LT1342 5V RS232 Transceiver with 3V Logic Interface U DESCRIPTIO FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ESD Protection Over ±10kV 3V Logic Interface Uses Small Capacitors: 0.1µF, 0.2µF 1µA Supply Current in Shutdown Low Power Driver Disable Operating Mode Pin Compatible with LT1137A 120kBaud Operation for RL = 3k, CL = 2500pF 250kBaud Operation for RL = 3k, CL = 1000pF CMOS Comparable Low Power: 60mW Operates from a 5V Supply and 3V Logic Supply Easy PC Layout: Flowthrough Architecture Rugged Bipolar Design Outputs Assume a High Impedance State When Off or Powered Down Absolutely No Latchup The LT®1342 is an advanced low power three-driver, fivereceiver RS232 transceiver. The LT1342 operates from a 5V supply and a 3V logic supply. Receiver outputs can interface directly to 3V logic circuits. Included on the chip is a shutdown pin for reducing supply current to near zero. All receivers and drivers assume high impedance states during shutdown. The driver disable function provides additional control of operating mode. When driver disable is high the charge pump and drivers turn off. Receivers continue to operate during driver disable. New ESD structures on the chip allow the LT1342 to survive multiple ±10kV strikes, eliminating the need for costly TransZorbs® on the RS232 line pins. The LT1342 is fully compliant with all EIA RS232 specifications and operates in excess of 120kbaud even driving heavy capacitive loads. UO APPLICATI ■ ■ S Notebook Computers Palmtop Computers , LTC and LT are registered trademarks of Linear Technology Corporation. TransZorb is a registered trademark of General Instruments, GSI. UO TYPICAL APPLICATI Output Waveforms V+ 0.1µF 5V VCC 2 × 0.1µF DRIVER 1 OUT RX1 IN DRIVER 2 OUT TO LINE RX2 IN RX3 IN RX4 IN DRIVER 3 OUT RX5 IN ON/OFF 3V VL 1 28 V – 2 27 3 LT1342 0.1µF 2 × 0.1µF 26 4 25 5 24 6 23 7 22 8 21 9 20 10 19 11 18 12 17 13 16 14 15 RECEIVER OUTPUT VL = 3V CL = 50pF DRIVER 1 IN RX1 OUT DRIVER 2 IN RX2 OUT RX3 OUT TO 3V LOGIC DRIVER ROUTPUT RL = 3k CL = 2500pF RX4 OUT DRIVER 3 IN RX5 OUT INPUT GND DRIVER DISABLE LT1342 • TA02 NC LT1342 • TA01 1 LT1342 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 Output Voltage Driver .................................................... – 30V to 30V Receiver .................................... – 0.3V to VCC + 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 ORDER PART NUMBER TOP VIEW V+ 1 28 V– 5V VCC 2 27 C2 – 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 DRIVER 3 OUT 11 18 RX5 OUT RX5 IN 12 17 GND 16 DRIVER DISABLE 15 NC ON/OFF 13 3V VL 14 LT1342CG LT1342CNW LT1342CSW G PACKAGE NW PACKAGE 28-LEAD PLASTIC SSOP 28-LEAD WIDE PDIP SW PACKAGE 28-LEAD WIDE 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. ELECTRICAL CHARACTERISTICS PARAMETER Power Supply Generator V + Output V – Output Supply Current (VCC) Logic Supply Current (VL) Supply Current When OFF (VCC) Logic Supply Current (VL) When OFF 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 (Note 2) CONDITIONS (Note 3) (Note 4) Shutdown (Note 5) Driver Disable Shutdown (Note 5) Driver Disable C1 = C2 = 0.2µF, C + = C – = 0.1µF Input Low Level (Device Shutdown) Input High Level (Device Enabled) 0V ≤ VON/OFF ≤ 5V Input Low Level (Drivers Enabled) Input High Level (Drivers Disabled) 0V ≤ VDRIVER DISABLE ≤ 5V MIN 8.6 –7 12 0.1 1 3 1 0.1 0.2 ● ● ● ● ● ● ● ● TYP 2.4 –15 2.4 –10 1.4 1.4 1.4 1.4 MAX 17 1 10 10 1 0.8 80 0.8 500 130 UNITS V V mA mA µA mA µA mA ms V V µA V V µA kHz LT1342 ELECTRICAL CHARACTERISTICS PARAMETER CONDITIONS Any Driver Output Voltage Swing Load = 3k to GND 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 Output Leakage Current Receivers 1 Through 4 Output Voltage Output Short-Circuit Current Propagation Delay Receiver 5 Output Voltage Output Short-Circuit Current Propagation Delay (Note 2) Positive Negative 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 tHL High to Low (Note 6) Output Transition tLH Low to High ● ● ● ● TYP 5 7.3 – 6.5 1.4 1.4 5 17 10 2 ● ±9 ● MAX 4 0.8 ● Shutdown (Note 4) 0 ≤ VOUT ≤ VCC ● Output Low, IOUT = – 1.6mA Output High, IOUT = 160µA Sinking Current, VOUT = VCC Sourcing Current, VOUT = 0V Output Transition tHL High to Low (Note 7) Output Transition tLH Low to High ● ● Output Low, IOUT = – 500µA Output High, IOUT = 160µA Sinking Current, VOUT = VCC Sourcing Current, VOUT = 0V Output Transition tHL High to Low (Note 7) Output Transition tLH Low to High ● ● 0.1 3 2.7 10 2.7 2 UNITS 15 6 0.6 0.5 1.3 1.3 V V V V µA mA µA kBaud kBaud V/µs V/µs µs µs 1.3 1.7 0.4 5 1 2.4 1 7 10 V V V kΩ µA –5 0.8 20 100 120 250 Input Low Threshold (VOUT = High) Input High Threshold (VOUT = Low) 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 the device may be impaired. Note 2: Testing done at VCC = 5V, VL = 3.3V and VON/OFF = 3V. Note 3: Supply current is measured with external capacitors C + = 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 measurements in shutdown are performed with VON/OFF ≤ 0.1V. Supply current measurements using driver disable are performed with VDRIVER DISABLE ≥ 3V. MIN 0.2 2.9 – 20 20 250 350 0.2 2.9 –4 4 1 1 30 0.4 –10 600 600 0.4 –2 3 3 V V mA mA ns ns 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 2.4V and tLH = 1.7V to 0.8V). Note 8: Data rate operation guaranteed by slew rate, short-circuit current and propagation delay tests. 3 LT1342 U W TYPICAL PERFOR A CE CHARACTERISTICS Driver Output Voltage 6 OUTPUT HIGH 2.75 VCC = 5.5V VCC = 5V VCC = 4.5V 4 2 0 VCC = 4.5V VCC = 5V VCC = 5.5V –2 –4 –6 –8 –10 –55 –25 2.50 2.25 2.00 INPUT HIGH 1.75 1.50 INPUT LOW 1.25 1.00 50 25 0 75 TEMPERATURE (°C) 100 0.50 –55 –25 125 50 25 0 75 TEMPERATURE (°C) LT1342 • TPC01 40 30 20 100 0 125 0 3.0 125 4 2.5 50 THRESHOLD VOLTAGE (V) 150 75 3 2 1 25 0 –55 –25 50 25 75 0 TEMPERATURE (°C) 100 0 –55 –25 125 50 25 0 75 TEMPERATURE (°C) 1.0 0 –55 –25 125 50 25 75 0 TEMPERATURE (°C) 100 125 LT1342 • TPC06 Driver Leakage in Shutdown 100 35 