LTC2844 3.3V Software-Selectable Multiprotocol Transceiver U FEATURES ■ ■ ■ ■ ■ DESCRIPTIO The LTC®2844 is a 4-driver/4-receiver multiprotocol transceiver. The LTC2844 and LTC2846 form the core of a complete software-selectable DTE or DCE interface port that supports the RS232, RS449, EIA530, EIA530-A, V.35, V.36 or X.21 protocols. The LTC2844 operates from a 3.3V supply and supplies provided by the LTC2846. The part is available in a 28-lead SSOP surface mount package. Software-Selectable Transceiver Supports: RS232, RS449, EIA530, EIA530-A, V.35, V.36, X.21 Operates from Single 3.3V Supply with LTC2846 TUV Rheinland of North America Inc. Certified NET1, NET2 and TBR2 Compliant, Report No.: TBR2/051501/02 Complete DTE or DCE Port with LTC2846 28-Lead SSOP Surface Mount Package U APPLICATIO S ■ ■ Data Networking CSU and DSU Data Routers U ■ , LTC and LT are registered trademarks of Linear Technology Corporation. TYPICAL APPLICATIO DTE or DCE Multiprotocol Serial Interface with DB-25 Connector LL CTS DSR DCD DTR RTS RXD TXC D3 R4 18 R3 R2 13 5 22 6 TXD D3 D2 D1 T T T 12 15 11 24 14 LTC2846 LTC2844 D4 SCTE RXC D2 D1 R1 10 8 23 20 19 4 1 7 R3 R2 T T 16 3 9 R1 17 2 TXD A (103) TXD B SCTE A (113) SCTE B TXC A (114) TXC B RXC A (115) RXC B RXD A (104) RXD B SG (102) SHIELD (101) RTS A (105) RTS B DTR A (108) DCD A (109) DTR B DCD B DSR A (107) CTS A (106) DSR B CTS B LL A (141) DB-25 CONNECTOR 2844 TA01 sn2844 2844fs 1 LTC2844 W W W AXI U U ABSOLUTE RATI GS U U W PACKAGE/ORDER I FOR ATIO (Note 1) Supply Voltage VCC ....................................................... –0.3V to 6.5V VIN ..................................................................... – 0.3V to 6.5V VEE ...................................................................... –10V to 0.3V VDD ..................................................................... – 0.3V to 10V Input Voltage Transmitters ............................ – 0.3V to (VCC + 0.3V) Receivers ................................................– 18V to 18V Logic Pins ............................... – 0.3V to (VCC + 0.3V) Output Voltage Transmitters .................. (VEE – 0.3V) to (VDD + 0.3V) Receivers ................................. – 0.3V to (VIN + 0.3V) Short-Circuit Duration Transmitter Output ...................................... Indefinite Receiver Output ........................................... Indefinite VEE ................................................................... 30 sec Operating Temperature Range LTC2844CG ............................................. 0°C to 70°C LTC2844IG ......................................... – 40°C to 85°C Storage Temperature Range ................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C ORDER PART NUMBER TOP VIEW VCC 1 28 VEE VDD 2 27 GND D1 3 D2 4 D3 5 R1 6 R2 7 R3 8 D4 9 LTC2844CG LTC2844IG 26 D1 A D1 25 D1 B D2 24 D2 A 23 D2 B D3 22 D3/R1 A R1 21 D3/R1 B 20 R2 A R2 R4 10 19 R2 B R3 M0 11 18 R3 A D4 M1 12 R4 M2 13 DCE/DTE 14 17 R3 B 16 D4/R4 A 15 VIN G PACKAGE 28-LEAD PLASTIC SSOP TJMAX = 125°C, θJA = 90°C/ W, θJC = 35°C/ W Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, VIN = 3.3V, VDD = 8V, VEE = – 7V for V.28, – 5.5V for V.10, V.11 (Notes 2, 3) SYMBOL PARAMETER CONDITIONS VCC Supply Current (DCE Mode, All Digital Pins = GND or VIN) RS530, RS530-A, X.21 Modes, No Load RS530, RS530-A, X.21 Modes, Full Load V.28 Mode, No Load V.28 Mode, Full Load No-Cable Mode MIN TYP MAX UNITS 2.7 95 1 1 600 120 2 2 1200 mA mA mA mA µA Supplies ICC ● ● ● ● IEE VEE Supply Current (DCE Mode Unless RS530, RS530-A, X.21 Modes, No Load Otherwise Noted, All Digital Pins = GND or VIN) RS530, X.21 Modes, Full Load (DTE Mode) RS530-A, Full Load (DTE Mode) V.28 Mode, No Load V.28 Mode, Full Load No-Cable Mode 1.6 14 25 1 7.5 10 mA mA mA mA mA µA IDD VDD Supply Current (DCE Mode, All Digital Pins = GND or VIN) RS530, RS530-A, X.21 Modes, No Load RS530, RS530-A, X.21 Modes, Full Load V.28 Mode, No Load V.28 Mode, Full Load No-Cable Mode 0.2 0.2 1 8 10 mA mA mA mA µA IVIN VIN Supply Current (DCE Mode, All Digital Pins = GND or VIN) All Modes Except No-Cable Mode 490 µA sn2844 2844fs 2 LTC2844 ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, VIN = 3.3V, VDD = 8V, VEE = – 7V for V.28, – 5.5V for V.10, V.11 (Notes 2, 3) SYMBOL PARAMETER CONDITIONS PD Internal Power Dissipation (DCE Mode, All Digital Pins = GND or VIN) RS530, RS530-A, X.21 Modes, Full Load V.28 Mode, Full Load MIN TYP MAX UNITS 210 54 mW mW Logic Inputs and Outputs VIH Logic Input High Voltage ● VIL Logic Input Low Voltage ● IIN Logic Input Current 2 V D1, D2, D3, D4 M0, M1, M2, DCE = GND M0, M1, M2, DCE = VIN ● ● ● – 30 – 75 2.7 3 VOH Output High Voltage IO = –3mA ● VOL Output Low Voltage IO = 1.6mA ● IOSR Output Short-Circuit Current 0V ≤ VO ≤ VIN ● IOZR Three-State Output Current M0 = M1 = M2 = VIN, VO = 0V M0 = M1 = M2 = VIN, VO = VIN ● ● VODO Open Circuit Differential Output Voltage RL = 1.95k (Figure 1) ● VODL Loaded Differential Output Voltage RL = 50Ω (Figure 1) – 30 0.8 V ±10 –120 ±10 µA µA µA V 0.2 0.4 V ±50 mA – 85 – 160 ±10 µA µA ±5 V 0.67VODO V V V.11 Driver ● 0.5VODO ±2 ∆VOD Change in Magnitude of Differential Output Voltage RL = 50Ω (Figure 1) ● 0.2 V VOC Common Mode Output Voltage RL = 50Ω (Figure 1) ● 3 V ∆VOC Change in Magnitude of Common Mode Output Voltage RL = 50Ω (Figure 1) ● 0.2 V ISS Short-Circuit Current VOUT = GND IOZ Output Leakage Current –0.25V ≤ VO ≤ 0.25V, Power Off or No-Cable Mode or Driver Disabled ● tr, tf Rise or Fall Time LTC2844C (Figures 2, 5) LTC2844I (Figures 2, 5) ● ● tPLH Input to Output LTC2844C (Figures 2, 5) LTC28441 (Figures 2, 5) tPHL Input to Output ∆t tSKEW ±150 mA ±1 ±100 µA 2 2 15 15 25 35 ns ns ● ● 20 20 40 40 65 75 ns ns LTC2844C (Figures 2, 5) LTC2844I (Figures 2, 5) ● ● 20 20 40 40 65 75 ns ns Input to Output Difference, tPLH – tPHL LTC2844C (Figures 2, 5) LTC2844I (Figures 2, 5) ● ● 0 0 3 3 12 17 ns ns Output to Output Skew (Figures 2, 5) 3 ns V.11 Receiver VTH Input Threshold Voltage –7V ≤ VCM ≤ 7V ● ∆VTH Input Hysteresis –7V ≤ VCM ≤ 7V ● IIN Input Current (A, B) –10V ≤ VA,B ≤ 10V ● RIN Input Impedance –10V ≤ VA,B ≤ 10V ● tr, tf Rise or Fall Time (Figures 2, 6) tPLH Input to Output LTC2844C CL = 50pF (Figures 2, 6) LTC2844I CL = 50pF (Figures 2, 6) – 0.2 0.2 15 15 40 mV ±0.66 mA 30 kΩ 15 ● ● 50 50 V ns 80 90 ns ns sn2844 2844fs 3 LTC2844 ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, VIN = 3.3V, VDD = 8V, VEE = – 7V for V.28, – 5.5V for V.10, V.11 (Notes 2, 3) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS tPHL Input to Output LTC2844C CL = 50pF (Figures 2, 6) LTC2844I CL = 50pF (Figures 2, 6) ● ● 50 50 80 90 ns ns ∆t Input to Output Difference, tPLH – tPHL LTC2844C CL = 50pF (Figures 2, 6) LTC2844I CL = 50pF (Figures 2, 6) ● ● 0 0 4 4 16 21 ns ns VO Output Voltage Open Circuit, RL = 3.9k ● ±4 ±6 V VT Output Voltage RL = 450Ω (Figure 3) RL = 450Ω (Figure 3) ● ISS Short-Circuit Current VO = GND IOZ Output Leakage Current –0.25V ≤ VO ≤ 0.25V, Power Off or No-Cable Mode or Driver Disabled tr, tf Rise or Fall Time RL = 450Ω, CL = 100pF (Figures 3, 7) 2 µs tPLH Input to Output RL = 450Ω, CL = 100pF (Figures 3, 7) 1 µs tPHL Input to Output RL = 450Ω, CL = 100pF (Figures 3, 7) 1 µs V.10 Driver ±3.6 0.9VO V ±0.1 ● ±150 mA ±100 µA V.10 Receiver VTH Receiver Input Threshold Voltage ∆VTH Receiver Input Hysteresis IIN Receiver Input Current –10V ≤ VA ≤ 10V ● RIN Receiver Input Impedance –10V ≤ VA ≤ 10V ● tr, tf Rise or Fall Time tPLH Input to Output tPHL ∆t ● –0.25 0.25 25 ● 15 V 50 mV ±0.66 mA 30 kΩ CL = 50pF (Figures 4, 8) 15 ns CL = 50pF (Figures 4, 8) 55 ns Input to Output CL = 50pF (Figures 4, 8) 109 ns Input to Output Difference, tPLH – tPHL CL = 50pF (Figures 4, 8) 60 ns VO Output Voltage Open Circuit RL = 3k (Figure 3) ● ● ISS Short-Circuit Current VO = GND ● IOZ Output Leakage Current –0.25V ≤ VO ≤ 0.25V, Power Off or No-Cable Mode or Driver Disabled ● SR Slew Rate RL = 3k, CL = 2500pF (Figures 3, 7) ● tPLH Input to Output RL = 3k, CL = 2500pF (Figures 3, 7) ● tPHL Input to Output RL = 3k, CL = 2500pF (Figures 3, 7) ● V.28 Driver ±5 ±8.5 ±1 4 ±10 V V ±150 mA ±100 µA 30 V/µs 1.3 2.5 µs 1.3 2.5 µs 0.8 V 0.1 0.3 V 5 7 kΩ V.28 Receiver VTHL Input Low Threshold Voltage ● VTLH Input High Threshold Voltage ● ∆VTH Receiver Input Hysterisis ● RIN Receiver Input Impedance –15V ≤ VA ≤ 15V tr, tf Rise or Fall Time CL = 50pF (Figures 4, 8) tPLH Input to Output CL = 50pF (Figures 4, 8) ● 60 100 ns tPHL Input to Output CL = 50pF (Figures 4, 8) ● 150 500 ns ● 2 3 V 15 ns sn2844 2844fs 4 LTC2844 ELECTRICAL CHARACTERISTICS Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: All currents into device pins are positive; all currents out of device are negative. All voltages are