Reference circuitry

To ensure good RF performance when designing PCBs, it is highly recommended to use the PCB layouts and component values provided by Nordic Semiconductor.

Documentation for the different package reference circuits, including Altium Designer files, PCB layout files, and PCB production files can be downloaded from www.nordicsemi.com.

In this section, there is a reference circuit for QKAA aQFN™94, showing the components and component values to support on-chip features in a design.

Some general guidance is summarized here:
  • When supplying power from a USB source only, VBUS must be connected to VDDH if USB is to be used.
  • Components required for DC/DC function are only needed if DC/DC mode is enabled for that regulator.
  • NFC can be used in any configuration.
  • USB can be used in any configuration as long as VBUS is supplied by the USB host.
  • The schematics include an optional, but recommended, series resistor on the USB supply for improved immunity to transient over-voltage during VBUS connection.

Circuit configuration no. 1

Circuit configuration number 1 for QKAA aQFN™94, showing the schematic and the bill of materials table.

Table 1. Configuration summary for circuit configuration no. 1
Config no. Supply configuration Enabled features
VDDH VDD       USB NFC
Config. 1 USB N/A       Yes No
Figure 1. Circuit configuration no. 1 schematic

Note: For PCB reference layouts, see the product page for the nRF5340 on www.nordicsemi.com.
Table 2. Bill of material for circuit configuration no. 1
Designator Value Description Footprint
C1, C13, C14, C16, C19, C21, C23, C24, C25 100 nF Capacitor, X5R, ±10 % 0201
C2, C3, C4, C5, C11 1.0 µF Capacitor, X5R, ±5 %, 6.3 V 0402
C6 2.2 µF Capacitor, X7R, ±10 % 0603
C7 4.7 µF Capacitor, X7R, ±10 % 0603
C8, C26 4.7 µF Capacitor, X7S, ±10 % 0603
C9 820 pF Capacitor, X7R, ±10 % 0201
C10 100 pF Capacitor, NP0, ±2 % 0201
C12 0.7 pF Capacitor, NP0, ±0.05 pF 0201
C18, C27 N.C. Not mounted 0201
L1, L3, L5 10 µH Inductor, 250 mA, ±20 %, 1.05 Ω 0603
L2, L4 15 nH Inductor, 250 mA, ±5 % 0201
L6 2.2 nH High frequency chip inductor, ±5 % 0201
R1 4.7 Ω Resistor, ±1 %, 0.05 W 0201
U1 nRF5340-QKAA Multi-protocol Bluetooth Low Energy, IEEE 802.15.4, ANT and 2.4GHz proprietary system-on-chip AQFN-94
X1 32 MHz XTAL SMD 2016, 32 MHz, Cl=8 pF, ±40 ppm XTAL_2016
X2 32.768 kHz XTAL SMD 2012, 32.768 kHz, Cl=9 pF, Total Tol: ±50 ppm XTAL_2012

PCB layout example

The PCB layout shown below is a reference layout for the aQFN™ package with internal LDO setup and VBUS supply.

Note: Pay attention to how the capacitor C12 is grounded. It is not directly connected to the ground plane, but grounded via pin J31 and to the VSS die pad. This is done to create additional filtering of harmonic components.

For all available reference layouts, see the product page for the nRF5340 on www.nordicsemi.com.

Figure 2. Top silk layer

Figure 3. Top layer

Figure 4. Mid layer 1

Figure 5. Mid layer 2

Figure 6. Bottom layer


This document was last updated on
2019-12-09.
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