Si4x6x radios can operate in High-performance or Low-power modes, which can be set in GLOBAL_CONFIG property. In order to save some current consumption (typically 2-3mA), low-power mode can be enabled, however it has some tradeoff in RX performance (sensitivity, linearity).
If the crystal parameters meet the requirements listed in AN785 section 1, both high-performance mode and low-power mode should result robust crystal operation on a properly designed PCB layout (crystal placed as close to the XTAL pins as possible).
In high-performance mode there is some margin on the required crystal parameters, but still it is recommended to stay within the ranges listed in AN785 section 1 for safe operation. Crystal start-up issues might occur if the parameters are not met.
In low-power mode meeting the required crystal parameters is more critical, i.e crystal start-up issues might happen even if the RF crystal parameters are near the edge. Low-power mode can be used robustly with a crystal that easily meets the recommended parameters. AN785 Table 1 provides a list of recommended crystals that will ensure safe operation both in high-performance and low-power mode.
If crystal start-up problem occurs in low-power mode, there are 2 possible options to avoid the issue:
Silicon Labs provides RF range calculators for customers to help estimating the actual range of their wireless applications. Simple RF Range Calculator is available to download from the following link below.
RF range depends on the following parameters:
Simple RF Range Calculator
Simple RF Range Calculator is for those customers who don’t want to deal with difficult RF questions, just simply would like to get fast and reasonable results for both outdoor and indoor environments.
Simple RF Range Calculator provides fast and accurate result as the customer selected the frequency band and set TX and RX parameters.
Frequency bands and custom frequency channels can also be selected.
TX Output Power and RX Sensitivity need to set up based on the radio device’s actual link parameters based on the data sheet.
If the exact antenna parameters are unknown notes at the right side can help to determine the closest values.
The achievable RF range depends on many other factors as well. See the following KBA article for further details on RF range factors: