LTE IoT 7 Click - power questions

[awneil]

I'm a bit confused about powering this board: https://www.mikroe.com/lte-iot-7-click

2023-06-01 (0)b.png (28 KiB) Viewed 510 times

Aside: "Buck" and "DC-DC" are generally used to describe a switching regulated - but the TPS7A7002 is a linear.

But elsewhere on the page we have:

2023-06-01 (1)a.png (72.23 KiB) Viewed 511 times

and:

2023-06-01 (2)a.png (50.85 KiB) Viewed 511 times

and ... (continued in next post)

[awneil]

... continued:

2023-06-01 (3)a.png (21.1 KiB) Viewed 510 times

Given that the main regulator (TPS7A7002) is just a step-down device, how can this board run from 3.3V

From the schematic, it looks like:

* the 3.3V from the mikroBUS (pin 7) powers the IO pins only - not the LTE module;

* the LTE module is only powered from the mikroBUS 5V supply (pin 10), or the USB.

Is that right?

In which case, this needs to be clarified throughout the page; including:

2023-06-01 (4)a.png (41.99 KiB) Viewed 510 times

needs to be clarified that it only affects the logic levels on the mikroBUS pins - nothing else.

Also, what does the V_INT pin on J1 do?

[awneil]

* the 3.3V from the mikroBUS (pin 7) powers the IO pins only - not the LTE module;

That's the default configuration as I received it, anyhow.

If the "VCC SEL" is changed to 5V:

lte-iot-7-click-thickbox_default-1a.jpg (188.56 KiB) Viewed 510 times

Then the entire board is powered from 5V, the interface operates at 5V, and nothing* uses the 3V3 - yes?

* Apart, possibly, from feeding power to the GNSS antenna - according to "GNSS ANT" setting.

[awneil]

what does the V_INT pin on J1 do?

Ah - found it!

V_INT is a 1.8V supply generated by the SARA module:

2023-06-02 (0)a.png (80.87 KiB) Viewed 504 times

[IvanJeremic]

Hi,

The click boards come with a default 3v3 and 5v pins, there are modules on the click board which need the 5v voltage, so if you move the jumper to 5v you will only need the 5v, looking at the schematic it does not look like there is any component that needs specifically 3v3.

You can see the schematic in the link below:
https://download.mikroe.com/documents/a ... c-v101.pdf

Regards,

Ivan.

[awneil]

Thanks.

I think the documentation needs to be updated to make this clear - in particular, the fact that this board will not work with 3.3V alone.

It needs:

• Either: both 3.3V and 5V

• Or: 5V only - which requires the link modification

[IvanJeremic]

Hi,

Thank you for your input.

I have sent a request to make these changes.

Regards,

Ivan.