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LTC1690 Differential Driver and Receiver Pair with Fail-Safe Receiver Output
FEATURES
s
DESCRIPTIO
s
s s s s
s
s s s s
No Damage or Latchup to 15kV ESD (Human Body Model), IEC1000-4-2 Level 4 (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 = 600A 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 Pin Compatible with the SN75179 and LTC490 Available in SO, MSOP and PDIP Packages
The LTC(R)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. 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 shutdown circuit which forces the driver outputs into a high impedance state. The LTC1690 is fully specified over the commercial and industrial temperature ranges. The LTC1690 is available in 8-Pin SO, MSOP and PDIP packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
s s s s
Battery-Powered RS485/RS422 Applications Low Power RS485/RS422 Transceiver Level Translator Line Repeater
TYPICAL APPLICATIO
LTC1690 5 D1 3 DRIVER 6 Z1 Y1 120
LTC1690 A2 120 7 B2 8 RECEIVER 2 R2
B2 D1
7 R1 2 RECEIVER 8
B1 120 A1
Z2 120
6 5 DRIVER 3 D2
Y2
1690 TA01
U
Driving a 1000 Foot STP Cable
A2 R2
1690 TA01a
U
U
1
LTC1690
ABSOLUTE MAXIMUM RATINGS
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 ........................................... 125C
PACKAGE/ORDER INFORMATION
ORDER PART NUMBER
TOP VIEW VCC R D GND 1 2 3 4 8 7 6 5 A B Z Y
TOP VIEW VCC 1 R2 D3 GND 4 D 5 R 8 7 6 A B Z Y
LTC1690CMS8
MS8 PACKAGE 8-LEAD PLASTIC MSOP TJMAX = 125C, JA = 200C/W
MS8 PART MARKING LTDA
Consult factory for Military Grade Parts
DC ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER VOD1 VOD2 VOD3 VOD VOC |VOC| VIH VIL IIN1 IIN2 VTH VTH Differential Driver Output Voltage (Unloaded) Differential Driver Output Voltage (with Load) Differential Driver Output Voltage (with Common Mode) Change in Magnitude of Driver Differential Output Voltage for Complementary Output States Driver Common Mode Output Voltage Change in Magnitude of Driver Common Mode Output Voltage for Complementary Output States Input High Voltage Input Low Voltage Input Current Input Current (A, B) Differential Input Threshold Voltage for Receiver Receiver Input Hysteresis
The q denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VCC = 5V 5% (Notes 2, 3)
CONDITIONS IO = 0 R = 50; (RS422) R = 22 or 27; (RS485), Figure 1 VTST = -7V to 12V, Figure 2 R = 22, 27 or 50, Figure 1 VTST = -7V to 12V, Figure 2 R = 22, 27 or 50, Figure 1 R = 22, 27 or 50, Figure 1 Driver Input (D) Driver Input (D) Driver Input (D) VCC = 0V or 5.25V, VIN = 12V VCC = 0V or 5.25V, VIN = -7V -7V VCM 12V VCM = 0V
q q q q q q q q q q q q
2
U
U
W
WW U
W
(Note 1)
Operating Temperature Range LTC1690C ........................................ 0C TA 70C LTC1690I ..................................... - 40C TA 85C Storage Temperature Range ................. - 65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C
ORDER PART NUMBER LTC1690CN8 LTC1690IN8 LTC1690CS8 LTC1690IS8 S8 PART MARKING 1690 1690I
S8 PACKAGE 8-LEAD PLASTIC SO
N8 PACKAGE 8-LEAD PLASTIC DIP
TJMAX = 125C, JA = 130C/W (N) TJMAX = 125C, JA = 135C/W (S)
MIN 2 1.5 1.5
TYP
MAX VCC 5 5 0.2 3 0.2
UNITS V V V V V V V V
2 0.8 2 1 -0.8 - 0.20 30 - 0.01
V A mA mA V mV
LTC1690
DC ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER VOH VOL RIN ICC IOSD1 IOSD2 IOZ IOSR tPLH tPHL tSKEW tr, tf tPLH tPHL tSKD fMAX Receiver Output High Voltage Receiver Output Low Voltage Receiver Input Resistance Supply Current Driver Short-Circuit Current, VOUT = HIGH Driver Short-Circuit Current, VOUT = LOW Driver Three-State Current (Y, Z) Receiver Short-Circuit Current 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 |tPLH - tPHL|, Differential Receiver Skew, Figure 3, Figure 5 Maximum Data Rate, Figure 3, Figure 5
The q denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VCC = 5V 5% (Notes 2, 3)
CONDITIONS IO = - 4mA, VID = 200mV IO = 4mA, VID = - 200mV -7V VCM 12V No Load -7V VO 10V -7V VO 10V -7V VO 10V, VCC = 0V 0V VO VCC RDIFF = 54, CL1 = CL2 = 100pF RDIFF = 54, CL1 = CL2 = 100pF RDIFF = 54, CL1 = CL2 = 100pF RDIFF = 54, CL1 = CL2 = 100pF RDIFF = 54, CL1 = CL2 = 100pF RDIFF = 54, CL1 = CL2 = 100pF RDIFF = 54, CL1 = CL2 = 100pF RDIFF = 54, CL1 = CL2 = 100pF
q q q q q q q q q q q q q
MIN 3.5
TYP
MAX 0.4
UNITS V V k A mA mA A mA ns ns ns ns ns ns ns Mbps
12 35 35
22 260 600 250 250 5 200 85 22.5 25 2.5 13 94 89 5 60 60 15 40 160 160
7 10 10 2 30 30 5
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 VCC = 5V and TA = 25C.
