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S2-LPDatasheetUltra-low power, high performance, sub-1 GHz transceiverFeatures Maturity status linkS2-LP Frequency bands:413-479 MHz (S2-LPQTR)––452-527 MHz (S2-LPCBQTR)–826-958 MHz (S2-LPQTR)–904-1055 MHz (S2-LPCBQTR)Modulation schemes:–2(G)FSK, 4(G)FSK–OOK, ASKAir data rate from 0.1 to 500 kbpsUltra-low power consumption:–7 mA RX–10 mA TX @ 10 dBmExcellent performance of receiver sensitivity: down to -130 dBmExcellent receiver selectivity and blockingProgrammable RF output power up to 16 dBmProgrammable RX digital filterProgrammable channel spacingFast start-up and frequency synthesizer settling timeAutomatic frequency offset compensation, AGC and symbol timing recoveryMore than 145 dB RF link budgetBattery indicator and low battery detectorRX and TX 128 bytes FIFO buffers4-wire SPI interfaceAutomatic packet acknowledgment and retransmissionEmbedded timeout protocol engineExcellent receiver selectivity ( 80 dB @ 2 MHz)ST companion integrated balun/filter chips are availableAntenna diversity algorithmFully integrated ultra-low power RC oscillatorWake-up driven by internal timer or external eventDigital real time RSSIFlexible packet length with dynamic payload lengthProgrammable preamble and SYNC word quality filtering and detectionEmbedded CSMA/CA engine based on listen-before-talk systemsIEEE 802.15.4g hardware packet support with whitening, FEC, CRC and dualSYNC word detectionWireless M-BUS supportedKNX-RF supportedEnables operations in the SIGFOX and MONARCH networksDS11896 - Rev 8 - May 2021For further information contact your local STMicroelectronics sales office.www.st.com

S2-LP Suitable to build systems targeting:–Europe: ETSI EN 300 220, category 1.5 natively compliant, ETSI EN 303131–US: FCC part 15 and part 90–Japan: ARIB STD T67, T108–China: SRRCOperating temperature range: -40 C to 105 CApplications DS11896 - Rev 8Sensors to CloudSmart meteringHome energy management systemsWireless alarm systemsSmart homeBuilding automationIndustrial monitoring and controlSmart lighting systemspage 2/89

S2-LPDescription1DescriptionThe S2-LP is a high performance ultra-low power RF transceiver, intended for RF wireless applications in thesub-1 GHz band. It is designed to operate in both the license-free ISM and SRD frequency bands at 433, 512,868 and 920 MHz, but can also be programmed to operate at other additional frequencies in the 413-479 MHz,452-527 MHz, 826-958 MHz, 904-1055 MHz bands.The S2-LP supports different modulation schemes: 2(G)FSK, 4(G)FSK, OOK and ASK. The air data rate isprogrammable from 0.1 to 500 kbps.The S2-LP can be used in systems with channel spacing down to 1 kHz enabling the narrow band operations.The S2-LP shows an RF link budget higher than 140 dB for long communication ranges and meets the regulatoryrequirements applicable in territories worldwide, including Europe, Japan, China and the USA.DS11896 - Rev 8page 3/89

S2-LPDetailed functional description2Detailed functional descriptionThe S2-LP integrates a configurable baseband modem with proprietary fully programmable packet formatallowing also: IEEE 802.15.4g applicationsThe hardware packet supports whitening, CRC, FEC and dual SYNC word detection.– Wireless M-Bus applicationsIn order to reduce the overall system power consumption and increase the communication reliability, the S2LP provides an embedded programmable automatic packet acknowledgment, automatic packet retransmission,CSMA/CA engine, low duty cycle protocol, RX sniff mode and timeout protocol.The S2-LP fully supports antenna diversity with an integrated antenna switching control algorithm.Transmitted/received data bytes are buffered in two different 128 bytes FIFOs (TX FIFO and RX FIFO),accessible via SPI interface for host processing.In addition, the reduced number of external components enables a cost effective solution permitting a compactPCB footprint.The S2-LP targets volume applications like: Sensors to Cloud Smart metering Home energy management systems Wireless alarm systems Smart home Building automation Industrial monitoring and controlFigure 1. Simplified S2-LP block diagramDS11896 - Rev 8page 4/89

