LTC1690CMS8#TRPBF [Linear]
LTC1690 - Differential Driver and Receiver Pair with Fail-Safe Receiver Output; Package: MSOP; Pins: 8; Temperature Range: 0°C to 70°C;
| 型号： | LTC1690CMS8#TRPBF |
| 厂家： | 
Linear |
| 描述： | LTC1690 - Differential Driver and Receiver Pair with Fail-Safe Receiver Output; Package: MSOP; Pins: 8; Temperature Range: 0°C to 70°C 驱动 光电二极管 接口集成电路 驱动器 |
| 文件： | 总12页 (文件大小：185K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC1690
Differential Driver and
Receiver Pair with Fail-Safe
Receiver Output
U
DESCRIPTIO
FEATURES
The LTC®1690 is a low power receiver/driver pair that is
compatible with the requirements of RS485 and RS422.
The receiver offers a fail-safe feature that guarantees a
high receiver output state when the inputs are left open,
shorted together or terminated with no signal present. No
external components are required to ensure the high
receiver output state.
■
No Damage or Latchup to
Model), IEC1000-4-2 Level 4 (
±
15kV ESD (Human Body
8kV) Contact and
±
Level 3 (±8kV) Air Discharge
■
Guaranteed High Receiver Output State for
Floating, Shorted or Terminated Inputs with No
Signal Present
■
■
■
■
Drives Low Cost Residential Telephone Wires
ICC = 600µA Max with No Load
Single 5V Supply
–7V to 12V Common Mode Range Permits ±7V
Ground Difference Between Devices on the Data Line
Power-Up/Down Glitch-Free Driver Outputs Permit
Live Insertion or Removal of Transceiver
Driver Maintains High Impedance with the Power Off
Up to 32 Transceivers on the Bus
Separate driver output and receiver input pins allow full
duplex operation. Excessive power dissipation caused by
bus contention or faults is prevented by a thermal shut-
down circuit which forces the driver outputs into a high
impedance state.
■
■
■
■
■
The LTC1690 is fully specified over the commercial and
industrialtemperatureranges. TheLTC1690isavailablein
8-Pin SO, MSOP and PDIP packages.
Pin Compatible with the SN75179 and LTC490
Available in SO, MSOP and PDIP Packages
, LTC and LT are registered trademarks of Linear Technology Corporation.
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APPLICATIO S
■
Battery-Powered RS485/RS422 Applications
■
Low Power RS485/RS422 Transceiver
■
Level Translator
Line Repeater
■
U
TYPICAL APPLICATIO
Driving a 1000 Foot STP Cable
LTC1690
LTC1690
5
6
Y1
A2
120Ω
8
7
D1
3
2
120Ω
D1
DRIVER
RECEIVER
R2
D2
B2
Z1
B2
A2
R2
7
8
B1
Z2
6
5
2
3
120Ω
120Ω
Y2
R1
RECEIVER
DRIVER
A1
1690 TA01a
1690 TA01
1
LTC1690
W W
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ABSOLUTE MAXIMUM RATINGS
(Note 1)
Supply Voltage (VCC) .............................................. 6.5V
Driver Input Voltage..................... –0.3V to (VCC + 0.3V)
