LINER LTC1318 Single 5v rs232/rs422/appletalk dce transceiver Datasheet

LTC1318
Single 5V
RS232/RS422/AppleTalk®
DCE Transceiver
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DESCRIPTION
FEATURES
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The LTC®1318 is a single 5V, RS232/RS422 transceiver
for connection to the DCE, or peripheral side of an interface
link. It includes an on-board charge pump to generate a
±8V supply which allows true RS232 output swings. The
charge pump requires only four external 0.1µF capacitors.
The LTC1318 includes two RS232 drivers, a differential
RS422 driver, a dedicated RS232 receiver, and a pin
selectable RS232/RS422 receiver which can receive either
single-ended or differential signals.
Single Chip Provides DCE RS232 or
RS422/AppleTalk DCE Port
Operates from a Single 5V Supply
Charge Pump Uses 0.1µF Capacitors
Output Common-Mode Voltage Range Exceeds
Power Supply Rails for All Drivers
Driver Outputs Are High Impedance with Power Off
Pin Selectable RS232/RS422 Receiver
Thermal Shutdown Protection
Drivers Are Short-Circuit Protected
The LTC1318 features driver outputs which can be taken
to common-mode voltages outside the power supply rails
without damage. Additionally, the driver outputs assume
a high impedance state when the power is shut off,
preventing externally applied signals from feeding back
into the power supplies. The RS232 devices will operate at
speeds up to 100kbaud. The RS422 devices will operate
up to 2Mbaud.
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APPLICATIONS
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Dual-Mode RS232/RS422 Peripherals
AppleTalk Peripherals
Single 5V Systems
The LTC1318 is available in a 24-lead SO Wide package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
AppleTalk and LocalTalk are registered trademarks of Apple Computer, Inc.
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TYPICAL APPLICATIONS
C1 +
0.1µF
0.1µF
C1
RS232
LINES
5V
1k
22Ω
22Ω
CHARGE
PUMP
–
1k
22Ω
22Ω
RXO1
TXI1
TXO2 RS232
TXI2
RXD
TXD +
RS422
LOCALTALK®
TRANSFORMER
TXD
(5V/DIV)
TO
DIGITAL
SYSTEM
22Ω
TXD+, TXD–
(2V/DIV)
RXDO
(5V/DIV)
RXDO/RXO2
TXD
RS232
RXMODE
RL = 100Ω
CL = 100pF
GND
22Ω
NC
22Ω
0.1µF
0.1µF
GND
VCC
TXD – RS422
22Ω
C2 +
RXI1 RS232
RXD –/RXI2
APPLETALK
NETWORK
C2 –
TXO1 RS232
+
Driver Output Waveforms
V–
V+
LTC1318
200ns/DIV
1318 TA02
NC
LT1318 • TA01
100pF × 4
1
LTC1318
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ABSOLUTE MAXIMUM RATINGS
PACKAGE/ORDER INFORMATION
(Note 1)
Supply Voltage:
VCC ...................................................................................... 7V
V+ ................................................................................... 13.2V
V – ............................................................................... – 13.2V
Input Voltage:
All Drivers .............................. – 0.3 to (VCC + 0.3V)
All Receivers ...................................... – 25V to 25V
RXMODE Pin ....................... – 0.3V to (VCC + 0.3V)
Output Voltage:
RS232 Drivers ................ (V + – 30V) to (V – + 30V)
RS422 Drivers ................................................ ±15V
All Receivers ........................ – 0.3V to (VCC + 0.3V)
