LT1537 Advanced Low Power 5V RS232 Transceiver with Small Capacitors DESCRIPTIO FEATURES n Low Cost The LT 1537 is a three-driver, five-receiver RS232 trans- n Uses Small Capacitors: 0.1F, 0.2F ceiver, pin compatible with the LT1137A, offering perfor- n 1A Supply Current in Shutdown mance improvements and two shutdown modes. The n 120kBaud Operation for R = 3k, C = 2500pF L L LT1537s charge pump is designed for extended compli- n 250kBaud Operation for R = 3k, C = 1000pF L L ance and can deliver over 35mA of load current. Supply n CMOS Comparable Low Power: 40mW current is typically 8mA, competitive with similar CMOS n Operates from a Single 5V Supply devices. An advanced driver output stage operates up to n Easy PC Layout: Flow-through Architecture 250kbaud while driving heavy capacitive loads. n Rugged Bipolar Design The LT1537 is fully compliant with all RS232 specifica- n Outputs Assume a High Impedance State When Off tions. Special bipolar construction techniques protect the or Powered Down drivers and receivers beyond the fault conditions stipu- n Improved Protection: RS232 I/O Lines Can Be Forced lated for RS232. Driver outputs and receiver inputs can be to 25V Without Damage shorted to 25V without damaging the device or the n Output Overvoltage Does Not Force Current Back power supply generator. In addition, the RS232 I/O pins into Supplies are resilient to multiple 5kV ESD strikes. n Absolutely No Latch-Up n Available in SO Package The transceiver has two shutdown modes. One mode disables the drivers and the charge pump, the other shuts APPLICATI S down all circuitry. While shut down, the drivers and receivers assume high impedance output states. n Notebook Computers n , LTC and LT are registered trademarks of Linear Technology Corporation. Palmtop Computers TYPICAL APPLICATI Output Waveforms + 28 V V 1 + LT1537 0.1F 2 27 0.1F 5V V CC 2 0.1F 3 26 RECEIVER + OUTPUT 2 0.1F 4 25 DRIVER IN C = 50pF L 5 24 DRIVER OUT RX OUT 6 23 R DRIVER RX IN DRIVER IN OUTPUT 7 22 DRIVER OUT RX OUT R = 3k L TO LOGIC 8 21 C = 2500pF L RX IN RX OUT TO 9 20 LINE RX IN RX OUT 10 19 RX IN DRIVER IN INPUT 11 18 DRIVER OUT RX OUT 12 17 GND RX IN 13 16 DRIVER LT1537 TA02 ON/OFF = 5V DISABLE 14 15 LT1537 TA01 1 + + UO UO ULT1537 ABSOLUTEXAI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) ORDER PART Supply Voltage (V ) ............................................. 5.5V TOP VIEW CC + NUMBER V ........................................................................ 13.2V + V 1 28 V V (Note 7) .......................................................... 6.5V 5V V 2 27 C2 CC + + LT1537CG Input Voltage C1 3 26 C2 + LT1537CSW C1 4 25 DRIVER IN Driver ........................................................... V to V DRIVER OUT 5 24 RX OUT Receiver ............................................... 25V to 25V RX IN 6 23 DRIVER IN Output Voltage DRIVER OUT 7 22 RX OUT + Driver ....................................... V 25V to V + 25V RX IN 8 21 RX OUT RX IN 9 20 RX OUT Receiver .................................... 0.3V to V + 0.3V CC RX IN 10 19 DRIVER IN Short Circuit Duration DRIVER OUT 11 18 RX OUT + V ................................................................... 30 sec RX IN 12 17 GND DRIVER V ................................................................... 30 sec ON/OFF 13 16 DISABLE 14 15 NC NC Driver Output .............................................. Indefinite Receiver Output .......................................... Indefinite SW PACKAGE G PACKAGE 28-LEAD PLASTIC SSOP 28-LEAD PLASTIC SO WIDE Operating Temperature Range LT1537C ................................................. 0C to 70C T = 150C, = 96C/ W (G) JMAX JA Storage Temperature Range ................ 65C to 150C T = 150C, = 85C/ W (SW) JMAX JA Lead Temperature (Soldering, 10 sec)................. 300C Consult factory for Industrial and Military grade parts. LECTR AL CHARACTERIST (Note 2) E IC ICS PARAMETER CONDITIONS MIN TYP MAX UNITS Power Supply Generator + V Output 8.6 V V Output 7.0 V Supply Current (V ) (Note 3) l 817 mA CC Supply Current When OFF (V ) Shutdown (Note 4) l 1.0 10 A CC DRIVER DISABLE 1.5 mA + Shutdown to Turn-On C , C = 0.1F, C1, C2 = 0.2F 0.2 ms ON/OFF Pin Thresholds Input LOW Level (Device Shutdown) l 1.4 0.8 V Input HIGH Level (Device Enabled) l 2.4 1.4 V ON/OFF Pin Current 0V V 5V l 15 80 A ON/OFF Driver Disable Pin Thresholds Input LOW Level (Drivers Enabled) l 1.4 0.8 V Input HIGH Level (Drivers Disabled) l 2.4 1.4 V Driver Disable Pin Current 0V V 5V l 10 500 A DRIVER DISABLE Oscillator Frequency 130 kHz Any Driver Output Voltage Swing Load = 3k to GND Positive l 5.0 7.5 V Negative l 6.3 5.0 V Logic Input Voltage Level Input LOW Level (V = HIGH) l 1.4 0.8 V OUT Input HIGH Level (V = LOW) l 2 1.4 OUT Logic Input Current 0.8V V 2V l 520 A IN Output Short-Circuit Current V = 0V 17 mA OUT 2 U W W W U WU