LTC1318 Single 5V RS232/RS422/AppleTalk® DCE Transceiver U DESCRIPTION FEATURES ■ ■ ■ ■ ■ ■ ■ ■ The LTC®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 0.1µF 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. Single Chip Provides DCE RS232 or RS422/AppleTalk DCE Port Operates from a Single 5V Supply Charge Pump Uses 0.1µF 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 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. U APPLICATIONS ■ ■ ■ Dual-Mode RS232/RS422 Peripherals AppleTalk Peripherals Single 5V Systems 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. U TYPICAL APPLICATIONS C1 + 0.1µF 0.1µF C1 RS232 LINES 5V 1k 22Ω 22Ω CHARGE PUMP – 1k 22Ω 22Ω RXO1 TXI1 TXO2 RS232 TXI2 RXD TXD + RS422 LOCALTALK® TRANSFORMER TXD (5V/DIV) TO DIGITAL SYSTEM 22Ω TXD+, TXD– (2V/DIV) RXDO (5V/DIV) RXDO/RXO2 TXD RS232 RXMODE RL = 100Ω CL = 100pF GND 22Ω NC 22Ω 0.1µF 0.1µF GND VCC TXD – RS422 22Ω C2 + RXI1 RS232 RXD –/RXI2 APPLETALK NETWORK C2 – TXO1 RS232 + Driver Output Waveforms V– V+ LTC1318 200ns/DIV 1318 TA02 NC LT1318 • TA01 100pF × 4 1 LTC1318 W U U W W W ABSOLUTE MAXIMUM RATINGS PACKAGE/ORDER INFORMATION (Note 1) 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 .................... 0°C to 70°C Lead Temperature (Soldering, 10 sec)................. 300°C ORDER PART NUMBER TOP VIEW V+ 1 24 V – C1 + 2 23 C2 – – 3 22 C2 + C1 LTC1318CSW RXI1 4 21 RXO1 TXO1 5 20 TXI1 TXO2 6 19 TXI2 VCC 7 18 GND RXD + 8 17 RXDO/RXO2 RXD –/RXI2 9 16 TXD TXD + 10 15 RXMODE TXD – 11 14 GND NC 12 13 NC SW PACKAGE 24-LEAD PLASTIC SO WIDE TJMAX = 125°C, θJA = 85°C/W Consult factory for Industrial and Military grade parts ELECTRICAL CHARACTERISTICS VS = 5V ±5%, C1 = C2 = 0.1µF, TA = 0°C to 70°C, unless otherwise specified. (Notes 2, 3) SYMBOL PARAMETER CONDITIONS MIN TYP MAX 9 30 UNITS Supplies ICC Supply Current No Load ● V+ mA Positive Charge Pump Output Voltage IOUT = 0mA IOUT = 10mA, VCC = 5V ● ● 7.8 6.8 8.8 7.4 V V V– Negative Charge Pump Output Voltage IOUT = 0mA IOUT = – 5mA, VCC = 5V ● ● –7.3 – 6.3 –8.6 –7.3 V V ±4 ±2 Differential Driver VOD Differential Driver Output Voltage No Load (Figure 1) RL = 100Ω (Figure 1) ● ● DVOD Change in Magnitude of Differential Output Voltage RL = 100Ω (Figure 1) ● VOC Common-Mode Output Voltage RL = 100Ω (Figure 1) ● IDSS Short-Circuit Output Current – 1V < VCMR < 7V ● VIL Input Low Voltage ● VIH Input High Voltage ● V V 0.2 3 35 200 0.8 2.0 V V mA V V Single-Ended Driver VO Output Voltage Swing RL = 3k ● ±5 7.3/–6.5 IOSS Short-Circuit Output Current VOUT = OV ● ±5 17 VIL Input Low Voltage ● VIH Input High Voltage ● 2 SR Output Slew Rate ● 4 2 RL = 3k, CL = 51pF V mA 0.8 V V 20 30 V/µS LTC1318 ELECTRICAL CHARACTERISTICS VS = 5V ±5%, C1 = C2 = 0.1µF, TA = 0°C to 70°C, unless otherwise specified. (Notes 2, 3) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Differential Receiver VTH Differential Receiver Threshold ● – 0.2 0.2 V CMR Common-Mode Input Range ● –7 7 V Hysteresis VCM = OV RIN Input Resistance TA = 25°C 30 VOL Output Low Voltage IOUT = –1.6mA VOH Output High