LT1331 3V RS562 or 5V/3V RS232 Transceiver with One Receiver Active in Shutdown U DESCRIPTIO FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ The LT ®1331 is a 3-driver, 5-receiver RS232 transceiver designed for 3V and mixed 3V/5V systems. Receivers operate from 3V logic supply V L, while the onboard charge pump and drivers operate from 5V or 3V supply V CC. RS232 Compatible 3V Operation 3V Logic Interface ESD Protection Over ±10kV 120kbaud Operation for RL = 3k, CL = 2500pF 250kbaud Operation for RL = 3k, CL = 1000pF One Low Power Receiver Remains Active While in Shutdown 60µA Supply Current in Shutdown Low Power Driver Disable Mode Uses Small Capacitors: 0.1µF, 0.2µF CMOS Comparable Low Power: 60mW Easy PC Layout: Flowthrough Architecture Rugged Bipolar Design Outputs Assume a High Impedance State When Off or Powered Down The transceiver has two shutdown modes. One mode disables the drivers and the charge pump, the other shuts down all circuitry except for one low power receiver which can be used for ring detection. The VCC supply may be shut down while in ring detection mode. While shut down, the drivers and receivers assume high impedance output states. The LT1331 is fully compliant with all EIA-RS232 specifications when VCC = 5V. If VCC = 3V, output drive levels are compatible with all known interface circuits. Special bipolar construction techniques protect the drivers and receivers beyond the fault conditions stipulated for RS232. The RS232 I/O pins are resilient to multiple ±10kV ESD strikes. An advanced driver output stage operates up to 120kbaud while driving heavy capacitive loads. UO APPLICATI ■ ■ S Notebook Computers Palmtop Computers , LTC and LT are registered trademarks of Linear Technology Corporation. UO TYPICAL APPLICATI 3.3V Operation 2 × 0.1µF + VCC = 3.3V DRIVER 1 OUT RX1 IN DRIVER 2 OUT TO LINE RX2 IN RX3 IN RX4 IN DRIVER 3 OUT RX5 IN (LOW-Q) ON/OFF 3.3V VL 2 3 27 LT1331 4 25 5 24 6 23 7 22 8 21 9 20 10 19 11 12 13 14 0.1µF 26 + 0.1µF RECEIVER OUTPUT CL = 50pF 28 V – 1 2 × 0.1µF + V+ + DRIVER 1 IN R DRIVER OUTPUT RL = 3k CL = 2500pF RX1 OUT DRIVER 2 IN RX2 OUT RX3 OUT TO LOGIC RX4 OUT DRIVER 3 IN 18 RX5 OUT (LOW-Q) 17 GND 16 DRIVER DISABLE 15 NC INPUT RING DETECT IN µCONTROLLER OR µPROCESSOR 1331 TA02 SHUTDOWN CONTROL OUT 1331 TA01 1 LT1331 U U RATI GS W W W W AXI U U ABSOLUTE PACKAGE/ORDER I FOR ATIO (Note 1) Supply Voltage (VCC) ................................................ 6V Supply Voltage (VL) .................................................. 6V V + ........................................................................ 13.2V V – ...................................................................... –13.2V Input Voltage Driver ........................................................... V + to V – Receiver ................................................ 30V to – 30V ON/OFF ...................................... – 0.3V to VCC + 0.3V DRIVER DISABLE ...................... – 0.3V to VCC + 0.3V Output Voltage Driver ................................................... – 30V to 30V Receiver ...................................... – 0.3V to VL + 0.3V Short Circuit Duration V + ................................................................... 