S2-LPDetailed functional descriptionThe receiver architecture is low-IF conversion, the received RF signal is amplified by a two-stage low-noiseamplifier (LNA) and down-converted in quadrature (I and Q) to the intermediate frequency (IF). LNA and IFamplifiers make up the RX front-end (RXFE) and have programmable gain. At IF, the ADCs digitalize the I/Qsignals. The demodulated data go to an external MCU either through the 128-byte RX FIFO, readable via SPI, ordirectly using a programmable GPIO pin.The transmitter part of the S2-LP is based on direct synthesis of the RF frequency. The power amplifier (PA) inputis the LO generated by the RF synthesizer, while the output level can be configured between -30 dBm and 14dBm ( 16 dBm in boost mode), at antenna level with 0.5 dB steps.The data to be transmitted can be provided by an external MCU either through the 128-byte TX FIFO writablevia SPI, or directly using a programmable GPIO pin. The S2-LP supports frequency hopping, TX/RX and antennadiversity switch control, extending the link range and improving performance.The S2-LP has a very efficient power management (PM) system. An integrated switched mode power supply(SMPS) regulator allows operation from a battery voltage ranging from 1.8 V to 3.6 V, and with powerconversion efficiency of 90%.A crystal must be connected between XIN and XOUT. It is digitally configurable to operate with different crystals.As an alternative, an external clock signal can be used to feed XIN for proper operation. The S2-LP also has anintegrated low-power RC oscillator, generating the 34.7 kHz signal used as a clock for the slowest timeouts.A standard 4-pin SPI bus is used to communicate with the external MCU. Four configurable general purpose I/Osare available.DS11896 - Rev 8page 5/89

S2-LPTypical application diagram and pin description3Typical application diagram and pin descriptionThis section describes three different application diagrams for the S2-LP. Two main configurations are available: HPM (high performance mode) configurationLPM (low power mode) configuration In the LPM operating mode the LDOs are bypassed and the SMPS provides the regulator voltage at 1.2 V. Notethat in LPM the PA is supplied from SMPS at 1.2 V (instead of 1.5 V as in HPM), so the max. output poweris lower than HPM. The figure below shows the suggested configuration with discrete matching network andSMPS-ON.Figure 2. Suggested application diagram (embedded SMPS used)Digital TTC4C28L7VSMPS2C30C21L10L9L8C29C31C32Figure 3. Suggested application diagram (embedded SMPS not used) shows the suggested configuration withdiscrete matching network and SMPS-OFF mode.DS11896 - Rev 8page 6/89

S2-LPTypical application diagram and pin descriptionFigure 3. Suggested application diagram (embedded SMPS not used)Digital 0L325EXT 1.2-1.8V L7VSMPS2C29C30C21L10L9L8C31C32Figure 4. Suggested application diagram HPM/LPM (integrated balun, embedded SMPS used)Digital 23456181716151413RX PRX 11896 - Rev 8page 7/89

S2-LPTypical application diagram and pin descriptionTable 1. Description of the external components of the typical application diagramsDS11896 - Rev 8HPM/LPM discrete balunDescriptionSMPS ONSMPS OFFHPM/LPMintegrated balunC0XXXDecoupling capacitor for on-chip voltage regulator todigital partC1X-XSMPS LC filter capacitorsC2, C3XXXCrystal loading capacitorsC4XXXDecoupling capacitor for on-chip voltage regulator tosynthesizer (LF part)C5XXXDecoupling capacitor for band-gap voltage referenceof VCO regulatorC6XXXDecoupling capacitor for on-chip voltage regulator toLNA-MIXERC29, C30, C31, C32XXTX LC filter/matching capacitorsC11, C13XXDC blocking capacitorsC16, C21XXC10, C14, C17XXL0X-XSMPS LC filter inductorL7XXXRF choke inductor or resonating inductor (upon RFnetwork topology)L8, L9, L10XXTX LC filter/matching inductorsL3, L5, L6XXRX balun/matching inductorsXTALXXComponentsXRF balun/matching capacitorsXCrystalpage 8/89

