nRF9160 DK v0.8.5

Power supply

nRF9160 DK (Development Kit) 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:

Figure 1. nRF9160 DK power supply options
nRF9160 DK power supply options
Figure 2. Power sources and switches
Schematic: nRF91 MLM1 DK power sources and switches

To ensure that only one of the power sources are used on the board 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:

  1. USB
  2. P15
  3. P28

This means that if power is connected to more than one the interfaces, the higher priority interface will be chosen to supply the board.

The supply voltage is then routed through the ON/OFF switch (SW9) to the common rail VSUPPLY, which acts as the source for the supply voltage regulators for the circuitry on the board.

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 board and the VSUPPLY. To avoid this, the power switches can be bypassed by shorting one of the solder bridges:

Table 1. Bypassing power switch
Power source Power switch bypass Voltage level
USB connector (J4) SB24 5 V
External supply (P28) SB36 3.3 V–5.5 V
VIN 3–5 V (P15) SB4 3.3 V–5.5 V
Note: Connect only one power source at a time in this case. Shorting the solder bridges removes the reverse voltage protection.