30 sec V – ................................................................... 30 sec Driver Output .............................................. Indefinite Receiver Output .......................................... Indefinite Operating Temperature Range .................... 0°C to 70°C Storage Temperature Range ................ – 65°C to 150°C Lead Temperature (Soldering, 10 sec)................. 300°C ELECTRICAL CHARACTERISTICS PARAMETER Power Supply Generator V + Output V – Output Supply Current (VCC) Supply Current (VL) Supply Current When OFF (VCC) Supply Current When OFF (VL) Supply Rise Time, Shutdown to Turn-On ON/OFF Pin Thresholds ON/OFF Pin Current DRIVER DISABLE Pin Thresholds DRIVER DISABLE Pin Current Oscillator Frequency 2 TOP VIEW V+ ORDER PART NUMBER 28 V – 1 27 C2 – 5V/3V VCC 2 C1+ 3 26 C2+ C1– 4 25 DRIVER 1 IN DRIVER 1 OUT 5 24 RX1 OUT RX1 IN 6 23 DRIVER 2 IN DRIVER 2 OUT 7 22 RX2 OUT RX2 IN 8 21 RX3 OUT RX3 IN 9 20 RX4 OUT RX4 IN 10 19 DRIVER 3 IN RX5 OUT 18 (LOW-Q) 17 GND 16 DRIVER DISABLE 15 NC DRIVER 3 OUT 11 RX5 IN (LOW-Q) 12 ON/OFF 13 3.3V VL 14 G PACKAGE 28-LEAD SSOP LT1331CG LT1331CNW LT1331CSW NW PACKAGE 28-LEAD PDIP SW PACKAGE 28-LEAD PLASTIC SO TJMAX = 125°C, θJA = 96°C/ W (G) TJMAX = 125°C, θJA = 56°C/ W (NW) TJMAX = 125°C, θJA = 85°C/ W (SW) Consult factory for Industrial and Military grade parts. (Note 2) CONDITIONS VCC = 5V VCC = 3.3V VCC = 5V VCC = 3.3V VCC = 5V (Note 3) VCC = 3.3V (Note 4) Shutdown (Note 5) Driver Disable Shutdown (Note 5) Driver Disable C1 = C2 = 0.2µF, C + = C – = 0.1µF Input Low Level (Device Shut Down) Input High Level (Device Enabled) 0V ≤ VON/OFF ≤ 5V Input Low Level (Drivers Enabled) Input High Level (Drivers Disabled) 0V ≤ VDRIVER DISABLE ≤ 5V MIN ● ● ● ● ● ● ● ● ● ● ● 2.4 –15 2.4 –10 TYP 8.6 5.5 – 7.0 – 4.8 12 12 3 2 0.1 60 3 0.2 1.4 1.4 1.4 1.4 MAX 17 17 5 50 1 100 5 0.8 80 0.8 500 130 UNITS V V V V mA mA mA µA mA µA mA ms V V µA V V µA kHz LT1331 ELECTRICAL CHARACTERISTICS PARAMETER Any Driver Output Voltage Swing, Positive Output Voltage Swing, Negative Logic Input Voltage Level Logic Input Current Output Short-Circuit Current Output Leakage Current Data Rate (Note 8) Slew Rate Propagation Delay Any Receiver Input Voltage Thresholds Hysteresis Input Resistance Receivers 1 Through 4 Output Voltage Output Short-Circuit Current Propagation Delay Output Leakage Current Receiver 5 (Low Q-Current RX) Output Voltage Output Short-Circuit Current Propagation Delay CONDITIONS MIN TYP 5.0 3.7 6.5 4.0 – 6.0 – 3.3 1.4 1.4 5 17 10 VCC = 5V, RL = 3k VCC = 3.3V, RL = 3k VCC = 5V, RL = 3k VCC = 3.3V, RL = 3k Input Low Level (VOUT = High) Input High Level (VOUT = Low) 0.8V ≤ VIN ≤ 2V VOUT = 0V Shutdown VOUT = ±30V (Note 5) RL = 3k, CL = 2500pF RL = 3k, CL = 1000pF RL = 3k, CL = 51pF RL = 3k, CL = 2500pF Output Transition t HL High to Low (Note 6) Output Transition t LH Low to High ● Input Low Threshold (VOUT = High) Input High Threshold (VOUT = Low) ● ● 0.8 ● 0.1 3 ● ● ● ● ±9 ● Output Low, IOUT = – 1.6mA Output High, IOUT = 160µA (VL = 3.3V) Sinking Current, VOUT = VCC Sourcing Current, VOUT = 0V Output Transition tHL High to Low (Note 7) Output Transition t LH Low to High Shutdown (Note 5) 0 ≤ VOUT ≤ VCC ● ● Output Low, IOUT = – 500µA Output High, IOUT = 160µA (VL = 3V) Sinking Current, VOUT = VCC Sourcing Current, VOUT = 0V Output Transition tHL High to Low (Note 7) Output Transition t LH Low to High ● ● 2.0 10 ● 2.0 2 UNITS 15 6 0.6 0.5 1.3 1.3 V V V V V V µA mA µA kBaud kBaud V/µs V/µs µs µs 1.3 1.7 0.4 5 2.4 1.0 7 V V V kΩ – 5.0 – 2.7 0.8 20 100 120 250 VIN = ±10V The ● denotes specifications which apply over the full operating temperature range (0°C ≤ TA ≤ 70°C for commercial grade). Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: Testing done at VCC = 5V, VL = 3.3V, and VON/OFF = 3V, unless otherwise stated. Note 3: Supply current is measured as the average over several charge pump cycles. C + = 1µF, C – = 0.1µF, C1 = C2 = 0.2µF. All outputs are open with all driver inputs tied high. Note 4: VL supply current is measured with all receiver outputs high. Note 5: Supply current and leakage current measurements in shutdown are performed with VON/OFF ≤ 0.1V. Supply current measurements using driver disable are performed with VDRIVER DISABLE ≥ 3V. 2.0 MAX 0.2 2.4 – 20 20 250 350 1 0.2 2.4 –4 4 1 1 30 0.4 – 10 600 600 10 0.4 –2 3 3 V V mA mA ns ns µA V V mA mA µs µs Note 6: For driver delay measurements, RL = 3k and CL = 51pF. Trigger points are set between the driver’s input logic threshold and the output transition to the zero crossing (t HL = 1.4V to 0V and tLH = 1.4V to 0V). Note 7: For receiver delay measurements, CL = 51pF. Trigger points are set between the receiver’s input logic threshold and the output transition to standard TTL/CMOS logic threshold (t HL = 1.3V to 2.0V and t LH = 1.7V to 0.8V). Note 8: Data rate operation guaranteed by slew rate, short-circuit current and propagation delay tests. 3 LT1331 U W TYPICAL PERFOR A CE CHARACTERISTICS Driver Short-Circuit Current Driver Output Voltage 30 VCC = 5V ISC+ ISC– 10 5 0 –55 –25 50 25 75 0 TEMPERATURE (°C) 7 100 DRIVER OUTPUT VOLTAGE (V) 20 15 OUTPUT LOW OUTPUT HIGH 25 DRIVER OUTPUT VOLTAGE (V) SHORT-CIRCUIT CURRENT (mA) Driver Output Voltage –2 8 VCC = 5V 6 5 VCC = 3.3V 4 RL = 3k 3 DRIVERS LOADED 3 2 –55 –25 125 50 25 75 0 TEMPERATURE (°C) 100 1331 G01 Driver Leakage in Shutdown 50 25 0 75 TEMPERATURE (°C) 100 12 10 8 –SLEW 6 +SLEW 2 0 1 3 4 2 LOAD CAPACITANCE (nF) THRESHOLD VOLTAGE (V) SUPPLY CURRENT (mA) VCC = 5V VCC = 3.3V 1 DRIVER 25 50 75 100 DATA RATE (kBAUD) 125 150 1131 G07 4 5 Receiver Short-Circuit Current 40 VL = 3.3V VL = 3.3V 2.50 2.25 2.00 INPUT HIGH 1.75 1.50 1.25 INPUT LOW 1.00 ISC– 30 ISC+ 20 10 0.75 0 0 3 4 2 LOAD CAPACITANCE (nF) 1331 G06 SHORT-CIRCUIT CURRENT (mA) 2.75 VCC = 3.3V 1 0 5 Receiver Input Thresholds 3 DRIVERS +SLEW 1331 G05 RL = 3k CL = 2500pF 10 –SLEW 6 2 3.00 20 8 4 Supply Current vs Data Rate 30 10 4 0 50 125 VCC = 3.3V 14 0 125 VCC = 5V 100 Slew Rate vs Load Capacitance VCC = 5V 1331 G04 40 50 25 75 0 TEMPERATURE (°C) 16 SLEW RATE (V/µs) SLEW RATE (V/µs) LEAKAGE CURRENT (µA) VOUT = –30V RL = 3k 3 DRIVERS LOADED –7 1331 G03 12 VOUT = 30V VCC = 5V –6 Slew Rate vs Load Capacitance 14 0.1 –55 –25 –5 –8 –55 –25 125 16 10 VCC = 3.3V –4 1331 G02 100 1 –3 0.50 –55 –25 50 25 0 75 TEMPERATURE (°C) 100 125 1331 G08 0 –55 –25 50 0 75 25 TEMPERATURE (°C) 100 125 1331 G09 LT1331 U U U PI FU CTIO S V + (Pin 1): Positive Supply Output. V + ≅ 2VCC – 1.5V. This pin requires an external capacitor for charge storage, chosen