Voltage IOUT = 160µA, VCC = 5V ● 3.5 IOSS Short-Circuit Output Current VO = GND or VCC ● ±7 0.8 ● 3 5 mV 7 0.4 kΩ V V ±85 mA Single-Ended Receiver VL Input Voltage Low Threshold ● VIH Input Voltage High Threshold ● Hysteresis ● 0.1 RIN Input Resistance TA = 25°C VOL Output Low Voltage IOUT = –4mA ● 3 VOH Output High Voltage IOUT = 4mA, VCC = 5V ● IOSS Short-Circuit Output Current VO = GND or VCC ● ±7 VILRXM RXMODE Input Low Voltage ● 0.8 VIHRXM RXMODE Input High Voltage IINRXM RXMODE Input Current ● VIN = OV or VCC ● 3.5 1.4 V 1.8 2.4 V 0.4 1.0 V 5 7 0.2 0.4 4.8 V –V ±85 1.6 1.6 kΩ mA V 2.0 V ±2 µA Switching Characteristics tPLH,HL Differential Driver Propagation Delay RL = 100Ω, CL = 100pF (Figures 2,3) ● 35 100 ns tSKEW Differential Driver Output to Output RL = 100Ω, CL = 100pF (Figures 2,3) ● 5 35 ns tR,F Differential Driver Rise, Fall Time RL = 100Ω, CL = 100pF (Figures 2,3) ● 15 50 ns tPLH,HL Differential Receiver Propagation Delay CL = 15pF, (Figures 4) ● 110 200 ns tSEL Receiver Mode Switching Time ● 25 100 ns The ● 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 = 25°C. 3 LTC1318 U W TYPICAL PERFORMANCE CHARACTERISTICS 10.0 2.4 10 9.6 9.4 9.2 9.0 8.8 8.6 8.4 8.2 8.0 0 10 40 30 20 50 TEMPERATURE (°C) 4 2 TA = 25°C VCC = 5V ILOAD = V+ TO V – 0 –2 –4 V– –6 9 12 6 LOAD CURRENT (mA) 4 3 2 3.5 2.0 1.5 1.0 0 10 20 30 40 50 60 70 80 90 100 LOAD CURRENT (mA) 10 6 4 2 TA = 25°C VCC = 5V 0 –2 –4 –6 NEGATIVE SWING 10000 1318 G07 4 88 86 84 0 10 40 30 20 50 TEMPERATURE (°C) 60 70 1318 G06 RS232 Driver Short-Circuit Current vs Temperature VCC = 5V 19.0 18.5 18.0 ISC– 17.5 ISC+ 17.0 16.5 16.0 15.5 –10 0 ISC– 90 19.5 POSITIVE SWING –8 100 1000 CAPACITANCE (pF) 92 20.0 8 DRIVER OUTPUT SWING (V) SLEW RATE (V/µs) 5 ISC+ 94 20 30 40 50 60 70 80 90 100 LOAD CURRENT (mA) SHORT-CIRCUIT CURRENT (mA) TA = 25°C VCC = 5V 10 96 80 0 10 25 70 VCC = 5V 98 RS232 Driver Output Swing vs Resistive Load 10 60 1318 G03 1318 G05 RS232 Driver Slew Rate vs Load Capacitance SR + 50 82 1318 G04 15 40 30 RS422 Driver Short-Circuit Current vs Temperature 2.5 0 SR – 20 TEMPERATURE (°C) 3.0 0.5 20 10 100 4.0 1 0 INPUT LOW (TXI1, TXI2) 0 SHORT-CIRCUIT CURRENT (mA) 5 INPUT LOW (TXD) 1.2 15 TA = 25°C VCC = 5V ILOAD FROM TXD+, TXD– TO GND 4.5 DRIVER OUTPUT SWING (V) DIFFERENTIAL OUTPUT SWING (V) 6 1.4 0.8 3 0 5.0 7 1.6 RS422 Driver Single-Ended Output Swing vs Load Current 10 8 INPUT HIGH (TXD) 1.8 1318 G02 RS422 Driver Differential Output Swing vs Load Current 9 INPUT HIGH (TXI1, TXI2) 2.0 1.0 –8 1318 G01 TA = 25°C VCC = 5V ILOAD FROM TXD+ TO TXD– VCC = 5V 2.2 6 –10 70 60 V+ 8 THRESHOLD VOLTAGE (V) CHARGE PUMP OUTPUT VOLTAGE (V) VCC = 5V 9.8 SUPPLY CURRENT (mA) TTL Input Threshold vs Temperature Charge Pump Output Voltage vs Load Current Supply Current vs Temperature 15.0 1 3 2 4 5 6 7 8 9 10 RESISTIVE LOAD (kΩ) 1318 G08 0 10 40 30 20 50 TEMPERATURE (°C) 60 70 1318 G09 LTC1318 U W TYPICAL PERFORMANCE CHARACTERISTICS RS232 Receiver Input Threshold vs Temperature RS422 Receiver Differential Threshold vs Temperature 100 2.4 24 THRESHOLD