LINER LT1781 Low power 5v rs232 dual driver/receiver with â±15kv esd protection Datasheet

LT1780/LT1781
Low Power 5V RS232
Dual Driver/Receiver with
±15kV ESD Protection
DESCRIPTIO
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FEATURES
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■
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■
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■
■
■
■
■
■
■
■
10mA Max Supply Current
ESD Protection to IEC 1000-4-2 Level 4
±15kV Air Gap, ±8kV Contact
Uses Small Capacitors: 0.1µF
120kBaud Operation for RL = 3k, CL = 2500pF
250kBaud Operation for RL = 3k, CL = 1000pF
Outputs Withstand ±30V Without Damage
CMOS Comparable Low Power: 40mW
Operates from a Single 5V Supply
Rugged Bipolar Design
Outputs Assume a High Impedance State When Off
or Powered Down
Meets All RS232 Specifications
Available With or Without Shutdown
Absolutely No Latch-up
The LT1780/LT1781 are direct upgrades to the LT1180A/
LT1181A, LT1280A/LT1281A and LT1381 for applications
which require the utmost ESD protection.
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APPLICATI
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The LT®1780/LT1781 are dual RS232 driver/receiver pairs
with integral charge pump to generate RS232 voltage
levels from a single 5V supply. Using only 0.1µF external
capacitors, these circuits consume only 40mW of power,
and can operate to 120kbaud even while driving heavy
capacitive loads. New ESD structures on the chip allow the
LT1780/LT1781 to survive ±15kV air gap and ±8kV contact ESD tests per IEC 1000-4-2, eliminating the need for
costly TransZorbs® on the RS232 line pins. The LT1780/
LT1781 are fully compliant with EIA RS232 standards.
Driver outputs are protected from overload, and can be
shorted to ground or up to ±30V without damage. During
SHUTDOWN or power-off conditions, driver and receiver
outputs are in a high impedance state, allowing line
sharing.
S
Portable Computers
Battery-Powered Systems
Power Supply Generator
Terminals
Modems
The LT1781 is available in 16-pin DIP,SO and SW packages. The LT1780 is supplied in 18-pin DIP and SW
packages for applications which require SHUTDOWN.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TransZorb is a registered trademark of General Instruments, GSI.
UO
TYPICAL APPLICATI
0.1µF
2
17
4
3
5
0.1µF
LOGIC
INPUTS
7
V – OUT
DRIVER
OUTPUT
RL = 3k
CL = 2500pF
0.1µF
6
12
15
11
8
13
14
RS232 OUTPUT
RECEIVER
OUTPUT
R
CL = 50pF
RS232 OUTPUT
RS232 INPUT
INPUT
5k
LOGIC
OUTPUTS
10
ON/OFF
V + OUT
0.1µF
LT1780
Output Waveforms
5V INPUT
18
9
5k
RS232 INPUT
1780/81 • TA02
16
1780/81 • TA01
1
LT1780/LT1781
W W
W
AXI U
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ABSOLUTE
RATI GS
(Note 1)
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
Supply Voltage (VCC) ................................................ 6V
V + ........................................................................ 13.2V
V – ...................................................................... –13.2V
Input Voltage
Driver ........................................................... V – to V +
Receiver ............................................... – 30V to 30V
ON/OFF ................................................. – 0.3V to 12V