referenced to device ground unless otherwise specified. Note 3: All typicals are given for VCC = 5V, VIN = 3.3V, VDD = 8V, VEE = – 7V for V.28, – 5.5V for V.10, V.11 and TA = 25°C. U W TYPICAL PERFOR A CE CHARACTERISTICS 26 TA = 25°C 120 110 IEE (mA) ICC (mA) 115 105 100 95 90 10 TA = 25°C 24 9 22 8 IDD (mA) 125 V.28 in DCE Mode (Three V.28 Drivers with Full Load) IDD vs Data Rate RS530-A in DTE Mode (Two V.10 Drivers with Full Load) IEE vs Data Rate RS530, X.21 in DCE Mode (Three V.11 Drivers with Full Load) ICC vs Data Rate 20 100 1000 DATA RATE (kBd) 7 18 6 16 5 14 10 10 10000 4 20 30 40 50 60 70 80 100 DATA RATE (kBd) TA = 25°C 10 20 30 40 50 60 70 80 100 DATA RATE (kBd) 2844 G02 2844 G01 2844 G03 RS530-A in DTE Mode (Two V.10 Drivers with Full Load) IEE vs Temperature RS530, X.21 in DCE Mode (Three V.11 Drivers with Full Load) ICC vs Temperature 105 100 V.28 in DCE Mode (Three V.28 Drivers with Full Load) IDD vs Temperature 23.5 8.20 25.4 8.15 25.3 8.10 90 25.1 IDD (mA) 95 IEE (mA) ICC (mA) 25.2 25.0 24.9 7.90 24.7 7.85 24.6 80 –40 –20 8.00 7.95 24.8 85 8.05 0 40 20 60 TEMPERATURE (°C) 80 100 2844 G04 24.5 –40 –20 0 20 40 60 TEMPERATURE (°C) 80 100 2844 G05 7.80 –40 –20 0 20 40 60 TEMPERATURE (°C) 80 100 2844 G06 sn2844 2844fs 5 LTC2844 U U U PI FU CTIO S VCC (Pin 1): Positive Supply for the Transceivers. Connect to VCC Pin 8 on LTC2846 or to 5V supply. Connect a 1µF capacitor to ground. VDD (Pin 2): Positive Supply Voltage for V.28. Connect to VDD Pin 7 on LTC2846 or 8V supply. Connect a 1µF capacitor to ground. D1 (Pin 3): TTL Level Driver 1 Input. D2 (Pin 4): TTL Level Driver 2 Input. D3 (Pin 5): TTL Level Driver 3 Input. R1 (Pin 6): CMOS Level Receiver 1 Output. Receiver outputs have a weak pull up to VIN when high impedance. R2 (Pin 7): CMOS Level Receiver 2 Output. R3 (Pin 8): CMOS Level Receiver 3 Output. D4 (Pin 9): TTL Level Driver 4 Input. R4 (Pin 10): CMOS Level Receiver 4 Output. M0 (Pin 11): TTL Level Mode Select Input 0. Mode select inputs pull up to VIN. M1 (Pin 12): TTL Level Mode Select Input 1. M2 (Pin 13): TTL Level Mode Select Input 2. DCE/DTE (Pin 14): TTL Level Mode Select Input. VIN (Pin 15): Positive Supply for the Receiver Outputs. 3V ≤ VIN ≤ 3.6V. Connect a 1µF capacitor to ground. D4/R4 A (Pin 16): Receiver 4 Inverting Input and Driver 4 Inverting Output. R3 B (Pin 17): Receiver 3 Noninverting Input. R3 A (Pin 18): Receiver 3 Inverting Input. R2 B (Pin 19): Receiver 2 Noninverting Input. R2 A (Pin 20): Receiver 2 Inverting Input. D3/R1 B (Pin 21): Receiver 1 Noninverting Input and Driver 3 Noninverting Output. D3/R1 A (Pin 22): Receiver 1 Inverting Input and Driver 3 Inverting Output. D2 B (Pin 23): Driver 2 Noninverting Output. D2 A (Pin 24): Driver 2 Inverting Output. D1 B (Pin 25): Driver 1 Noninverting Output. D1 A (Pin 26): Driver 1 Inverting Output. GND (Pin 27): Ground. VEE (Pin 28): Negative Supply Voltage. Connect to VEE Pin␣ 31 on LTC2846 or to – 7V supply. Connect a 1µF capacitor to ground. sn2844 2844fs 6 LTC2844 W BLOCK DIAGRA TEST CIRCUITS VCC 1 28 VEE VDD 2 27 GND A RL 26 D1A D1 3 VOD D1 B 24 D2A D2 4 VOC RL 25 D1B 2844 F01 Figure 1. V.11 Driver Test Circuit D2 23 D2B 25 D3/R1 A D3 5 D3 10k 20k 6k B RL 100Ω S3 A 10k CL 100pF B CL 100pF A R CL 20k 21 D3/R1 B R1 6 R1 2844 F02 20 R2A 20k Figure 2. V.11 Driver/Receiver AC Test Circuit 6k 10k R2 7 S3 R2 10k D A 19 R2B 20k RL CL 18 R3A 20k 6k 2844 F03 10k R3 8 S3 R3 Figure 3. V.10/V.28 Driver Test Circuit 10k 17 R3B 20k D4 9 D4 16 D4/R4 A 10k R4 10 20k D A A R CL 6k R4 S3 2844 F04 Figure 4. V.10/V.28 Receiver Test Circuit M0 11 M1 12 MODE SELECTION LOGIC M2 13 DCE/DTE 14 15 VIN 2844 BD sn2844 2844fs 7 LTC2844 U W ODE SELECTIO MODE NAME Not Used (Default V.11) RS530A RS530 X.21 V.35 RS449/V.36 V.28/RS232 No Cable Not Used (Default V.11) RS530A RS530 X.21 V.35 RS449/V.36 V.28/RS232 No Cable M2 M1 M0 DCE /DTE (Note 1) (Note 1) (Note 1) D1 D3 D4 D2 D1 D2 D3 D4A A B A B A B 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 0 0 0 0 0 0 0 0 TTL TTL TTL TTL TTL TTL TTL X X X X X X X X X TTL TTL TTL TTL TTL TTL TTL X V.11 V.11 V.11 V.11 V.28 V.11 V.28 Z V.11 V.11 V.11 V.11 Z V.11 Z Z V.11 V.10 V.11 V.11 V.28 V.11 V.28 Z V.11 Z V.11 V.11 Z V.11 Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z V.10 V.10 V.10 V.10 V.28 V.10 V.28 Z 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 1 1 1 1 1 1 1 1 TTL TTL