Short-Circuit Duration:
V + or V – to GND .......................................... 30 sec
Driver or Receiver Outputs ...................... Indefinite
Operating Temperature Range .................... 0°C to 70°C
Lead Temperature (Soldering, 10 sec)................. 300°C
ORDER PART
NUMBER
TOP VIEW
V+ 1
24 V –
C1 +
2
23 C2 –
–
3
22 C2 +
C1
LTC1318CSW
RXI1 4
21 RXO1
TXO1 5
20 TXI1
TXO2 6
19 TXI2
VCC 7
18 GND
RXD + 8
17 RXDO/RXO2
RXD –/RXI2 9
16 TXD
TXD + 10
15 RXMODE
TXD – 11
14 GND
NC 12
13 NC
SW PACKAGE
24-LEAD PLASTIC SO WIDE
TJMAX = 125°C, θJA = 85°C/W
Consult factory for Industrial and Military grade parts
ELECTRICAL CHARACTERISTICS
VS = 5V ±5%, C1 = C2 = 0.1µF, TA = 0°C to 70°C, unless otherwise specified. (Notes 2, 3)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
9
30
UNITS
Supplies
ICC
Supply Current
No Load
●
V+
mA
Positive Charge Pump Output Voltage
IOUT = 0mA
IOUT = 10mA, VCC = 5V
●
●
7.8
6.8
8.8
7.4
V
V
V–
Negative Charge Pump Output Voltage
IOUT = 0mA
IOUT = – 5mA, VCC = 5V
●
●
–7.3
– 6.3
–8.6
–7.3
V
V
±4
±2
Differential Driver
VOD
Differential Driver Output Voltage
No Load (Figure 1)
RL = 100Ω (Figure 1)
●
●
DVOD
Change in Magnitude of Differential
Output Voltage
RL = 100Ω (Figure 1)
●
VOC
Common-Mode Output Voltage
RL = 100Ω (Figure 1)
●
IDSS
Short-Circuit Output Current
– 1V < VCMR < 7V
●
VIL
Input Low Voltage
●
VIH
Input High Voltage
●
V
V
0.2
3
35
200
0.8
2.0
V
V
mA
V
V
Single-Ended Driver
VO
Output Voltage Swing
RL = 3k
●
±5
7.3/–6.5
IOSS
Short-Circuit Output Current
VOUT = OV
●
±5
17
VIL
Input Low Voltage
●
VIH
Input High Voltage
●
2
SR
Output Slew Rate
●
4
2
RL = 3k, CL = 51pF
V
mA
0.8
V
V
20
30
V/µS
LTC1318
ELECTRICAL CHARACTERISTICS
VS = 5V ±5%, C1 = C2 = 0.1µF, TA = 0°C to 70°C, unless otherwise specified. (Notes 2, 3)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Differential Receiver
VTH
Differential Receiver Threshold
●
– 0.2
0.2
V
CMR
Common-Mode Input Range
●
–7
7
V
Hysteresis
VCM = OV
RIN
Input Resistance
TA = 25°C
30
VOL
Output Low Voltage
IOUT = –1.6mA
VOH
Output High Voltage
IOUT = 160µA, VCC = 5V
●
3.5
IOSS
Short-Circuit Output Current
VO = GND or VCC
●
±7
0.8
●
3
5
mV
7
0.4
kΩ
V
V
±85
mA
Single-Ended Receiver
VL
Input Voltage Low Threshold
●
VIH
Input Voltage High Threshold
●
Hysteresis
●
0.1
RIN
Input Resistance
TA = 25°C
VOL
Output Low Voltage
IOUT = –4mA
●
3
VOH
Output High Voltage
IOUT = 4mA, VCC = 5V
●
IOSS
Short-Circuit Output Current
VO = GND or VCC
●
±7
VILRXM
RXMODE Input Low Voltage
●
0.8
VIHRXM
RXMODE Input High Voltage
IINRXM
RXMODE Input Current
●
VIN = OV or VCC
●
3.5
1.4
V
1.8
2.4
V
0.4
1.0
V
5
7
0.2
0.4
4.8
V
–V
±85
1.6
1.6
kΩ
mA
V
2.0
V
±2
µA
Switching Characteristics
tPLH,HL
Differential Driver Propagation Delay
RL = 100Ω, CL = 100pF (Figures 2,3)
●
35
100
ns
tSKEW
Differential Driver Output to Output
RL = 100Ω, CL = 100pF (Figures 2,3)
●
5
35
ns
tR,F
Differential Driver Rise, Fall Time
RL = 100Ω, CL = 100pF (Figures 2,3)
●
15
50
ns
tPLH,HL
Differential Receiver Propagation Delay
CL = 15pF, (Figures 4)
●
110
200
ns
tSEL
Receiver Mode Switching Time
●
25
100
ns
The ● denotes specifications which apply over the full operating
temperature range.
