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| LTC1318 Single 5V RS232/RS422/AppleTalk(R) DCE Transceiver FEATURES s s s s DESCRIPTION The LTC(R)1318 is a single 5V, RS232/RS422 transceiver for connection to the DCE, or peripheral side of an interface link. It includes an on-board charge pump to generate a 8V supply which allows true RS232 output swings. The charge pump requires only four external 0.1F capacitors. The LTC1318 includes two RS232 drivers, a differential RS422 driver, a dedicated RS232 receiver, and a pin selectable RS232/RS422 receiver which can receive either single-ended or differential signals. The LTC1318 features driver outputs which can be taken to common-mode voltages outside the power supply rails without damage. Additionally, the driver outputs assume a high impedance state when the power is shut off, preventing externally applied signals from feeding back into the power supplies. The RS232 devices will operate at speeds up to 100kbaud. The RS422 devices will operate up to 2Mbaud. The LTC1318 is available in a 24-lead SO Wide package. , LTC and LT are registered trademarks of Linear Technology Corporation. AppleTalk and LocalTalk are registered trademarks of Apple Computer, Inc. s s s s Single Chip Provides DCE RS232 or RS422/AppleTalk DCE Port Operates from a Single 5V Supply Charge Pump Uses 0.1F Capacitors Output Common-Mode Voltage Range Exceeds Power Supply Rails for All Drivers Driver Outputs Are High Impedance with Power Off Pin Selectable RS232/RS422 Receiver Thermal Shutdown Protection Drivers Are Short-Circuit Protected APPLICATIONS s s s Dual-Mode RS232/RS422 Peripherals AppleTalk Peripherals Single 5V Systems TYPICAL APPLICATIONS V+ 0.1F 0.1F C1 + C1 - V- CHARGE PUMP C2 - C2 + RXO1 TXI1 TXI2 GND RS422 RXDO/RXO2 TXD RS232 RXMODE GND LTC1318 NC LT1318 * TA01 0.1F 0.1F TXD (5V/DIV) RXI1 RS232 RS232 LINES TXO1 RS232 TXO2 RS232 5V 1k 22 22 VCC RXD + TO DIGITAL SYSTEM TXD+, TXD- (2V/DIV) RXD -/RXI2 1k APPLETALK NETWORK 22 22 TXD + RXDO (5V/DIV) TXD - RS422 22 22 NC 22 LOCALTALK(R) TRANSFORMER 22 100pF x 4 U U U Driver Output Waveforms RL = 100 CL = 100pF 200ns/DIV 1318 TA02 1 LTC1318 ABSOLUTE MAXIMUM RATINGS (Note 1) PACKAGE/ORDER INFORMATION TOP VIEW V+ 1 C1 + C1 - Supply Voltage: VCC ...................................................................................... 7V V+ ................................................................................... 13.2V V - ............................................................................... - 13.2V Input Voltage: All Drivers .............................. - 0.3 to (VCC + 0.3V) All Receivers ...................................... - 25V to 25V RXMODE Pin ....................... - 0.3V to (VCC + 0.3V) Output Voltage: RS232 Drivers ................ (V + - 30V) to (V - + 30V) RS422 Drivers ................................................ 15V All Receivers ........................ - 0.3V to (VCC + 0.3V) Short-Circuit Duration: V + or V - to GND .......................................... 30 sec Driver or Receiver Outputs ...................... Indefinite Operating Temperature Range .................... 0C to 70C Lead Temperature (Soldering, 10 sec)................. 