nRF9160 DK has a flexible and configurable power supply system to allow software development and testing using different power sources and to facilitate accurate power measurements.
The power source options are:
- Universal Serial Bus (USB) connector J6 (5 V)
- External supply on P21 (3.0 V–5.5 V)
- VIN 3–5 V on P20 (3.0 V–5.5 V)
To ensure that only one of the power sources are used on the Development Kit (DK) at a time, power switches are implemented on each of them as shown in Power sources and switches. These switches prioritize the supply sources in the following manner:
- USB
- P20
- P21
This means that if power is connected to more than one the interfaces, the higher priority interface will be chosen to supply the DK.
The supply voltage is then routed through the ON/OFF switch (SW8) to the common rail VSUPPLY, which acts as the source for the supply voltage regulators for the circuitry on the DK.
The supply flows from VOUT to VIN, which is correct. The body diode of the internal transistor powers the VSUPPLY net, which supplies the gates controlling the enable signal of the switches.
The power switches will introduce a small voltage drop between the power source connected to the DK and the VSUPPLY. To avoid this, the power switches can be bypassed by shorting one of the solder bridges as shown in the following table:
| Power source | Power switch bypass | Voltage level |
|---|---|---|
| USB connector (J6) | SB29 | 5 V |
| External supply (P21) | SB30 | 3.0 V–5.5 V |
| VIN 3–5 V (P20) | SB31 | 3.0 V–5.5 V |