Note 1: Absolute maximum ratings are those values beyond which the life
of the device may be impaired.
Note 2: All currents into device pins are negative, all currents out of device
pins are positive. All voltages are referenced to ground unless otherwise
specified.
Note 3: All typicals are given at VCC = 5V, TA = 25°C.
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LTC1318
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TYPICAL PERFORMANCE CHARACTERISTICS
10.0
2.4
10
9.6
9.4
9.2
9.0
8.8
8.6
8.4
8.2
8.0
0
10
40
30
20
50
TEMPERATURE (°C)
4
2
TA = 25°C
VCC = 5V
ILOAD = V+ TO V –
0
–2
–4
V–
–6
9
12
6
LOAD CURRENT (mA)
4
3
2
3.5
2.0
1.5
1.0
0
10 20 30 40 50 60 70 80 90 100
LOAD CURRENT (mA)
10
6
4
2
TA = 25°C
VCC = 5V
0
–2
–4
–6
NEGATIVE SWING
10000
1318 G07
4
88
86
84
0
10
40
30
20
50
TEMPERATURE (°C)
60
70
1318 G06
RS232 Driver Short-Circuit
Current vs Temperature
VCC = 5V
19.0
18.5
18.0
ISC–
17.5
ISC+
17.0
16.5
16.0
15.5
–10
0
ISC–
90
19.5
POSITIVE SWING
–8
100
1000
CAPACITANCE (pF)
92
20.0
8
DRIVER OUTPUT SWING (V)
SLEW RATE (V/µs)
5
ISC+
94
20 30 40 50 60 70 80 90 100
LOAD CURRENT (mA)
SHORT-CIRCUIT CURRENT (mA)
TA = 25°C
VCC = 5V
10
96
80
0
10
25
70
VCC = 5V
98
RS232 Driver Output Swing vs
Resistive Load
10
60
1318 G03
1318 G05
RS232 Driver Slew Rate vs
Load Capacitance
SR +
50
82
1318 G04
15
40
30
RS422 Driver Short-Circuit
Current vs Temperature
2.5
0
SR –
20
TEMPERATURE (°C)
3.0
0.5
20
10
100
4.0
1
0
INPUT LOW (TXI1, TXI2)
0
SHORT-CIRCUIT CURRENT (mA)
5
INPUT LOW (TXD)
1.2
15
TA = 25°C
VCC = 5V
ILOAD FROM TXD+,
TXD– TO GND
4.5
DRIVER OUTPUT SWING (V)
DIFFERENTIAL OUTPUT SWING (V)
6
1.4
0.8
3
0
5.0
7
1.6
RS422 Driver Single-Ended
Output Swing vs Load Current
10
8
INPUT HIGH (TXD)
1.8
1318 G02
RS422 Driver Differential Output
Swing vs Load Current
9
INPUT HIGH (TXI1, TXI2)
2.0
1.0
–8
1318 G01
TA = 25°C
VCC = 5V
ILOAD FROM
TXD+ TO TXD–
VCC = 5V
2.2
6
–10
70
60
V+
8
THRESHOLD VOLTAGE (V)
CHARGE PUMP OUTPUT VOLTAGE (V)
VCC = 5V
9.8
SUPPLY CURRENT (mA)
TTL Input Threshold
vs Temperature
Charge Pump Output Voltage
vs Load Current
Supply Current vs Temperature
15.0
1
3
2
4 5 6 7 8 9 10
RESISTIVE LOAD (kΩ)
1318 G08
0
10
40
30
20
50
TEMPERATURE (°C)
60
70
1318 G09
LTC1318
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TYPICAL PERFORMANCE CHARACTERISTICS
RS232 Receiver Input Threshold
vs Temperature
RS422 Receiver Differential
Threshold vs Temperature
100
2.4
24
THRESHOLD VOLTAGE (V)
2.2
80
INPUT HIGH
70
60
INPUT LOW
50
40
30
VCC = 5V
VCC = 5V
SHORT-CIRCUIT CURRENT (mA)
VCC = 5V
90
THRESHOLD VOLTAGE (mV)
TTL Output Short-Circuit Current
vs Temperature
INPUT HIGH (RXDO/RXO2)
2.0
1.8
INPUT HIGH (RXO1)
1.6
1.4
INPUT LOW (RXO1)
1.2
INPUT LOW (RXDO/RXO2)
1.0
20
10
20
30
40
50
60
70
TEMPERATURE (°C)
RXO1
20
18
RXDO/RXO2
16
14
12
10
0.8
0
22
0
10
20
30
40
50
60
70
TEMPERATURE (°C)
1318 G10
0
10
40
30
50
20
TEMPERATURE (°C)
1318 G11
60
70
1318 G12
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PIN FUNCTIONS
V + (Pin 1): Charge Pump Positive Output. This pin requires a 0.1µF capacitor to ground. Under normal operation this pin maintains a voltage of about 8.8V above
ground. An external load can be connected between this
pin and ground or V –.
