Powering ZED-F9T Timing Module With Wires from a Power Supply

GPS/GNSS
1

I am using the Sparkfun GNSS Timing Breakout circuit with the ZED-F9T module. I know that it can be powered with USB-C or Qwiic pins, but after configuring the module I would instead like to power it with power and ground wires sending in 3.3V from a regulated battery source. Is this possible for this device and how might I make this modification?I believed this might somehow be possible via the “MEAS” jumper input but I am unsure.

2

You could just modify a qwiic cable wired directly to the battery and power via qwiic, or like you mentioned you could try soldering to the MEAS jumper pad https://cdn.sparkfun.com/assets/6/c/2/5/b/SparkFun_GNSS_Timing-ZED-F9T_Schematic.pdf

3

Hi @izsneha ,

Please be aware that the MEAS jumper is connected directly to the USB-C VBUS power. This is normally 5V. It is also “upstream” of the 3.3V regulator. It feeds the 3.3V regulator U5 (AP2112K):

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To use MEAS as a voltage input, you must open the jumper on the back of the board:

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Then feed in a voltage of >= 3.6V ( and <= 5.5V) so the regulator can regulate it to 3.3V. The pad next to the PWR LED feeds the regulator:

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If you feed in 3.3V here, the regulator will not work correctly. The ZED will receive approximately 3.0V and will probably not work correctly.

If you want to power the board from another regulated 3.3V supply, the easiest way is to use one of the 3.3V breakout pads. But you can also use the Qwiic 3.3V pin if you want to.

I hope this helps,
Paul

4

Hi Paul,

Thank you for your reply. It was really helpful. Could you clarify that the breakout pads you are referring to are the 3.3V labeled pins on the board? There are also 3 of them – is there a specific one you would recommend using to power the board with 3.3V from a regulated source? From the manual it also seems like the pins are for power output, not input, so I just wanted to confirm that they can also take in input power. Thank you again!

5

I think the schematic shows the connectors attached to the same net. And you can check with a multi-meter in continuity mode.

So 3.3V and GND.

If connecting to the UART of another MCU, use that connector.

If you have multiple sources, or possibility to plug in different supplies, I’d probably use diodes.