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LT1537 Advanced Low Power 5V RS232 Transceiver with Small Capacitors
FEATURES
s s s s s s s s s s
DESCRIPTIO
s
s
s s
Low Cost Uses Small Capacitors: 0.1F, 0.2F 1A 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 (R)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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATI
s s
S
Notebook Computers Palmtop Computers
TYPICAL APPLICATI
+
0.1F 2 x 0.1F V+ 5V VCC 1 2 3 4 DRIVER OUT RX IN DRIVER OUT TO LINE RX IN RX IN RX IN DRIVER OUT RX IN ON/OFF = 5V 5 6 7 8 9 10 11 12 13 14 LT1537
28 27 25 24 23 22 21 20 19 18 17 16 15 26
V- 0.1F
RECEIVER OUTPUT CL = 50pF R DRIVER OUTPUT RL = 3k CL = 2500pF
DRIVER IN RX OUT DRIVER IN RX OUT RX OUT RX OUT DRIVER IN RX OUT GND DRIVER DISABLE
LT1537 * TA01
+
+
2 x 0.1F
TO LOGIC
INPUT
U
Output Waveforms
LT1537 * TA02
+
UO
UO
1
LT1537 ABSOLUTE
(Note 1)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW V+ 1 5V VCC 2 C1+ C1- 3 4 28 V - 27 C2 - 26 C2+ 25 DRIVER IN 24 RX OUT 23 DRIVER IN 22 RX OUT 21 RX OUT 20 RX OUT 19 DRIVER IN 18 RX OUT 17 GND 16 DRIVER DISABLE 15 NC SW PACKAGE 28-LEAD PLASTIC SO WIDE
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 ................................................. 0C to 70C Storage Temperature Range ................ - 65C to 150C Lead Temperature (Soldering, 10 sec)................. 300C
ORDER PART NUMBER LT1537CG LT1537CSW
DRIVER OUT 5 RX IN 6 DRIVER OUT 7 RX IN 8 RX IN 9 RX IN 10 DRIVER OUT 11 RX IN 12 ON/OFF 13 NC 14 G PACKAGE 28-LEAD PLASTIC SSOP
TJMAX = 150C, JA = 96C/ W (G) TJMAX = 150C, JA = 85C/ 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 CONDITIONS
(Note 2)
MIN TYP 8.6 - 7.0 8 1.0 1.5 0.2 1.4 1.4 1.4 1.4 130 MAX UNITS V V mA A mA ms V V A V V A kHz V V V A mA
(Note 3) Shutdown (Note 4) DRIVER DISABLE C +, C - = 0.1F, C1, C2 = 0.2F 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
q q
17 10
q q q q q q
0.8 80 0.8 500
2.4 -15 2.4 -10
Load = 3k to GND Input LOW Level (VOUT = HIGH) Input HIGH Level (VOUT = LOW) 0.8V VIN 2V VOUT = 0V
Positive Negative
q q q q q
5.0
2
7.5 - 6.3 1.4 1.4 5 17
- 5.0 0.8 20
2
U
W
U
U
WW
W
LT1537
ELECTRICAL CHARACTERISTICS
PARAMETER Any Driver Output Leakage Current Data Rate Slew Rate Propagation Delay Any Receiver Input Voltage Thresholds Hysteresis Input Resistance Output Voltage Output Leakage Current Output Short-Circuit Current Propagation Delay CONDITIONS
(Note 2)
MIN
q
TYP 10
MAX 100
UNITS A kBaud kBaud V/s V/s s s V V V k V V A mA mA ns ns
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) VIN = 10V Output LOW, IOUT = - 1.6mA Output HIGH, IOUT = 160A (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
120 250 4 15 15 0.6 0.5 1.3 1.7 0.4 5 0.2 4.2 1 - 20 20 250 350 30 1.3 1.3
q q q q q q
0.8 0.1 3 3.5
2.4 1.0 7 0.4 10 - 10 600 600
10
The q denotes specifications which apply over the operating temperature range (0C TA 70C for commercial grade and - 40C TA 85C 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 = 0.2F, C + = C - = 0.1F. 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.
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.
