LTC2870/LTC2871 – RS232/RS485 Multiprotocol Transceivers ...

1 LTC2870/LTC28711 28701fbFor more information applicaTionsDescripTionRS232/RS485 Multiprotocol Transceivers with Integrated Termination The LTC 2870/LTC2871 are robust pin-configurable mul-tiprotocol Transceivers , supporting RS232, RS485, and RS422 protocols, operating on a single 3V to supply. The LTC2870 can be configured as two RS232 single-ended Transceivers or one RS485 differential transceiver on shared I/O lines. The LTC2871 offers independent con-trol of two RS232 Transceivers and one RS485 transceiver , each on dedicated I/O integrated termination resistors allow for easy interface reconfiguration, eliminating external resistors and control relays. Half-duplex switches allow four-wire and two-wire RS485 configurations. Loopback mode steers the driver inputs to the receiver outputs for diagnostic RS485 receivers support up to 256 nodes per bus, and feature full failsafe operation for floating, shorted or terminated integrated DC/DC boost converter uses a tiny 2mm inductor and one capacitor, eliminating the need for multiple supplies for driving RS232 , LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Analog Devices, Inc.

2 All other trademarks are the property of their respective Switching with Automatic Termination SelectionFeaTuresapplicaTions nOne RS485 and Two RS232 Transceivers n3V to Supply Voltage n20 Mbps RS485 and 500kbps RS232 nAutomatic Selection of Integrated RS485 (120 ) and RS232 (5k )Termination Resistors nHalf-/Full-Duplex RS485 Switching nHigh ESD: 26kV (LTC2870), 16kV (LTC2871) nLogic Loopback Mode to Logic Interface nSupports Up to 256 RS485 Nodes nRS485 Receiver Failsafe Eliminates UART Lockup nH-Grade Available for the LTC2870 ( 40 C to 125 C) nAvailable in 28-Pin 4mm 5mm QFN and TSSOP (LTC2870), and 38-Pin 5mm 7mm QFN and TSSOP (LTC2871) nSoftware Selectable RS232/RS485 /RS422 Interface nPoint-of-Sale Terminals nCable Repeaters nProtocol TranslatorsSimultaneous Protocols and RS485 Termination SwitchingRS485 Duplex Switching28701 TO VCC3V TO TO VCC3V TO TO VCC3V TO 120 YZABDI,DYRO,RAH/FLTC2870,LTC2871 HALFFULLRS485RS232 ONOFFVDDVEEGND1 F1 FVLVCC220nF10 HVDDVEEGND1 F1 FCAP FVLVCC220nF10 HVDDVEEGND1 F1 FCAP FVLVCC220nF10 HLTC2870/LTC28712 28701fbFor more information VIEW29 VEEUFD PACKAGE28-LEAD (4mm 5mm) PLASTIC QFN11121328 27 26 25 241423654321 VEERARB485/232 RXENDXENDYDZABVCCYGNDZVCCVDDTE485H/FLBVL VCCGNDFENGNDCAPVEEGNDSW71718192021221681 5 TJMAX = 150 C, JA = 43 C/W EXPOSED PAD (PIN 29)

3 IS VEE, MUST BE SOLDERED TO PCB1234567891011121314 TOP VIEWFE PACKAGE28-LEAD PLASTIC TSSOP2827262524232221201918171615 LBH/FTE485 VEERARB485/232 RXENDXENDYDZFENGNDCAPVLVCCGNDABVCCYGNDZV CCVDDSWGNDVEE29 VEE TJMAX = 150 C, JA = 30 C/W EXPOSED PAD (PIN 29) IS VEE, MUST BE SOLDERED TO PCBabsoluTe MaxiMuM raTingsInput Supplies VCC, VL .. to 7 VGenerated Supplies VDD ..VCC to 7. 5 V VEE .. to 7. 5 V SW .. to (VDD + ) CAP .. to (VEE ) A, B, Y, Z, RIN1, RIN2, DOUT1, DOUT2 .. 15V to 15 VDI, DZ, DY, RXEN, DXEN, LB, H/F, TE485, RX485, DX485, RX232, DX232, DIN1, DIN2, 485/232, CH2.. to 7V(Notes 1 and 2)pin conFiguraTionFEN, RA, RB, RO, ROUT1, ROUT2 .. to (VL + )Differential Enabled Terminator Voltage (A-B or Y-Z) .. 6 VOperating Temperature LTC2870C/LTC2871C.

