SX1235

The SX1235 is a highly integrated RF transceiver optimized for operation compliant with ETSI EN 300 220 receiver category 1. In conjunction with an external SAW filter the SX1235 is designed to pass the category 1 testing with substantial regulatory margin, simplifying end-user production test requirements. The SX1235 retains the highly integrated architecture of the SX123x family, minimizing external components while delivering the highest level of performance. For hybrid systems with non category 1 elements within an alarm system the SX1235 offers the advantage of programmable narrow-band and wide-band communication modes without the need tomodify external components. This makes the SX1235 suitable for integrated home automation, security and alarm systems that require legacy compatibility.

The is a highly integrated RF transceiver optimized for operation compliant with ETSI 300 220 receiver category 1. In conjunction with an external SAW filter the SX1235 is designed to pass the category 1 testing with substantial regulatory margin, simplifying end-user production test requirements. The SX1235 retains the highly integrated architecture of the SX123x family, minimizing external components while delivering the highest level of performance. For hybrid systems with non category 1 elements within an alarm system the SX1235 offers the advantage of programmable narrow-band and wide-band communication modes without the need tomodify external components. This makes the SX1235 suitable for integrated home automation, security and alarm systems that require legacy compatibility.

High sensitivity: down to -123 dBm at 1.2 kbps High selectivity: 60 dB typ. ACR High linearity: 50 dB typ. of adjacent channel saturation 80 dB Blocking immunity, 100 dB with SAW Image rejection of over 45 dB Low current: = 9.3 mA, 100nA register retention Programmable output power +20 dBm 1 dB steps Optional high efficiency or fully regulated PA connections for reliable M2M performance and optimal battery lifetime Voltage operation from 3.7 V Narrowband integrated synthesizer with a resolution 61 Hz FSK, GFSK, MSK, GMSK and OOK modulation Automated, fast frequency correction & timing recovery Over 115 dB Dynamic Range RSSI Packet engine with CRC 64 byte FIFO Preamble and RSSI based channel activity detection

Category 1 Social Alarm Systems Category 1 Fire, Smoke and Toxic Gas Detection Category 1 Lone Worker Systems Home and Building Automation Wireless Alarm and Security Systems Industrial Monitoring and Control

General Description............................................................................................................................................... Simplified Block Diagram............................................................................................................................... 10 Pin and Marking Diagram..............................................................................................................................11 Pin Description...............................................................................................................................................12 ESD Notice.................................................................................................................................................... 13 Absolute Maximum Ratings........................................................................................................................... 13 Operating Range............................................................................................................................................ 13 ETSI Category 1 Specification.......................................................................................................................14

2.4.1. SAW Filter Specification............................................................................................................................ 14 2.4.2. Category 1 Test Conditions....................................................................................................................... 14 2.4.3. System Performance (Absolute Units) with a SAW as Defined 14 2.4.4. System Performance (Regulatory Margin)................................................................................................ 15 2.4.5. Measurement Configuration for Category 1 Testing................................................................................. 2.4.6. 869 MHz Category 1 Reference Design Module 16 2.5. Circuit Specification....................................................................................................................................... 18 2.5.1. Power Consumption.................................................................................................................................. 18 2.5.2. Frequency Synthesis................................................................................................................................. 18 2.5.3. Receiver.................................................................................................................................................... 19 2.5.4. Transmitter................................................................................................................................................ 20 2.5.5. Digital Specification................................................................................................................................... 21 3. Chip Description.................................................................................................................................................... Power Supply Strategy.................................................................................................................................. 23 Low Battery Detector..................................................................................................................................... 23 Frequency Synthesis.....................................................................................................................................24

3.3.1. Reference Oscillator.................................................................................................................................. 24 3.3.2. CLKOUT Output........................................................................................................................................ 24 3.3.3. PLL Architecture........................................................................................................................................ 3.3.4. RC Oscillator............................................................................................................................................. 26 3.4. Transmitter Description..................................................................................................................................27 3.4.1. Architecture Description............................................................................................................................ 27 3.4.2. Bit Rate Setting......................................................................................................................................... 27 3.4.3. FSK Modulation......................................................................................................................................... 28 3.4.4. OOK Modulation........................................................................................................................................ 29 3.4.5. Modulation Shaping................................................................................................................................... 3.4.6. RF Power Amplifiers.................................................................................................................................. 29 3.4.7. High Power +20 dBm Operation...............................................................................................................30 3.4.8. Over Current Protection............................................................................................................................31 3.5. Receiver Description......................................................................................................................................32

3.5.1. Overview................................................................................................................................................... 32 3.5.2. Automatic Gain Control - AGC.................................................................................................................. 32 3.5.3. RSSI.......................................................................................................................................................... 33 3.5.4. Channel Filter............................................................................................................................................ 34 3.5.5. FSK Demodulator...................................................................................................................................... 35 3.5.6. OOK Demodulator..................................................................................................................................... 35 3.5.7. Bit Synchronizer........................................................................................................................................ 37 3.5.8. Frequency Error Indicator.......................................................................................................................... AFC...........................................................................................................................................................39 3.5.10. Preamble Detector.................................................................................................................................. 39 3.5.11. Image Rejection Mixer.............................................................................................................................40 3.5.12. Image and RSSI Calibration.................................................................................................................... Temperature Measurement........................................................................................................................... 40 Timeout Function........................................................................................................................................... 41 General Overview.......................................................................................................................................... 42 Startup Times................................................................................................................................................. 42

4.2.1. Transmitter Startup Time...........................................................................................................................43 4.2.2. Receiver Startup Time............................................................................................................................... 43 4.2.3. Time to RSSI Evaluation........................................................................................................................... to Rx Turnaround Time........................................................................................................................ Rx to Tx..................................................................................................................................................... 44 4.2.6. Receiver Hopping, Tx to Tx..................................................................................................................................................... 4.3. 4.4. Receiver Startup Options...............................................................................................................................46 Receiver Restarting Methods......................................................................................................................... 46

4.4.1. Restart Upon User Request...................................................................................................................... 46 4.4.2. Automatic Restart after valid Packet Reception........................................................................................47 4.4.3. Automatic Restart when Packet Collision is Detected............................................................................... 47 4.5. Top Level Sequencer.....................................................................................................................................48 4.5.1. Sequencer States...................................................................................................................................... 48 4.5.2. Sequencer Transitions..............................................................................................................................49 4.5.3. Timers....................................................................................................................................................... 50 4.5.4. Sequencer State Machine.........................................................................................................................51 5. Data Processing.................................................................................................................................................... 52 5.1. Overview........................................................................................................................................................ 52 5.1.1. Block Diagram........................................................................................................................................... 52 5.1.2. Data Operation Modes.............................................................................................................................. 52 5.2. Control Block Description............................................................................................................................... 53