TXD – (Pin 11): Differential RS422 Driver Inverting Output.
C1+, C1– (Pins 2, 3): C1 Inputs. Connect a 0.1µF capacitor
between C1+ and C1–.
RXMODE (Pin 15): This pin controls the state of the
differential/single-ended receiver. When RXMODE is low,
the receiver is in differential mode and will receive RS422
compatible signals at RXD + and RXD – /RXI2 (pins 8
and 9). When RXMODE goes high, the receiver enters
single-ended mode and will receive RS232 compatible
signals at RXD –/RXI2. RXD + is disabled in single-ended
mode. Both modes use the RXDO/RXO2 pin (pin 17) as
their output.
RXI1 (Pin 4): First RS232 Single-Ended Receiver Input.
This is an inverting receiver.
TXO1, TXO2 (Pins 5,6): RS232 Single-Ended Driver Outputs.
VCC (Pin 7): Positive Supply Input. Apply 4.75V ≤ VCC ≤
5.25V to this pin. A 0.1µF bypass capacitor is required.
RXD+ (Pin 8): When RXMODE (pin 15) is low, this pin acts
as the differential RS422 receiver positive input. When
RXMODE is high, this pin is disabled.
RXD –/RXI2 (Pin 9): When RXMODE (pin 15) is low, this
pin acts as the differential RS422 receiver negative input.
When RXMODE is high, this pin acts as the second RS232
receiver input. The receiver is inverting in RS232 mode.
TXD +
(Pin 10): Differential RS422 Driver Noninverting
Output.
NC (Pins 12,13): No Internal Connection.
GND (Pins 14, 18): Power Supply Ground. Connect both
pins to each other and to the ground.
TXD (Pin 16): Differential RS422 Driver Input (TTL Compatible).
RXDO/RXO2 (Pin 17): This is the output of the configurable
differential/single-ended receiver.
TXI1, TXI2 (Pins 20, 19): RS232 Driver Inputs (TTL
Compatible). Both are inverting inputs.
RXO1 (Pin 21): First RS232 Receiver Outputs (TTL compatible).
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LTC1318
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PIN FUNCTIONS
C2+, C2– (Pins 22, 23): C2 inputs. Connect a 0.1µF capacitor
between C2 + and C2 –.
V – (Pin 24): Charge Pump Negative Output. This pin
requires a 0.1µF capacitor to ground. Under normal opera-
tion, this pin maintains a voltage of about 8.6V below
ground. An external load can be connected between this
pin and ground or V +.
TEST CIRCUITS
+
RL/2
TXD
TXD+
VOD
+
TXD–
RL/2
CL
TXD +
TXD
TXD
–
RD
CL
VOC
Figure 1.
Figure 2.