4 0 C to 70 C LTC2870I/LTC2871I .. 40 C to 85 C LTC2870H .. 40 C to 125 CStorage Temperature Range .. 65 C to 125 CLead Temperature (Soldering, 10 sec) FE CLTC2870/LTC28713 28701fbFor more information inForMaTionLEAD FREE FINISHTAPE AND REELPART MARKINGPACKAGE DESCRIPTIONTEMPERATURE RANGELTC2870 CFE#PBF LTC2870 IFE#PBFLTC2870 CFE#TRPBF LTC2870 IFE#TRPBFLTC 2870FE LTC 2870FE28-Lead Plastic TSSOP 28-Lead Plastic TSSOP0 C to 70 C 40 C to 85 CLTC2870 CUFD#PBF LTC2870 IUFD#PBF LTC2870 HUFD#PBFLTC2870 CUFD#TRPBF LTC2870 IUFD#TRPBF LTC2870 HUFD#TRPBF2870 2870 287028-Lead (4mm 5mm) Plastic QFN 28-Lead (4mm 5mm) Plastic QFN 28-Lead (4mm 5mm) Plastic QFN0 C to 70 C 40 C to 85 C 40 C to 125 CLTC2871 CFE#PBF LTC2871 IFE#PBFLTC2871 CFE#TRPBF LTC2871 IFE#TRPBFLTC2871FE LTC2871FE38-Lead Plastic TSSOP 38-Lead Plastic TSSOP0 C to 70 C 40 C to 85 CLTC2871 CUHF#PBF LTC2871 IUHF#PBFLTC2871 CUHF#TRPBF LTC2871 IUHF#TRPBF2871 287138-Lead (5mm 7mm) Plastic QFN 38-Lead (5mm 7mm) Plastic QFN0 C to 70 C 40 C to 85 CConsult LTC Marketing for parts specified with wider operating temperature ranges.

5 Consult LTC Marketing for information on non-standard lead based finish more information on lead free part marking, go to: For more information on tape and reel specifications, go to: VIEW39 VEEUHF PACKAGE38-LEAD (5mm 7mm) PLASTIC QFN1718193837363534333224252627282930318 7654321 VEEROUT1 ROUT2CH2RX485DX485 DIDIN1 DIN2DX232RX232 VEERIN1 RIN2 ABVCCYGNDZDOUT1 DOUT2 VCCVDDTE485H/FLBVLROVCCGNDFENGNDCAPVEEGN DSWVEE232221209101112 TJMAX = 150 C, JA = 34 C/W EXPOSED PAD (PIN 39) IS VEE, MUST BE SOLDERED TO PCB12345678910111213141516171819 TOP VIEWFE PACKAGE38-LEAD PLASTIC SSOP383736353433323130292827262524232221 20 VLLBH/FTE485 VEEROUT1 ROUT2CH2RX485DX485 DIDIN1 DIN2DX232RX232 VEEFENGNDCAPROVCCGNDRIN1 RIN2 ABVCCYGNDZDOUT1 DOUT2 VCCVDDVEESWGNDVEE39 VEE TJMAX = 150 C, JA = 28 C/W EXPOSED PAD (PIN 39) IS VEE, MUST BE SOLDERED TO PCBpin conFiguraTionsPART NUMBERCONFIGURABLE transceiver COMBINATIONS (RS485 + RS232)PACKAGESTEMPERATURE GRADESLTC2870(0 + 0)

6 , (1 + 0), (0 + 2)28-Lead QFN, 28-Lead TSSOPC, I, H (QFN)LTC2871(0 + 0), (1 + 0), (1 + 1), (1 + 2), (0 + 1), (0 + 2)38-Lead QFN, 38-Lead TSSOPC, IproDucT selecTion #orderinfoLTC2870/LTC28714 28701fbFor more information characTerisTics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25 C. VCC = VL = , TE485 = 0V, LB = 0V unless otherwise SupplyVCCS upply Voltage Operating Supply Voltage Operating RangeVL Supply Current in Shutdown ModeRXEN = VL, DXEN = TE485 = FEN = 0V, (LTC2870) DX485 = DX232 = TE485 = FEN = H/F = 0V, RX485 = RX232 = VL (LTC2871)l860 AVCC Supply Current in transceiver Mode (Outputs Unloaded) (Note 3)485/232 = DXEN = VL, RXEN = 0V, DY/DZ = 0V or VL (LTC2870) DX485 = DX232 = VL, RX485 = RX232 = 0V, DI/DIN1/DIN2 = 0V or VL (LTC2871) Supply Current in transceiver Mode (Outputs Unloaded)l05 ARS485 Driver|VOD|Differential Output VoltageRL = , VCC = 3V (Figure 1) RL = 27 , VCC = 3V (Figure 1) RL = 50 , VCC = (Figure 1)