S2-LPPin diagram3.1Pin diagram20CSn21GPIO 022GPIO 123GPIO 224GPIO 3VR DIGFigure 5. Pin diagram, QFN24 (4x4 mm) package19SCLKVDD SMPS181SDISMPS1S2-LPQTR217SMPS2SDO163VDD DIG/RXXOUT154RX XIN145RX-SDN1363.211VR RF10TX9VDD TX/VCO8VREF VCO7VR SYNTHVDD ANA/SYNTH25 - GND12Pin descriptionTable 2. PinoutDS11896 - Rev 8NumberPin namePin typeDescription1VDD SMPSPower1.8 V to 3.6 V analog power supply for SMPS only.2SMPS1Analog out1.1 V to 1.8 V SMPS regulator output to be externally filtered3SMPS2Analog in1.1 V to 1.8 V SMPS voltage input after LC filtering applied to SMPS1 output4XOUTAnalog outCrystal oscillator output. Connect to an external crystal or leave floating if drivingthe XIN pin with an external clock source5XINAnalog inCrystal oscillator input. Connect to an external crystal or to an external clocksource. If using an external clock source, DC coupling with a minimum 0.2 VDClevel is recommended and minimum AC amplitude of 400 mVpp (however, theinstantaneous level at input cannot exceed the 0 – 1.4 V range)6SDNDigital inShutdown input pin. SDN should be ‘0’ in all modes, except shutdown mode7VDD ANA/SYNTHPower1.8 V to 3.6 V power8VR SYNTHAnalog in/out1.2 V SYNTH-LDO output for decoupling9VREF VCOAnalog out1.2 V VCO-LDO band-gap reference voltage decoupling10VDD VCO/TXPower1.8 V to 3.6 V power supply11TXRF outputRF output signalpage 9/89

S2-LPPin descriptionDS11896 - Rev 8NumberPin namePin typeDescription12VR RFAnalog in/out1.2 V RX-LDO output for decoupling13RXnRF in14RXpRF in15VDD RX/DIGPower1.8 V to 3.6 V power supply16SDODigital outSPI slave data output17SDIDigital inSPI slave data input18SCLKDigital inSPI slave clock input19CSnDigital inSPI chip select20GPIO0Digital I/O21GPIO1Digital I/O22GPIO2Digital I/O23GPIO3Digital I/O24VR DIGAnalog in/out1.2 V digital power supply output for decoupling25GNDGroundExposed pad connected to the ground of the application boardDifferential RF input signals for the LNAGeneral purpose I/O that may be configured through the SPI registers to performvarious functionspage 10/89

S2-LPSpecifications4Specifications4.1Absolute maximum ratingsAbsolute maximum ratings are those values above which damage to the device may occur. Functional operationunder these conditions is not implied. All voltages refer to GND.Table 3. Absolute maximum ratings4.2ParameterMin.Typ.Max.UnitSupply and SMPS pins-0.3 3.9DC voltage on VREG pins-0.3 3.9DC voltage on digital input pins-0.3 3.9DC voltage on digital output pins-0.3 3.9DC voltage on ground pins-0.3 3.9DC voltage on analog pins-0.3 1.8DC voltage on TX pin-0.3 3.9Storage temperature range-40 125 CVESD-HBM-500 500VVOperating rangeTable 4. Operating rangeParameterMin.Typ.Max.UnitOperating battery supply voltage (VBAT)1.8(1)3.03.6VOperating ambient temperature range-4025 105 C1. 2 V when the device works in boost mode with SMPS ON.4.3Thermal propertiesTable 5. Thermal data4.4ParameterQFN24UnitThermal resistance junction-ambient66 C/WPower consumptionCharacteristics measured over recommended operating conditions unless otherwise specified. Typical valuesare referred to 25 C temperature, VBAT 3.3 V. All performance is referred to the STEVAL-FKI433V2 orSTEVAL-FKI868V2 with a 50 Ohm antenna connector.DS11896 - Rev 8page 11/89

