xe1205 Semtech Corporation, xe1205 Datasheet - Page 18

• Manufacturer Part Number: xe1205
• Description: Low-power, High Link Budget Integrated Uhf Transceiver
• Manufacturer: Semtech Corporation

The XE1205 is set to transmit mode when MCParam_Select_mode is low by setting MCParam_Chip_mode(1:0) to 10 .
If MCParam_Select_mode is high the XE1205 is set to transmit mode by setting pins SW(1:0) to 10 .
The data directly modulates the LO, or an (optional) pulse shaping filter can be used resulting in an adjacent channel
power down to -37dBm at 25kHz for an output power up to 10dBm.
In continuous mode the transmitted data is sent directly to the frequency synthesizer.
In buffered mode the data is first written into the sixteen byte FIFO via the SPI interface; data from the FIFO is used to
modulate the frequency synthesizer.
5.3.1
The output power of the power amplifier is programmable on four values with the register TXParam_Power (please refer
to section 7.2.4 below), as shown in Table 10, where RFOP values are given in the Electrical Specifications section
4.2.2.
5.3.2
The transmitter works in continuous mode if the bit MCParam_Buffered_mode is low. The transmit data should be
applied to pin DATA if register bit Data_unidir is low or pin NSS_DATA if register bit Data_unidir is high. Figure 11 shows
the transmitter chain in continuous mode:
The pulse shaping function is enabled by setting TXParam_Filter to
is used as data clock in the transmission and this clock is generated at a frequency according to the selected bit rate.
The DCLK signal is supplied to the microcontroller via the pin IRQ_1 which must update the data on the falling edge. The
data is sampled at the rising edge of DCLK and filtered.
© Semtech 2007
5.3
Output power
Transmitter in continuous mode
TRANSMITTER SECTION
modulator
TXParam_Filter
TXParam_POWER
Figure 11: Transmitter data path in continuous mode
0
1
Table 10: Output power settings
0 0
0 1
1 0
1 1
Data shaping
Output power
18
filter
RFOP1
RFOP2
RFOP3
RFOP4
. If the filtering option is selected, the DCLK signal
MCParam_Data_unidir
datain
0
1
NSS_DATA
IRQ_1
XE1205
DATA
www.semtech.com