Driver Output Voltages ................................. –7V to 10V
Receiver Input Voltages ......................................... ±14V
Receiver Output Voltage .............. –0.3V to (VCC + 0.3V)
Junction Temperature........................................... 125°C
Operating Temperature Range
LTC1690C ........................................ 0°C ≤ TA ≤ 70°C
LTC1690I..................................... –40°C ≤ TA ≤ 85°C
Storage Temperature Range ................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
U
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PACKAGE/ORDER INFORMATION
ORDER PART
NUMBER
ORDER PART
NUMBER
TOP VIEW
TOP VIEW
V
1
2
3
4
A
B
Z
Y
8
7
6
5
CC
R
LTC1690CN8
LTC1690IN8
LTC1690CS8
LTC1690IS8
R
V
1
2
3
4
8 A
7 B
CC
R
D
LTC1690CMS8
6
5
Z
Y
D
GND
D
GND
MS8 PACKAGE
8-LEAD PLASTIC MSOP
S8 PACKAGE
8-LEAD PLASTIC SO
N8 PACKAGE
8-LEAD PLASTIC DIP
TJMAX = 125°C, θJA = 200°C/W
MS8 PART MARKING
LTDA
S8 PART MARKING
TJMAX = 125°C, θJA = 130°C/W (N)
TJMAX = 125°C, θJA = 135°C/W (S)
1690
1690I
Consult factory for Military Grade Parts
The ● denotes the specifications which apply over the full operating
DC ELECTRICAL CHARACTERISTICS
temperature range, otherwise specifications are at TA = 25°C. VCC = 5V ±5% (Notes 2, 3)
SYMBOL PARAMETER CONDITIONS
MIN
TYP
MAX
UNITS
V
V
Differential Driver Output Voltage (Unloaded)
Differential Driver Output Voltage (with Load)
I = 0
●
V
CC
V
OD1
OD2
O
R = 50Ω; (RS422)
R = 22Ω or 27Ω; (RS485), Figure 1
●
●
2
1.5
V
V
5
5
V
Differential Driver Output Voltage (with Common Mode)
V
= –7V to 12V, Figure 2
TST
1.5
V
V
OD3
∆V
Change in Magnitude of Driver Differential Output
Voltage for Complementary Output States
R = 22Ω, 27Ω or 50Ω, Figure 1
= –7V to 12V, Figure 2
●
0.2
OD
V
TST
V
Driver Common Mode Output Voltage
R = 22Ω, 27Ω or 50Ω, Figure 1
R = 22Ω, 27Ω or 50Ω, Figure 1
●
●
3
V
V
OC
∆|V
|
Change in Magnitude of Driver Common Mode
Output Voltage for Complementary Output States
0.2
OC
V
V
Input High Voltage
Input Low Voltage
Input Current
Driver Input (D)
Driver Input (D)
Driver Input (D)
●
●
●
2
V
V
IH
IL
0.8
I
I
±2
µA
IN1
IN2
Input Current (A, B)
V
V
= 0V or 5.25V, V = 12V
= 0V or 5.25V, V = –7V
●
●
1
–0.8
mA
mA
CC
CC
IN
IN
V
Differential Input Threshold Voltage for Receiver
Receiver Input Hysteresis
–7V ≤ V ≤ 12V
●
–0.20
–0.01
V
TH
CM
∆V
V
= 0V
CM
±30
mV
TH
2
LTC1690
The ● denotes the specifications which apply over the full operating
DC ELECTRICAL CHARACTERISTICS
temperature range, otherwise specifications are at TA = 25°C. VCC = 5V ±5% (Notes 2, 3)
SYMBOL PARAMETER CONDITIONS
I = –4mA, V = 200mV
MIN
TYP
MAX
UNITS
V
V
V
Receiver Output High Voltage
Receiver Output Low Voltage
Receiver Input Resistance
Supply Current
●
●
●
●
3.5