Output Voltage
Driver ...................................... V+ – 30V to V – + 30V
Receiver .................................... – 0.3V to VCC + 0.3V
U
W
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PACKAGE/ORDER I FOR ATIO
TOP VIEW
C1+
1
16 VCC
V+
2
15 GND
C1 –
3
14 TR1 OUT
C2+
4
13 REC1 IN
C2 –
5
12 REC1 OUT
V–
6
11 TR1 IN
TR1 IN
TR2 OUT
7
10 TR2 IN
11
TR2 IN
REC2 IN
8
9
10
REC2 OUT
NC
1
18
ON/OFF
C1+
2
17
VCC
V+
3
16
GND
C1 –
4
15
TR1 OUT
C2+
5
14
REC1 IN
C2 –
6
13
REC1 OUT
V–
7
12
TR2 OUT
8
REC2 IN
9
N PACKAGE
18-LEAD PLASTIC DIP
TOP VIEW
ORDER
PART
NUMBER
LT1780CN
LT1780CSW
ORDER
PART
NUMBER
LT1781CN
LT1781CS
LT1781CSW
REC2 OUT
S PACKAGE
SW PACKAGE
N PACKAGE
16-LEAD PLASTIC DIP 16-LEAD PLASTIC SO 16-LEAD PLASTIC SO
SW PACKAGE
18-LEAD PLASTIC SO
TJMAX = 125°C, θJA = 90°C/ W, θJC = 46°C/W (N)
TJMAX = 125°C, θJA = 95°C/ W, θJC = 34°C/W (S)
TJMAX = 125°C, θJA = 95°C/ W, θJC = 27°C/W (SW)
TJMAX = 125°C, θJA = 80°C/ W, θJC = 36°C/W (N)
TJMAX = 125°C, θJA = 90°C/ W, θJC = 26°C/W (SW)
Consult factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS
(Note 2)
PARAMETER
Power Supply Generator
V + Output
V – Output
Supply Current (VCC)
CONDITIONS
Supply Current When OFF (VCC)
Supply Rise Time
SHUTDOWN to Turn-On
ON/OFF Pin Thresholds
SHUTDOWN (Note 4) LT1780 Only
C1 = C2 = C3 = C4 = 0.1µF
LT1780 Only
Input Low Level (Device SHUTDOWN)
Input High Level (Device Enabled)
0V ≤ VON/OFF ≤ 5V
ON/OFF Pin Current
Oscillator Frequency
Driver
Output Voltage Swing
Logic Input Voltage Level
2
MIN
TYP
7.9
–7
8
(Note 3), TA = 25°C
●
●
●
●
0.8
●
– 15
1
0.2
0.2
1.2
1.6
MAX
10
14
10
2.4
80
130
Load = 3k to GND
Input Low Level (VOUT = High)
Input High Level (VOUT = Low)
Positive
Negative
●
●
●
●
5.0
2.0
7.5
– 6.3
1.4
1.4
–5
0.8
UNITS
V
V
mA
mA
µA
ms
ms
V
V
µA
kHz
V
V
V
V
LT1780/LT1781
ELECTRICAL CHARACTERISTICS
PARAMETER
CONDITIONS
Logic Input Current
0.8V ≤ VIN ≤ 2.0V
(Note 2)
MIN
●
±7
Output Short-Circuit Current
VOUT = 0V
Output Leakage Current
SHUTDOWN VOUT = ±30V (Note 4)
Data Rate
RL = 3k, CL = 2500pF
RL = 3k, CL = 1000pF
120
250
Slew Rate
RL = 3k, CL = 51pF
RL = 3k, CL = 2500pF
4
Propagation Delay
TYP
MAX
5
20
17
10
●
Output Transition tHL High-to-Low (Note 5)
Output Transition tLH Low-to-High
UNITS
µA
mA
100
µA
kBaud
kBaud
15
7
30
V/µs
V/µs
0.6
0.5
1.3
1.3
µs
µs
1.3
1.7
2.4
V
V
Receiver
Input Voltage Thresholds
Input Low Threshold (VOUT = High)
Input High Threshold (VOUT = Low)
0.8
Hysteresis
Input Resistance
●
V IN = ±10V
0.1
0.4
1
V
3
5
7
kΩ
Output Leakage Current
SHUTDOWN (Note 4) 0 ≤ VOUT ≤ VCC
●
1
10
µA
Output Voltage
Output Low, IOUT = – 1.6mA
Output High, IOUT = 160µA (VCC = 5V)
●
●
0.4
3.5
0.2
4.2
V
V
– 20
20
– 10
10
mA
mA
250
350
600
600
ns
ns
Output Short-Circuit Current
Propagation Delay
Sinking Current, VOUT = VCC
Sourcing Current, VOUT = 0V
Output Transition tHL High-to-Low (Note 6)
Output Transition tLH Low-to-High
The ● denotes specifications which apply over the operating temperature
range.
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, unless otherwise
specified.
Note 3: Supply current is measured as the average over several charge
pump cycles. C + = C – = C1 = C2 = 0.1µF. All outputs are open, with all
driver inputs tied high.