300C 24 V - 23 C2 - 22 C2 + 21 RXO1 20 TXI1 19 TXI2 18 GND 17 RXDO/RXO2 16 TXD 15 RXMODE 14 GND 13 NC ORDER PART NUMBER LTC1318CSW 2 3 RXI1 4 TXO1 5 TXO2 6 VCC 7 RXD + 8 RXD -/RXI2 9 TXD + 10 TXD - 11 NC 12 SW PACKAGE 24-LEAD PLASTIC SO WIDE TJMAX = 125C, JA = 85C/W Consult factory for Industrial and Military grade parts ELECTRICAL CHARACTERISTICS VS = 5V 5%, C1 = C2 = 0.1F, TA = 0C to 70C, unless otherwise specified. (Notes 2, 3) SYMBOL Supplies ICC V+ V- Supply Current Positive Charge Pump Output Voltage Negative Charge Pump Output Voltage No Load IOUT = 0mA IOUT = 10mA, VCC = 5V IOUT = 0mA IOUT = - 5mA, VCC = 5V No Load (Figure 1) RL = 100 (Figure 1) RL = 100 (Figure 1) RL = 100 (Figure 1) - 1V < VCMR < 7V q q q q q PARAMETER CONDITIONS MIN TYP 9 MAX 30 UNITS mA V V V V V V 7.8 6.8 -7.3 - 6.3 4 2 8.8 7.4 -8.6 -7.3 Differential Driver VOD DVOD VOC IDSS VIL VIH VO IOSS VIL VIH SR Differential Driver Output Voltage Change in Magnitude of Differential Output Voltage Common-Mode Output Voltage Short-Circuit Output Current Input Low Voltage Input High Voltage Output Voltage Swing Short-Circuit Output Current Input Low Voltage Input High Voltage Output Slew Rate RL = 3k, CL = 51pF RL = 3k VOUT = OV q q q q q q q 0.2 3 35 2.0 5 5 2 4 20 30 7.3/-6.5 17 0.8 200 0.8 mA V V V mA V V V/S Single-Ended Driver q q q q q 2 U V V W U WW W LTC1318 ELECTRICAL CHARACTERISTICS VS = 5V 5%, C1 = C2 = 0.1F, TA = 0C to 70C, unless otherwise specified. (Notes 2, 3) SYMBOL VTH CMR RIN VOL VOH IOSS VL VIH RIN VOL VOH IOSS VILRXM VIHRXM IINRXM tPLH,HL tSKEW tR,F tPLH,HL tSEL PARAMETER Differential Receiver Threshold Common-Mode Input Range Hysteresis Input Resistance Output Low Voltage Output High Voltage Short-Circuit Output Current Input Voltage Low Threshold Input Voltage High Threshold Hysteresis Input Resistance Output Low Voltage Output High Voltage Short-Circuit Output Current RXMODE Input Low Voltage RXMODE Input High Voltage RXMODE Input Current Differential Driver Propagation Delay Differential Driver Output to Output Differential Driver Rise, Fall Time Differential Receiver Propagation Delay Receiver Mode Switching Time VIN = OV or VCC RL = 100, CL = 100pF (Figures 2,3) RL = 100, CL = 100pF (Figures 2,3) RL = 100, CL = 100pF (Figures 2,3) CL = 15pF, (Figures 4) TA = 25C IOUT = -4mA IOUT = 4mA, VCC = 5V VO = GND or VCC q q q q q q CONDITIONS q q MIN - 0.2 -7 TYP MAX 0.2 7 UNITS V V mV k V V mA V Differential Receiver VCM = OV TA = 25C IOUT = -1.6mA IOUT = 160A, VCC = 5V VO = GND or VCC q 30 3 5 7 0.4 q q 3.5 7 0.8 0.1 3 3.5 7 0.8 1.6 1.6 2.0 2 35 5 15 110 25 100 35 50 200 100 1.4 1.8 0.4 5 0.2 4.8 85 2.4 1.0 7 0.4 85 Single-Ended Receiver q q q V V k V -V mA V V A ns ns ns ns ns Switching Characteristics q q q q q The q denotes specifications which apply over the full operating temperature range. Note 1: Absolute maximum ratings are those values beyond which the life of the device may be impaired. Note 2: All currents into device pins are negative, all currents out of device pins are positive. All voltages are referenced to ground unless otherwise specified. Note 3: All typicals are given at VCC = 5V, TA = 25C. 3 LTC1318 TYPICAL PERFORMANCE CHARACTERISTICS Supply Current vs Temperature 10.0 CHARGE