S2-LPPower consumptionTable 6. Low-power state power consumptionParameterTest conditionsSupply 0Sleep (FIFOs retained)0.95Ready350UnitµATable 7. Power consumption in reception TA 25 C, VDD 3.3 V, fc 868 MHzParameterTest conditionsMin.RX @ sensitivity levelRX in sniff mode @ 1.2 kbpsSupply current(1)RX in LDC mode @ 38.4 kbps (4)LPM typ.8.67.2Max.0.9RX in sniff mode @ 38.4 kbps (2)RX in LDC mode @ 1.2 kbps (3)HPM typ.UnitmA0.8-21µA31. Using 2-FSK, FREQDEV 2.4 kHz, DR 1.2 kbps, 4 bytes preamble and 8 kHz ch. filter. Where the receiver wakes up atregular intervals to look for an incoming packet.2. Using 2-FSK, FREQDEV 20 kHz, DR 38.4 kbps, 24 bytes preamble and 100 kHz ch. filter. Where the receiver wakes upat regular intervals to look for an incoming packet.3. Check for data packet every 1 second in LDC mode. 2-FSK, FREQDEV 1.2 kHz DEV and 8 kHz ch. filter, DR 1.2 kbps,internal RC oscillator used as sleep timer. Sniff timer enabled.4. Check for data packet every 1 second in LDC mode. 2-FSK, FREQDEV 20 kHz, DR 38.4 kbps and 100 kHz ch. filter,internal 34.6 kHz RC oscillator used as sleep timer. Sniff timer enabled.Table 8. Power consumption in transmission fc 915 MHzParameterTest conditionsSupply currentMin.Typ.TX CW @ 14 dBm22TX CW @ 10 dBm(1)12.5TX CW @ 16 dBm in Boost (2)32Max.UnitmA1. SMPS output voltage 1.2 V, LDOs disable.2. SMPS output voltage 1.8 V.Table 9. Power consumption in transmission fc 840-868 MHzParameterTest conditionsMin.Typ.TX CW @ 14 dBmSupply currentTX CW @ 10Max.20dBm(1)mA11.5TX CW @ 16 dBm in Boost (2)Unit291. SMPS output voltage 1.2 V, LDOs disable.2. SMPS output voltage 1.8 V.Table 10. Power consumption in transmission fc 434 MHzDS11896 - Rev 8ParameterTest conditionsSupply currentTX CW @ 14 dBm(1)Min.Typ.21Max.UnitmApage 12/89

S2-LPGeneral characterizationParameterTest conditionsSupply currentTX CW @ 10 dBm(2)Min.Typ.Max.UnitmA11.51. SMPS output voltage 1.6 V.2. SMPS output voltage 1.2 V, LDOs disable.Table 11. Power consumption in transmission fc 510 MHzParameterTest conditionsSupply currentMin.Typ.TX CW @ 14 dBm19TX CW @ 10 dBm(1)12TX CW @ 15 dBm(2)27Max.UnitmA1. SMPS output voltage 1.2 V, LDOs disable.2. SMPS output voltage 1.8 V.4.5General characterizationTable 12. General characteristicsParameterTyp.Unit413 - 479452-527Frequency range826 - 958MHz904-1055Data rate DR2-(G)FSK0.1 - 2504-(G)FSK0.2 - 500OOK/ASK0.1 -125kbpsData rate accuracy 100ppmFrequency deviation FDEV0.15 - 500kHzIf "Manchester" or "3-out-of-6" or FEC coding options are enabled the actual bit rate is affected as follows:Table 13. Data rate with different coding optionsDS11896 - Rev 8Coding option4(G)FSK data rate [kbps]NRZ500FEC250Manchester2503-out-of-6333.3page 13/89

S2-LPFrequency synthesizer4.6Frequency synthesizerTable 14. Frequency synthesizer parametersParameterTest conditions50 MHzUnitFrequency step sizeOut-loop divider ratio 423.8Hz10 kHz-109100 kHz-1101 MHz-12410 MHz-14110 kHz-108100 kHz-1091 MHz-12410 MHz-14010 kHz-102100 kHz-1031 MHz-11710 MHz-13810 kHz-102100 kHz-1021 MHz-11710 MHz-138RF carrier phase noise 433 MHzRF carrier phase noise 510 MHzRF carrier phase noise 868 MHzRF carrier phase noise 915 MHz4.7dBc/HzCrystal oscillatorCharacteristics measured over recommended operating conditions unless otherwise specified. All typical valuesare referred to 25 C temperature, VBAT 3.0 V.The device supports crystals in the range [24-26] MHz and [48-52] MHz.If the crystal is in the [24–26] MHz range, both the analog and the digital parts must work at this frequency.Otherwise, if a crystal in the [48-52] MHz range is used, the analog part must work at this frequency and thedigital part at this frequency divided by 2. From now on in this document the XTAL oscillator will be indicated withfXO and the digital clock with fdigThe divider for the digital part can be set by the PD CLKDIV bit of the XO RCO CONFIG1 in the following way: if a [48 – 52] MHz crystal is used, this bit must be 0 (digital divider enabled): fdig fxo2(1)if a [24 – 26] MHz crystal is used, this bit must be 1 (digital divider disabled):fdig fxo(2)The safest procedure to disable the divider without any risk of glitches in the digital clock is to switch intoSTANDBY mode, hence, disable the divider through register setting, and then come back to the READY state.In order to avoid potential RF performance degradations, the crystal frequency should be chosen to satisfy thefollowing equation:FnFCH ROUND n CH fXO 1MHzfXO(3)where n is an integer in the set [1-7, B] (B is the synthesizer’s divider ratio).DS11896 - Rev 8page 14/89