SUPPLY CURRENT (mA) ON THRESHOLD 1.5 1.0 OFF THRESHOLD 0.5 30 3DRIVERS LOADED R L = 3k 25 2DRIVERS LOADED R L = 3k 20 1DRIVER LOADED R L = 3k 15 NO LOAD 10 10 1 VOUT = 30V VOUT = –30V 5 50 25 75 0 TEMPERATURE (°C) 100 125 LT1342 • TPC07 4 100 40 2.5 0 –55 –25 1.5 Supply Current ON/OFF Thresholds 150 2.0 LT1342 • TPC05 3.0 125 0.5 LT1342 • TPC04 2.0 75 50 100 DATA RATE (kBAUD) Driver Disable Threshold Supply Current in Driver Disable 100 25 LT1342 • TPC03 5 SUPPLY CURRENT (mA) SUPPLY CURRENT (µA) 50 LT1342 • TPC02 Supply Current in Shutdown THRESHOLD VOLTAGE (V) 60 10 0.75 OUTPUT LOW 3DRIVERS ACTIVE RL = 3k CL = 2500pF 70 SUPPLY CURRENT (mA) RL = 3k Supply Current vs Data Rate 80 LEAKAGE CURRENT ( µA) DRIVER OUTPUT VOLTAGE (V) 8 Receiver Input Thresholds 3.00 THRESHOLD VOLTAGE (V) 10 0 –55 –25 50 25 0 75 TEMPERATURE (°C) 100 125 LT1341 • TPC08 0.1 –55 –25 50 25 0 75 TEMPERATURE (°C) 100 125 LT1342 • TPC09 LT1342 U W TYPICAL PERFOR A CE CHARACTERISTICS Driver Short-Circuit Current Receiver Short-Circuit Current 50 25 SHORT-CIRCUIT CURRENT (mA) SHORT-CIRCUIT CURRENT (mA) 30 ISC+ 20 15 ISC– 10 5 0 –55 –25 50 25 75 0 TEMPERATURE (°C) 100 125 40 RX1 TO RX4 ISC– 30 RX1 TO RX4 ISC+ 20 RX5 ISC– 10 RX5 ISC+ 0 –55 –25 50 25 0 75 TEMPERATURE (°C) 100 125 LT1342 • TPC11 LT1342 • TPC10 Driver Output Waveforms Receiver Output Waveforms RX5 OUTPUT CL = 50pF DRIVER OUTPUT RL = 3k RX1 TO RX4 OUTPUT CL = 50pF DRIVER OUTPUT RL = 3k CL = 2500pF INPUT INPUT VL = 3V LT1342 • TPC12 LT1342 • TPC13 U U U PI FU CTIO S VCC: 5V Input Supply Pin. This pin should be decoupled with a 0.1µF ceramic capacitor close to the package pin. Insufficient supply bypassing can result in low output drive levels and erratic charge pump operation. VL: 3V Logic Supply Pin. Provides power to the receiver outputs. Decouple with a 0.1µF ceramic capacitor. GND: Ground Pin. ON/OFF: A TTL/CMOS Compatible Operating Mode Control. A logic low puts the device in the low power shutdown mode. Drivers and receivers assume a high impedance state in shutdown. The transceiver consumes almost no supply current while in shutdown. A logic high fully enables the transceiver. An ON/OFF logic low signal supersedes the state of the DRIVER DISABLE pin. DRIVER DISABLE: This pin provides an alternate control for the charge pump and RS232 drivers. A logic high on this pin shuts down the charge pump and places all drivers in a high impedance state. All five receivers remain active under these conditions. Floating the DRIVER DISABLE pin or driving it to a logic low level fully enables the transceiver. A logic low on the ON/OFF pin supersedes the state of the DRIVER DISABLE pin. Supply current drops to 3mA when in driver disable mode. V +: Positive Supply Output (RS232 Drivers). V + ≈ 2VCC – 1.5V. This pin requires an external charge storage capacitor C ≥ 0.1µF, tied to ground or VCC. With multiple transceivers, the V + and V – pins may be paralleled into common charge storage capacitors. Larger value capacitors may be used to reduce supply ripple. 