OH
OL
O
ID
I = 4mA, V = –200mV
0.4
V
O
ID
R
–7V ≤ V ≤ 12V
12
22
kΩ
µA
mA
mA
µA
mA
ns
IN
CM
I
I
I
I
I
t
t
t
No Load
260
600
250
250
200
85
CC
Driver Short-Circuit Current, V
Driver Short-Circuit Current, V
= HIGH
= LOW
–7V ≤ V ≤ 10V
35
35
OSD1
OSD2
OZ
OUT
O
–7V ≤ V ≤ 10V
OUT
O
Driver Three-State Current (Y, Z)
Receiver Short-Circuit Current
–7V ≤ V ≤ 10V, V = 0V
●
●
●
●
●
●
●
●
5
O
CC
0V ≤ V ≤ V
CC
7
OSR
PLH
PHL
SKEW
O
Driver Input to Output, Figure 3, Figure 4
Driver Input to Output, Figure 3, Figure 4
Driver Output to Output, Figure 3, Figure 4
Driver Rise or Fall Time, Figure 3, Figure 4
Receiver Input to Output, Figure 3, Figure 5
Receiver Input to Output, Figure 3, Figure 5
R
R
R
R
R
R
R
R
= 54Ω, C = C = 100pF
10
10
22.5
25
2.5
13
94
89
5
60
DIFF
DIFF
DIFF
DIFF
DIFF
DIFF
DIFF
DIFF
L1
L2
= 54Ω, C = C = 100pF
60
ns
L1
L2
= 54Ω, C = C = 100pF
15
ns
L1
L2
t , t
= 54Ω, C = C = 100pF
2
40
ns
r
f
PLH
PHL
SKD
MAX
L1
L2
t
t
t
f
= 54Ω, C = C = 100pF
30
30
160
160
ns
L1
L2
= 54Ω, C = C = 100pF
ns
L1
L2
|t
PLH
– t |, Differential Receiver Skew, Figure 3, Figure 5
PHL
= 54Ω, C = C = 100pF
ns
L1
L2
Maximum Data Rate, Figure 3, Figure 5
= 54Ω, C = C = 100pF
●
5
Mbps
L1
L2
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 positive; all currents out of device
pins are negative. All voltages are referenced to device ground unless
otherwise specified.
Note 3: All typicals are given for V = 5V and T = 25°C.
CC
A
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TYPICAL PERFOR A CE CHARACTERISTICS
Receiver Input Threshold Voltage
(Output High) vs Temperature
Receiver Input Threshold Voltage
(Output Low) vs Temperature
Receiver Hysteresis vs
Temperature
0
–20
0
–20
100
90
80
70
60
50
40
30
20
10
0
V
CC
= 5V
V
= 5V
CC
V
= 5V
CC
V
V
= 12V
= 0V
CM
–40
–40
CM
–60
–60
V
= 12V
CM
V
V
= 12V
= –7V
CM
–80
–80
V
= 0V
CM
V
CM
= –7V
–100
–120
–140
–160
–180
–200
–100
–120
–140
–160
–180
–200
V
CM
= 0V
V
= –7V
CM
CM
–55 –35 –15
5
25 45 65 85 105 125
–55 –35 –15
5
25 45 65 85 105 125
–55 –35 –15
5
25 45 65 85 105 125
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
1690 G01
1690 G02
1690 G03
3
LTC1690
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Receiver Input Offset Voltage vs
Temperature
Receiver Input Threshold Voltage
vs Supply Voltage
Receiver Output High Voltage vs
Output Current
–40
–60
0
–20
–25
–20
–15
–10
–5
V
CC
= 5V
T
= 25°C
T
= 25°C
CC
A
A
V
= 4.75V
–40
OUTPUT HIGH
V
CM
= 0V
–60
–80
V
V
= –7V
= 12V
CM
–80
–100
–120
–140
–160
–180
–200
–100
–120
–140
–160
OUTPUT LOW
CM
0
–55 –35 –15
5
25 45 65 85 105 125
4.5
4.75
5
5.25
5.5
4.5
4
3
5
2.5
2
3.5
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
RECEIVER OUTPUT HIGH VOLTAGE (V)
1690 G04
1690 G05
1690 G06
