Si4721-B20-GM Silicon Labs

Si4720/21-B20 BROADCAST FM RADIO TRANSCEIVER FOR PORTABLE APPLICATIONS Features Full FM RX and TX in 3 x 3 QFN Adjustable seek parameters Worldwide FM RX band support Adjustable mono/stereo blend Compliant with worldwide FM TX Adjustable soft mute regulations Advanced modulation control Excellent real-world performance Audio dynamic range control Supports integrated TX/RX antenna Audio silence detector Ordering Information: Programmable transmit output Programmable reference clock See page 41. voltage input Frequency synthesizer with 2-wire and 3-wire control integrated VCO Pin Assignments interface Integrated LDO regulator 2.7 to 5.5 V supply voltage Si4720/21 2 Minimal BOM (15 mm ) 3 x 3 x 0.55 mm 20-pin Pb-free (Top View) QFN package Digital audio output (Si4721 only) RDS/RDBS encoder/decoder (Si4721 only) Digital audio input 20 19 18 17 NC 1 16 Applications FMI 2 15 RIN/DOUT Cellular handsets/hands-free Wireless speakers/microphone RFGND 3 14 LOUT/DFS GND MP3 players Satellite digital audio radios PAD TXO 4 13 ROUT/DIN Portable media players Personal computers/notebooks RST 5 12 GND 6 11 VDD 7 8 9 10 Description The Si4720/21 integrates the complete tuner and transmit functions for FM broadcast reception and standards-compliant, unlicensed FM broadcast stereo transmission. Users must comply with local radio Patents pending frequency (RF) transmission regulations. Notes: Functional Block Diagram 1. To ensure proper operation and FM transceiver performance, follow the guidelines in AN383: 3 mm x 3 mm Si4720/21 QFN Universal Layout Guide. Tx/Rx Ant TXO LIN/DFS Skyworks will evaluate schematics and L1 layouts for qualified customers. 120 nH RIN/DOUT 2. Place the Si4720/21 as close as Rx Ant* ADC DAC ROUT/DIN possible to the antenna jack, and keep FMI LNA PGA DSP the FMI trace as short as possible. RFGND ADC DAC LOUT/DFS AGC 2.75.5 V VDD CONTROL LDO AFC GPO GND C1 INTERFACE 22 uF *Note: Dedicated Rx antenna is optional Skyworks Solutions, Inc. Phone 781 376-3000 Fax 781 376-3100 sales skyworksinc.com www.skyworksinc.com Rev. 1.0 Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice November 9, 2021 RCLK MUX GPO1 GPO2/INT GPO3/DCLK SEN SCLK SDIO RST VIO SEN NC SCLK GPO1 SDIO RCLK GPO2/INT GPO3/DCLK VIO LIN/DFSSi4720/21-B20 TABLE OF CONTENTS Section Page 1. Electrical Specifications .4 2. Test Circuit .18 2.1. Test Circuit Schematic .18 2.2. Test Circuit Bill of Materials 18 3. Typical Application Schematic .19 3.1. Analog Audio Inputs/Outputs 19 3.2. Typical Application Bill of Materials 19 3.3. Digital Audio Inputs/Outputs .20 3.4. Typical Application Schematic Bill of Materials .20 4. Universal AM/FM RX/FM TX Application Schematic 21 4.1. Universal AM/FM RX/FM TX Bill of Materials 22 5. Functional Description .23 5.1. Overview 23 5.2. Application Schematics and Operating Modes .24 5.3. FM Receiver .24 5.4. Integrated Antenna Support .25 5.5. Receiver Digital Audio Interface (Si4721 Only) .25 5.6. Stereo Audio Processing 26 5.7. De-Emphasis .27 5.8. Stereo DAC 27 5.9. Soft Mute 27 5.10. RDS/RBDS Processor (Si4721 Only) .27 5.11. Tuning .27 5.12. Seek 27 5.13. Reference Clock .27 5.14. FM Transmitter 28 5.15. Receive Power Scan 28 5.16. Transmitter Digital Audio Interface .29 5.17. Line Input 30 5.18. Audio Dynamic Range Control 31 5.19. Audio Limiter 32 5.20. Pre-emphasis and De-emphasis .32 5.21. RDS/RBDS Processor (Si4721 Only) .32 5.22. Tuning .32 5.23. Reference Clock .32 5.24. Control Interface .32 5.25. GPO Outputs 34 5.26. Reset, Powerup, and Powerdown 34 5.27. Programming with Commands 34 6. Commands and Properties 35 7. Pin Descriptions: Si4720/21-GM 40 2 Skyworks Solutions, Inc. Phone 781 376-3000 Fax 781 376-3100 sales skyworksinc.com www.skyworksinc.com Rev. 1.0 Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice November 9, 2021