RFM66W Datasheet, PDF (81/87 Pages) List of Unclassifed Manufacturers – 868 & 915MHz Ultra Low Power High Link Budget Integrated UHF Transceiver

WIRELESS & SENSING
RFM66W
DATASHEET
7. Application Information
7.1. Crystal Resonator Specification
Table 31 shows the crystal resonator specification for the crystal reference oscillator circuit of the RFM66W.
This specification covers the full range of operation of the RFM66W and is employed in the reference design.
Table 31 Crystal Specification
Symbol Description
Conditions
Min
Typ
Max Unit
FXOSC XTAL Frequency
-
32
-
MHz
RS
XTAL Serial Resistance
-
30
140 ohms
C0
XTAL Shunt Capacitance
-
2.8
7
pF
CFOOT External Foot Capacitance On each pin XTA and XTB
8
15
22 pF
CLOAD Crystal Load Capacitance
6
-
12 pF
Notes - the initial frequency tolerance, temperature stability and ageing performance should be chosen in accordance
with the target operating temperature range and the receiver bandwidth selected.
- the loading capacitance should be applied externally, and adapted to the actual Cload specification of the XTAL.
7.2. Reset of the Chip
A power-on reset of the RFM66W is triggered at power up. Additionally, a manual reset can be issued by controlling pin 6.
7.2.1. POR
If the application requires the disconnection of VDD from the RFM66W, despite of the extremely low Sleep Mode current,
the user should wait for 10 ms from of the end of the POR cycle before commencing communications over the SPI bus.
Pin 6 (Reset) should be left floating during the POR sequence.
VDD
Pin 6
(output)
Undefined
Wait for Chip is ready from
10 ms this point on
Figure 37. POR Timing Diagram
Please note that any CLKOUT activity can also be used to detect that the chip is ready.
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