TTL TTL TTL TTL TTL X TTL TTL TTL TTL TTL TTL TTL X X X X X X X X X V.11 V.11 V.11 V.11 V.28 V.11 V.28 Z V.11 V.11 V.11 V.11 Z V.11 Z Z V.11 V.10 V.11 V.11 V.28 V.11 V.28 Z V.11 Z V.11 V.11 Z V.11 Z Z V.11 V.11 V.11 V.11 V.28 V.11 V.28 Z V.11 V.11 V.11 V.11 Z V.11 Z Z Z Z Z Z Z Z Z Z Note 1: Driver inputs are TTL level compatible. MODE NAME Not Used (Default V.11) RS530A RS530 X.21 V.35 RS449/V.36 V.28/RS232 No Cable Not Used (Default V.11) RS530A RS530 X.21 V.35 RS449/V.36 V.28/RS232 No Cable M2 M1 M0 (Note 2) R1 (Note 2) R2 (Note 2) R3 DCE /DTE A B A B A B (Note 2) (Note 3) (Note 3) (Note 3) R4A R1 R2 R4 R3 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 0 0 0 0 0 0 0 0 V.11 V.11 V.11 V.11 V.28 V.11 V.28 30k V.11 V.11 V.11 V.11 30k V.11 30k 30k V.11 V.10 V.11 V.11 V.28 V.11 V.28 30k V.11 30k V.11 V.11 30k V.11 30k 30k V.11 V.11 V.11 V.11 V.28 V.11 V.28 30k V.11 V.11 V.11 V.11 30k V.11 30k 30k 30k 30k 30k 30k 30k 30k 30k 30k CMOS CMOS CMOS CMOS CMOS CMOS CMOS Z CMOS CMOS CMOS CMOS CMOS CMOS CMOS Z Z Z Z Z Z Z Z Z 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 1 1 1 1 1 1 1 1 30k 30k 30k 30k 30k 30k 30k 30k 30k 30k 30k 30k 30k 30k 30k 30k V.11 V.10 V.11 V.11 V.28 V.11 V.28 30k V.11 30k V.11 V.11 30k V.11 30k 30k V.11 V.11 V.11 V.11 V.28 V.11 V.28 30k V.11 V.11 V.11 V.11 30k V.11 30k 30k V.10 V.10 V.10 V.10 V.28 V.10 V.28 30k Z Z Z Z Z Z Z Z CMOS CMOS CMOS CMOS CMOS CMOS CMOS Z CMOS CMOS CMOS CMOS CMOS CMOS CMOS Z Note 2: Unused receiver inputs are terminated with 30k to ground. Note 3: Receiver outputs are CMOS level compatible and have a weak pull-up to VIN when Z. sn2844 2844fs 8 LTC2844 U W W SWITCHI G TI E WAVEFOR S 3V f = 1MHz : t r ≤ 10ns : t f ≤ 10ns 1.5V D 0V 1.5V t PHL t PLH VO B–A –VO 90% 50% 10% tr 90% VDIFF = V(A) – V(B) 1/2 VO 50% 10% tf A VO B t SKEW t SKEW 2844 F05 Figure 5. V.11, V.35 Driver Propagation Delays VOD2 B–A –VOD2 f = 1MHz : t r ≤ 10ns : t f ≤ 10ns 0V INPUT t PLH 0V t PHL VOH R VOL 1.65V OUTPUT 1.65V 2844 F06 Figure 6. V.11, V.35 Receiver Propagation Delays 3V 1.5V 1.5V D 0V VO t PHL t PLH 3V 3V 0V A 0V –3V –VO 2844 F07 –3V tf tr Figure 7. V.10, V.28 Driver Propagation Delays VIH RECEIVER THRESHOLD A VIL VOH R VOL t PHL RECEIVER THRESHOLD t PLH 1.65V 1.65V 2844 F08 Figure 8. V.10, V.28 Receiver Propagation Delays sn2844 2844fs 9 LTC2844 U U W U APPLICATIONS INFORMATION Overview A complete DCE-to-DTE interface operating in EIA530 mode is shown in Figure 9. The LTC2846 of each port is used to generate the clock and data signals. The LTC2844 is used to generate the control signals along with LL (local loop-back). Cable termination is used only for the clock and data signals. The control signals do not need any external resistors. The LTC2846/LTC2844 form the core of a complete software-selectable DTE or DCE interface port that supports the RS232, RS449, EIA530, EIA530-A, V.35, V.36 or X.21 protocols. SERIAL CONTROLLER DTE DCE LTC2846 LTC2846 SERIAL CONTROLLER TXD D1 TXD 103Ω R3 TXD SCTE D2 SCTE 103Ω R2 SCTE R1 D3 TXC R1 103Ω TXC D3 TXC RXC R2 103Ω RXC D2 RXC RXD R3 103Ω RXD D1 RXD LTC2844 LTC2844 RTS D1 RTS R3 RTS DTR D2 DTR R2 DTR D3 R1 DCD R1 DCD D3 DCD DSR R2 DSR D2 DSR CTS R3 CTS D1 CTS LL LL D4 R4 R4 LL D4 2844 F09 Figure 9. Complete Multiprotocol Interface in EIA530 Mode sn2844 2844fs 10 LTC2844 U U W U APPLICATIONS INFORMATION Mode Selection The interface protocol is selected using the mode select pins M0, M1 and M2 (see the Mode Selection table). For example, if the port is configured as a V.35 interface, the mode selection pins should be M2 = 1, M1 = 0, M0 = 0. For the control signals, the drivers and receivers will operate in V.28 (RS232) electrical mode. For the clock and data signals, the drivers and receivers will operate in V.35 electrical mode. The DCE/DTE pin will configure the port for DCE mode when high, and DTE when low. The interface protocol may be selected simply by plugging the appropriate interface cable into the connector. The mode pins are routed to the connector and are left unconnected (1) or wired to ground (0) in the cable as shown in Figure 10. The internal pull-up current sources will ensure a binary 1 when a pin is left unconnected and that the LTC2846/ LTC2844 enter the no-cable mode when the cable is removed. In the no-cable mode the LTC2846/LTC2844 supply current drops to less than 900µA and all driver outputs are