Receiver Output Low Voltage vs
Output Current
Receiver Output High Voltage vs
Temperature
Receiver Output Low Voltage vs
Temperature
40
35
30
25
20
15
10
5
4.8
4.6
4.4
4.2
4.0
3.8
3.6
3.4
3.2
3.0
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
I = 8mA
CC
T
= 25°C
CC
I = 8mA
CC
A
V
= 4.75V
V
= 4.75V
V
= 4.75V
0
0
0.2 0.4 0.6 0.8
1
1.2 1.4 1.6 1.8
2
–55 –35 –15
5
25 45 65 85 105 125
–55 –35 –15
5
25 45 65 85 105 125
TEMPERATURE (°C)
RECEIVER OUTPUT LOW VOLTAGE (V)
TEMPERATURE (°C)
1690 G07
1690 G08
1690 G09
Receiver Propagation Delay vs
Temperature
Receiver Skew
Temperature
tPLH – tPHL vs
Receiver Propagation Delay vs
Supply Voltage
10
9
110
100
90
120
110
100
90
V
= 5V
V
= 5V
CC
CC
t
t
PLH
PHL
8
t
t
PLH
PHL
7
6
80
5
70
80
4
60
70
3
2
50
60
–55 –35 –15
5
25 45 65 85 105 125
4.5 4.6 4.7 4.8 4.9
5
5.1 5.2 5.3 5.4 5.5
–55 –35 –15
5
25 45 65 85 105 125
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
1690 G11
1690 G12
1690 G10
4
LTC1690
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Receiver Short-Circuit Current vs
Temperature
Logic Input Threshold Voltage vs
Temperature
Supply Current vs Temperature
70
60
50
40
30
20
10
0
340
320
300
280
260
240
220
200
180
160
140
120
1.75
1.70
1.65
1.60
1.55
1.50
V
= 5.25V
CC
V
V
= 5.25V
= 5V
CC
CC
OUTPUT LOW
V
= 5.25V
CC
V
= 4.75V
CC
OUTPUT HIGH
V
= 5V
CC
V
= 4.75V
CC
–55 –35 –15
5
25 45 65 85 105 125
–55 –35 –15
5
25 45 65 85 105 125
–55 –35 –15
5
25 45 65 85 105 125
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
1690 G13
1690 G14
1690 G15
Driver Differential Output Voltage
vs Temperature
Driver Differential Output Voltage
vs Temperature
Driver Differential Output Voltage
vs Temperature
2.9
2.7
2.5
2.3
2.1
1.9
1.7
1.5
2.9
2.7
2.5
2.3
2.1
1.9
1.7
1.5
3.4
3.2
3.0
2.8
2.6
2.4
2.2
R
= 54Ω
R
= 44Ω
R = 100Ω
L
L
L
V
= 5.25V
CC
V
= 5V
V
= 5.25V
CC
CC
V
= 5.25V
CC
V
V
= 5V
CC
V
V
V
= 5V
CC
CC
CC
= 4.75V
= 4.5V
V
= 4.5V
CC
V
= 4.75V
CC
V
= 4.5V
CC
= 4.75V
CC
–55 –35 –15
5
25 45 65 85 105 125
–55 –35 –15
5
25 45 65 85 105 125
–55 –35 –15
5
25 45 65 85 105 125
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
1690 G17
1690 G16
1690 G18
Driver Common Mode Output
Voltage vs Temperature
Driver Common Mode Output
Voltage vs Temperature
Driver Common Mode Output
Voltage vs Temperature
3.0
2.5
2.0
1.5
1.0
0.5
0
3.0
2.5
2.0
1.5
1.0
0.5
0
3.0
2.5
2.0
1.5
1.0
0.5
0
V
= 5.25V
V
= 5.25V
CC
V
= 5.25V
CC
CC
V
= 5V
V
V
= 5V
V
V
= 5V
V
CC
CC
CC
= 4.75V
V
= 4.75V
V
= 4.75V
V
CC
CC
CC
= 4.5V
= 4.5V
= 4.5V
CC
CC
CC
R
= 44Ω
R
= 54Ω
R
= 100Ω
L
L
L
–55 –35 –15
5
25 45 65 85 105 125
–55 –35 –15
5
25 45 65 85 105 125
–55 –35 –15
5
25 45 65 85 105 125
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
1690 G19
1690 G20
1690 G21
5
