AMX Schematics & Layout

[Tinkerer]

For higher inductance coils it would be an advantage to have a higher voltage (for example VTXSW ) at Q7.
The impedance of high turn, high inductance coils is higher.
Higher voltage will reduce the compensation time, important with short cycle times.

[Carl-NC]

OK, thanks.

[Mdtoday]

Carl,
I had a look over your PCB layout and noticed a couple of minor things.
Two or three tracks around D1,D2,R2 could be beefed up to match other tracks.
Maybe increase track width section at pads on the SPI connector, purely based on my experience with JLPCB, PCBWAY boards in the past where, thin tracks to larger connector pads are not all that reliable….not a game stopper but maybe worth increasing track width section just at pads.

Nice work on the layout btw.

[Carl-NC]

It will take some time for me to clean up the BOM and get proper part numbers entered. I'll post it when done.

[wtrk]

Hello Carl.
Could you please share if possible BOM and CPL files for assembling directly to jlc

[Carl-NC]

I did a quick-check with JLC, 5 boards will run $40 USD plus shipping. That's not bad; it's 4 layers and 5.6" x 3.75" (143mm x 96mm).

Most passives are 0805, a few are larger. Chips are SOIC and SOT23, except for the ADC which is MSOP-16. I just noticed D7 & D8 are SOD323, I'll change them to SOD123.

[Carl-NC]

Here is Rev 0.3 of the schematics. No major changes, but a lot of detail changes in order to finish the layout.

AMX_SchRev0.3.pdf

Also, I have completed the layout. It is also called Rev 0.3 and I will leave it for a while so others can review and offer feedback. I also like to chew on a layout for a few days before I send it to JLC.

AMX_GerberRev0.3.zip

Here is a preview:

[Olly]

When I did a quick read of the data sheet I was under the impression that the total bipolar input range was +/- 10.24V, or +/- 5.12V per input pin. Fig 5 & 6 suggest that it is actually +/- 10.24V per pin, so we could increase the opamp supplies to +/- 10V. All of the power supply chips can handle this so it is a matter of changing some resistor values. All of the opamps can also handle this except for the MAX412, but that was just a placeholder anyway until I decide on the real opamp. So the design does not need any changes to support +/- 10V. Supporting +/- 12V requires adding an external reference to the ADC and I'd rather not do that right now.

Thanks Carl, good flexible design

[Carl-NC]

When I did a quick read of the data sheet I was under the impression that the total bipolar input range was +/- 10.24V, or +/- 5.12V per input pin. Fig 5 & 6 suggest that it is actually +/- 10.24V per pin, so we could increase the opamp supplies to +/- 10V. All of the power supply chips can handle this so it is a matter of changing some resistor values. All of the opamps can also handle this except for the MAX412, but that was just a placeholder anyway until I decide on the real opamp. So the design does not need any changes to support +/- 10V. Supporting +/- 12V requires adding an external reference to the ADC and I'd rather not do that right now.

[Olly]

Here is Rev 0.2. Based on feedback from Willy & Olly (see the TX thread). I've changed the simple sample-holds into a differential integrator to get more resolution for the tilt measurement. Also put in some real FET switch numbers and fixed a few other things.

[ATTACH]n411310[/ATTACH]

Hi Carl, I was wondering whether it might be advantageous to increase the op amp supply voltage to somewhere closer to +/- 12V in order to make full use of the wide input voltage range of the ADC?

I expect this should improve SNR somewhat.

Regards,
Olly

[Carl-NC]

For me, this first board is for bench testing. It will be mated with some kind of micro eval board. But if I can, I'll try to make it fit a particular box.

[ivconic]

Hi Carl,

If you need a good PCB size for your detector projects and if all the components fit, choose one of the following board sizes.

1) PCB size 134x70mm (LxW). This PCB size fits nicely in many different and easy available enclosures of the size 160x80x56-90mm (LxWxH).
2) PCB size 151x98mm (LxW). This PCB size fits in an standard enclosure of the size 160x110x90mm (LxWxH)
3) PCB size 145x75mm (LxW). This PCB size fits for the Hammond 1591XXDBK enclosure series 152x82x51mm (LxWxH)
4) PCB size 172x110mm (LxW). This PCB size fits for the standard Pollin enclosure of the size 200x120x90mm (LxWxH)

Another solution is we to design our own enclosure and 3D print it.
So I propose total freedom in designing the pcb with no compromises on account of quality of pcb design.

[GeoMax]

Hi Carl,

If you need a good PCB size for your detector projects and if all the components fit, choose one of the following board sizes.

1) PCB size 134x70mm (LxW). This PCB size fits nicely in many different and easy available enclosures of the size 160x80x56-90mm (LxWxH).
2) PCB size 151x98mm (LxW). This PCB size fits in an standard enclosure of the size 160x110x90mm (LxWxH)
3) PCB size 145x75mm (LxW). This PCB size fits for the Hammond 1591XXDBK enclosure series 152x82x51mm (LxWxH)
4) PCB size 172x110mm (LxW). This PCB size fits for the standard Pollin enclosure of the size 200x120x90mm (LxWxH)

[Carl-NC]

Layout is progressing, though slowly. I've made it to the hard part, where I need to figure out the power planes. Total board size is currently 100x150mm.

[Carl-NC]

Here is Rev 0.2. Based on feedback from Willy & Olly (see the TX thread). I've changed the simple sample-holds into a differential integrator to get more resolution for the tilt measurement. Also put in some real FET switch numbers and fixed a few other things.

AMX_SchRev0.2.pdf