to minimize ripple to acceptable levels. A minimum size of 0.1µF is recommended. VCC (Pin 2): Power Supply for Charge Pump and Drivers. Proper circuit operation is insured for VCC = 3V to 6V. VCC = 5V operation gives full RS232 compliant performance, 3V operation results in lower driver output amplitude. The VCC pin should be decoupled with a 0.1µF ceramic capacitor. C1+, C1–, C2 +, C2 – (Pins 3, 4, 26, 27): These pins require two external capacitors C ≥ 0.2µF. One from C1+ to C1–, and another from C2 + to C2 –. To maintain charge pump efficiency, the capacitor’s effective series resistance should be less than 2Ω. Low ESR tantalum capacitors work well in this application, small value ceramic capacitors may also be used with minimal reduction in charge pump compliance. DRIVER OUT (Pins 5, 7, 11): RS232 Driver Outputs. Outputs are in a high impedance state when in shutdown, driver disable, or VCC = 0V. Outputs are fully short-circuit protected from V – + 30V to V + – 30V. Although the outputs are protected, short circuits on one output can load the power supply generator and may disrupt the signal levels of the other outputs. The driver outputs are protected against ESD to ±10kV for human body model discharges. Output levels of – 3.3V to 4V are achieved when the circuit is operated with VCC = 3.3V. RX IN (Pins 6, 8, 9, 10): Receiver Inputs with 0.4V of Hysteresis for Noise Immunity. These pins accept RS232 level signals (±30V) into a protected 5k terminating resistor. The receiver inputs are protected against ESD to ±10kV for human body model discharges. LOW-Q RX IN (Pin 12): Low Power Receiver Input. This receiver remains active in shutdown mode, consuming only 60µA from supply VL. This receiver has the same input and protection characteristics as receivers RX1 through RX4. ON/OFF (Pin 13): A TTL/CMOS Compatible Operating Mode Control. A logic low puts the device in the shutdown mode. All drivers and four of the receivers go to a high impedance state, and the VCC supply may be turned off. A logic high fully enables the transceiver. VL (Pin 14): Power Supply for Receivers. This pin should be powered to the same voltage as the logic circuits connected to the receiver outputs, either 5V or 3V. The VL pin should be decoupled with a 0.1µF ceramic capacitor. DRIVER DISABLE (Pin 16): A logic high shuts down the charge pump, placing all drivers in a high impedance state. All receivers remain active. Floating the pin, or driving it to a logic low, fully enables the transceiver. A low voltage on the ON/OFF pin supersedes the state of the driver disable control. GND (Pin 17): Ground. LOW-Q RX OUT (Pin 18): Low Power Receiver Output. This pin produces the same output levels as standard receivers, with slightly decreased speed and short-circuit current. DRIVER IN (Pins 19, 23, 25): RS232 Driver Inputs. Inputs are TTL/CMOS compatible. Tie unused inputs to VCC. RX OUT (Pins 20, 21, 22, 24): Receiver Outputs. RX1 through RX4 outputs are in a high impedance state when in shutdown mode to allow data line sharing. Outputs, including LOW-Q RX OUT, are fully short-circuit protected to ground, VCC, or VL. Output voltage levels are determined by the choice of power supply VL. V – (Pin 28): Negative Supply Output. V – ≅ – (2VCC – 2.5V). This pin requires an external charge storage capacitor, chosen to minimize ripple on V –. A minimum value of 0.1µF is recommended. 