Nordic Semiconductor nRF52 DK - Page 11

Hardware description
Figure 7: Power supply options (back)
The 5 V from the USB is regulated down to 3.3 V through an onboard voltage regulator. The battery and
external power supply are not regulated. The power from the regulator and external supply is routed
through diodes for reverse voltage protection (D1 and D7), where the circuit is supplied from the source
with the highest voltage. The power from the battery is routed through a load switch and a transistor.
These are controlled by the regulator voltage or external voltage, so if any of the two other sources are
present, the battery is disconnected from the circuit.
Note: When USB is not powered, the interface MCU is in dormant state and draws an additional
current of ~ 20 μA to maintain the reset button functionality. This affects current consumption, but
not the nRF52832 current measurements, as described in Measuring current on page 25.
C18
100nF
C17
1.0µF
C16
1.0
µ
F
Vin
GND
Vout
U3
AP7333-33SAG-7
VDD
R6
N.C.
SB9
VDD_nRFVBUS
SB10
SB11
TP14
VBUS'
V5V
TP12
TP13
1
2
P21
Pin List 1x2, Angled
1
2
P22
Pin List 1x2, Angled
+
Bat1
Bat Holder CR2032
VREG_IN
VBUS'
VIO
SB35
VREG_OUT
VIN
A2
VOUT
A1
CTRL
B2
GND
B1
U11
TCK106AG
R48
1M0
VSUPPLY
VSUPPLY
R47
1M0
VSUPPLY
VEXT_DETECT
R46
1M0
VSUPPLY
SB34
SB33
R60
1M0
R44
33k
R45
47k
VBUS'
VREG_DETECT
VEXT_DETECT
USB_DETECT
C56
100nF
VSUPPLY
VSUPPLY
VEXT_DETECT
VBAT
C57
100nF
VSUPPLY
SB12
R49
100k
Q4A
TSM250N02DCQ RFG
Q4B
TSM250N02DCQ RFG
Q5A
TSM2537CQ RFG
Q5B
TSM2537CQ RFG
Q3A
TSM2537CQ RFG
Q3B
TSM2537CQ RFG
R50
220k
R51
220k
D7
NSR0620P2T5G
D1
NSR0620P2T5G
Not mounted
D8
NSR0620P2T5G
SW6
Switch
GND
VCC
U12
NC7SV11L6X
GND
VCC
U13
NC7SV11L6X
VREG_DETECT
VREG_DETECT
Figure 8: Power supply circuitry
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