forced into a high impedance state. The mode selection may also be accomplished by using jumpers to connect the mode pins to ground or VIN. CONNECTOR (DATA) M0 LTC2846 M1 M2 DCE/DTE 15 16 18 19 NC NC CABLE LTC2844 DCE/DTE M2 M1 M0 14 13 12 11 2844 F10 (DATA) Figure 10. Single Port DCE V.35 Mode Selection in the Cable sn2844 2844fs 11 LTC2844 U U W U APPLICATIONS INFORMATION Cable Termination Traditional implementations have included switching resistors with expensive relays, or required the user to change termination modules every time the interface standard has changed. Custom cables have been used with the termination in the cable head or separate terminations are built on the board and a custom cable routes the signals to the appropriate termination. Switching the termination with FETs is difficult because the FETs must remain off even though the signal voltage is beyond the supply voltage for the FET drivers or the power is off. The V.10 receiver configuration in the LTC2844 is shown in Figure 13. In V.10 mode switch S3 inside the LTC2844 is turned off.The noninverting input is disconnected inside the LTC2844 receiver and connected to ground. The cable termination is then the 30k input impedance to ground of the LTC2844 V.10 receiver. IZ Using the LTC2846/LTC2844 solves the cable termination switching problem. Via software control, appropriate termination for the V.10 (RS423), V.11 (RS422), V.28 (RS232) and V.35 electrical protocols is chosen. 3.25mA –3V –10V VZ 3V 10V V.10 (RS423) Interface A typical V.10 unbalanced interface is shown in Figure 11. A V.10 single-ended generator output A with ground C is connected to a differential receiver with inputs A' connected to A, and input C' connected to the signal return ground C. Usually, no cable termination is required for V.10 interfaces, but the receiver inputs must be compliant with the impedance curve shown in Figure 12. 2844 F12 –3.25mA Figure 12. V.10 Receiver Input Impedance A' BALANCED INTERCONNECTING CABLE GENERATOR A R8 6k LOAD CABLE TERMINATION LTC2844 R6 10k S3 RECEIVER RECEIVER A' R4 20k B' C R5 20k C' Figure 11. Typical V.10 Interface 2844 F11 C' GND R7 10k 2844 F13 Figure 13. V.10 Receiver Configuration sn2844 2844fs 12 LTC2844 U U W U APPLICATIONS INFORMATION V.11 (RS422) Interface V.28 (RS232) Interface A typical V.11 balanced interface is shown in Figure 14. A V.11 differential generator with outputs A and B with ground C is connected to a differential receiver with ground C', inputs A' connected to A, B' connected to B. The V.11 interface has a differential termination at the receiver end that has a minimum value of 100Ω. The termination resistor is optional in the V.11 specification, but for the high speed clock and data lines, the termination is required to prevent reflections from corrupting the data. The receiver inputs must also be compliant with the impedance curve shown in Figure 12. A typical V.28 unbalanced interface is shown in Figure 16. A V.28 single-ended generator output A with ground C is connected to a single-ended receiver with input A' connected to A, ground C' connected via the signal return ground C. In V.11 mode, all switches are off except S1 of the LTC2846’s receivers which connects a 103Ω differential termination impedance to the cable as shown in Figure 151. The LTC2844 only handles control signals, so no termination other than its V.11 receivers’ 30k input impedance is necessary. In V.28 mode all switches are off except S3 inside the LTC2846/LTC2844 which connects a 6k (R8) impedance to ground in parallel with 20k (R5) plus 10k (R6) for a combined impedance of 5k as shown in Figure 17. The noninverting input is disconnected inside the LTC2846/ LTC2844 receiver and connected to a TTL level reference voltage for a 1.4V receiver trip point. A' BALANCED INTERCONNECTING CABLE GENERATOR LOAD CABLE TERMINATION LTC2846 R1 51.5Ω R6 10k RECEIVER S1 S2 A' A B B' C C' R8 6k R5 20k 100Ω MIN B' R3 124Ω R2 51.5Ω R7 10k R4 20k C' 2844 F14 GND 2844 F15 Figure 15. V.11 Receiver Configuration Figure 14. Typical V.11 Interface A' BALANCED INTERCONNECTING CABLE GENERATOR A LTC2844 R8 6k LOAD CABLE TERMINATION R5 20k R6 10k S3 RECEIVER RECEIVER A' R4 20k B' C RECEIVER S3 C' 2844 F16 C' Figure 16. Typical V.28 Interface GND R7 10k 2844 F17 Figure 17. V.28 Receiver Configuration 1Actually, there is no switch S1 in receivers