TYPICAL PERFOR A CE CHARACTERISTICS
Receiver Input Threshold Voltage (Output High) vs Temperature
RECEIVER INPUT THRESHOLD VOLTAGE (mV) RECEIVER INPUT THRESHOLD VOLTAGE (mV)
0 -20 -40 -60 -80 -100 -120 -140 -160 -180 -200 -55 -35 -15 5 25 45 65 85 105 125 TEMPERATURE (C)
1690 G01
VCM = 12V VCM = 0V VCM = -7V
-60 -80 -100 -120 -140 -160 -180 -200 -55 -35 -15 5 25 45 65 85 105 125 TEMPERATURE (C)
1690 G02
RECEIVER HYSTERESIS (mV)
UW
VCC = 5V
Receiver Input Threshold Voltage (Output Low) vs Temperature
0 -20 -40 VCM = 12V VCM = 0V VCC = 5V 100 90 80 70 60 50 40 30 20 10
Receiver Hysteresis vs Temperature
VCC = 5V
VCM = 12V VCM = 0V
VCM = -7V
VCM = -7V
0 -55 -35 -15
5 25 45 65 85 105 125 TEMPERATURE (C)
1690 G03
3
LTC1690 TYPICAL PERFOR A CE CHARACTERISTICS
Receiver Input Offset Voltage vs Temperature
RECEIVER INPUT OFFSET VOLTAGE (mV)
-40 -60 -80 -100 -120 -140 -160 -180 -200 -55 -35 -15
-60 -80 -100 -120 -140 -160 4.5
VCM = 0V VCM = -7V
OUTPUT HIGH
RECEIVER OUTPUT CURRENT (mA)
-20
VCC = 5V
RECEIVER INPUT THRESHOLD VOLTAGE (mV)
0
VCM = 12V
5 25 45 65 85 105 125 TEMPERATURE (C)
1690 G04
Receiver Output Low Voltage vs Output Current
40
4.8
RECEIVER OUTPUT HIGH VOLTAGE (V)
RECEIVER OUTPUT CURRENT (mA)
35 30 25 20 15 10 5 0 0
4.6 4.4 4.2 4.0 3.8 3.6 3.4 3.2
RECEIVER OUTPUT LOW VOLTAGE (V)
TA = 25C VCC = 4.75V
0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 RECEIVER OUTPUT LOW VOLTAGE (V)
Receiver Propagation Delay vs Temperature
120 RECEIVER PROPAGATION DELAY (ns) VCC = 5V 110 RECEIVER SKEW (ns) 100 90 tPHL 80 70 60 -55 -35 -15 tPLH 10 9 8 7 6 5 4 3 5 25 45 65 85 105 125 TEMPERATURE (C)
1690 G10
RECEIVER PROPAGATION DELAY (ns)
4
UW
1690 G07
Receiver Input Threshold Voltage vs Supply Voltage
-40 TA = 25C
Receiver Output High Voltage vs Output Current
-25 TA = 25C VCC = 4.75V
-20
-15
OUTPUT LOW
-10
-5
0
4.75 5 5.25 SUPPLY VOLTAGE (V) 5.5
1690 G05
5
4.5 4 3 2.5 3.5 RECEIVER OUTPUT HIGH VOLTAGE (V)
2
1690 G06
Receiver Output High Voltage vs Temperature
0.7
I = 8mA VCC = 4.75V
Receiver Output Low Voltage vs Temperature
I = 8mA VCC = 4.75V
0.6 0.5 0.4 0.3 0.2 0.1
2
3.0 -55 -35 -15
5 25 45 65 85 105 125 TEMPERATURE (C)
1690 G08
0 -55 -35 -15
5 25 45 65 85 105 125 TEMPERATURE (C)
1690 G09
Receiver Skew tPLH - tPHL vs Temperature
110 VCC = 5V 100 90 80 70 60 50
Receiver Propagation Delay vs Supply Voltage
tPLH tPHL
2 -55 -35 -15
5 25 45 65 85 105 125 TEMPERATURE (C)
1690 G11
4.5 4.6 4.7 4.8 4.9 5 5.1 5.2 5.3 5.4 5.5 SUPPLY VOLTAGE (V)
1690 G12
LTC1690 TYPICAL PERFOR A CE CHARACTERISTICS