5 LT1331 U W U UO APPLICATI S I FOR ATIO Power Saving Operational Modes Mixed 5V/3V Operation The LT1331 has both shutdown and driver disable operating modes. These operating modes can optimize power consumption based upon applications needs. When operated with VCC = 5V and VL = 3.3V supplies, the RS232 drivers meet or exceed all RS232 or V.28 communication interface standards. Data rates up to 120kbaud are supported, and all standard RS232 compatible mice may be driven by the LT1331. The shutdown control turns off all circuitry except for Low-Q RX5. RX5 operates entirely from the VL power supply, so the power consumption from VCC drops to zero. The VCC power supply may be turned off while in shutdwon, which may allow greater power savings in some systems. When RX5 detects a signal, this information can be used to wake up the system for full operation. If more than one line must be monitored, the driver disable mode provides a power efficient operating option. The driver disable mode turns off the charge pumps and RS232 drivers, but keeps all five receivers active. Power consumption in driver disable mode is 3mA from VL and less than 100µA from VCC. 3V Operation VCC = 3.3V operation of the LT1331 results in lower driver output swing than with VCC = 5V. The driver output swing, when operated with VCC = 3.3V, is guaranteed to be at least –2.7V to 3.7V, with typical swing being –3.3V to 4V. This insures compatibility with all commonly used RS232 and RS562 interface circuits. Table 1 summarizes the receiver input threshold specifications for RS232 circuits from many manufacturers. Table 1. Commonly Used RS232 Interface Circuit Receiver Thresholds MANUFACTURER Linear Technology Texas Instruments Maxim Sipex Motorola National 6 PART NUMBER LT1080 LT1137A LT1330 LT1281 All Others SN75189 SN75189A MAX232 SN75C185 MAX232A MAX241 SP232 SP301 MC1489 MC1489A DS1489 DS14C89A COMPATIBLE ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ INPUT LOW THRESHOLD MIN TYP MAX 0.8 1.3 – 0.8 1.3 – 0.8 1.3 – 0.8 1.3 – INPUT HIGH THRESHOLD MIN TYP MAX – 1.7 2.4 – 1.7 2.4 – 1.7 2.4 – 1.7 2.4 0.65 0.65 0.8 0.65 0.8 0.6 0.8 0.75 0.75 0.75 0.75 0.5 0.9 1.55 – 1.6 – – – 1.75 1.0 1.75 1.0 1.3 1.0 1.0 1.2 1.0 1.3 1.2 1.2 – – 0.8 1.0 – 1.25 1.25 – 1.25 – – – 1.35 1.25 1.25 1.25 1.9 1.3 1.9 1.7 2.1 1.8 1.5 1.7 – – 1.95 1.25 – 1.6 2.25 2.4 2.55 2.4 2.4 2.4 2.5 1.5 2.25 1.5 2.7 LT1331 U ESD PROTECTIO ESD Test Circuit + 0.1µF 0.1µF 2 + 26 LT1331 0.2µF 4 25 5 24 6 23 7 22 8 21 9 20 10 19 11 18 12 17 13 16 14 15 RX1 IN DRIVER 2 OUT RX2 IN RX3 IN RX4 IN DRIVER 3 OUT RX5 IN (LOW-Q) ON/OFF 3.3V 0.1µF 0.2µF 27 3 DRIVER 1 OUT RS232 LINE PINS PROTECTED TO ±10kV 28 V – 1 + + + V+ 5V VCC + The RS232 line inputs of the LT1331 have on-chip protection from ESD transients up to ±10kV. The protection structures act to divert the static discharge safely to system ground. In order for the ESD protection to function effectively, the power supply and ground pins of the LT1331 must be connected to ground through low impedances. The power supply decoupling capacitors and charge pump storage capacitors provide this low impedance in normal