Si4356RXModule-UG Si4356-RX-434 STANDALONE RECEIVER MODULE USERS GUIDE 1. Overview This document describes the basic use of the 4356-RX-434 small standalone receiver module. The schematic of the module is shown in Figure 1. Figure 1. 4356-RX-434 Standalone Receiver Module Schematic The module contains the Si4356 Standalone Sub-GHz Receiver RF IC, a Zener diode or LDO, a low-cost SMD crystal, and the 4-element discrete matching balun transformer. Because the Si4356 RF IC is pin configurable, the module can operate in RX mode with different configurations. Different carrier frequencies, data rates, modulation types, frequency deviations, and receiver bandwidths can be set by the configuration selector pins (SEL0SEL3). These pins are connected to GND, VDD RF, OUT0 (pin 12), or OUT1 (pin 14). The Si4356 provides the received RAW data on pin 14. The receiver performance can be significantly improved by adding a low-pass filter to the RX data output. These optional RC components are represented by R3 and C5 in Figure 1. Component values have to be calculated based on the expected data rate, where DR=1/(2*pi*R*C). For 2.4 kbps, a good combination could be 1 k with 47 nF. For 1 kbps, use 100 nF. The element values of the 4-element discrete matching balun transformer depend on the operating frequency. The Rev. 1.2 12/15 Copyright 2015 by Silicon Laboratories Si4356RXModule-UG Nort Recommended for New DesignsSi4356RXModule-UG element values can be found in the Si4356 data sheet and are detailed in AN643: Si446x/Si4362 RX LNA Matching. The module is +5 V compatible therefore, supply voltages up to +5 V can be connected to the VDD. Meanwhile, the Si4356 RF IC does not tolerate voltages above +3.6 V (VDD RF). This voltage conversion between the VDD and VDD RF (see Figure1) is ensured by a Zener diode or an LDO one of them should be mounted simultaneously. Do not directly connect +5 V to the pins of the Si4356 RF IC The default and typical supply voltage for the VDD is +5 V while using an LDO to drive 3.3 V for the Si4356 RF IC (VDD RF). If using a Zener diode, the R1 resistor value must be determined according to the Zener diode and the supply voltages. The RST pin of the Si4356 RF IC on the small RX module is directly connected to the GND, which means that it is not possible to reset the radio chip externally. For this reason, it is strongly recommended to ensure the exact VDD requirements for the radio chip for a proper power-on-reset (POR), as documented in the Si4356 data sheet. If the documented radio VDD requirements are not carefully followed for a proper POR, and if the VDD RF is not stable, then it is recommended to place some very large valued capacitors (100 of F range) on the VDD and VDD RF lines in order to avoid any unintentionalrese due to the unstable VDD RF (and the lack of the proper POR) that could get the radio chip into an undefined state. 2 Rev. 1.2 Nort Recommended for New Designs