TYPICAL PERFOR A CE CHARACTERISTICS
Driver Output Voltage
10 8 OUTPUT HIGH 3.00 2.75
THRESHOLD VOLTAGE (V)
DRIVER OUTPUT VOLTAGE (V)
6 4 2 0 -2 -4 -6 -8 -10 -50 -25 OUTPUT LOW 50 25 0 75 TEMPERATURE (C) RL = 3k 100 125 VCC = 5V VCC = 5.5V VCC = 4.5V VCC = 5.5V VCC = 5V VCC = 4.5V
2.25 2.00 1.75 1.50 1.25 1.00 0.75 0.50 -55 -25 50 25 0 75 TEMPERATURE (C) 100 125 INPUT LOW INPUT HIGH
SUPPLY CURRENT (mA)
UW
LT1537 * TPC01
Receiver Input Thresholds
80 70 60 50 40 30 20 10 0
Supply Current vs Data Rate
3 DRIVERS ACTIVE RL = 3k CL = 2500pF
2.50
0
25
50 100 75 DATA RATE (kBAUD)
125
150
ILT1537 * TPC02
LTX1537 * TPC03
3
LT1537
TYPICAL PERFOR A CE CHARACTERISTICS
Positive Supply Output Compliance Curve
10
NEGATIVE SUPPLY OUTPUT (V)
POSITIVE SUPPLY OUTPUT (V)
THRESHOLD VOLTAGE (V)
8
6
4
2
0
0
5 10 POSITIVE LOAD CURRENT (mA)
On/Off Thresholds
3.0 2.5
THRESHOLD VOLTAGE (V)
LEAKAGE CURRENT (A)
SUPPLY VOLTAGE (mA)
2.0 ON THRESHOLD 1.5 1.0 OFF THRESHOLD 0.5 0 -55
-25
75 0 25 50 TEMPERATURE (C)
Driver Output Short-Circuit Current
30 30 ISC+
SHORT-CIRCUIT CURRENT (mA)
SHORT-CIRCUIT CURRENT (mA)
25 20 ISC- 15 10 5 0 -55 -25
50 25 75 0 TEMPERATURE (C)
4
UW
15
LT1537 * TPC04
Negative Supply Output Compliance Curve
-10
Driver Disable Threshold
3.0 2.5 2.0 1.5 1.0 0.5 0 -55
-8
-6
-4
-2
0
0
5 10 NEGATIVE LOAD CURRENT (mA)
15
-25
75 0 25 50 TEMPERATURE (C)
100
125
LT1537 * TPC05
LT1537 * TPC06
Supply Current
40 20kBAUD 35 30 25 20 15 10 5 0 -55 -25 0 50 75 25 TEMPERATURE (C) 100 125 3 DRIVERS LOADED RL = 3k 2 DRIVERS LOADED RL = 3k 1 DRIVERS LOADED RL = 3k NO LOAD 100
Driver Leakage in Shutdown
10
1
VOUT = 15V VOUT = -15V
100
125
0.1 -55 -25
50 25 0 75 TEMPERATURE (C)
100
125
LT1537 * TPC07
LT1537 * TPC08
LT1537 * TPC09
Receiver Short-Circuit Current
25 20 15 ISC- 10 5 0 -55 -25 ISC+
100
125
50 25 75 0 TEMPERATURE (C)
100
125
LT1537 * TPC10
LT1537 * TPC11
LT1537
TYPICAL PERFOR A CE CHARACTERISTICS
Shutdown to Driver Output
DRIVER OUTPUT HIGH RL = 3k 10 5 0 DRIVER - 5 OUTPUT LOW RL = 3k - 10 ON/OFF PIN DRIVER OUTPUT RL = 3k CL = 2500pF DRIVER OUTPUT RL = 3k
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 0.1F 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 0.1F, 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 0.1F. V - is short-circuit proof for 30 seconds. C1+, C1-, C2+, C2 -: Commutating Capacitor Inputs. These pins require two external capacitors C 0.2F: 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 2. 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.
UW
Driver Output Waveforms
INPUT
LT1537 * TPC12
LT1537 * TPC13
U
U
U
5
LT1537
PI FU CTIO S
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. 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.