PUMP OUTPUT VOLTAGE (V) 9.8 9.6 VCC = 5V THRESHOLD VOLTAGE (V) SUPPLY CURRENT (mA) 9.4 9.2 9.0 8.8 8.6 8.4 8.2 8.0 0 10 40 30 20 50 TEMPERATURE (C) 60 70 RS422 Driver Differential Output Swing vs Load Current 10 DIFFERENTIAL OUTPUT SWING (V) 9 8 7 6 5 4 3 2 1 0 0 SHORT-CIRCUIT CURRENT (mA) DRIVER OUTPUT SWING (V) TA = 25C VCC = 5V ILOAD FROM TXD+ TO TXD- 10 20 30 40 50 60 70 80 90 100 LOAD CURRENT (mA) 1318 G04 RS232 Driver Slew Rate vs Load Capacitance 25 TA = 25C VCC = 5V SLEW RATE (V/s) SR - 15 SR + DRIVER OUTPUT SWING (V) 20 6 4 2 0 -2 -4 -6 -8 NEGATIVE SWING TA = 25C VCC = 5V SHORT-CIRCUIT CURRENT (mA) 10 5 0 10 100 1000 CAPACITANCE (pF) 10000 1318 G07 4 UW 1318 G01 Charge Pump Output Voltage vs Load Current 10 8 6 4 2 0 -2 -4 -6 -8 -10 0 3 9 12 6 LOAD CURRENT (mA) 15 1318 G02 TTL Input Threshold vs Temperature 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0 10 20 30 40 50 60 70 TEMPERATURE (C) 1318 G03 V+ VCC = 5V INPUT HIGH (TXI1, TXI2) INPUT HIGH (TXD) TA = 25C VCC = 5V ILOAD = V+ TO V - INPUT LOW (TXD) INPUT LOW (TXI1, TXI2) V- RS422 Driver Single-Ended Output Swing vs Load Current 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 0 10 20 30 40 50 60 70 80 90 100 LOAD CURRENT (mA) 1318 G05 RS422 Driver Short-Circuit Current vs Temperature 100 98 96 94 92 90 88 86 84 82 80 0 10 40 30 20 50 TEMPERATURE (C) 60 70 ISC+ ISC- VCC = 5V TA = 25C VCC = 5V ILOAD FROM TXD+, TXD- TO GND 1318 G06 RS232 Driver Output Swing vs Resistive Load 10 8 POSITIVE SWING 20.0 19.5 19.0 18.5 18.0 17.5 17.0 16.5 16.0 15.5 15.0 RS232 Driver Short-Circuit Current vs Temperature VCC = 5V ISC- ISC+ -10 1 3 2 4 5 6 7 8 9 10 RESISTIVE LOAD (k) 1318 G08 0 10 40 30 20 50 TEMPERATURE (C) 60 70 1318 G09 LTC1318 TYPICAL PERFORMANCE CHARACTERISTICS RS422 Receiver Differential Threshold vs Temperature 100 90 VCC = 5V THRESHOLD VOLTAGE (V) SHORT-CIRCUIT CURRENT (mA) THRESHOLD VOLTAGE (mV) 80 70 60 50 40 30 20 0 10 20 30 INPUT HIGH INPUT LOW 40 50 TEMPERATURE (C) 1318 G10 PIN FUNCTIONS V + (Pin 1): Charge Pump Positive Output. This pin requires a 0.1F capacitor to ground. Under normal operation this pin maintains a voltage of about 8.8V above ground. An external load can be connected between this pin and ground or V -. C1+, C1- (Pins 2, 3): C1 Inputs. Connect a 0.1F capacitor between C1+ and C1-. RXI1 (Pin 4): First RS232 Single-Ended Receiver Input. This is an inverting receiver. TXO1, TXO2 (Pins 5,6): RS232 Single-Ended Driver Outputs. VCC (Pin 7): Positive Supply Input. Apply 4.75V VCC 5.25V to this pin. A 0.1F bypass capacitor is required. RXD+ (Pin 8): When RXMODE (pin 15) is low, this pin acts as the differential RS422 receiver positive input. When RXMODE is high, this pin is disabled. RXD -/RXI2 (Pin 9): When RXMODE (pin 15) is low, this pin acts as the differential RS422 receiver negative input. When RXMODE is high, this pin acts as the second RS232 receiver input. The receiver is inverting in RS232 mode. (Pin 10): Differential RS422 Driver Noninverting Output. TXD + TXD - (Pin 11): Differential RS422 Driver Inverting Output. NC (Pins 12,13): No Internal Connection. GND (Pins 14, 18): Power Supply Ground. Connect both pins to each other and to the ground. RXMODE (Pin 15): This