Icky
exxos wrote:
Mon Nov 12, 2018 2:08 pm


EDIT:
I'd say this one is the best candidate to try next...

https://uk.farnell.com/microchip/mic631 ... st=MIC6315

Even though I detest evil bay....

https://www.ebay.co.uk/itm/5pcs-SOT-143 ... :rk:1:pf:0

It would be far quicker to obtain these than wait for them to come from a pcb fab house for a month...
Challenge accepted

Re: RESET circuit tweaks

Posted: Mon Nov 12, 2018 7:47 pm
by exxos
Icky wrote:
Mon Nov 12, 2018 7:19 pm

Challenge accepted
:dualthumbup:

Re: RESET circuit tweaks

Posted: Wed Nov 14, 2018 11:20 pm
by Icky
exxos wrote:
Mon Nov 12, 2018 7:47 pm
Icky wrote:
Mon Nov 12, 2018 7:19 pm

Challenge accepted
:dualthumbup:
Step one of challenge get the boards - tick

IMG_3274.png
IMG_3274.png (1.33 MiB) Viewed 1180 times

Re: RESET circuit tweaks

Posted: Wed Nov 14, 2018 11:22 pm
by exxos
Icky wrote:
Wed Nov 14, 2018 11:20 pm
Step one of challenge get the boards - tick
:dualthumbup:

Re: RESET circuit tweaks

Posted: Fri Nov 16, 2018 2:49 pm
by Icky
I rebuilt the original reset circuit as a hack to leave the reset circuit part of the board empty ready for testing the new reset chip.

Thought I would just share the ugliness of my hack that allows me to boot and reset. Made even the more ugly as I had to use lead free solder.

However it works and I can pull the chip out to test.

IMG_3288.png
IMG_3288.png (454.2 KiB) Viewed 1143 times

Re: RESET circuit tweaks

Posted: Fri Nov 16, 2018 3:00 pm
by PhilC
9 out of 10 for ugliness, some of those connections look far too well soldered for a 10.

Re: RESET circuit tweaks

Posted: Fri Nov 16, 2018 5:45 pm
by PaulJ
Icky wrote:
Fri Nov 16, 2018 2:49 pm
I rebuilt the original reset circuit as a hack to leave the reset circuit part of the board empty ready for testing the new reset chip.

Thought I would just share the ugliness of my hack that allows me to boot and reset. Made even the more ugly as I had to use lead free solder.

However it works and I can pull the chip out to test.


IMG_3288.png
Man if that was a Joe Master cap in the center it would look like a blue beatle being eaten by ants!! :) :) :)