SI4455 Datasheet, PDF (19/40 Pages) Silicon Laboratories – 20-Pin 3x3 mm QFN package

Si4455
4.1.1. Configuration Table
The configuration table is a list of predefined configurations that have been optimized for performance and
validated by Silicon Labs. These configurations are listed for many common application conditions and so most
users will be able to find the configuration they need in this table. These configurations are set to provide optimized
performance for a given application and can be implemented with low design risk. Once the list item is selected,
the specific frequency, power level, and packet handler features can also be applied.
4.1.2. Radio Configuration Application
The Radio Configuration Application provides an intuitive interface for directly modifying the device configuration.
Using this control panel, the device parameters such as modulation type, data rate, frequency deviation, and any
packet related settings can be set. The program then takes these parameters and automatically determines the
appropriate device settings. This method allows the user to have complete flexibility in determining the
configuration of the device without the need to translate the system requirements into device specific properties.
The resulting configuration array is automatically generated and available for use in the user's program. The
resulting configuration array is obfuscated; therefore, its content changes every time a new array is generated,
even if the input parameters are the same.
4.2. Configuration Options
4.2.1. Frequency Band
The Si4455 can operate in the 283–350 MHz, 425–525 MHz, or 850–960 MHz bands. One of these three bands
will be selected during the configuration setup and then the specific transmission frequency that will be used within
this band can be selected.
4.2.2. Modulation Type
The Si4455 can operate using On/Off Keying (OOK), Frequency Shift Keying (FSK), or Gaussian Frequency Shift
Keying (GFSK). OOK modulation is the most basic modulation type available. It is the most power-efficient method
and does not require as high oscillator accuracy as FSK. FSK provides the best sensitivity and range performance,
but generally requires more precision from the oscillator used. GFSK is a version of FSK where the signal is
passed through a Gaussian filter, limiting its spectral width. As a result, the out-of-band components of the signal
are reduced.
The Si4455 also has an option for Manchester coding. This method provides a state transition at each bit and so
allows for more reliable clock recovery. Manchester code is available only when using the packet handler option
and, if selected, will be applied to the entire packet (the preamble pattern is set to continuous “1” if the Manchester
mode is enabled; therefore, the chip rate of the resulting preamble pattern is the same as for the rest of the packet).
The polarity can be configured to a “10” or “01”.
C lo c k
D a ta
1
0
1
0
0
1
1
1
M a n ch e ste r
Figure 6. Manchester Code Example
Rev 1.1
19