Note 4: Supply current measurements in SHUTDOWN are performed with
VON/OFF ≤ 0.1V.
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).
3
LT1780/LT1781
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Driver Maximum Output Voltage
vs Load Capacitance
Driver Minimum Output Voltage
vs Load Capacitance
8.0
Driver Output Voltage
10
–4.0
8
7.0
20k BAUD
6.5
60k BAUD
6.0
120k BAUD
5.5
DRIVER OUTPUT VOLTAGE (V)
–4.5
PEAK OUTPUT VOLTAGE (V)
PEAK OUTPUT VOLTAGE (V)
7.5
120k BAUD
–5.0
60k BAUD
–5.5
20k BAUD
–6.0
–6.5
RL = 3k
6
4
2
0
–2
–4
VCC = 5.5V
VCC = 5V
VCC = 4.5V
OUTPUT HIGH
OUTPUT LOW
VCC = 4.5V
VCC = 5V
VCC = 5.5V
–6
–8
5.0
–7.0
0
1
2
3 4 5 6 7 8
LOAD CAPACITANCE (nF)
9
10
0
1780 • G01
1
2
3 4 5 6 7 8
LOAD CAPACITANCE (nF)
9
10
50
25
0
75
TEMPERATURE (°C)
1780 • G02
50
2 DRIVERS ACTIVE
RL = 3k
CL = 2500pF
2.75
2.50
SUPPLY CURRENT (mA)
40
2.25
INPUT HIGH
2.00
1.75
INPUT LOW
1.50
1.25
1.00
30
20
10
0.75
0.50
–55 –25
0
50
25
0
75
TEMPERATURE (°C)
100
125
0
25
50
75
100
DATA RATE (kBAUD)
2.5
20
SUPPLY CURRENT (mA)
THRESHOLD VOLTAGE (V)
25
ON THRESHOLD
1.5
1.0
OFF THRESHOLD
50
25
75
0
TEMPERATURE (°C)
100
125
1780 • G06
4
2 DRIVERS LOADED RL = 3k
15
10
1 DRIVER LOADED RL = 3k
NO LOAD
5
0.5
0
–55 –25
150
Supply Current
ON/OFF Thresholds
2.0
125
1780 • G05
1780 • G04
3.0
100
125
1780 • G03
Supply Current vs Data Rate
Receiver Input Thresholds
3.00
THRESHOLD VOLTAGE (V)
–10
–55 –25
0
–55 –25
50
25
0
75
TEMPERATURE (°C)
100
125
1780 • G07
LT1780/LT1781
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Driver Leakage in Shutdown
Driver Short-Circuit Current
100
( µA)
SHORT-CIRCUIT CURRENT (mA)
30
LEAKAGE CURRENT
10
VOUT = 30V
1
VOUT = –30V
0.1
–55 –25
50
25
0
75
TEMPERATURE (°C)
100
25
ISC +
20
15
ISC –
10
5
0
–55 –25
125
50
25
75
0
TEMPERATURE (°C)
1780 • G08
125
1780 • G09
Receiver Short-Circuit Current
Slew Rate vs Load Capacitance
50
16
14
40
12
RX ISC –
SLEW RATE (V/µs)
SHORT-CIRCUIT CURRENT (mA)
100
30
RX ISC +
20
10
8
+SLEW
6
–SLEW
4
10
2
0
–55 –25
50
25
0
75
TEMPERATURE (°C)
100
125
0
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
LOAD CAPACITANCE (nF)
1780 • G10
1780 • G11
Shutdown to Driver Outputs
Driver Output Waveforms
10V
DRIVER 1
OUTPUT
5V
DRIVER OUTPUT
RL = 3k
CL = 2500pF
GND
GND
DRIVER 2
OUTPUT
– 5V
DRIVER OUTPUT
RL = 3k
– 10V
ON/OFF PIN
INPUT
1780 • G12
1780 • G13
5
LT1780/LT1781
U
U
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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.
GND: Ground Pin.
ON/OFF: A TTL/CMOS Compatible Operating Mode Control. A logic low puts the LT1780 in SHUTDOWN mode.
Supply current drops to zero and both driver and receiver
outputs assume a high impedance state. A logic high fully
enables the device.
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.
V –: Negative Supply Output (RS232 Drivers).