S2-LPRF receiverTable 15. Crystal oscillator characteristicsParameterTest conditionsCrystal frequencyMin. Typ. Max.24264852Frequency tolerance (1)MHz 40Minimum requirement on external reference phase noise maskfXO 26 MHz , to avoid degradation on synthesizer phase/noise-135100 kHz-1401 MHz-14010 MHzdBc/Hz-1404313VBAT 1.8 V,fXO 26 MHzStart-up time (2)ppm10 kHzProgrammable trans-conductance of the oscillator at start-upUnitmS100µs1. Including initial tolerance, crystal loading, aging, and temperature dependence. The acceptable crystal tolerance dependson RF frequency and channel spacing/bandwidth.2. Start-up times are crystal dependent. The crystal oscillator trans-conductance can be tuned to compensate the variation ofcrystal oscillator series resistance.Table 16. Ultra-low power RC oscillatorParameterTest conditionsTyp.Calibrated frequencyCalibrated RC oscillator frequency is derived from crystal oscillatorfrequency.Unit33.3 (1) kHzFrequency accuracy after calibration 1%1. Depending on the crystal frequency, the reported value is referring to 50 MHz.4.8RF receiverCharacteristics measured over recommended operating conditions unless otherwise specified. All typical valuesare referred to 25 C temperature, VBAT 3.3 V, no frequency offset in the RX signal. The whole performance isreferred to the STEVAL-FKI433V2, STEVAL-FKI512V1 or STEVAL-FKI868V2 with a 50 Ohm antenna connector.Table 17. RF receiver characteristicsParameterTest conditionsReceiver channel bandwidthCHFDS11896 - Rev 8HPM/LPMSMPSon typ.Unit1-800kHz433 MHz-15868 MHz-15433 MHz10868 MHz10Interferers are continuous wave @ 6 MHz and 12 MHz 433 MHzInput third order intercept pointoffset from carrier868 MHz-25RX input return lossMax. RX gain, tied (RX TX) matching networksSaturation 1% BER2-FSK 1.2 kHz FDEV, DR 1.2 kbps, CHF 4 kHz8868 MHz8Max. RX gain433 MHz200 // 1.5R // C868 MHz200 // 1.5Max. RX gain, tied (RX TX) matching networksDifferential input impedance atLNAdBm-25433 MHzRX noise figuredBdBΩ//pFpage 15/89

S2-LPRF receiver4.8.1Blocking and selectivity at 433 MHzTable 18. Blocking and selectivity at 433 MHzTest conditionHPMSMPS on(typ.) 12.5 kHz (adjacentchannel)6456-12.5 kHz (adjacentchannel)6456 25 kHz (alternatechannel)6559-25 kHz (alternatechannel)6559Image rejection6063 2 MHz8181 10 MHz8285 100 kHz (adjacentchannel)5037-100 kHz (adjacentchannel)5037 200 kHz (alternatechannel)5145-200 kHz (alternatechannel)5145Image rejection5658 2 MHz6767 10 MHz6972ParameterSelectivity and blocking 1%BER @ 2-GFSK BT 0.5 1.2 kHz FDEV, DR 1.2 kbps, CHF 4 kHzSelectivity and blocking 1%BER @ 2-GFSK BT 0.5 20 kHz FDEV, DR 38.4 kbps, CHF 100 kHz4.8.2LPMSMPS ON Unittyp.dBdBSensitivity at 433 MHzTable 19. Sensitivity at 433 MHzParameterTest conditionsHPM/LPM SMPS on (typ.)DR 0.3 kbps, FDEV 0.25 kHz, CHF 1 kHz-128SensitivityDR 1.2 kbps, FDEV 1.2 kHz, CHF 4 kHz-1221% BER @ 2-GFSK BT 0.5DR 38.4 kbps, FDEV 20 kHz, CHF 100 kHz-109DR 250 kbps, FDEV 125 kHz, CHF 780 kHz-101DR 4.8 kbps, DEV 2.4 kHz, CHF 10 kHz-114DR 9.6 kbps, DEV 4.8 kHz, CHF 20 kHz-111DR 19.2 kbps, DEV 9.6 kHz, CHF 40 kHz-108DR 0.3 kbps, CHF 1 kHz-120Sensitivity1% BER @ 4-GFSK BT 0.5DS11896 - Rev 8SensitivityDR 1.2 kbps, CHF 4 kHz-1181% BER @ OOKDR 38.4 kbps, CHF 100 kHz-104DR 125 kbps, CHF 250 kHz-100UnitdBmdBmdBmpage 16/89