R2 and R3. However, for simplicity, all termination networks on the LTC2846 can be treated identically if it is assumed that an S1 switch exists and is always closed on the R2 and R3 receivers. sn2844 2844fs 13 LTC2844 U U W U APPLICATIONS INFORMATION V.35 Interface No-Cable Mode A typical V.35 balanced interface is shown in Figure 18. A V.35 differential generator with outputs A and B with ground C is connected to a differential receiver with ground C', inputs A' connected to A, B' connected to B. The V.35 interface requires a T or delta network termination at the receiver end and the generator end. The receiver differential impedance measured at the connector must be 100Ω␣ ±10Ω, and the impedance between shorted terminals (A' and B') and ground C' must be 150Ω ±15Ω. The no-cable mode (M0 = M1 = M2 = 1) is intended for the case when the cable is disconnected from the connector. The bias circuitry, drivers and receivers are turned off, the driver outputs are forced into a high impedance state, and the supply current drops to less than 600µA. In V.35 mode, both switches S1 and S2 inside the LTC2846 are on, connecting the T network impedance as shown in Figure 19. The 30k input impedance of the receiver is placed in parallel with the T network termination, but does not affect the overall input impedance significantly. The generator differential impedance must be 50Ω to 150Ω and the impedance between shorted terminals (A and B) and ground C must be 150Ω ±15Ω. For the generator termination, switches S1 and S2 are both on as shown in Figure 20. BALANCED INTERCONNECTING CABLE GENERATOR LTC2846 Supplies The LTC2846 uses an internal capacitive charge pump to generate VDD and VEE as shown in Figure 21. A voltage doubler generates about 8V on VDD and a voltage inverter generates about – 7.5V for VEE. Three 1µF surface mounted tantalum or ceramic capacitors are required for C1, C2 and C3. The VEE capacitor C4 should be a minimum of 3.3µF. All capacitors are 16V and should be placed as close as possible to the LTC2846 to reduce EMI. The LTC2846 has an internal boost switching regulator which generates a 5V output from the 3.3V supply as shown in Figure 22. The 5V VCC supplies its internal charge pump and transceivers as well as its companion chip. A' LTC2846 LOAD CABLE TERMINATION R1 51.5Ω R6 10k A' A S1 S2 50Ω 125Ω 50Ω 125Ω 50Ω 50Ω B B' C C' R8 6k RECEIVER R5 20k R3 124Ω R2 51.5Ω B' RECEIVER S3 R7 10k R4 20k GND C' 2844 F19 2844 F18 Figure 19. V.35 Receiver Configuration Figure 18. Typical V.35 Interface A 7 LTC2846 C3 1µF 51.5Ω C1 1µF 5 S1 V.35 DRIVER 124Ω 6 S2 51.5Ω 8 5V B VDD C2 + 33 C1+ C2 – 32 C2 1µF LTC2846 C1– VCC VEE GND 31 30 + C4 3.3µF C5 10µF C 2844 F21 2844 F20 Figure 20. V.35 Driver Figure 21. Charge Pump sn2844 2844fs 14 LTC2844 U U W U APPLICATIONS INFORMATION L1 5.6µH VIN 3.3V D1 3 C6 10µF SHDN VIN VCC 5V 480mA 36 SW BOOST SWITCHING REGULATOR 35 4 SHDN FB GND 2, 34 R1 13k C5 10µF R2 4.3k C1,C2: TAIYO YUDEN X5R JMK316BJ106ML D1: ON SEMICONDUCTOR MBR0520 L1: SUMIDA CR43-5R6 2844 F22 Figure 22. Boost Switching Regulator Receiver Fail-Safe All LTC2846/LTC2844 receivers feature fail-safe operation in all modes. If the receiver inputs are left floating or shorted together by a termination resistor, the receiver output will always be forced to a logic high. DTE vs DCE Operation The DCE/DTE pin acts as an enable for Driver 3/Receiver␣ 1 in the LTC2846, and Driver 3/Receiver 1 and Receiver 4/ Driver 4 in the LTC2844. The LTC2846/LTC2844 can be configured for either DTE or DCE operation in one of two ways: a dedicated DTE or DCE port with a connector of appropriate gender or a port with one connector that can be configured for DTE or DCE operation by rerouting the signals to the LTC2846/LTC2844 using a dedicated DTE cable or dedicated DCE cable. A dedicated DTE port using a DB-25 male connector is shown in Figure 23. The interface mode is selected by logic outputs from the controller or from jumpers to either VIN or GND on the mode select pins. A port with one DB-25 connector, but can be configured for either DTE or DCE operation is shown in Figure 24. The configuration requires separate cables for proper signal routing in DTE or DCE operation. For example, in DTE mode, the TXD signal is routed to Pins 2 and 14 via Driver␣ 1 in the LTC2846. In DCE mode, Driver 1 now routes the RXD signal to