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SX1261/2
Data Sheet Rev. 1.1
DS.SX1261-2.W.APP December 2017
SX1261/2
Long Range, Low Power, sub-GHz
RF Transceiver
www.semtech.com
Figure A: SX1261/2 Block Diagram
General Description
SX1261 and SX1262 sub-GHz radio transceivers are ideal for
long range wireless applications. Both devices are
designed for long battery life with just 4.2 mA of active
receive current consumption. The SX1261 can transmit up
to +15 dBm and the SX1262 can transmit up to +22 dBm
with highly efficient integrated power amplifiers.
These devices support LoRa® modulation for LPWAN use
cases and (G)FSK modulation for legacy use cases. The
devices are highly configurable to meet different
application requirements utilizing the global LoRaWAN
TM
standard or proprietary protocols.
The devices are designed to comply with the physical layer
requirements of the LoRaWAN
TM
specification released by
the LoRa Alliance
TM
.
The radio is suitable for systems targeting compliance with
radio regulations including but not limited to ETSI EN 300
220, FCC CFR 47 Part 15, China regulatory requirements
and the Japanese ARIB T-108. Continuous frequency
coverage from 150 MHz to 960 MHz allows the support of
all major sub-GHz ISM bands around the world.
Applications
The level of integration and the low consumption within
SX1261/2 enable a new generation of Internet of Things
applications.
• Smart meters
• Supply chain and logistics
• Building automation
• Agricultural sensors
• Smart cities
• Retail store sensors
• Asset tracking
• Street lights
• Parking sensors
• Environmental sensors
• Healthcare
• Safety and security sensors
• Remote control applications
LoRa
TM
Modem
Analog Front End & Data Conversion
FSK
Modem
Data
Buffer
ADC
PA
LNA
Matching
+
LPF
LDODC-DC
SPI
Protocol
Engine
OSC
PLL
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Data Sheet Rev. 1.1
DS.SX1261-2.W.APP December 2017
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Ordering Information
QFN 24 Package, Pb-free, Halogen free, RoHS/WEEE compliant product.
Revision History
Part Number Delivery Minimum Order Quantity
SX1261IMLTRT Tape & Reel 3’000 pieces
SX1262IMLTRT Tape & Reel 3’000 pieces
Version ECO Date Modifications
1.0 039166 October 2017 First Release
1.1 040046 December 2017
Addition of a note “when using a TCXO" to explain the XTA cap value change
with TCXO in chapter 4.1.3 XTAL Control Block
New sub-chapter 5.1.5 “Considerations on the DC-DC Inductor Selection”
Addition of a note recommending 12 symbols of LoRa preamble for optimal
performances in chapter 6.1.1.1 Spreading Factor
Addition of a note on SetLoRaSymbNumTimeout in chapter 9.6 Receive Mode
Correction of RandomNumber Gen[] values in chapter 12.1 Register Map
SX1261/2
Data Sheet Rev. 1.1
DS.SX1261-2.W.APP December 2017
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Table of Contents
1. Architecture.....................................................................................................................................................................................................11
2. Pin Connection ...............................................................................................................................................................................................12
2.1 I/O Description ..................................................................................................................................................................................12
2.2 Package View .....................................................................................................................................................................................13
3. Specifications ..................................................................................................................................................................................................14
3.1 ESD Notice ...........................................................................................................................................................................................14
3.2 Absolute Maximum Ratings .........................................................................................................................................................14
3.3 Operating Range ...............................................................................................................................................................................14
3.4 Crystal Specifications ......................................................................................................................................................................15
3.5 Electrical Specifications ..................................................................................................................................................................15
3.5.1 Power Consumption ...........................................................................................................................................................16
3.5.2 General Specifications........................................................................................................................................................18
3.5.3 Receive Mode Specifications............................................................................................................................................19
3.5.4 Transmit Mode Specifications .........................................................................................................................................21
3.5.5 Digital I/O Specifications ...................................................................................................................................................21
4. Circuit Description.........................................................................................................................................................................................22
4.1 Clock References ...............................................................................................................................................................................22
4.1.1 RC Frequency References..................................................................................................................................................22
4.1.2 High-Precision Frequency Reference............................................................................................................................22
4.1.3 XTAL Control Block ..............................................................................................................................................................23
4.1.4 TCXO Control Block .............................................................................................................................................................24
4.2 Phase-Locked Loop (PLL) ...............................................................................................................................................................24
4.3 Receiver ................................................................................................................................................................................................25
4.3.1 Intermediate Frequencies .................................................................................................................................................25
4.4 Transmitter ..........................................................................................................................................................................................26
4.4.1 SX1261 Power Amplifier Specifics..................................................................................................................................27
4.4.2 SX1262 Power Amplifier Specifics..................................................................................................................................29
4.4.3 Power Amplifier Summary................................................................................................................................................31
5. Power Distribution ........................................................................................................................................................................................32
5.1 Selecting DC-DC Converter or LDO Regulation ....................................................................................................................32
5.1.1 Option A: SX1261 with DC-DC Regulator ....................................................................................................................33
5.1.2 Option B: SX1261 with LDO Regulator .........................................................................................................................34
5.1.3 Option C: SX1262 with DC-DC Regulator ....................................................................................................................34
5.1.4 Option D: SX1262 with LDO Regulator.........................................................................................................................35
5.1.5 Consideration on the DC-DC Inductor Selection......................................................................................................35