LTC1690
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Driver Differential Output Voltage
vs Output Current
Driver Output High Voltage vs
Output Current
Driver Output Low Voltage vs
Output Current
100
90
80
70
60
50
40
30
20
10
0
–100
–80
–60
–40
–20
0
100
90
80
70
60
50
40
30
20
10
0
T
= 25°C
CC
T
= 25°C
CC
T
= 25°C
A
A
A
V
= 5V
V
= 5V
0
0.5
1
1.5
2
2.5
3
0
1
2
3
4
0
1
2
3
4
5
DRIVER OUTPUT LOW VOLTAGE (V)
DRIVER OUTPUT HIGH VOLTAGE (V)
DRIVER DIFFERENTIAL OUTPUT VOLTAGE (V)
1690 G24
1690 G23
1690 G22
Driver Propagation Delay vs
Temperature
Driver Propagation Delay vs
Supply Voltage
Driver Skew vs Temperature
30
25
20
15
10
5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
30
25
20
15
10
5
V
= 5V
V
= 5V
CC
CC
t
t
PHL
t
t
PHL
PLH
PLH
0
0
4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 5.3 5.4 5.5
SUPPLY VOLTAGE (V)
–55 –35 –15
5
25 45 65 85 105 125
–55 –35 –15
5
25 45 65 85 105 125
TEMPERATURE (°C)
TEMPERATURE (°C)
1690 G27
1690 G26
1690 G25
Driver Short-Circuit Current vs
Temperature
Receiver Input Resistance vs
Temperature
250
200
150
100
50
25
V
= 5.25V
V
= 5V
CC
CC
24
23
22
21
20
OUTPUT HIGH
SHORT TO –7V
V
V
= 12V
= –7V
CM
CM
OUTPUT LOW
SHORT TO 10V
0
–55 –35 –15
5
25 45 65 85 105 125
–55 –35 –15
5
25 45 65 85 105 125
TEMPERATURE (°C)
TEMPERATURE (°C)
1690 G29
1690 G30
6
LTC1690
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PIN FUNCTIONS
VCC (Pin 1): Positive Supply. 4.75V < VCC < 5.25V.
Y (Pin 5): Driver Output.
Z (Pin 6): Driver Output.
B (Pin 7): Receiver Input.
A (Pin 8): Receiver Input.
R (Pin 2): Receiver Output. R is high if (A – B) ≥ –10mV
and low if (A – B) ≤ –200mV.
D (Pin 3): Driver Input. If D is high, Y is taken high and Z
is taken low. If D is low, Y is taken low and Z is taken high.
GND (Pin 4): Ground.
TEST CIRCUITS
+
+
Y
C
C
A
B
L1
L2
375Ω
Y
Y
R
D
R
DIFF
R
V
OD2
+
Z
V
60Ω
375Ω
V
OD3
TST
R
15pF
V
OC
–7V TO 12V
Z
Z
1690 F02
1690 F01
1690 F03
Figure 1. Driver
DC Test Load #1
Figure 2. Driver
DC Test Load #2
Figure 3. Driver/Receiver
Timing Test Load
U
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SWITCHI G TI E WAVEFOR S
V
3V
OD2
f = 1MHz, t ≤ 10ns, t ≤ 10ns
r
f
A – B
–V
0V
0V
D
1.5V
1.5V
f = 1MHz, t ≤ 10ns, t ≤ 10ns
r
f
INPUT
0V
OD2
t
t
t
t
PLH
PLH
PHL
PHL
5V
V
O
90%
90%
50%
10%
50%
10%
R
V
1.5V
– t
1.5V
V
O
= V(A) – V(B)
OUTPUT
–V
O
Z
OL
t
t
f
r
1690 F05
NOTE: t
= |t
|
SKD
PHL PLH
V
O
Figure 5. Receiver Propagation Delays
Y
t
t
SKEW
1690 F04
SKEW
1/2 V
O
Figure 4. Driver Propagation Delays
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FUNCTION TABLES
Driver
Receiver
A – B
D
1
0
Z
0
1
Y
1
0
R
≥ –0.01V
≤ –0.20V
1
0
1
1
Inputs Open
Inputs Shorted
Note: Table valid with or without termination resistors.