Pins 2 and 14. Multiprotocol Interface with RL, LL, TM and a DB-25 Connector If the RL, LL and TM signals are implemented, there are not enough drivers and receivers available in the LTC2846/ LTC2844. In Figure 25, the required control signals are handled by the LTC2845. The LTC2845 has an additional single-ended driver/receiver pair that can handle two more optional control signals such as TM and LL. Cable-Selectable Multiprotocol Interface A cable-selectable multiprotocol DTE/DCE interface is shown in Figure 26. The select lines M0, M1 and DCE/DTE are brought out to the connector. The mode is selected by the cable by wiring M0 (connector Pin 18) and M1 (connector Pin 21) and DCE/DTE (connector Pin 25) to ground (connector Pin 7) or letting them float. If M0, M1 or DCE/ DTE is floating, internal pull-up current sources will pull the signals to VIN. The select bit M2 is floating and therefore, internally pulled high. When the cable is pulled out, the interface will go into the no-cable mode. Compliance Testing The LTC2846/LTC2844 chipset has been tested by TUV Rheinland of North America Inc. and passed the NET1, NET2 and TBR2 requirements. Copies of the test report are available from LTC or TUV Rheinland of North America Inc. The title of the report is Test Report No. TBR2/051501/02 The address of TUV Rheinland of North America Inc. is: TUV Rheinland of North America Inc. 1775, Old Highway 8 NW, Suite 107 St. Paul, MN 55112 Tel. (651) 639-0775 Fax (651) 639-0873 sn2844 2844fs 15 LTC2844 U TYPICAL APPLICATIO S D1 MBR0520 L1 5.6µH 3 C6 10µF SHDN 4 7 C3 1µF 36 BOOST SWITCHING REGULATOR 5 C1 1µF VCC 5V 33 30 LTC2846 9 D1 10 SCTE R2 4.3k T D2 C5 10µF C2 1µF 31 CHARGE PUMP 8 TXD 35 32 6 VCC 5V R1 13k T + VIN 3.3V C4 3.3µF 29 2 28 14 27 24 26 11 25 15 24 12 23 17 22 9 21 3 20 16 TXD A (103) TXD B SCTE A (113) SCTE B 11 D3 12 TXC 15 16 18 19 C8 1µF RTS DTR R2 14 RXD C7 1µF R1 13 RXC T R3 T T M0 7 M1 M2 17 VIN 3.3V DCE/DTE 1 VCC 2 VDD 3 VEE GND D1 4 D2 5 DSR CTS LL 6 R1 7 R2 8 R3 10 R4 9 M0 M1 M2 11 12 13 14 RXC A (115) RXC B RXD A (104) RXD B SG SHIELD DB-25 MALE CONNECTOR 28 C9 1µF 27 TXC B 26 4 25 19 24 20 23 23 RTS A (105) RTS B DTR A (108) DTR B D3 LTC2844 DCD 1 TXC A (114) 22 8 21 10 20 6 19 22 18 5 17 13 16 18 DCD A (109) DCD B DSR A (107) DSR B CTS A (106) CTS B LL A (141) D4 M0 M1 VIN 15 C10 1µF VIN 3.3V M2 DCE/DTE 2844 F23 Figure 23. Controller-Selectable Multiprotocol DTE Port with DB-25 Connector sn2844 2844fs 16 LTC2844 U TYPICAL APPLICATIO S D1 MBR0520 L1 5.6µH 3 C6 10µF SHDN 4 7 C3 1µF 36 BOOST SWITCHING REGULATOR 5 C1 1µF VCC 5V 6 8 9 D1 10 DTE_SCTE/DCE_RXC T D2 R2 4.3k 33 30 LTC2846 DTE_TXD/DCE_RXD 35 T C5 10µF C2 1µF 32 31 CHARGE PUMP VCC 5V R1 13k + VIN 3.3V C4 3.3µF 29 2 28 14 27 24 26 11 25 15 24 12 23 17 22 9 21 3 20 16 DTE DCE TXD A RXD A TXD B RXD B SCTE A RXC A SCTE B RXC B TXC A TXC A TXC B TXC B RXC A SCTE A RXC B SCTE B RXD A TXD A RXD B TXD B 11 D3 12 DTE_TXC/DCE_TXC 15 16 18 19 DTE_RTS/DCE_CTS DTE_DTR/DCE_DSR R2 14 DTE_RXD/DCE_TXD C7 1µF R1 13 DTE_RXC/DCE_SCTE C8 1µF T R3 T T M0 7 M1 M2 DCE/DTE 1 VCC 2 VDD 3 VEE GND D1 4 D2 5 DTE_DSR/DCE_DTR DTE_CTS/DCE_RTS DTE_LL/DCE_LL 6 R1 7 R2 8 R3 10 R4 9 M0 M1 M2 DCE/DTE 11 12 13 14 SHIELD DB-25 CONNECTOR 28 C9 1µF 27 SG 26 4 25 19 24 20 23 23 RTS A CTS A RTS B CTS B DTR A DSR A DTR B DSR B DCD A DCD A D3 LTC2844 DTE_DCD/DCE_DCD 1 17 VIN 3.3V 22 8 21 10 20 6 19 22 18 5 17 13 16 18 DCD B DCD B DSR A DTR A DSR B DTR B CTS A RTS A CTS B RTS B LL A LL A D4 M0 M1 VIN 15 C10 1µF VIN 3.3V M2 DCE/DTE 2844 F25 Figure 24. Controller-Selectable Multiprotocol DTE/DCE Port with DB-25 Connector sn2844 2844fs 17 LTC2844 U TYPICAL APPLICATIO S D1 MBR0520 L1 5.6µH 36 3 C6 10µF SHDN 4 7 C3 1µF BOOST SWITCHING REGULATOR 5 C1 1µF VCC 5V 8 LTC2846 D1 10 DTE_SCTE/DCE_RXC T D2 R2 4.3k 33 30 9 DTE_TXD/DCE_RXD 35 T C5 10µF C2 1µF 32 31 CHARGE PUMP 6 VCC 5V R1 13k + VIN 3.3V C4 3.3µF 29 2 28 14 27 24 26 11 25 15 24 12 23 17 22 9 21 3 20 16 DTE TXD A DCE RXD A TXD B RXD B SCTE A RXC A SCTE B RXC B TXC A TXC A TXC B TXC B RXC A SCTE A RXC B SCTE B RXD A TXD A RXD B TXD B 11 D3 12 DTE_TXC/DCE_TXC 15 16 18 19 DTE_RTS/DCE_CTS DTE_DTR/DCE_DSR C8 1µF T R2 14 DTE_RXD/DCE_TXD C7 1µF R1 13 DTE_RXC/DCE_SCTE T T R3 M0 7 M1 M2 1, 19 VCC 2 VDD 3 VEE GND D1 4 D2 5 DTE_DSR/DCE_DTR DTE_CTS/DCE_RTS DTE_LL/DCE_RI DTE_RI/DCE_LL DTE_TM/DCE_RL DTE_RL/DCE_TM M0 M1 M2 DCE/DTE 6 R1 