5.2 Flexible DIO Supply .........................................................................................................................................................................36
6. Modems ............................................................................................................................................................................................................37
6.1 LoRa® Modem ....................................................................................................................................................................................37
6.1.1 Modulation Parameter .......................................................................................................................................................37
6.1.2 LoRa® Packet Engine ...........................................................................................................................................................39
6.1.3 LoRa® Frame...........................................................................................................................................................................40
6.1.4 LoRa® Time-on-Air................................................................................................................................................................41
6.1.5 LoRa® Channel Activity Detection (CAD) .....................................................................................................................41
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6.2 FSK Modem .........................................................................................................................................................................................42
6.2.1 Modulation Parameter .......................................................................................................................................................42
6.2.2 FSK Packet Engine................................................................................................................................................................43
6.2.3 FSK Packet Format ...............................................................................................................................................................44
7. Data Buffer .......................................................................................................................................................................................................47
7.1 Principle of Operation .....................................................................................................................................................................47
7.2 Data Buffer in Receive Mode ........................................................................................................................................................48
7.3 Data Buffer in Transmit Mode ......................................................................................................................................................48
7.4 Using the Data Buffer ......................................................................................................................................................................48
8. Digital Interface and Control .....................................................................................................................................................................49
8.1 Reset ......................................................................................................................................................................................................49
8.2 SPI Interface ........................................................................................................................................................................................49
8.2.1 SPI Timing When the Transceiver is in Active Mode................................................................................................49
8.2.2 SPI Timing When the Transceiver Leaves Sleep Mode ...........................................................................................50
8.3 Multi-Purpose Digital Input/Output (DIO) ..............................................................................................................................51
8.3.1 BUSY Control Line ................................................................................................................................................................51
8.3.2 Digital Input/Output ...........................................................................................................................................................53
8.4 Digital Interface Status versus Chip modes ............................................................................................................................53
8.5 IRQ Handling ......................................................................................................................................................................................54
9. Operational Modes .......................................................................................................................................................................................55
9.1 Startup ..................................................................................................................................................................................................55
9.2 Calibrate ...............................................................................................................................................................................................55
9.2.1 Image Calibration for Specific Frequency Bands......................................................................................................55
9.3 Sleep Mode .........................................................................................................................................................................................56
9.4 Standby (STDBY) Mode ..................................................................................................................................................................56
9.5 Frequency Synthesis (FS) Mode ..................................................................................................................................................57
9.6 Receive (RX) Mode ...........................................................................................................................................................................57
9.7 Transmit (TX) Mode .........................................................................................................................................................................58
9.7.1 PA Ramping............................................................................................................................................................................58
9.8 Active Mode Switching Time .......................................................................................................................................................58
9.9 Transceiver Circuit Modes Graphical Illustration ..................................................................................................................59
10. Host Controller Interface..........................................................................................................................................................................60
10.1 Command Structure .....................................................................................................................................................................60
10.2 Transaction Termination .............................................................................................................................................................60
11. List of Commands ......................................................................................................................................................................................61
11.1 Operational Modes Commands ................................................................................................................................................61
11.2 Register and Buffer Access Commands .................................................................................................................................62
11.3 DIO and IRQ Control ......................................................................................................................................................................62
11.4 RF, Modulation and Packet Commands .................................................................................................................................62
11.5 Status Commands ..........................................................................................................................................................................63
12. Register Map .................................................................................................................................................................................................64
12.1 Register Table ..................................................................................................................................................................................64