7
LTC1690
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APPLICATIONS INFORMATION
A typical application is shown in Figure 6. Two twisted pair
wires connect two driver/receiver pairs for full duplex data
transmission. Notethatthedriverandreceiveroutputsare
always enabled. If the outputs must be disabled, use the
LTC491. There are no restrictions on where the chips are
connected, and it isn’t necessary to have the chips con-
nected to the ends of the wire. However, the wires must be
terminated at the ends with a resistor equal to their
characteristic impedance, typically 120Ω. Because only
one driver can be connected on the bus, the cable need
only be terminated at the receiving end. The optional
shields around the twisted pair are connected to GND at
one end and help reduce unwanted noise.
logic 1 state when the receiver inputs are left floating or
shorted together. This is achieved without external com-
ponents by designing the trip-point of the LTC1690 to be
within –200mV to –10mV. If the receiver output must be
a logic 0 instead of a logic 1, external components are
required.
The LTC1690 fail-safe receiver is designed to reject fast
–7V to 12V common mode steps at its inputs. The slew
rate that the receiver will reject is typically 400V/µs, but
–7V to 12V steps in 10ns can be tolerated if the frequency
of the common mode step is moderate (<600kHz).
Driver-Receiver Crosstalk
The LTC1690 can be used as a line repeater as shown in
Figure 7. If the cable is longer that 4000 feet, the LTC1690
is inserted in the middle of the cable with the receiver
output connected back to the driver input.
The driver outputs generate fast rise and fall times. If the
LTC1690 receiver inputs are not terminated and floating,
switching noise from the LTC1690 driver can couple into
the receiver inputs and cause the receiver output to glitch.
This can be prevented by ensuring that the receiver inputs
are terminated with a 100Ω or 120Ω resistor, depending
on the type of cable used. A cable capacitance that is
greater than 10pF (≈1ft of cable) also prevents glitches if
no termination is present. The receiver inputs should not
be driven typically above 8MHz to prevent glitches.
Receiver Fail-Safe
Some encoding schemes require that the output of the
receiver maintains a known state (usually a logic 1) when
data transmission ends and all drivers on the line are
forced into three-state. The receiver of the LTC1690 has a
fail-safe feature which guarantees the output to be in a
5V
5V
1
1
LTC1690
LTC1690
SHIELD
5
6
8
3
2
120Ω
D
DRIVER
RECEIVER
R
D
7
0.01µF
0.01µF
SHIELD
7
8
6
5
2
4
3
4
120Ω
R
RECEIVER
DRIVER
1690 F06
Figure 6. Typical Application
8
LTC1690
U
W U U
APPLICATIONS INFORMATION
Fault Protection
toVCC, thecurrentwillbelimitedtoamaximumof250mA.
If the die temperature rises above 150°C, the thermal
shutdown circuit three-states the driver outputs to open
thecurrentpath. Whenthediecoolsdowntoabout130°C,
the driver outputs are taken out of three-state. If the short
persists, the part will heat again and the cycle will repeat.
Thisthermaloscillationoccursatabout10Hzandprotects
the part from excessive power dissipation. The average
fault current drops as the driver cycles between active and
three-state.Whentheshortisremoved,thepartwillreturn
to normal operation.
When shorted to –7V or 10V at room temperature, the
short-circuit current in the driver outputs is limited by
internal resistance or protection circuitry to 250mA maxi-
mum. Over the industrial temperature range, the absolute
maximum positive voltage at any driver output should be
limited to 10V to avoid damage to the driver outputs. At
higher ambient temperatures, the rise in die temperature
due to the short-circuit current may trip the thermal
shutdown circuit.