ESD PROTECTIO
0.2F 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
4 5 6 7 8 9 10 11 12 13 14
25 24 23 22 21 20 19 18 17 16 15
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
TYPICAL APPLICATIO S
LT1537 Driving Remote Powered LTC1382
2 x 0.1F
+
DRIVER V+
2 x 0.1F
VCC
ON/OFF = 5V
+
0.1F
+
5.1V 0.1F 0.1F
+
LTC(R)1382
V+
+
0.1F
+
0.1F
VCC LT1537 V-
DRIVER LOGIC INPUT LOGIC OUTPUT DRIVER RECEIVER RECEIVER THREE RECEIVERS NOT USED RS232 OUTPUT RS232 OUTPUT
RECEIVER RECEIVER DRIVER DRIVER LOGIC INPUT LOGIC OUTPUT
ON/OFF = 5V
6
+
0.1F
V- 0.1F
+
0.1F
LT1537 * TA03
+
0.1F
0.1F
+
3
26
+
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.
+
+
U
U
U
U
U
ESD Test Circuit
V+ 1 LT1537 28 27 V- 0.1F 0.2F
+
+
5V VCC 2
LT1537
TYPICAL APPLICATIO S
Typical Mouse Driving Application
V+ V- 1 2 3 4 DRIVER 1 OUT (1) DCD DSR RX RTS OPTICS V- TX CTS DTR (5) (9) RI RX1 IN DRIVER 2 OUT RX2 IN RX3 IN 5 6 7 8 9 LT1537 28 27 25 DRIVER 1 IN 24 RX1 OUT 23 DRIVER 2 IN 22 RX2 OUT 21 RX3 OUT 20 RX4 OUT 19 DRIVER 3 IN 18 RX5 OUT 17 GND 16 DRIVER DISABLE 15 LOGIC "1" MOUSE DATA LOGIC "0" 26
2 x 0.1F V+ LOGIC
RX4 IN 10 DRIVER 3 OUT 11 RX5 IN 12 ON/OFF = 5V 13 14
DB9
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)
0.022 - 0.037 (0.55 - 0.95)
0.0256 (0.65) BSC
*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)
28SSOP 0694
1 2 3 4 5 6 7 8 9 10 11 12 13 14
S Package 28-Lead Plastic SOL
0.291 - 0.299 (7.391 - 7.595) (NOTE 2) 0.010 - 0.029 x 45 (0.254 - 0.737)
0.697 - 0.712 (17.70 - 18.08) (NOTE 2) 28 27 26 25 24 23 22 21 20 19 18 17 16 15
0.005 (0.127) RAD MIN
0.093 - 0.104 (2.362 - 2.642) 0 - 8 TYP
0.037 - 0.045 (0.940 - 1.143)
NOTE 1 0.050 (1.270) TYP 0.014 - 0.019 (0.356 - 0.482) 1 2 3 4 5 6 7 8 9 10 11 12 13 14
0.009 - 0.013 (0.229 - 0.330)
NOTE 1 0.016 - 0.050 (0.406 - 1.270)
0.004 - 0.012 (0.102 - 0.305)
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).
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.
+
MOUSE
+
LOGIC "0"
LT1137A * TA04
0.394 - 0.419 (10.007 - 10.643)
+
U
U
+
0.1F
5V VCC
2 x 0.1F
0.1F
SOL28 0392
7
LT1537 RELATED PARTS
PART NUMBER
LT1137A LT1138A LT1237 LT1330 LT1331 LTC1337 LTC1338
DESCRIPTION
5V 3-Driver/5-Receiver RS232 Transceiver with Shutdown 5V 5-Driver/3-Receiver RS232 Transceiver 5V 3-Driver/5-Receiver RS232 Transceiver with One Receiver Active in Shutdown 5V 3-Driver/5-Receiver RS232 Transceiver with 3V Logic Interface and Shutdown 5V 3-Driver/5-Receiver RS232 Transceiver with 3V Logic Interface and Receiver Active in Shutdown Ultra-Low Power 5V 3-Driver/5-Receiver RS232 Transceiver with Shutdown 5V 5-Driver/3-Receiver RS232 Transceiver with Shutdown
COMMENTS
Premium Performance Upgrade to LT1537 Premium Performance DCE, Compliment to LT1537 Lower Power, Premium Performance Upgrade to LT1537 Premium Performance Device for 5V Systems with 3V Logic Supplies LT1330 with Low Power Receiver That Stays Active During Shutdown Ultra-Low Power, Premium Performance Upgrade to LT1537 Ultra-Low Power, Peripheral-Side Compliment to LT1537
8
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7487
(408) 432-1900 q FAX: (408) 434-0507 q TELEX: 499-3977
LT/GP 0595 10K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1995

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