application of the circuit. The only constraint is that low ESR capacitors must be used for bypassing and charge storage. ESD testing must be done with pins VCC, VL, V +, V – and GND shorted to ground or connected with low ESR capacitors. DRIVER 1 IN RX1 OUT DRIVER 2 IN RX2 OUT RX3 OUT RX4 OUT DRIVER 3 IN RX5 OUT (LOW-Q) GND DRIVER DISABLE NC 1331 ESD TC 0.1µF U PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted. G Package 28-Lead Plastic SSOP (0.209) (LTC DWG # 05-08-1640) 0.205 – 0.212** (5.20 – 5.38) 0.397 – 0.407* (10.07 – 10.33) 28 27 26 25 24 23 22 21 20 19 18 17 16 15 0.068 – 0.078 (1.73 – 1.99) 0° – 8° 0.0256 (0.65) BSC 0.022 – 0.037 (0.55 – 0.95) 0.005 – 0.009 (0.13 – 0.22) *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSIONS DO NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE 0.301 – 0.311 (7.65 – 7.90) 0.002 – 0.008 (0.05 – 0.21) 0.010 – 0.015 (0.25 – 0.38) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 G28 SSOP 0694 NW Package 28-Lead PDIP (Wide 0.600) (LTC DWG # 05-08-1520) 0.600 – 0.625 (15.240 – 15.875) 0.015 (0.381) MIN 0.150 ± 0.005 (3.810 ± 0.127) 0.070 (1.778) TYP 0.045 – 0.065 (1.143 – 1.651) 1.455* (36.957) MAX 28 27 26 25 24 23 22 21 20 19 18 17 16 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 0.009 – 0.015 (0.229 – 0.381) +0.035 0.625 –0.015 0.035 – 0.080 (0.889 – 2.032) 0.125 (3.175) 0.100 ± 0.010 MIN (2.540 ± 0.254) *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm) ( 15.87 +0.889 –0.381 ) 0.018 ± 0.003 (0.457 ± 0.076) 0.505 – 0.560* (12.827 – 14.224) 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. N28 1197 7 LT1331 U PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted. SW Package 28-Lead Plastic Small Outline (Wide 0.300) (LTC DWG # 05-08-1620) 0.697 – 0.712* (17.70 – 18.08) 0.291 – 0.299** (7.391 – 7.595) 0.010 – 0.029 × 45° (0.254 – 0.737) 0.093 – 0.104 (2.362 – 2.642) 0.037 – 0.045 (0.940 – 1.143) 0.050 (1.270) TYP 0.014 – 0.019 (0.356 – 0.482) TYP 0.004 – 0.012 (0.102 – 0.305) 28 27 26 25 24 23 22 21 20 19 18 17 16 15 0° – 8° TYP 0.009 – 0.013 (0.229 – 0.330) NOTE 1 NOTE 1 0.394 – 0.419 (10.007 – 10.643) 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 *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE 1 2 3 4 5 6 7 8 9 10 11 12 13 14 S28 (WIDE) 0996 UO TYPICAL APPLICATI Mixed 5V/3V Supply Operation 2 × 0.1µF + VCC = 5V DRIVER 1 OUT RX1 IN DRIVER 2 OUT RX2 IN TO LINE RX3 IN RX4 IN DRIVER 3 OUT RX5 IN (LOW-Q) ON/OFF VL = 3.3V 28 V – 2 27 3 LT1331 26 4 25 5 24 6 23 7 22 8 21 9 20 10 19 11 12 13 14 + 0.1µF 1 + V+ + 2 × 0.1µF 0.1µF RECEIVER OUTPUT CL = 50pF DRIVER 1 IN RX1 OUT DRIVER 2 IN RX2 OUT RX3 OUT TO LOGIC DRIVER OUTPUT RL = 3k CL = 2500pF RX4 OUT DRIVER 3 IN 18 RX5 OUT (LOW-Q) 17 GND 16 DRIVER DISABLE 15 NC INPUT 1331 TA04 1331 TA03 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1130A/LT1140A 5V RS232 Transceivers with Small Capacitors 10kV ESD LT1137A 3-DR/5-RX RS232 Transceiver 15kV ESD LTC1349 5V Low Power, 3-DR/5-RX RS232 Transceiver 2 RXs Active in Shutdown LTC1385 3.3V Low Power EIA/TIA-562 Transceiver LT1780/LT1781 2-DR/2-RX RS232 Transceivers 8 Linear Technology Corporation 15kV ESD 1331fa LT/TP 0998 REV A 2K • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com LINEAR TECHNOLOGY CORPORATION 1993