The receiver inputs can withstand the entire –7V to 12V
RS485 common mode range without damage.
If the outputs of two or more LTC1690 drivers are shorted
directly, the driver outputs cannot supply enough current
to activate the thermal shutdown. Thus, the thermal shut-
down circuit will not prevent contention faults when two
drivers are active on the bus at the same time.
The LTC1690 includes a thermal shutdown circuit that
protects the part against prolonged shorts at the driver
outputs. If a driver output is shorted to another output or
LTC1690
5
3
DATA
OUT
D
R
DRIVER
6
8
7
2
120Ω
DATA
IN
RECEIVER
1690 F07
Figure 7. Line Repeater
9
LTC1690
U
W U U
APPLICATIONS INFORMATION
Cables and Data Rate
ESD PROTECTION
The transmission line of choice for RS485 applications is
a twisted pair. There are coaxial cables (twinaxial) made
for this purpose that contain straight pairs, but these are
less flexible, more bulky and more costly than twisted
pairs. Many cable manufacturers offer a broad range of
120Ω cables designed for RS485 applications.
TheESDperformanceoftheLTC1690driveroutputs(Z,Y)
and the receiver inputs (A, B) is as follows:
a) Meets ±15kV Human Body Model (100pF, 1.5kΩ).
b) MeetsIEC1000-4-2Level4(±8kV)contactmodespeci-
fications.
c) Meets IEC1000-4-2 Level 3 (±8kV) air discharge speci-
Losses in a transmission line are a complex combination
of DC conductor loss, AC losses (skin effect), leakage and
AC losses in the dielectric. In good polyethylene cables
such as Belden 9841, the conductor losses and dielectric
losses are of the same order of magnitude, leading to
relatively low overall loss (Figure 8).
fications.
ThislevelofESDperformancemeansthatexternalvoltage
suppressors are not required in many applications, when
compared with parts that are only protected to ±2kV. The
LTC1690 driver input (D) and receiver output are pro-
tected to ±2kV per the Human Body Model.
When using low loss cable, Figure 9 can be used as a
guideline for choosing the maximum length for a given
datarate. WithlowerqualityPVCcables, thedielectricloss
factor can be 1000 times worse. PVC twisted pairs have
terrible losses at high data rates (>100kbits/s), reducing
the maximum cable length. At low data rates, they are
acceptable and are more economical. The LTC1690 is
tested and guaranteed to drive CAT 5 cable and termina-
tions as well as common low cost residential telephone
wire.
When powered up, the LTC1690 does not latch up or
sustain damage when the Z, Y, A or B pins are subjected
to any of the conditions listed above. The data during the
ESD event may be corrupted, but after the event the
LTC1690 continues to operate normally.
The additional ESD protection at the LTC1690 Z, Y, A and
B pins is important in applications where these pins are
exposed to the external world via socket connections.
10
10k
1k
1.0
100
10
0.1
0.1
1.0
10
100
10k
100k
1M 2.5M
10M
FREQUENCY (MHz)
DATA RATE (bps)
1690 F08
1690 F09
Figure 8. Attenuation vs Frequency for Belden 9841
Figure 9. RS485 Cable Length Recommended. Applies
for 24 Gauge, Polyethylene Dielectric Twisted Pair
10
LTC1690
U
PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted.