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SWITCHING WAVEFORMS
3V
f = 1MHz: tr ≤ 10ns: tf ≤ 10ns
1.5V
TXD
1.5V
0V
tPLH
tPHL
VO
90%
50%
10%
–VO
VDIFF = V(TXD +) – V(TXD – )
1/2 VO
tr
90%
50%
10%
tf
–
VO
TXD +
tSKEW
tSKEW
LT1318 • F03
Figure 3. Differential Driver
V OD2
f = 1MHz: tr ≤ 10ns: tf ≤ 10ns
(RXD+) – (RXD–)
–VOD2
tPLH
tPHL
VOH
VOL
1.5V
1.5V
LT1318 • F04
Figure 4. Differential Receiver
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RXD
RXI2
RXD0/RXD2
CL
1318 F02
1318 F01
RXDO
–/
–
–
TXD
RXD +
LTC1318
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APPLICATION INFORMATION
Interface Standards
The LTC1318 provides compatibility with both RS232 and
RS422/AppleTalk/LocalTalk standards in a single chip,
enabling a system to communicate using either protocol
as necessary. The LTC1318 provides two RS232 singleended drivers, one RS422 differential driver, and two
receivers. One of the receivers is a dedicated RS232
single-ended receiver, while the other can be configured
for RS232 (single-ended) or RS422 (differential) operation by controlling the logic state of the select pin. All
single-ended drivers and receivers meet the RS232C
specification for output swing, load driving capacity and
input range, and can additionally transmit and receive
signals as high as 100kbaud. The differential driver and
receiver can interface to both RS422 and AppleTalk networks, and can transmit and receive signals at rates
exceeding 2Mbaud.
to the C1 +/C1– and C2 +/C2 – pins, and two hold caps, one
from V + to ground and one from V – to ground. The charge
pump has enough extra capacity to drive light external
loads and still meet RS232 specifications; it will support a
10mA load from V + to ground or a 5mA from V + to V –
(Figure 5).
5V
1
2
0.1µF
3
8V AT 5mA
V+
0.1µF
EXTERNAL
DEVICE
LTC1318
22
0.1µF
23
0.1µF
V–
24
– 7V AT 5mA
LT1318 • F05
Figure 5.
Fault Protection
The LTC1318 incorporates many protection features to
make it as “bustproof” as possible. All driver outputs and
receiver inputs are protected against ESD strikes to ±6kV,
eliminating the need for external protection devices in
most applications. All driver outputs can be taken outside
the power supply rails without damage and will not allow
current to be forced back into the supplies, preventing the
output fault from affecting other logic circuits using the
same power supply. Additionally, the driver outputs enter
a high impedance state when the power is removed,
preventing the system from loading the data lines when it
is shut off. All driver and receiver outputs are protected
against short circuits to ground or to the supply rails.
Charge Pump Power Supply
The LTC1318 includes an on-board charge pump to generate the voltages necessary for true RS232 compatible
output swing. This charge pump requires just four external 0.1µF capacitors to operate; two flying caps connected
Configurable RS422/RS232 Receiver
There are two line receivers in the LTC1318. One is a
dedicated RS232 receiver; the other can receive both
single-ended RS232 signals and differential RS422 signals. This second receiver has two inputs: RXD + (pin 8)
and RXD– (pin 9) to accept differential signals. The RXD+
input is disabled in single-ended mode. The receiver mode
is set by the RXMODE (pin 15). A low level on RXMODE
configures the receiver in differential mode; it accepts
input at RXD+ and RXD– and outputs the data at RXDO (pin
17). A high level at RXMODE forces the receiver into
single-ended mode; RXD+ is disabled, pin 9 switches
identity from RXD– to RXI2, and pin 17 switches from
RXDO to RXO2, the single-ended data output. In this mode
the receiver accepts RS232 signals at RXI2 and outputs
the data through RXO2. The receiver becomes inverting in
single-ended mode. This receiver can switch between its
two modes within 100ns, allowing the system to sense the
input signal and configure itself accordingly.
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.
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LTC1318
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PACKAGE DESCRIPTION
Dimensions in inches (millimeters) unless otherwise noted.
S PACKAGE
24-Lead Plastic SOL
24
23
22
21
0.598 – 0.614
(15.190 – 15.600)
(NOTE 2)
20 19 18 17 16
15
14
13
0.394 – 0.419
(10.007 – 10.643)
NOTE 1
1
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)
2
3
4
5
6
7
8
9
10
11
12
0.037 – 0.045
(0.940 – 1.143)
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)
0.050
(1.270)
TYP
0.004 – 0.012
(0.102 – 0.305)
0.014 – 0.019
(0.356 – 0.482)
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).
8
Linear Technology Corporation
SOL24 0392
LT/GP 0295 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