VOLTAGE (V) 2.2 80 INPUT HIGH 70 60 INPUT LOW 50 40 30 VCC = 5V VCC = 5V SHORT-CIRCUIT CURRENT (mA) VCC = 5V 90 THRESHOLD VOLTAGE (mV) TTL Output Short-Circuit Current vs Temperature INPUT HIGH (RXDO/RXO2) 2.0 1.8 INPUT HIGH (RXO1) 1.6 1.4 INPUT LOW (RXO1) 1.2 INPUT LOW (RXDO/RXO2) 1.0 20 10 20 30 40 50 60 70 TEMPERATURE (°C) RXO1 20 18 RXDO/RXO2 16 14 12 10 0.8 0 22 0 10 20 30 40 50 60 70 TEMPERATURE (°C) 1318 G10 0 10 40 30 50 20 TEMPERATURE (°C) 1318 G11 60 70 1318 G12 U U U PIN FUNCTIONS V + (Pin 1): Charge Pump Positive Output. This pin requires a 0.1µF 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 –. TXD – (Pin 11): Differential RS422 Driver Inverting Output. C1+, C1– (Pins 2, 3): C1 Inputs. Connect a 0.1µF capacitor between C1+ and C1–. 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. 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 0.1µF 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. TXD + (Pin 10): Differential RS422 Driver Noninverting 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. 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). 5 LTC1318 U U U PIN FUNCTIONS C2+, C2– (Pins 22, 23): C2 inputs. Connect a 0.1µF capacitor between C2 + and C2 –. V – (Pin 24): Charge Pump Negative Output. This pin requires a 0.1µF capacitor to ground. Under normal opera- tion, 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+ VOD + TXD– RL/2 CL TXD + TXD TXD – RD CL VOC Figure 1. Figure 2. W U SWITCHING WAVEFORMS 3V f = 1MHz: tr ≤ 10ns: tf ≤ 10ns 1.5V TXD 1.5V 0V tPLH tPHL VO 90% 50% 10% –VO VDIFF = V(TXD +) – V(TXD – ) 1/2 VO tr 90% 50% 10% tf – VO TXD + tSKEW tSKEW LT1318 • F03 Figure 3. Differential Driver V OD2 f = 1MHz: tr ≤ 10ns: tf ≤ 10ns (RXD+) – (RXD–) –VOD2 tPLH tPHL VOH VOL 1.5V 1.5V LT1318 • F04 Figure 4. Differential Receiver 6 RXD RXI2 RXD0/RXD2 CL 1318 F02 1318 F01 RXDO –/ – – TXD RXD + LTC1318 U W U U 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. 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 1 2 0.1µF 3 8V AT 5mA V+ 0.1µF EXTERNAL DEVICE LTC1318 22 0.1µF 23 0.1µF V– 24 – 7V AT 5mA LT1318 • F05 Figure 5. 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 0.1µF 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. 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. 7 LTC1318 U PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. S PACKAGE 24-Lead Plastic SOL 24 23 22 21 0.598 – 0.614 (15.190 – 15.600) (NOTE 2) 20 19 18 17 16 15 14 13 0.394 – 0.419 (10.007 – 10.643) NOTE 1 1 0.005 (0.127) RAD MIN 0.291 – 0.299 (7.391 – 7.595) (NOTE 2) 0.010 – 0.029 × 45° (0.254 – 0.737) 2 3 4 5 6 7 8 9 10 11 12 0.037 – 0.045 (0.940 – 1.143) 0.093 – 0.104 (2.362 – 2.642) 0° – 8° TYP 0.009 – 0.013 (0.229 – 0.330) NOTE 1 0.016 – 0.050 (0.406 – 1.270) 0.050 (1.270) TYP 0.004 – 0.012 (0.102 – 0.305) 0.014 – 0.019 (0.356 – 0.482) 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 SOL24 0392 LT/GP 0295 10K • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7487 (408) 432-1900 ● FAX: (408) 434-0507 ● TELEX: 499-3977 LINEAR TECHNOLOGY CORPORATION 1995