MS8 Package
8-Lead Plastic MSOP
(LTC DWG # 05-08-1660)
0.118 ± 0.004*
(3.00 ± 0.102)
8
7
6
5
0.040 ± 0.006
(1.02 ± 0.15)
0.034 ± 0.004
(0.86 ± 0.102)
0.007
(0.18)
0° – 6° TYP
0.118 ± 0.004**
(3.00 ± 0.102)
SEATING
PLANE
0.193 ± 0.006
(4.90 ± 0.15)
0.012
(0.30)
REF
0.021 ± 0.006
(0.53 ± 0.015)
0.006 ± 0.004
(0.15 ± 0.102)
0.0256
(0.65)
BSC
MSOP (MS8) 1098
1
2
3
4
* DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH,
PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
N8 Package
8-Lead PDIP (Narrow 0.300)
(LTC DWG # 05-08-1510)
0.400*
(10.160)
MAX
0.130 ± 0.005
0.300 – 0.325
0.045 – 0.065
(3.302 ± 0.127)
(1.143 – 1.651)
(7.620 – 8.255)
8
7
6
5
0.065
(1.651)
TYP
0.255 ± 0.015*
(6.477 ± 0.381)
0.009 – 0.015
(0.229 – 0.381)
0.125
(3.175)
MIN
0.020
(0.508)
MIN
+0.035
–0.015
1
2
4
3
0.325
0.018 ± 0.003
(0.457 ± 0.076)
0.100
(2.54)
BSC
+0.889
8.255
(
)
N8 1098
–0.381
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)
S8 Package
8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 – 0.197*
(4.801 – 5.004)
0.010 – 0.020
(0.254 – 0.508)
7
5
8
6
× 45°
0.053 – 0.069
(1.346 – 1.752)
0.004 – 0.010
(0.101 – 0.254)
0.008 – 0.010
(0.203 – 0.254)
0°– 8° TYP
0.150 – 0.157**
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
0.016 – 0.050
(0.406 – 1.270)
0.050
(1.270)
BSC
0.014 – 0.019
(0.355 – 0.483)
TYP
*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
1
3
4
2
SO8 1298
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 represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
11
LTC1690
U
TYPICAL APPLICATIONS
Receiver with Low Fail-Safe Output
RS232 Receiver
5V
1.2k
2.7k
RS232 IN
120Ω
RX
2.7k
RX
RECEIVER
RECEIVER
1.2k
1690 TA02
1690 TA03
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
Low Power
LTC485
5V Low Power RS485 Interface Transceiver
LTC1480
3.3V Ultralow Power RS485 Transceiver with Shutdown
5V Ultralow Power RS485 Transceiver with Shutdown
5V Low Power RS485 Transceiver with Carrier Detect Output
Lower Supply Voltage
Lowest Power
LTC1481
LTC1482
Low Power, High Output State when Inputs are Open,
Shorted or Terminated, ±15kV ESD Protection
LTC1483
LTC1484
5V Ultralow Power RS485 Low EMI Transceiver with Shutdown
5V Low Power RS485 Transceiver with Fail-Safe Receiver Circuit
Low EMI, Lowest Power
Low Power, High Output State when Inputs are Open,
Shorted or Terminated, ±15kV ESD Protection
LTC1485
LTC1487
5V RS485 Transceiver
High Speed, 10Mbps
5V Ultralow Power RS485 with Low EMI, Shutdown and
High Input Impedance
Highest Input Impedance, Low EMI, Lowest Power
LTC490
5V Differential Driver and Receiver Pair
5V Low Power RS485 Full-Duplex Transceiver
Isolated RS485 Transceiver
Low Power, Pin Compatible with LTC1690
Low Power
LTC491
LTC1535
2500V
Isolation, Full Duplex
RMS
LTC1685
52Mbps, RS485 Fail-Safe Transceiver
Pin Compatible with LTC485
Pin Compatible with LTC490/LTC491
±15kV ESD Protection
LTC1686/LTC1687
LT1785/LT1791
52Mbps, RS485 Fail-Safe Driver/Receiver
±60V Fault Protected RS485 Half-/Full-Duplex Transceiver
1690f LT/TP 0400 4K • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
12
●
●
LINEAR TECHNOLOGY CORPORATION 1998
(408)432-1900 FAX:(408)434-0507 www.linear-tech.com
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