V – ≈ –(2VCC – 2.5V). This pin requires an external charge
storage capacitor C ≥ 0.1µF. Larger value capacitors may
be used to reduce supply ripple. With multiple transceivers, the V+ and V – pins may be paralleled into common
capacitors.
TR1 IN, TR2 IN: RS232 Driver Input Pins. These inputs are
TTL/CMOS compatible. Inputs should not be allowed to
float. Tie unused inputs to VCC.
6
TR1 OUT, TR2 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 or VCC = 0V. 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 IEC-1000-4-2
Level 4 discharges.
REC1 IN, REC2 IN: Receiver Inputs. These pins accept
RS232 level signals (±30V) into a protected 5k terminating resistor. The receiver inputs are protected against ESD
to IEC-1000-4-2 Level 4 discharges. Each receiver provides 0.4V of hysteresis for noise immunity. Open receiver
inputs result in a logic high receiver output state.
REC1 OUT, REC2 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 the SHUTDOWN mode.
C1 +, C1 –, C2 +, C2 –: Commutating Capacitor Inputs.
These pins require two external capacitors C ≥ 0.1µF: one
from C1+ to C1– and another from C2+ to C2 –. C1 should
be deleted if a separate 12V supply is available and
connected to pin C1+. Similarly, C2 should be deleted if a
separate – 12V supply is connected to pin V –.
LT1780/LT1781
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ESD PROTECTIO
ESD Test Circuit
The RS232 line inputs of the LT1780/LT1781 have on-chip
protection from ESD transients up to ±15kV air gap and
±8kV contact tested to IEC-1000-4-2 test methods. 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 circuit 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.
NC
C1+ 2
0.1µF
V+ 3
0.1µF
C1– 4
C2+
0.1µF
LT1780
16 GND
15
0.1µF
DR1 OUT
RS232
LINE PINS
PROTECTED
TO IEC-1000-4-2
13
RX1 OUT LEVEL 4
14
12
8
11
9
10
RX2 IN
ON/OFF
17 5V VCC
V– 7
DR2 OUT
RS232
LINE PINS
PROTECTED
TO IEC-1000-4-2
LEVEL 4
5
C2 – 6
0.1µF
18
1
RX1 IN
DR1 IN
DR2 IN
RX2 OUT
1780 • ESD TC
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TYPICAL APPLICATIO
Operation Using 5V and 12V Power Supplies
12V INPUT
2
17
4
3
5V INPUT
LT1780
5
0.1µF
LOGIC
INPUTS
7
–12VOUT
0.1µF
6
12
15
11
8
13
14
RS232 OUTPUT
RS232 OUTPUT
RS232 INPUT
5k
LOGIC
OUTPUTS
10
9
RS232 INPUT
5k
ON/OFF
18
16
1780/81 • TA03
7
LT1780/LT1781
U
PACKAGE DESCRIPTIO
Dimensions in inches (millimeters) unless otherwise noted.
N Package
16-Lead PDIP (Narrow 0.300)
(LTC DWG # 05-08-1510)
0.770*
(19.558)
MAX
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
0.255 ± 0.015*
(6.477 ± 0.381)
0.130 ± 0.005
(3.302 ± 0.127)
0.300 – 0.325
(7.620 – 8.255)
0.009 – 0.015
(0.229 – 0.381)
(
0.020
(0.508)
MIN
+0.035
0.325 –0.015
8.255
+0.889
–0.381
0.045 – 0.065
(1.143 – 1.651)
)
0.065
(1.651)
TYP
0.125
(3.175)
MIN
0.018 ± 0.003
(0.457 ± 0.076)
0.100 ± 0.010
(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)
N16 1197
N Package
18-Lead PDIP (Narrow 0.300)
(LTC DWG # 05-08-1510)
0.900*
(22.860)
MAX
18
17
16
15
14
13
12
11
10
1
2
3
4
5
6
7
8
9
0.255 ± 0.015*
(6.477 ± 0.381)
0.130 ± 0.005
(3.302 ± 0.127)
0.300 – 0.325
(7.620 – 8.255)
0.009 – 0.015
(0.229 – 0.381)
+0.035
0.325 –0.015
0.045 – 0.065
(1.143 – 1.651)
0.020
(0.508)
MIN
0.065
(1.651)
TYP
0.005
(0.127)
MIN
0.100 ± 0.010
(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)
(
8
+0.889
8.255
–0.381
)
0.125
(3.175)
MIN
0.018 ± 0.003
(0.457 ± 0.076)
N18 1197
LT1780/LT1781
U
PACKAGE DESCRIPTIO
Dimensions in inches (millimeters) unless otherwise noted.