S2-LPRF receiver4.8.3Blocking and selectivity @ 510 MHzTable 20. Blocking and selectivity @ 510 MHzParameterTest conditionsSelectivity and blocking 1% BER @ 2-GFSK BT 0.5, 1.2 kHz FDEV,DR 1.2 kbps, CHF 4 kHzSelectivity and blocking 1% BER @ 2-GFSK BT 0.5, 20 kHz FDEV, DR 38.4 kbps, CHF 100 kHz4.8.4HPMLPMSMPS on SMPS on Unit(typ.)(typ.) 12.5 kHz (adjacentchannel)6456-12.5 kHz (adjacentchannel)6556 25 kHz (alternatechannel)6459-25 kHz (alternatechannel)6559Image rejection6063 2 MHz8181 10 MHz8285 100 kHz (adjacentchannel)5037-100 kHz (adjacentchannel)5037 200 kHz (alternatechannel)5145-200 kHz (alternatechannel)5145Image rejection5658 2 MHz6767 10 MHz6972dBdBSensitivity at 510 MHzTable 21. Sensitivity at 510 MHzParameterTest conditionsHPM/LPM SMPS on (typ.)DR 0.3 kbps, FDEV 0.25 kHz, CHF 1 kHz-128SensitivityDR 1.2 kbps, FDEV 1.2 kHz, CHF 4 kHz-1221% BER @ 2-GFSK BT 0.5DR 38.4 kbps, FDEV 20 kHz, CHF 100 kHz-109DR 250 kbps, FDEV 125 kHz, CHF 780 kHz-101DR 4.8 kbps, DEV 2.4 kHz, CHF 10 kHz-114DR 9.6 kbps, DEV 4.8 kHz, CHF 20 kHz-111DR 19.2 kbps, DEV 9.6 kHz, CHF 40 kHz-108DR 0.3 kbps, CHF 1 kHz-120Sensitivity1% BER @ 4-GFSK BT 0.5DS11896 - Rev 8SensitivityDR 1.2 kbps, CHF 4 kHz-1181% BER @ OOKDR 38.4 kbps, CHF 100 kHz-104DR 125 kbps, CHF 250 kHz-100UnitdBmdBmdBmpage 17/89

S2-LPRF receiver4.8.5Blocking and selectivity at 840-868 MHzTable 22. Blocking and selectivity @ 840-868 MHzParameterTest conditions 12.5 kHz (adjacentchannel)5850-12.5 kHz (adjacentchannel)5850 25 kHz (alternatechannel)5951-25 kHz (alternatechannel)5951Image rejection5860 2 MHz8181 10 MHz8286 100 kHz (adjacentchannel)4433-100 kHz (adjacentchannel)4433 200 kHz (alternatechannel)4539-200 kHz (alternatechannel)4539Image rejection5055 2 MHz6770 10 MHz6973Selectivity and blocking 1% BER @ 2-GFSK BT 0.5, 1.2 kHz FDEV,DR 1.2 kbps, CHF 4 kHzSelectivity and blocking 1% BER @ 2-GFSK BT 0.5, 20 kHz FDEV, DR 38.4 kbps, CHF 100 kHz4.8.6HPMLPMSMPS on SMPS on Unit(typ.)(typ.)dBdBSensitivity at 840-868 MHzTable 23. Sensitivity at 840-868 MHzParameterTest conditionsHPM/LPM/SMPS on typ.DR 0.3 kbps, FDEV 0.25 kHz, CHF 1 kHz-128SensitivityDR 1.2 kbps, FDEV 1.2 kHz, CHF 4 kHz-1221% BER @ 2-GFSK BT 0.5DR 38.4 kbps, FDEV 20 kHz, CHF 100 kHz-109DR 250 kbps, FDEV 125 kHz, CHF 780 kHz-101DR 4.8 kbps, DEV 2.4 kHz, CHF 10 kHz-114DR 9.6 kbps, DEV 4.8 kHz, CHF 20 kHz-111DR 19.2 kbps, DEV 9.6 kHz, CHF 40 kHz-108DR 0.3 kbps, CHF 1 kHz-120Sensitivity1% BER @ 4-GFSK BT 0.5DS11896 - Rev 8SensitivityDR 1.2 kbps, CHF 4 kHz-1181% BER @ OOKDR 38.4 kbps, CHF 100 kHz-104DR 125 kbps, CHF 250 kHz-100UnitdBmdBmdBmpage 18/89