5 LT1342 U U U PI FU CTIO S V –: Negative Supply Output (RS232 Drivers). V – ≈ –(2VCC – 2.5V). This pin requires an external charge storage capacitor C ≥ 0.1µF. To reduce supply ripple, increase the size of the storage capacitor. C1+, C1–, C2+, C2 –: Commutating Capacitor Inputs. These pins require two external capacitors C ≥ 0.2µF: one from C1+ to C1–, and another from C2 + to C2 –. The capacitor’s effective series resistance should be less than 2Ω. For C ≥ 1µF, low ESR tantalum capacitors work well in this application, although small value ceramic capacitors may be used with a minimal reduction in charge pump compliance. For operation with an external 12V supply, omit C1 and connect the 12V supply to pin C1+. Pin V + may also be shorted to C1+ when a separate supply is used. The 12V supply must be bypassed with a 0.1F capacitor. DRIVER IN: RS232 Driver Input Pins. These inputs are compatible with TTL or CMOS logic. Tie unused inputs to VCC or VL. DRIVER OUT: Driver Outputs at RS232 Voltage Levels. Driver output swing meets RS232 levels for loads up to 3k. Slew rates are controlled for lightly loaded lines. Output current capability is sufficient for load conditions up to 2500pF. Outputs are in a high impedance state when in shutdown mode, VCC = 0V, or when the DRIVER DISABLE pin is active. Outputs are fully shortcircuit protected from V – + 30V to V + – 30V. Applying higher voltages will not damage the device if the overdrive is moderately current limited. 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 ±10V for human body model discharges. RX IN: Receiver Inputs. 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. Each receiver provides 0.4V of hysteresis for noise immunity. Open receiver inputs assume a logic low state. RX OUT: Receiver Outputs with 3.3V Logic Compatible Voltage Levels. Outputs are in a high impedance state when in shutdown mode to allow data line sharing. Outputs are fully short-circuit protected to ground or VCC or VL with the power on, off, or in shutdown mode. Receiver output level is determined by VL supply voltage. Use VL = 3.3V for interfacing with 3.3V logic, VL = 5V for interfacing with 5V logic. U ESD PROTECTIO The RS232 line inputs of the LT1342 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 LT1342 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, V +, V – and GND shorted to ground or connected with low ESR capacitors. ESD Test Circuit V+ 5V VCC 0.1µF 2 LT1342 3 26 0.2µF 4 25 5 24 6 23 7 22 8 21 9 20 10 19 11 18 12 17 13 ON/OFF 14 3V VL 16 RX1 IN DRIVER 2 OUT RX2 IN RX3 IN RX4 IN DRIVER 3 OUT RX5 IN V– 27 0.1µF DRIVER 1 OUT RS232 LINE PINS PROTECTED TO ±10kV 28 1 15 0.1µF 0.2µF DRIVER 1 IN RX1 OUT DRIVER 2 IN RX2 OUT RX3 OUT RX4 OUT DRIVER 3 IN RX5 OUT GND DRIVER DISABLE NC LT1342 • ESD TC 0.1µF 6 LT1342 U PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted. G Package 28-Lead Plastic SSOP (0.209) (LTC DWG # 