7 R2 8 R3 9 D4 10 R4 17 R5 18 11 12 13 14 SHIELD 36 DB-25 CONNECTOR C9 1µF 35 34 4 33 19 32 20 31 23 RTS A CTS A RTS B CTS B DTR A DSR A DTR B DSR B DCD A DCD A D3 LTC2845 DTE_DCD/DCE_DCD 1 17 VIN 3.3V DCE/DTE SG D5 M0 M1 8 29 10 28 6 27 22 26 5 25 24 13 23 * 22 25 21 21 20 VIN 15 D4ENB M2 DCE/DTE 30 R4EN 16 C10 1µF VIN 3.3V DCD B DCD B DSR A DTR A DSR B DTR B CTS A RTS A CTS B 18 LL RTS B RI RI LL TM RL RL TM *OPTIONAL 2844 F26 NC Figure 25. Controller-Selectable Multiprotocol DTE/DCE Port with RL, LL, TM and DB-25 Connector sn2844 2844fs 18 LTC2844 U TYPICAL APPLICATIO S D1 MBR0520 L1 5.6µH 3 C6 10µF SHDN 4 7 C3 1µF 36 BOOST SWITCHING REGULATOR 5 C1 1µF 33 30 LTC2846 9 D1 10 DTE_SCTE/DCE_RXC R2 4.3k T D2 C5 10µF C2 1µF 31 CHARGE PUMP 8 DTE_TXD/DCE_RXD 35 32 6 VCC 5V VCC 5V R1 13k T + VIN 3.3V C4 3.3µF 29 2 28 14 27 24 26 11 25 15 24 12 23 17 22 9 21 3 20 16 DTE DCE TXD A RXD A TXD B RXD B SCTE A RXC A SCTE B RXC B TXC A TXC A 11 D3 12 DTE_TXC/DCE_TXC R1 13 DTE_RXC/DCE_SCTE R2 14 DTE_RXD/DCE_TXD 15 16 NC 18 19 T R3 T T M0 7 M1 M2 1 17 VIN 3.3V DCE/DTE TXC B TXC B RXC A SCTE A RXC B SCTE B RXD A TXD A RXD B TXD B SG SHIELD DB-25 CONNECTOR C7 1µF C8 1µF 1 VCC 2 VDD VEE GND 25 DCE/DTE 21 M1 18 M0 4 RTS A 19 RTS B 20 DTR A 23 DTR B 28 C9 1µF 27 26 3 DTE_RTS/DCE_CTS D1 24 4 DTE_DTR/DCE_DSR 25 D2 5 23 6 R1 7 DTE_DSR/DCE_DTR R2 8 DTE_CTS/DCE_RTS R3 10 12 NC 13 14 22 8 21 10 20 6 19 22 18 5 13 17 R4 9 11 CTS B DSR A DSR B D3 LTC2844 DTE_DCD/DCE_DCD CTS A 16 CABLE WIRING FOR MODE SELECTION 15 MODE V.35 RS449, V.36 RS232 D4 M0 M1 M2 DCE/DTE VIN C10 1µF VIN 3.3V PIN 18 PIN 7 NC PIN 7 DCD A DCD A DCD B DCD B DSR A DTR A DSR B DTR B CTS A RTS A CTS B RTS B PIN 21 PIN 7 PIN 7 NC CABLE WIRING FOR DTE/DCE SELECTION MODE DTE DCE PIN 25 PIN 7 NC 2844 F27 Figure 26. Cable-Selectable Multiprotocol DTE/DCE Port with DB-25 Connector sn2844 2844fs Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 19 LTC2844 U PACKAGE DESCRIPTIO G Package 28-Lead Plastic SSOP (5.3mm) (Reference LTC DWG # 05-08-1640) 9.90 – 10.50* (.390 – .413) 28 27 26 25 24 23 22 21 20 19 18 17 16 15 1.25 ±0.12 7.8 – 8.2 5.3 – 5.7 0.42 ±0.03 7.40 – 8.20 (.291 – .323) 0.65 BSC 1 2 3 4 5 6 7 8 9 10 11 12 13 14 RECOMMENDED SOLDER PAD LAYOUT 5.00 – 5.60** (.197 – .221) 2.0 (.079) 0° – 8° 0.09 – 0.25 (.0035 – .010) 0.55 – 0.95 (.022 – .037) NOTE: 1. CONTROLLING DIMENSION: MILLIMETERS MILLIMETERS 2. DIMENSIONS ARE IN (INCHES) 0.65 (.0256) BSC 0.22 – 0.38 (.009 – .015) 0.05 (.002) G28 SSOP 0802 3. DRAWING NOT TO SCALE *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED .152mm (.006") PER SIDE **DIMENSIONS DO NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED .254mm (.010") PER SIDE RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC1321 Dual RS232/RS485 Transceiver Two RS232 Driver/Receiver Pairs or Two RS485 Driver/Receiver Pairs LTC1334 Single 5V RS232/RS485 Multiprotocol Transceiver Two RS232 Driver/Receiver or Four RS232 Driver/Receiver Pairs LTC1343 Software-Selectable Multiprotocol Transceiver 4-Driver/4-Receiver for Data and Clock Signals LTC1344A Software-Selectable Cable Terminator Perfect for Terminating the LTC1543 (Not Needed with LTC1546) LTC1345 Single Supply V.35 Transceiver 3-Driver/3-Receiver for Data and Clock Signals LTC1346A Dual Supply V.35 Transceiver 3-Driver/3-Receiver for Data and Clock Signals LTC1543 Software-Selectable Multiprotocol Transceiver Terminated with LTC1344A for Data and Clock Signals, Companion to LTC1544 or LTC1545 for Control Signals LTC1544 Software-Selectable Multiprotocol Transceiver Companion to LTC1546 or LTC1543 for Control Signals Including LL LTC1545 Software-Selectable Multiprotocol Transceiver 5-Driver/5-Receiver Companion to LTC1546 or LTC1543 for Control Signals Including LL, TM and RL LTC1546 Software-Selectable Multiprotocol Transceiver 3-Driver/3-Receiver with Termination for Data and Clock Signals LTC2845 3.3V Software-Selectable Multiprotocol Transceiver 3.3V Supply, 5-Driver/5-Receiver Companion to LTC2846 for Control Signals Including LL, TM and RL LTC2846 3.3V Software-Selectable Multiprotocol Transceiver 3.3V Supply, 3-Driver/3-Receiver with Termination for Data and Clock Signals, Generates the Required 5V and ±8V Supplies for LTC2846 and Companion Parts sn2844 2844fs 20 Linear Technology Corporation LT/TP 0503 1K • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2002