Datasheet
Revision 1.5 Page 35 of 41
nRF905 Product Specification
15 Application Examples
15.1 Differential Connection to a Loop Antenna
Figure 12. nRF905 Application schematic, differential connection to a loop antenna (433MHz)
Table 28. Recommended external components, differential connection to a loop antenna (433MHz)
Component Description Size Value Tol. Units
C1 NP0 ceramic chip capacitor, (Crystal oscillator) 0603 22
±5% pF
C2 NP0 ceramic chip capacitor, (Crystal oscillator) 0603 22
±5% pF
C3 NP0 ceramic chip capacitor, (PA supply decoupling) 0603 180
±5% pF
C4 X7R ceramic chip capacitor, (PA supply decoupling) 0603 3.3
±10% nF
C5 NP0 ceramic chip capacitor, (Supply decoupling) 0603 33
±5% pF
C6 X7R ceramic chip capacitor, (Supply decoupling) 0603 4.7
±10% nF
C7 X7R ceramic chip capacitor, (Supply decoupling) 0603 10
±10% nF
C8 NP0 ceramic chip capacitor, (Supply decoupling) 0603 33
±5% pF
C9 NP0 ceramic chip capacitor, (Antenna tuning) 0603 3.9 ±0.1 pF
C10 NP0 ceramic chip capacitor, (Antenna tuning)
0603 6.8 ±0.1 pF
C11 NP0 ceramic chip capacitor, (Antenna tuning)
0603 4.7 ±0.1 pF
C12 NP0 ceramic chip capacitor, (Antenna tuning) 0603 27
±5% pF
C13 NP0 ceramic chip capacitor, (Antenna tuning) 0603 27
±5% pF
R1 0.1W chip resistor, (Crystal oscillator bias) 0603 1
±5% MΩ
R2 0.1W chip resistor, (Reference bias)
0603 22 ±1% kΩ
U1 nRF905 Transceiver QFN32L/5x5
X1 Crystal, C
L
= 12pF LxWxH =
4.0x2.5x0.8
16 ±60ppm MHz
C2
22pF
0603
C6
4.7nF
0603
C5
33pF
0603
R2
22K
0603
C7
10nF
0603
VDD
C1
22pF
0603
R1
1M
X1
16 MHz
TRX_ C E
1
VSS
24
VSS
18
VDD
17
VSS
16
PWR_UP
2
uPCLK
3
VDD
4
VSS
5
CD
6
AM
7
DR
8
VSS
9
MI S O
10
MO S I
11
SCK
12
XC2
15
XC1
14
CSN
13
VDD _PA
19
ANT1
20
ANT2
21
VSS
22
IR EF
23
nRF905
VDD
25
VSS
26
VSS
27
VSS
28
VSS
29
VSS
30
DVDD_ 1V2
31
TXEN
32
U1
nRF905
VDD
C4
3.3nF
0603
C8
33pF
0603
VDD
TXEN
TRX_ C E
PWR_UP
CD
AM
DR
SPI_MISO
SPI_MOSI
SPI_SC K
SPI_C SN
uPCLK
C3
180pF
C10
6.8pF
C11
4.7pF
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J1
Loop Antenna, 433MHz
35x20mm
C9
3.9pF
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C12
27pF
C13
27pF