S2-LPRF receiver4.8.7Blocking and selectivity at 915 MHzTable 24. Blocking and selectivity at 915 MHzTest conditionHPM/SMPS ontyp. 12.5 kHz (adjacentchannel)5850-12.5 kHz (adjacentchannel)5850 25 kHz (alternatechannel)5951-25 kHz (alternatechannel)5951Image rejection5860 2 MHz8181 10 MHz8286 100 kHz (adjacentchannel)4433-100 kHz (adjacentchannel)4433 200 kHz (alternatechannel)4539-200 kHz (alternatechannel)4539Image rejection5055 2 MHz6770 10 MHz6973ParameterSelectivity and blocking 1%BER @ 2-GFSK BT 0.5 1.2 kHz FDEV, DR 1.2 kbps, CHF 4 kHzSelectivity and blocking 1%BER @ 2-GFSK BT 0.5 20 kHz FDEV, DR 38.4 kbps, CHF 100 kHz4.8.8LPM/SMPS on Unittyp.dBdBSensitivity at 915 MHzTable 25. Sensitivity at 915 MHzParameterTest conditionsHPM/LPM/SMPS on typ.DR 0.3 kbps, FDEV 0.25 kHz, CHF 1 kHz-128SensitivityDR 1.2 kbps, FDEV 1.2 kHz, CHF 4 kHz-1221% BER @ 2-GFSK BT 0.5DR 38.4 kbps, FDEV 20 kHz, CHF 100 kHz-109DR 250 kbps, FDEV 125 kHz, CHF 780 kHz-101DR 4.8 kbps, DEV 2.4 kHz, CHF 10 kHz-114DR 9.6 kbps, DEV 4.8 kHz, CHF 20 kHz-111DR 19.2 kbps, DEV 9.6 kHz, CHF 40 kHz-108DR 0.3 kbps, CHF 1 kHz-120Sensitivity1% BER @ 4-GFSK BT 0.5DS11896 - Rev 8SensitivityDR 1.2 kbps, CHF 4 kHz-1181% BER @ OOKDR 38.4 kbps, CHF 100 kHz-104DR 125 kbps, CHF 250 kHz-100UnitdBmdBmdBmpage 19/89

S2-LPRF transmitter4.9RF transmitterCharacteristics measured over recommended operating conditions unless otherwise specified. All typical valuesare referred to 25 C temperature, VBAT 3.3 V. All performance is referred to the STEVAL-FKI433V2 orSTEVAL-FKI868V2 with a 50 Ω antenna connector.Table 26. RF transmitter characteristicsParameterTest conditionsHPM typ.LPM typ.Maximum output powerCW @ antenna level1410Maximum output power in boost modeCW @ antenna level1612Minimum output powerCW @ antenna level-30-30Output power step-10 output power 10 dBm0.50.5Output power step (1)Output power 10 dBm1(1)UnitdBmdB1. In this case the register 0x64 is set to 0x4A.Table 27. PA impedanceParameterOptimum load impedanceMax permitted VSWR @ antenna levelTest conditionsTyp.433 MHz56 25j510 MHz24 14j868 MHz30 24j920 MHz29 23j433 MHz2510 MHz2868 MHz5920 MHz5UnitΩTable 28. Regulatory standardsFrequency bandSuitable for compliance with:ETSI EN300 220 category 1.5413 - 479 MHzFCC part 15, FCC part 90452 - 527 MHzARIB STD-T67Chinese SRRCETSI EN300 220-2 category 1.5826 - 958 MHzFCC part 15904 - 1055 MHzARIB STD-T108Chinese SRRC4.9.1Harmonic emission at 433 MHzTable 29. Harmonic emission at 433 MHzDS11896 - Rev 8ParameterTest conditionsSMPS onUnitH1CW14dBmpage 20/89

S2-LPRF transmitter4.9.2ParameterTest conditionsSMPS mHarmonic emission at 510 MHzTable 30. Harmonic emission at 510 MHz4.9.3ParameterTest conditionsHPM/LPM/SMPS UnitdBmHarmonic emission at 840-868 MHzTable 31. Harmonic emission at 840-868 MHz4.9.4ParameterTest conditionsHPM/LPM/SMPS UnitdBmHarmonic emission at 915 MHzTable 32. Harmonic emission at 915 MHzDS11896 - Rev 8ParameterTest conditionsHPM/LPM/SMPS onH1CW14H2CW-46H3CW-55H4CW-46H5CW-49UnitdBmpage 21/89

