RESET circuit tweaks

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Icky
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Re: RESET circuit tweaks

Post by Icky » Mon Nov 12, 2018 7:03 am

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

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Re: RESET circuit tweaks

Post by exxos » Mon Nov 12, 2018 1:21 pm

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.
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Re: RESET circuit tweaks

Post by exxos » Mon Nov 12, 2018 2:08 pm

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...
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

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Re: RESET circuit tweaks

Post by Icky » Mon Nov 12, 2018 7:19 pm

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

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Re: RESET circuit tweaks

Post by exxos » Mon Nov 12, 2018 7:47 pm

Icky wrote:
Mon Nov 12, 2018 7:19 pm

Challenge accepted
:dualthumbup:
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Re: RESET circuit tweaks

Post by Icky » Wed Nov 14, 2018 11:20 pm

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

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Re: RESET circuit tweaks

Post by exxos » Wed Nov 14, 2018 11:22 pm

Icky wrote:
Wed Nov 14, 2018 11:20 pm
Step one of challenge get the boards - tick
:dualthumbup:
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

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Re: RESET circuit tweaks

Post by Icky » 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
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Re: RESET circuit tweaks

Post by PhilC » Fri Nov 16, 2018 3:00 pm

9 out of 10 for ugliness, some of those connections look far too well soldered for a 10.
If it ain't broke, test it to Destruction.

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Re: RESET circuit tweaks

Post by PaulJ » Fri Nov 16, 2018 5:45 pm

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
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