SW Package
16-Lead Plastic Small Outline (Wide 0.300)
(LTC DWG # 05-08-1620)
0.398 – 0.413*
(10.109 – 10.490)
16
15
14
13
12
11 10
9
0.394 – 0.419
(10.007 – 10.643)
NOTE 1
0.291 – 0.299**
(7.391 – 7.595)
1
2
3
4
5
6
7
8
0.093 – 0.104
(2.362 – 2.642)
0.010 – 0.029 × 45°
(0.254 – 0.737)
0.037 – 0.045
(0.940 – 1.143)
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
0.004 – 0.012
(0.102 – 0.305)
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
S16 (WIDE) 0396
*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
9
LT1780/LT1781
U
PACKAGE DESCRIPTIO
Dimensions in inches (millimeters) unless otherwise noted.
SW Package
18-Lead Plastic Small Outline (Wide 0.300)
(LTC DWG # 05-08-1620)
0.447 – 0.463*
(11.354 – 11.760)
18
17
16
15
14
13
12
11
10
0.394 – 0.419
(10.007 – 10.643)
SEE NOTE
0.291 – 0.299**
(7.391 – 7.595)
1
2
3
4
5
6
7
8
9
0.093 – 0.104
(2.362 – 2.642)
0.010 – 0.029 × 45°
(0.254 – 0.737)
0.037 – 0.045
(0.940 – 1.143)
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
*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
10
0.004 – 0.012
(0.102 – 0.305)
S18 (WIDE) 0396
LT1780/LT1781
U
PACKAGE DESCRIPTIO
Dimensions in inches (millimeters) unless otherwise noted.
S Package
16-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.386 – 0.394*
(9.804 – 10.008)
16
15
14
13
12
11
10
9
0.150 – 0.157**
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
1
0.010 – 0.020
× 45°
(0.254 – 0.508)
0.008 – 0.010
(0.203 – 0.254)
2
3
4
5
6
0.053 – 0.069
(1.346 – 1.752)
0.014 – 0.019
(0.355 – 0.483)
8
0.004 – 0.010
(0.101 – 0.254)
0° – 8° TYP
0.016 – 0.050
0.406 – 1.270
7
0.050
(1.270)
TYP
S16 0695
*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.
11
LT1780/LT1781
U
TYPICAL APPLICATIO
Supporting an LT1039 (Triple Driver/Receiver)
SHUTDOWN
5V
18
TTL INPUT
TTL INPUT
VCC
ON/OFF
LT1780
17
11
8
12
15
18
RS232 OUTPUT
TTL INPUT
RS232 OUTPUT
TTL INPUT
TTL INPUT
TTL OUTPUT
14
13
RS232 INPUT
TTL OUTPUT
VCC
ON/OFF
LT1039
15
4
13
6
11
8
16
3
5k
TTL OUTPUT
RS232 INPUT
TTL OUTPUT
14
5
5k
2
1µF
4
5
1µF
6
RS232 OUTPUT
RS232 OUTPUT
RS232 OUTPUT
RS232 INPUT
30k
9
10
17
RS232 INPUT
30k
C1+
TTL OUTPUT
7
12
RS232 INPUT
30k
C1–
C2 +
C2 –
V+
3
1
V+
V–
7
9
V–
GND
16
1µF
1µF
GND
10
1780/81 • TA04
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT1137A
3Driver/5Receiver RS232 Transceiver
IEC-1000-4-2 Level 4 ESD Compliance
LTC1383
5V Low Power RS232 2Driver/2Receiver Transceiver
Low Supply Current ICC = 220µA
LTC1387
Single 5V RS232/RS485 Multiprotocol Transceiver
Configurable as Dual RS232 or Single RS485 Transceiver
12
Linear Technology Corporation
17801f LT/TP 0498 4K • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com
 LINEAR TECHNOLOGY CORPORATION 1998
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