S2-LPDigital interface specification4.10ParameterTest conditionsHPM/LPM/SMPS onH6CW-48H7CW-51UnitdBmDigital interface specificationTable 33. Digital SPI input, output and GPIO specificationParameterTest conditionsTyp.Max.UnitSPI clock frequency810MHzPort I/O capacitance1.4pFFrom 0.1*VDD to 0.9*VDD, CL 20 pF (lowoutput current programming)6.0nsFrom 0.1*VDD to 0.9*VDD, CL 20 pF (highoutput current programming)2.5From 0.1*VDD to 0.9*VDD, CL 20 pF (lowoutput current programming)7.0From 0.1*VDD to 0.9*VDD, CL 20 pF (highoutput current programming)2.5Rise timeFall timeMin.nsVDD/2 0.3Logic high level input voltageVVDD/8 0.3Logic low level input voltageV(5/8)*IOH -2.4 mA (-4.2 mA into high output currentmode).High level output voltageVDD V0.1IOL 2.0 mA ( 4.0 mA into high outputcurrent mode).Low level output voltage0.5CSn low to positive edge on SCLK in lowpower mode state40CSn low to positive edge on SCLK inready state4.11Vµs30nsBattery indicatorCharacteristics measured over recommended operating conditions unless otherwise specified. All typical valuesare referred to 25 C temperature, VBAT 3.0 V.Table 34. Battery indicator and low battery detectorParameterMin. Typ. Max. UnitBattery level thresholds #12.1Battery level thresholds #22.3Battery level thresholds #32.5Battery level thresholds #42.7Brownout thresholdDS11896 - Rev 8Test conditionsMeasured in slow battery variation (static) conditions (inaccuratemode)V1.5page 22/89

S2-LPBattery indicatorParameterTest conditionsBrownout thresholdMeasured in slow battery variation (static) conditions (accuratemode)Brownout threshold hysteresisNote:DS11896 - Rev 8Min. Typ. Max. Unit1.7V70mVFor battery-powered equipment, the TX does not transmit at a wrong frequency under low battery voltageconditions. It remains on either channel or stops transmitting. The latter can of course be realized by using alock detect and/or by switching off the PA under control of the battery monitor. For testing reasons this control isenabled/disabled by SPI.page 23/89

S2-LPBlock description5Block description5.1Power managementThe S2-LP integrates a high efficiency step-down converter cascaded with LDOs meant to supply both analogand digital parts. However, an LDO directly fed by the external battery provides a controlled voltage to the datainterface block.S2-LP’s power management (PM) strategy, besides the basic functionality of providing different blocks with propersupplies, faces two main constraints: the first one is to implement such a power distribution with maximumefficiency, and the second one is to guarantee the isolation among critical blocks.The efficiency target is obtained by using a switch mode power supply (SMPS) which converts the battery voltage(1.8 V - 3.6 V) to a lower voltage (settable from 1.2 V to 1.8 V) with efficiency higher than 90%.The SMPS output voltage can be controlled by the SET SMPS LVL field in the PM CONF0 register. The relationbetween the SET SMPS LVL and the VOUT of the SMPS is given by the following table:Table 35. SMPS output voltageSET SMPS LVLSMPS output voltage001b1.2 V010b1.3 V011b1.4 V100b1.5 V101b1.6 V110b1.7 V111b1.8 VThe SMPS output voltage can be controlled in TX only or for both RX and TX according to the SMPS LVL MODEbit of the PM CONF1 register. 1: SMPS output level will depend upon the value in PM CONFIG register just in TX state, while in RX state itwill be fixed to 1.4 V. 0: SMPS output level will depend upon the value written in the PM CONFIG0 register (SET SMPS LEVELfield) both in RX and TX state.The SMPS switching frequency is settable by the 2 registers PM CONF3 and PM CONF2.If the KRM EN is 0, then the digital divider by 4 enabled. In this case SMPS' switching frequency is:Fsw fdig4(4)If the KRM EN is 1, the SMPS' switching frequency can be set by the KRM word ac

1 Description. The S2-LP is a high performance ultra-low power RF transceiver, intended for RF wireless applications in the sub-1 GHz band. It is designed to operate in both the license-free ISM and SRD frequency bands at 433, 512,