XE1203SKC868XE2 Semtech, XE1203SKC868XE2 Datasheet - Page 30

• Manufacturer Part Number: XE1203SKC868XE2
• Description: KIT STARTER FOR XE1203 868MHZ
• Manufacturer: Semtech
• Series: TrueRF™r
• Type: Transceiver, ISMr

Specifications of XE1203SKC868XE2

• Frequency: 868MHz
• For Use With/related Products: XE1203 (868MHz)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

5.5
5.6
The XE1203F can be used with a 39 MHz crystal operating in fundamental mode or in 3
overtone operation, an internal resistor to be switched across the crystal terminals XTA and XTB is required. This
resistor can be selected by programming the ADParam_Resxosc(3:0) parameter. The required value depends on
the overtone crystal specification.
When using 3
attempt to start at the fundamental frequency of the crystal. It will only switch to the overtone mode when properly
programmed through the 3-wire interface bus. As a result, if a microcontroller uses the XE1203F CLKOUT as a
clock source it is advisable to allow the oscillator frequency to settle before undertaking any time or timing sensitive
operations.
For fundamental mode operation, the ADParam_Resxosc(3:0) parameter is set to the default value of ”0000’’. This
switches a 3.8 MΩ resistance across the crystal terminals.
When register “RTParam_Clkout” is set to “1” , the reference frequency is divided by 4, 8, 16 or 32, depending on
the value of the register “ADParam_Clkfreq”, and provides a reference signal at CLKOUT for a microcontroller or
external circuitry. If the reference frequency is 39 MHz, then the output frequency available at CLKOUT is as
defined in Table 20 below:
When the XE1203F is in sleep mode, CLKOUT is disabled even if RTParam_Clkout remains high.
The internally generated power-on-reset signal sets the RTParam, FSParam, ADParam and Pattern registers to
the 00hex value.
There is one important exception for CLKOUT. Although the RTPAram_CLkout is set to ”0” at power-on reset,
meaning the feature should be disabled, the XE1203F will generate a CLKOUT signal after a power-on reset to
provide a clock signal to a possible microcontroller connected to it. After a power-on reset, CLKOUT will be the
lowest available frequency, e.g. 1.22 MHz with a 39 MHz reference frequency. Then, on the first rising edge of the
/EN signal – for example after a programming sequence via the 3-wire interface bus - the content of the
configuration registers will be updated. If the RTParam Configuration Register has not been programmed during
this first sequence after a power-on reset, the CLKOUT clock signal will be disabled. It is strongly advised to
initialize the RTPAram_CLkout parameter appropriately during the first programming sequence after a power-on
reset, especially if an external microcontroller does use this CLKOUT clock signal to operate.
It is recommended to initialize the XE1203F registers immediately after power-up.
© Semtech 2008
CLOCK OUTPUT INTERFACE
DEFAULT SETTINGS AT POWER-UP
rd
overtone mode, the user should be aware that during its power up the XE1203F oscillator will
ADParam_Clkfreq
00
01
10
11
Table 20: Clock Output Frequency Selection
30
CLKOUT frequency
1.22 MHz
2.44 MHz
4.87 MHz
9.75 MHz
rd
overtone mode. For third
XE1203F
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