EEZ Bench Box 3 (BB3) and beyond...

[prasimix]

I just tested the ULN2803A I have, and it starts working from 1.6V. Maybe too close to 1.8V to be considered safe to operate.

[prasimix]

In DIB 2.0 I added Quad SPI (QSPI) as one of the communication channels. Unlike standard SPI where there is MOSI and MISO (both unidirectional) here there are 4 lines that are bidirectional. The question arises how to isolate it? Does anyone know of a 4-bit bidirectional digital isolator?

[prasimix]

To make things more complicated, the rail voltage on one side should go down to 1.8V. So unfortunately, for example, Onsemi NCID9401 is not a viable candidate.

[Kean]

Maybe the Silicon Labs/Skyworks Si86SQ44BE which seems to be designed specially for QSPI as it support direction input from one side (output at other) as well as output enable control from both sides.

https://www.skyworksinc.com/-/media/SkyWorks/SL/documents/public/data-sheets/si86s6xx-datasheet.pdf

Listed at LCSC, but not currently in stock.  And Digikey/Mouser don't currently stock it either.  You'd probably have to go direct to Skyworks.
An eval board is available that you could maybe borrow chips from https://www.skyworksinc.com/en/Products/Isolation/Evaluation-Kits/digital-isolator/Si86SSxx-KIT

Alternative is to use a pair of TI 4-bit uni-directional isolators (e.g. ISO6740 or faster ISO7740) plus one extra single channel for isolation of the direction signal for output enables.  A little more expensive, and uses more board space, but the parts are readily available.

I've not used either of these, it is just something I have researched.  The QSPI host controller will need to generate the direction signal.

Further, for 1.8V rail support the TI parts should work, but the Skyworks would need a separate level shifter...

[prasimix]

Thanks Kean, I can find SI86SQ44 on Mouser and Digikey, price is similar to Onsemi, and yes, also will requires additional level shifter on 1.8V side. It has a slight advantage in terms of speed, going up to 150 Mbps.

[prasimix]

Example of module isolation if it would use QSPI to communicate with the Master MCU. There is still the question of the QSPI CLK which if it is also bidirectional then another 1-bit bidirectional isolator will need to be added:

[Kean]

As far as I know, the clock will always be unidirectional.

Won't you need to pass the chip select signal through the isolators as well?  Or did I miss something?

[prasimix]

Chip select is CSA and it's unique for each module. So, I'd like to use it to enable/disable QSPI isolator.

[Crazoff]

Hello. Can you tell me what output pulsations does BB3 provide at the output of the DCP-405 and DCM220 modules?

[prasimix]

DCP405 supports programming lists and function generator where you can generate e.g. sine wave up to 200 Hz. All that you can check in online simulator: https://www.envox.eu/web-simulator/

[Crazoff]

I meant the noise at the output

[prasimix]

Check under Measurements tab: https://www.envox.eu/dc-power-modules/dcp405-power-module/ (although it was done with entry level Rigol DSO)

[Crazoff]

Hello. I'm starting BB3 little by little. So far, I have mounted only the DCM220. Everything worked without any problems. initialized, calibrated. Tell me, does the HID USB mouse not work? The USB keyboard is working fine. MCU r3B4 + bb3-v1.7.hex

[Crazoff]

There is a connection with the computer, he also sees the memory card.