7 L l 26 VCC VCCV V V |VOD|Difference in Magnitude of Differential Output Voltage for Complementary Output StatesRL = 27 , VCC = 3V (Figure 1) RL = 50 , VCC = (Figure 1)l VVOCC ommon Mode Output VoltageRL = 27 or 50 (Figure 1)l3V |VOC|Difference in Magnitude of Common Mode Output Voltage for Complementary Output StatesRL = 27 or 50 (Figure 1) (High Impedance) Output CurrentVOUT = 12V or 7V, VCC = 0V or (Figure 2)l 100125 AIOSD485 Maximum Short-Circuit Current 7V VOUT 12V (Figure 2)l 250250mARS485 ReceiverIIN485 Input CurrentVIN = 12V or 7V, VCC = 0V or (Figure 3) (Note 5)l 100125 ARIN485 Input ResistanceVIN = 12V or 7V, VCC = 0V or (Figure 3) (Note 5)l96125k Differential Input Signal Threshold Voltage (A-B) 7V (A or B) 12V (Note 5)l 200mVInput HysteresisB = 0V (Notes 3, 5)220mVDifferential Input Failsafe Threshold Voltage 7V (A or B) 12V, (A-B) Rising (Note 5)l 200 700mVInput DC Failsafe HysteresisB = 0V (Note 5)35mVVOLO utput Low VoltageOutput Low, I(RA, RO) = 3mA (Sinking), 3V VL Low, I(RA, RO) = 1mA (Sinking), VL < High VoltageOutput High, I(RA, RO) = 3mA (Sourcing), 3V VL High, I(RA, RO) = 1mA (Sourcing), VL < 3 VlVL (High Impedance) Output Current0V (RA, RO) VL, VL = 5 AShort-Circuit Output Current0V (RA, RO)

8 VL, VL = 125mALTC2870/LTC28715 28701fbFor more information characTerisTics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25 C. VCC = VL = , TE485 = 0V, LB = 0V unless otherwise ResistorTE485 = VL, A B = 2V, B = 7V, 0V, 10V (Figure 8) (Note 5)l108120156 RS232 DriverVOLDO utput Low VoltageRL = 3k ; VEE 5 High VoltageRL = 3k ; VDD (High Impedance) Output CurrentY or Z (LTC2870) = 15V RS232 Receiver Enabled DOUT1 or DOUT2 (LTC2871) = 15Vl l 156 10 A AOutput Short-Circuit CurrentDriver Output = 0Vl 35 90mARS232 ReceiverInput Threshold Low VoltageI(RA, RB, ROUT1, ROUT2) = 1mA (Sinking) VL High VoltageI(RA, RB, ROUT1, ROUT2) = 1mA (Sourcing) VL Resistance 15V (A, B, RIN1, RIN2) 15V, RS232 Receiver Enabledl357k Three-State (High Impedance) Output Current0V (RA, RB, ROUT1, ROUT2) VLl0 5 AOutput Short-Circuit CurrentVL = 0V (RA, RB, ROUT1, ROUT2)

9 VLl 25 50mALogic InputsThreshold VLVI nput Currentl0 5 APower Supply GeneratorVDDR egulated VDD Output VoltageRS232 Drivers Enabled, Outputs Loaded with RL = 3k to GND, DIN1/DY = VL, DIN2/DZ = 0V (Note 3)7 VVEER egulated VEE Output Voltage Interface Pins (A, B, Y, Z)Human Body Model to GND or VCC, Powered or Unpowered (Note 7) 26kVLTC2871 Interface Pins (A, B, Y, Z, RIN1, RIN2, DOUT1, DOUT2) 16kVAll Other PinsHuman Body Model (Note 7) 4kVLTC2870/LTC28716 28701fbFor more information characTerisTics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25 C.

10 VCC = VL = , TE485 = 0V, LB = 0V unless otherwise noted. VL AC CharacteristicsMaximum Data Rate(Note 3)l20 MbpstPLHD485 tPHLD485 Driver Propagation DelayRDIFF = 54 , CL = 100pF (Figure 4)l2070nsDriver Propagation Delay Difference |tPLHD485 tPHLD485|RDIFF = 54 , CL = 100pF (Figure 4)l16nstSKEWD485 Driver Skew (Y to Z)RDIFF = 54 , CL = 100pF (Figure 4)l1 6nstRD485, tFD485 Driver Rise or Fall TimeRDIFF = 54 , CL = 100pF (Figure 4)l15nstZLD485, tZHD485, tLZD485, tHZD485 Driver Output Enable or Disable TimeFEN = VL, RL = 500 , CL = 50pF (Figure 5)l120nstZHSD485, tZLSD485 Driver Enable from ShutdownRL = 500 , CL = 50pF (Figure 5)l8 stPLHR485, tPHLR485 Receiver Input to OutputCL = 15pF, VCM = , |A B| = (Figure 6) (Note 5)l6585nstSKEWR485 Differential Receiver Skew |tPLHR485 tPHLR485|CL = 15pF (Figure 6)