© Semtech 2006 www.semtech.com
23
XE1202A TrueRF™
5.2.6 Supplementary configuration
Configuration settings to optimize device performance under certain operation conditions are described in Table 19
below:
Name
Bits Byte Address
Description
TParam_BW
2 10011
Bandwidth decoding map:
Baseband filter bandwidth
(RTParam_BW):
0 -> default values:
RTParam_BW(1:0) = 00 => 10 kHz
RTParam_BW(1:0) = 01 => 20 kHz
RTParam_BW(1:0) = 10 => 40 kHz
RTParam_BW(1:0) = 11 => 200 kHz
1 -> new values:
RTParam_BW(1:0) = 00 => 14.3 kHz
RTParam_BW(1:0) = 01 => 28.5 kHz
RTParam_BW(1:0) = 10 => 66.7 kHz
RTParam_BW(1:0) = 11 => 100 kHz
TParam_HPF
5-3 10110
Cut-off frequency of the HPF stages
allowing to cancel the DC and low-
frequency offsets in the baseband
circuit:
0 0 0 -> 660 Hz (default value)
0 0 1 -> 1.48 kHz
0 1 0 -> 1.75 kHz
0 1 1 -> 1.96 kHz
1 0 0 -> 2.55 kHz
1 0 1 -> 3.34 kHz
1 1 0 -> 5.11 kHz
1 1 1 -> 10.2 kHz
Table 19: Supplementary configuration
Using TParam_BW allows intermediate bandwidths to be accessed; these additional bandwidths can be selected to
optimize the sensitivity and the selectivity of the applications for which the signal bandwidth is different from the 4
default filter bandwidths.
The wake-up time of the receiver may be reduced by increasing the cut-off frequency of the HPF stages. This is
accomplished by changing the value of TParam_HPF.
Note that the selected cut-off frequency should be less than (∆f – (BR/2)) to avoid sensitivity degradation.
5.3 Operating Modes
The XE1202A TrueRF™ has 4 main operating modes as set by the MODE[2:0] inputs as illustrated in Table 20
below. Switching between modes is only possible when the /EN signal is low. The actual change will be applied to
the transceiver upon the rising edge of the /EN signal.
Over the operating supply and temperature range, set-up and hold time for MODE[2:0] on the rising edge of /EN is
200 ns, while the negative pulse duration on /EN is 2 µs minimum. Please refer to Figure 9:
