LT1537 Advanced Low Power 5V RS232 Transceiver with Small Capacitors U DESCRIPTIO FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Low Cost Uses Small Capacitors: 0.1µF, 0.2µF 1µA Supply Current in Shutdown 120kBaud Operation for RL = 3k, CL = 2500pF 250kBaud Operation for RL = 3k, CL = 1000pF CMOS Comparable Low Power: 40mW Operates from a Single 5V Supply Easy PC Layout: Flow-through Architecture Rugged Bipolar Design Outputs Assume a High Impedance State When Off or Powered Down Improved Protection: RS232 I/O Lines Can Be Forced to ±25V Without Damage Output Overvoltage Does Not Force Current Back into Supplies Absolutely No Latch-Up Available in SO Package The LT ®1537 is a three-driver, five-receiver RS232 transceiver, pin compatible with the LT1137A, offering performance improvements and two shutdown modes. The LT1537’s charge pump is designed for extended compliance and can deliver over 35mA of load current. Supply current is typically 8mA, competitive with similar CMOS devices. An advanced driver output stage operates up to 250kbaud while driving heavy capacitive loads. The LT1537 is fully compliant with all RS232 specifications. Special bipolar construction techniques protect the drivers and receivers beyond the fault conditions stipulated for RS232. Driver outputs and receiver inputs can be shorted to ±25V without damaging the device or the power supply generator. In addition, the RS232 I/O pins are resilient to multiple ±5kV ESD strikes. The transceiver has two shutdown modes. One mode disables the drivers and the charge pump, the other shuts down all circuitry. While shut down, the drivers and receivers assume high impedance output states. UO APPLICATI ■ ■ S Notebook Computers Palmtop Computers , LTC and LT are registered trademarks of Linear Technology Corporation. UO TYPICAL APPLICATI 2 × 0.1µF 5V VCC + DRIVER OUT RX IN DRIVER OUT TO LINE RX IN RX IN RX IN DRIVER OUT RX IN ON/OFF = 5V 2 LT1537 Output Waveforms V– 27 3 26 4 25 5 24 6 23 7 22 8 21 9 20 10 19 11 18 12 17 13 16 14 15 + + 0.1µF 28 1 2 × 0.1µF + V+ 0.1µF RECEIVER OUTPUT CL = 50pF DRIVER IN RX OUT R DRIVER IN RX OUT RX OUT TO LOGIC DRIVER OUTPUT RL = 3k CL = 2500pF RX OUT DRIVER IN INPUT RX OUT GND DRIVER DISABLE LT1537 • TA02 LT1537 • TA01 1 LT1537 U U RATI GS W W W W AXI U U ABSOLUTE PACKAGE/ORDER I FOR ATIO (Note 1) Supply Voltage (VCC) ............................................. 5.5V V + ........................................................................ 13.2V V – (Note 7) .......................................................... – 6.5V Input Voltage Driver ........................................................... V – to V + Receiver ............................................... – 25V to 25V Output Voltage Driver ....................................... V + – 25V to V – + 25V 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 LT1537C ................................................. 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 IN DRIVER OUT 5 24 RX OUT RX IN 6 23 DRIVER IN DRIVER OUT 7 22 RX OUT RX IN 8 21 RX OUT RX IN 9 20 RX OUT RX IN 10 19 DRIVER IN DRIVER OUT 11 18 RX OUT RX IN 12 17 GND 16 DRIVER DISABLE 15 NC ON/OFF 13 NC 14 G PACKAGE 28-LEAD PLASTIC SSOP LT1537CG LT1537CSW SW PACKAGE 28-LEAD PLASTIC SO WIDE TJMAX = 150°C, θJA = 96°C/ W (G) TJMAX = 150°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) Supply Current When OFF (VCC) Shutdown to Turn-On ON/OFF Pin Thresholds ON/OFF Pin Current Driver Disable Pin Thresholds Driver Disable Pin Current Oscillator Frequency Any Driver Output Voltage Swing Logic Input Voltage Level Logic Input Current Output Short-Circuit Current 2 (Note 2) CONDITIONS MIN (Note 3) Shutdown (Note 4) DRIVER DISABLE C +, C – = 0.1µF, C1, C2 = 0.2µF 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 ● ● ● ● ● ● ● ● 2.4 –15 2.4 –10 TYP 8.6 – 7.0 8 1.0 1.5 0.2 1.4 1.4 1.4 1.4 MAX 17 10 0.8 80 0.8 500 130 Load = 3k to GND Input LOW Level (VOUT = HIGH) Input HIGH Level (VOUT = LOW) 0.8V ≤ VIN ≤ 2V VOUT = 0V Positive Negative ● ● ● ● ● 5.0 2 7.5 – 6.3 1.4 1.4 5 ±17 – 5.0 0.8 20 UNITS V V mA µA mA ms V V µA V V µA kHz V V V µA mA LT1537 ELECTRICAL CHARACTERISTICS PARAMETER Any Driver Output Leakage Current Data Rate (Note 2) CONDITIONS Slew Rate Propagation Delay Any Receiver Input Voltage Thresholds Hysteresis Input Resistance Output Voltage MIN Shutdown VOUT = ±15V (Note 4) RL = 3k, CL = 2500pF RL = 3k, CL = 1000pF RL = 3k, CL = 51pF RL = 3k, CL = 2500pF Output Transition tHL HIGH to LOW (Note 5) Output Transition tLH LOW to HIGH ● Input LOW Threshold (VOUT = HIGH) Input HIGH Threshold (VOUT = LOW) ● ● ● Propagation Delay The ● denotes specifications which apply over the operating temperature range (0°C ≤ TA ≤ 70°C for commercial grade and – 40°C ≤ TA ≤ 85°C for industrial 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 and VON/OFF = 3V. C1 = C2 = 0.2µF, C + = C – = 0.1µF. Note 3: Supply current is measured with driver and receiver outputs unloaded and the driver inputs tied high. Note 4: 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. MAX UNITS 10 100 15 15 0.6 0.5 30 µA kBaud kBaud V/µs V/µs µs µs 120 250 4 VIN = ±10V Output LOW, IOUT = – 1.6mA Output HIGH, IOUT = 160µA (VCC = 5V) Shutdown (Note 4) 0 ≤ VOUT ≤ VCC Sinking Current, VOUT = VCC Sourcing Current, VOUT = 0V Output Transition tHL HIGH to LOW (Note 6) Output Transition tLH LOW to HIGH Output Leakage Current Output Short-Circuit Current TYP 0.8 0.1 3 ● ● ● 3.5 10 1.3 1.7 0.4 5 0.2 4.2 1 – 20 20 250 350 1.3 1.3 V V V kΩ V V µA mA mA ns ns 2.4 1.0 7 0.4 10 – 10 600 600 Note 5: 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 6: 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 7: Absolute maximum externally applied voltage. Internal charge pump may force a larger value on this pin. U W TYPICAL PERFOR A CE CHARACTERISTICS Driver Output Voltage OUTPUT HIGH 8 6 4 VCC = 5.5V 2 VCC = 5V VCC = 4.5V 0 –2 –4 VCC = 5V VCC = 5.5V VCC = 4.5V –6 –8 –10 –50 –25 OUTPUT LOW 50 25 0 75 TEMPERATURE (°C) Supply Current vs Data Rate 80 2.75 THRESHOLD VOLTAGE (V) DRIVER OUTPUT VOLTAGE (V) Receiver Input Thresholds 3.00 100 2.50 2.25 2.00 INPUT HIGH 1.75 1.50 1.25 INPUT LOW 1.00 125 LT1537 • TPC01 0.50 –55 –25 60 50 40 30 20 10 0.75 RL = 3k 3 DRIVERS ACTIVE RL = 3k CL = 2500pF 70 SUPPLY CURRENT (mA) 10 50 25 0 75 TEMPERATURE (°C) 100 125 ILT1537 • TPC02 0 0 25 50 100 75 DATA RATE (kBAUD) 125 150 LTX1537 • TPC03 3 LT1537 U W TYPICAL PERFOR A CE CHARACTERISTICS Positive Supply Output Compliance Curve Negative Supply Output Compliance Curve 6 4 2 5 10 POSITIVE LOAD CURRENT (mA) 2.5 –8 –6 –4 –2 0 0 3.0 THRESHOLD VOLTAGE (V) NEGATIVE SUPPLY OUTPUT (V) POSITIVE SUPPLY OUTPUT (V) 8 0 Driver Disable Threshold –10 10 15 2.0 1.5 1.0 0.5 0 0 –55 15 5 10 NEGATIVE LOAD CURRENT (mA) –25 75 0 25 50 TEMPERATURE (°C) LT1537 • TPC05 LT1537 • TPC04 On/Off Thresholds 