13. Commands Interface..................................................................................................................................................................................66
13.1 Operational Modes Functions ...................................................................................................................................................66
13.1.1 SetSleep.................................................................................................................................................................................66
13.1.2 SetStandby...........................................................................................................................................................................67
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13.1.3 SetFs........................................................................................................................................................................................67
13.1.4 SetTx .......................................................................................................................................................................................67
13.1.5 SetRx.......................................................................................................................................................................................68
13.1.6 StopTimerOnPreamble....................................................................................................................................................69
13.1.7 SetRxDutyCycle ..................................................................................................................................................................70
13.1.8 SetCAD...................................................................................................................................................................................72
13.1.9 SetTxContinuousWave.....................................................................................................................................................72
13.1.10 SetTxInfinitePreamble ...................................................................................................................................................73
13.1.11 SetRegulatorMode..........................................................................................................................................................73
13.1.12 Calibrate Function...........................................................................................................................................................73
13.1.13 CalibrateImage.................................................................................................................................................................74
13.1.14 SetPaConfig.......................................................................................................................................................................75
13.1.15 SetRxTxFallbackMode....................................................................................................................................................76
13.2 Registers and Buffer Access ........................................................................................................................................................77
13.2.1 WriteRegister Function....................................................................................................................................................77
13.2.2 ReadRegister Function.....................................................................................................................................................77
13.2.3 WriteBuffer Function ........................................................................................................................................................77
13.2.4 ReadBuffer Function.........................................................................................................................................................78
13.3 DIO and IRQ Control Functions .................................................................................................................................................78
13.3.1 SetDioIrqParams.................................................................................................................................................................78
13.3.2 IrqMask ..................................................................................................................................................................................78
13.3.3 GetIrqStatus .........................................................................................................................................................................79
13.3.4 ClearIrqStatus......................................................................................................................................................................80
13.3.5 SetDIO2AsRfSwitchCtrl ....................................................................................................................................................80
13.3.6 SetDIO3AsTCXOCtrl ..........................................................................................................................................................80
13.4 RF Modulation and Packet-Related Functions ....................................................................................................................82
13.4.1 SetRfFrequency...................................................................................................................................................................82
13.4.2 SetPacketType.....................................................................................................................................................................82
13.4.3 GetPacketType....................................................................................................................................................................83
13.4.4 SetTxParams ........................................................................................................................................................................83
13.4.5 SetModulationParams......................................................................................................................................................84
13.4.6 SetPacketParams................................................................................................................................................................87
13.4.7 SetCadParams .....................................................................................................................................................................91
13.4.8 SetBufferBaseAddress ......................................................................................................................................................93
13.4.9 SetLoRaSymbNumTimeout............................................................................................................................................93
13.5 Communication Status Information .......................................................................................................................................94
13.5.1 GetStatus...............................................................................................................................................................................94
13.5.2 GetRxBufferStatus..............................................................................................................................................................95
13.5.3 GetPacketStatus .................................................................................................................................................................95
13.5.4 GetRssiInst ............................................................................................................................................................................96
13.5.5 GetStats .................................................................................................................................................................................96
13.5.6 ResetStats .............................................................................................................................................................................96
13.6 Miscellaneous ..................................................................................................................................................................................97
13.6.1 GetDeviceErrors..................................................................................................................................................................97
13.6.2 ClearDeviceErrors...............................................................................................................................................................97
14. Application ...................................................................................................................................................................................................98
