nRF903 Nordic VLSI, nRF903 Datasheet - Page 17

• Manufacturer Part Number: nRF903
• Description: Multichannel RF Transceiver 433/868/915MHz
• Manufacturer: Nordic VLSI

PRODUCT SPECIFICATION
When specifying a crystal, keep in mind that the frequency deviation requirement is
accounts for both frequency tolerance ( f/f) and temperature variations in the crystal
frequency.
Example: For a 868MHz system, a crystal frequency tolerance ( f/f) of 15ppm,
leaves 5ppm for drift due to temperature variations.
As temperature characteristics are closely related to crystal cost, it is advisable not to
exaggerate the crystal specification. Note that it is
requirement. If the transmitter and receiver will not be operating at opposite
temperature extremes at the same time (maximum difference), the requirements
towards temperature characteristics may be relaxed accordingly.
Note that frequency difference between the transmitter and receiver will result in
sensitivity loss, which is proportional to the total frequency offset. Figure 9 shows
sensitivity as a function of total frequency offset.
The key parameters for the nRF903 crystal reference are as follows:
Nordic VLSI ASA
Revision: 3.1
Chequers electronic
Epson
Raltron
Golledge
Fox Electronics
Jauch
20ppm for 868/915MHz operation and 40ppm for 433MHz operation. This
-100
-105
f
ESR
C
C
-75
-80
-85
-90
-95
c
=11.0592MHz
0,max
L
-120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10
=12pF
Table 15. Vendors and part no. for suitable 11.0592MHz crystals
Figure 9. Sensitivity vs. total TX/RX frequency offset (Typical)
max
=7pF
=60
-
Vestre Rosten 81, N-7075 Tiller, Norway
www.chequers-electronic.com
www.epson-electronics.de
www.raltron.com
www.golledge.com
www.foxonline.com
www.jauch.de
(nRF903 internal load is 11.5pF 8%. Application layout on
page 29 adds approx. 0.5pF load)
Qhtrà &ÂsÃ"!
Frequency offset [kHz]
0
10
CQ11.0592 / SMD0705
MA-406H
SA-315H / 315HZ
H10S
GSX-2
FD
JXS 75
-
20
Phone [phone]
30
40
that set the crystal oscillator
50
60
70
80
-
90 100 110 120
Fax [phone]
December 2002