125 LT1537 • TPC06 Supply Current 3.0 100 Driver Leakage in Shutdown 40 100 20kBAUD SUPPLY VOLTAGE (mA) THRESHOLD VOLTAGE (V) 2.0 ON THRESHOLD 1.5 1.0 OFF THRESHOLD 0.5 0 –55 30 25 3 DRIVERS LOADED RL = 3k 20 2 DRIVERS LOADED RL = 3k 15 1 DRIVERS LOADED RL = 3k 10 NO LOAD 10 VOUT = 15V 1 VOUT = –15V 5 –25 75 0 25 50 TEMPERATURE (°C) 100 0 –55 125 –25 0 50 75 25 TEMPERATURE (°C) 100 Driver Output Short-Circuit Current 50 25 0 75 TEMPERATURE (°C) ISC+ 25 20 ISC– 15 10 5 50 25 75 0 TEMPERATURE (°C) 100 125 LT1537 • TPC10 25 20 ISC+ 15 ISC– 10 5 0 –55 –25 100 125 LT1537 • TPC09 Receiver Short-Circuit Current SHORT-CIRCUIT CURRENT (mA) SHORT-CIRCUIT CURRENT (mA) 0.1 –55 –25 30 30 0 –55 –25 125 LT1537 • TPC08 LT1537 • TPC07 4 LEAKAGE CURRENT (µA) 35 2.5 50 25 75 0 TEMPERATURE (°C) 100 125 LT1537 • TPC11 LT1537 U W TYPICAL PERFOR A CE CHARACTERISTICS Driver Output Waveforms Shutdown to Driver Output DRIVER OUTPUT HIGH RL = 3k DRIVER OUTPUT RL = 3k 10 5 0 DRIVER OUTPUT RL = 3k CL = 2500pF DRIVER – 5 OUTPUT LOW RL = 3k – 10 INPUT ON/OFF PIN LT1537 • TPC12 LT1537 • TPC13 U U U PI FU CTIO S VCC: 5V Input Supply Pin. Supply current drops to zero in the shutdown mode. 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. GND: Ground Pin. ON/OFF: TTL/CMOS Compatible Operating Mode Control. A logic LOW puts the device in the shutdown mode which reduces input supply current to zero and places all of the drivers and receivers in high impedance state. A logic HIGH fully enables the transceiver. 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. 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 1.5mA 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. Larger value capacitors may be used to reduce supply ripple. With multiple transceivers, the V + and V – pins may be paralleled into common capacitors. For large numbers of transceivers, increasing the size of the shared common storage capacitors is recommended to reduce ripple. V –: Negative Supply Output (RS232 Drivers). V – ≈ –(2VCC – 2.5V). This pin requires an external charge storage capacitor C ≥ 0.1µF. V – is short-circuit proof for 30 seconds. 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 –. To maintain charge pump efficiency, the capacitor’s effective series resistance should be less than 2Ω. Low ESR ceramic capacitors work well in this application. DRIVER IN: RS232 Driver Input Pins. These inputs are TTL/CMOS compatible. Inputs should not be allowed to float. Tie unused inputs to VCC. 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 short-circuit protected from V – + 25V to V + – 25V. 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 ±5kV for human body model discharges. 5 LT1537 U U U PI FU CTIO S RX OUT: Receiver Outputs with TTL/CMOS 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 with the power on, off, or in shutdown mode. RX IN: Receiver Inputs. These pins accept RS232 level signals (± 25V) into a protected 5k terminating resistor. The receiver inputs are protected against ESD to ±5kV for human body model discharges. Each receiver provides 0.4V of hysteresis for noise immunity. Open receiver inputs assume a logic low state. U ESD PROTECTIO ESD Test Circuit + LT1537 5V VCC 2 + 0.1µF 0.1µF + 0.2µF DRIVER 1 OUT RX1 IN DRIVER 2 OUT RS232 LINE PINS PROTECTED TO ± 5kV RX2 IN RX3 IN RX4 IN DRIVER 3 OUT RX5 IN ON/OFF V– 28 1 27 3 26 4 25 5 24 6 23 7 22 8 21 9 20 10 19 11 18 12 17 13 16 14 15 + V+ 0.1µF 0.2µF + The RS232 line inputs of the LT1537 have on-chip protection from ESD transients up to ±5kV during shutdown or power ON state. 