pin controls the state of the differential/single-ended receiver. When RXMODE is low, the receiver is in differential mode and will receive RS422 compatible signals at RXD + and RXD - /RXI2 (pins 8 and 9). When RXMODE goes high, the receiver enters single-ended mode and will receive RS232 compatible signals at RXD -/RXI2. RXD + is disabled in single-ended mode. Both modes use the RXDO/RXO2 pin (pin 17) as their output. TXD (Pin 16): Differential RS422 Driver Input (TTL Compatible). RXDO/RXO2 (Pin 17): This is the output of the configurable differential/single-ended receiver. TXI1, TXI2 (Pins 20, 19): RS232 Driver Inputs (TTL Compatible). Both are inverting inputs. RXO1 (Pin 21): First RS232 Receiver Outputs (TTL compatible). UW 60 RS232 Receiver Input Threshold vs Temperature 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 70 0 10 20 30 40 50 60 70 TEMPERATURE (C) 1318 G11 TTL Output Short-Circuit Current vs Temperature 24 VCC = 5V 22 20 18 RXDO/RXO2 16 14 12 10 0 10 40 30 50 20 TEMPERATURE (C) 60 70 VCC = 5V INPUT HIGH (RXDO/RXO2) INPUT HIGH (RXO1) RXO1 INPUT LOW (RXO1) INPUT LOW (RXDO/RXO2) 1318 G12 U U U 5 LTC1318 PIN FUNCTIONS C2+, C2- (Pins 22, 23): C2 inputs. Connect a 0.1F capacitor between C2 + and C2 -. V - (Pin 24): Charge Pump Negative Output. This pin requires a 0.1F capacitor to ground. Under normal operation, this pin maintains a voltage of about 8.6V below ground. An external load can be connected between this pin and ground or V +. TEST CIRCUITS + RL/2 TXD TXD+ TXD- RL/2 VOD SWITCHING WAVEFORMS 3V TXD 0V tPLH VO -VO TXD - 1.5V VO TXD + tSKEW tSKEW LT1318 * F03 V OD2 (RXD+) - (RXD-) -VOD2 tPLH VOH RXDO VOL 6 W U U U U TXD TXD + TXD - CL RD CL RXD + RXD RXI2 -/ RXD0/RXD2 CL + VOC - - 1318 F01 1318 F02 Figure 1. Figure 2. f = 1MHz: tr 10ns: tf 10ns 1.5V tPHL 90% 50% 10% tr VDIFF = V(TXD +) - V(TXD - ) 1/2 VO 90% 50% 10% tf Figure 3. Differential Driver f = 1MHz: tr 10ns: tf 10ns tPHL 1.5V 1.5V LT1318 * F04 Figure 4. Differential Receiver LTC1318 APPLICATION INFORMATION Interface Standards The LTC1318 provides compatibility with both RS232 and RS422/AppleTalk/LocalTalk standards in a single chip, enabling a system to communicate using either protocol as necessary. The LTC1318 provides two RS232 singleended drivers, one RS422 differential driver, and two receivers. One of the receivers is a dedicated RS232 single-ended receiver, while the other can be configured for RS232 (single-ended) or RS422 (differential) operation by controlling the logic state of the select pin. All single-ended drivers and receivers meet the RS232C specification for output swing, load driving capacity and input range, and can additionally transmit and receive signals as high as 100kbaud. The differential driver and receiver can interface to both RS422 and AppleTalk networks, and can transmit and receive signals at rates exceeding 2Mbaud. Fault Protection The LTC1318 incorporates many protection features to make it as "bustproof" as possible. All driver outputs and receiver inputs are protected against ESD strikes to 6kV, eliminating the need for external protection devices in most applications. All driver outputs can be taken outside the power supply rails without damage