05-08-1640) 0.397 – 0.407* (10.07 – 10.33) 0.205 – 0.212** (5.20 – 5.38) 0.068 – 0.078 (1.73 – 1.99) 28 27 26 25 24 23 22 21 20 19 18 17 16 15 0° – 8° 0.0256 (0.65) BSC 0.010 – 0.015 (0.25 – 0.38) 0.005 – 0.009 0.022 – 0.037 (0.13 – 0.22) (0.55 – 0.95) 0.301 – 0.311 (7.65 – 7.90) 0.002 – 0.008 (0.05 – 0.21) *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 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) 0.150 ± 0.005 (3.810 ± 0.127) 0.600 – 0.625 (15.240 – 15.875) 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 1 2 3 4 5 6 7 8 9 10 11 12 13 0.015 (0.381) MIN 0.009 – 0.015 (0.229 – 0.381) ( +0.035 0.625 –0.015 15.87 +0.889 –0.381 ) 15 0.505 – 0.560* (12.827 – 14.224) 0.125 (3.175) MIN 0.018 ± 0.003 (0.457 ± 0.076) 0.035 – 0.080 (0.889 – 2.032) 0.100 ± 0.010 (2.540 ± 0.254) 14 N28 1197 *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm) SW Package 28-Lead Plastic Small Outline (Wide 0.300) (LTC DWG # 05-08-1620) 0.291 – 0.299** (7.391 – 7.595) 0.010 – 0.029 × 45° 0.093 – 0.104 (2.362 – 2.642) (0.254 – 0.737) 0.037 – 0.045 (0.940 – 1.143) 0.697 – 0.712* (17.70 – 18.08) 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 0.016 – 0.050 (0.406 – 1.270) 0.050 (1.270) TYP 0.014 – 0.019 (0.356 – 0.482) TYP 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 0.394 – 0.419 (10.007 – 10.643) NOTE 1 0.004 – 0.012 (0.102 – 0.305) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 S28 (WIDE) 0996 *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 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 LT1342 U TYPICAL APPLICATIO S Operation Using 5V and 12V Power Supplies 5V VCC 12V V + 0.1µF 0.1µF V+ VCC 1 C1+ 3 26 C1– 4 25 5 24 6 23 7 22 8 21 9 20 10 19 11 18 12 17 13 16 14 15 DRIVER 1 OUT RX1 IN DRIVER 2 OUT RX2 IN TO LINE RX3 IN RX4 IN DRIVER 3 OUT RX5 IN ON/0FF = 5V 3V VL 28 2 LT1342 V– 27 0.1µF 2 × 0.1µF DRIVER 1 IN RX1 OUT DRIVER 2 IN RX2 OUT TO LOGIC RX3 OUT RX4 OUT DRIVER 3 IN RX5 OUT GND DRIVER DISABLE NC 0.1µF LT1342 • TA03 Typical Mouse Driving Application V+ 0.1µF 5V VCC MOUSE 2 × 0.1µF (1) OPTICS (5) (9) LT1342 27 3 26 25 DRIVER 1 IN 5 24 DCD RX1 IN 6 RX1 OUT 23 DRIVER 2 IN DSR DRIVER 2 OUT 7 22 RX RX2 IN 8 RX2 OUT 21 RX3 OUT RTS RX3 IN 9 20 RX4 IN 10 RX4 OUT 19 DRIVER 3 IN CTS DRIVER 3 OUT 11 18 DTR RX5 IN 12 17 13 16 14 15 RI ON/OFF 3V VL 0.1µF 2 × 0.1µF 4 TX V– 2 DRIVER 1 OUT V+ LOGIC 28 V – 1 LOGIC “0” LOGIC “0” MOUSE DATA LOGIC “1” RX5 OUT GND DRIVER DISABLE NC DB9 LT1342 • TA04 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1137A 3-DR/5-RX RS232 Transceiver ±15kV IEC-1000-4-2 ESD Protection LTC1327 3-DR/5-RX RS562 Transceiver 3.3V Operation LT1330 3-DR/5-RX RS232 3V Logic Interface LT1331 3-DR/5-RX RS232/RS562 Transceiver 5V RS232 or 3V RS562 Operation LTC1347 3-DR/5-RX Micropower RS232 Transceiver 5 Receivers Active in Shutdown LTC1348 3-DR/5-RX RS232 Transceiver True RS232 from 3V 8 Linear Technology Corporation 1342fa LT/TP 1098 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