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 LT1537 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. DRIVER 1 IN RX1 OUT DRIVER 2 IN RX2 OUT RX3 OUT RX4 OUT DRIVER 3 IN RX5 OUT GND DRIVER DISABLE LT1537 • ESD TC U TYPICAL APPLICATIO S LT1537 Driving Remote Powered LTC1382 + + 2 × 0.1µF 2 × 0.1µF ON/OFF = 5V VCC DRIVER + + V+ 0.1µF 0.1µF LT1537 V– 0.1µF 0.1µF + DRIVER ON/OFF = 5V 0.1µF + LTC®1382 V– 0.1µF RECEIVER RS232 OUTPUT RECEIVER RECEIVER LOGIC OUTPUT + VCC DRIVER LOGIC INPUT V+ + 0.1µF + + 0.1µF 5.1V LOGIC OUTPUT DRIVER RS232 OUTPUT RECEIVER DRIVER LOGIC INPUT THREE RECEIVERS NOT USED LT1537 • TA03 6 LT1537 U TYPICAL APPLICATIO S Typical Mouse Driving Application + 5V VCC 2 × 0.1µF (1) OPTICS 25 DRIVER 1 IN 24 RX1 OUT DCD RX1 IN 6 23 DRIVER 2 IN DSR DRIVER 2 OUT 7 22 RX2 OUT RX RX2 IN 8 21 RX3 OUT RTS RX3 IN 9 20 RX4 OUT 0.1µF LOGIC “0” LOGIC “0” MOUSE DATA LOGIC “1” 18 RX5 OUT 17 GND RX5 IN 12 16 DRIVER DISABLE ON/OFF = 5V 13 RI 2 × 0.1µF 19 DRIVER 3 IN RX4 IN 10 DRIVER 3 OUT 11 DTR (9) 26 5 CTS (5) 27 3 4 TX V– 2 DRIVER 1 OUT V+ LOGIC LT1537 + 0.1µF MOUSE V– 28 1 + V+ + 15 14 DB9 LT1137A • TA04 U PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted. G Package 28-Lead SSOP 0.397 – 0.407* (10.07 – 10.33) 28 27 26 25 24 23 22 21 20 19 18 17 16 15 0.205 – 0.212* (5.20 – 5.38) 0.068 – 0.078 (1.73 – 1.99) 0.301 – 0.311 (7.65 – 7.90) 0° – 8° 0.005 – 0.009 (0.13 – 0.22) 0.0256 (0.65) BSC 0.022 – 0.037 (0.55 – 0.95) *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006 INCH (0.15mm). 0.010 – 0.015 (0.25 – 0.38) 0.002 – 0.008 (0.05 – 0.21) S Package 28-Lead Plastic SOL 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) 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) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 28SSOP 0694 0.697 – 0.712 (17.70 – 18.08) (NOTE 2) 28 27 26 25 24 23 22 21 20 19 18 17 16 15 0.037 – 0.045 (0.940 – 1.143) 0.394 – 0.419 (10.007 – 10.643) NOTE 1 0.050 (1.270) TYP 0.014 – 0.019 0.004 – 0.012 (0.102 – 0.305) (0.356 – 0.482) 1 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 3 4 5 6 7 8 9 10 11 12 13 14 SOL28 0392 2. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006 INCH (0.15mm). 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 LT1537 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1137A 5V 3-Driver/5-Receiver RS232 Transceiver with Shutdown Premium Performance Upgrade to LT1537 LT1138A 5V 5-Driver/3-Receiver RS232 Transceiver Premium Performance DCE, Compliment to LT1537 LT1237 5V 3-Driver/5-Receiver RS232 Transceiver with One Receiver Active in Shutdown Lower Power, Premium Performance Upgrade to LT1537 LT1330 5V 3-Driver/5-Receiver RS232 Transceiver with 3V Logic Interface and Shutdown Premium Performance Device for 5V Systems with 3V Logic Supplies LT1331 5V 3-Driver/5-Receiver RS232 Transceiver with 3V Logic Interface and Receiver Active in Shutdown LT1330 with Low Power Receiver That Stays Active During Shutdown LTC1337 Ultra-Low Power 5V 3-Driver/5-Receiver RS232 Transceiver with Shutdown Ultra-Low Power, Premium Performance Upgrade to LT1537 LTC1338 5V 5-Driver/3-Receiver RS232 Transceiver with Shutdown Ultra-Low Power, Peripheral-Side Compliment to LT1537 8 Linear Technology Corporation LT/GP 0595 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