and will not allow current to be forced back into the supplies, preventing the output fault from affecting other logic circuits using the same power supply. Additionally, the driver outputs enter a high impedance state when the power is removed, preventing the system from loading the data lines when it is shut off. All driver and receiver outputs are protected against short circuits to ground or to the supply rails. Charge Pump Power Supply The LTC1318 includes an on-board charge pump to generate the voltages necessary for true RS232 compatible output swing. This charge pump requires just four external 0.1F capacitors to operate; two flying caps connected Configurable RS422/RS232 Receiver There are two line receivers in the LTC1318. One is a dedicated RS232 receiver; the other can receive both single-ended RS232 signals and differential RS422 signals. This second receiver has two inputs: RXD + (pin 8) and RXD- (pin 9) to accept differential signals. The RXD+ input is disabled in single-ended mode. The receiver mode is set by the RXMODE (pin 15). A low level on RXMODE configures the receiver in differential mode; it accepts input at RXD+ and RXD- and outputs the data at RXDO (pin 17). A high level at RXMODE forces the receiver into single-ended mode; RXD+ is disabled, pin 9 switches identity from RXD- to RXI2, and pin 17 switches from RXDO to RXO2, the single-ended data output. In this mode the receiver accepts RS232 signals at RXI2 and outputs the data through RXO2. The receiver becomes inverting in single-ended mode. This receiver can switch between its two modes within 100ns, allowing the system to sense the input signal and configure itself accordingly. to the C1 +/C1- and C2 +/C2 - pins, and two hold caps, one from V + to ground and one from V - to ground. The charge pump has enough extra capacity to drive light external loads and still meet RS232 specifications; it will support a 10mA load from V + to ground or a 5mA from V + to V - (Figure 5). 5V 2 0.1F 3 LTC1318 22 0.1F 23 24 - 7V AT 5mA LT1318 * F05 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. U W UU 1 8V AT 5mA V+ 0.1F EXTERNAL DEVICE 0.1F V- Figure 5. 7 LTC1318 PACKAGE DESCRIPTION 0.005 (0.127) RAD MIN 0.291 - 0.299 (7.391 - 7.595) (NOTE 2) 0.010 - 0.029 x 45 (0.254 - 0.737) 0.009 - 0.013 (0.229 - 0.330) NOTE 1 0.016 - 0.050 (0.406 - 1.270) NOTE: 1. PIN 1 IDENT, NOTCH ON TOP AND CAVITIES ON THE BOTTOM OF PACKAGES ARE THE MANUFACTURING OPTIONS. THE PART MAY BE SUPPLIED WITH OR WITHOUT ANY OF THE OPTIONS. 2. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006 INCH (0.15mm). 8 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7487 (408) 432-1900 q FAX: (408) 434-0507 q TELEX: 499-3977 U Dimensions in inches (millimeters) unless otherwise noted. S PACKAGE 24-Lead Plastic SOL 0.598 - 0.614 (15.190 - 15.600) (NOTE 2) 20 19 18 17 16 24 23 22 21 15 14 13 NOTE 1 0.394 - 0.419 (10.007 - 10.643) 1 2 3 4 5 6 7 8 9 10 11 12 0.093 - 0.104 (2.362 - 2.642) 0.037 - 0.045 (0.940 - 1.143) 0 - 8 TYP 0.050 (1.270) TYP 0.004 - 0.012 (0.102 - 0.305) 0.014 - 0.019 (0.356 - 0.482) SOL24 0392 LT/GP 0295 10K * PRINTED IN USA (c) LINEAR TECHNOLOGY CORPORATION 1995 |
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