Receiver Short-Circuit Current vs Temperature
70 SHORT-CIRCUIT CURRENT (mA) VCC = 5.25V 60 50 40 30 20 10 0 -55 -35 -15 OUTPUT HIGH OUTPUT LOW SUPPLY CURRENT (A) 340 320 300 280 260 240 220 200 180 160 140 5 25 45 65 85 105 125 TEMPERATURE (C)
1690 G13
LOGIC INPUT THRESHOLD VOLTAGE (V)
Driver Differential Output Voltage vs Temperature
DRIVER DIFFERENTIAL OUTPUT VOLTAGE (V) DRIVER DIFFERENTIAL OUTPUT VOLTAGE (V) 2.9 RL = 44 2.7 2.5 2.3 2.1 1.9 VCC = 4.5V 1.7 1.5 -55 -35 -15 VCC = 4.75V 5 25 45 65 85 105 125 TEMPERATURE (C)
1690 G16
2.7 2.5 2.3 2.1
VCC = 5.25V VCC = 5V
RL = 54
DRIVER DIFFERENTIAL OUTPUT VOLTAGE (V)
VCC = 5.25V VCC = 5V
Driver Common Mode Output Voltage vs Temperature
DRIVER COMMON MODE OUTPUT VOLTAGE (V) DRIVER COMMON MODE OUTPUT VOLTAGE (V) 3.0 2.5 VCC = 5.25V 2.0 1.5 1.0 0.5 RL = 44 0 -55 -35 -15 5 25 45 65 85 105 125 TEMPERATURE (C)
1690 G19
2.5 VCC = 5.25V 2.0 1.5 1.0 0.5 RL = 54 0 -55 -35 -15 5 25 45 65 85 105 125 TEMPERATURE (C)
1690 G20
DRIVER COMMON MODE OUTPUT VOLTAGE (V)
VCC = 5V VCC = 4.75V VCC = 4.5V
UW
Supply Current vs Temperature
1.75
Logic Input Threshold Voltage vs Temperature
1.70
VCC = 5.25V
VCC = 5.25V
1.65 VCC = 5V 1.60
VCC = 4.75V VCC = 5V
1.55
VCC = 4.75V
120 -55 -35 -15
5 25 45 65 85 105 125 TEMPERATURE (C)
1690 G14
1.50 -55 -35 -15
5 25 45 65 85 105 125 TEMPERATURE (C)
1690 G15
Driver Differential Output Voltage vs Temperature
2.9
3.4
Driver Differential Output Voltage vs Temperature
RL = 100 3.2 3.0 2.8 2.6 2.4 2.2 -55 -35 -15 VCC = 5.25V VCC = 5V VCC = 4.75V VCC = 4.5V
VCC = 4.5V 1.9 1.7 1.5 -55 -35 -15 VCC = 4.75V
5 25 45 65 85 105 125 TEMPERATURE (C)
1690 G17
5 25 45 65 85 105 125 TEMPERATURE (C)
1690 G18
Driver Common Mode Output Voltage vs Temperature
3.0 3.0 2.5
Driver Common Mode Output Voltage vs Temperature
VCC = 5V VCC = 4.75V VCC = 4.5V
VCC = 5.25V 2.0 1.5 1.0 0.5 RL = 100 0 -55 -35 -15
VCC = 5V VCC = 4.75V VCC = 4.5V
5 25 45 65 85 105 125 TEMPERATURE (C)
1690 G21
5
LTC1690 TYPICAL PERFOR A CE CHARACTERISTICS
Driver Differential Output Voltage vs Output Current
100 90 80 OUTPUT CURRENT (mA) OUTPUT CURRENT (mA) 70 60 50 40 30 20 10 0 0 1 2 3 4 5 DRIVER DIFFERENTIAL OUTPUT VOLTAGE (V)
1690 G22
TA = 25C -80
OUTPUT CURRENT (mA)
Driver Propagation Delay vs Temperature
30 DRIVER PROPAGATION DELAY (ns) VCC = 5V 25 20 15 10 5 0 -55 -35 -15 tPHL DRIVER SKEW (ns) tPLH 3.5 3.0 2.5 2.0 1.5 4.0
DRIVER PROPAGATION DELAY (ns)
5 25 45 65 85 105 125 TEMPERATURE (C)
1690 G25
Driver Short-Circuit Current vs Temperature
DRIVER SHORT-CIRCUIT CURRENT (mA) 250 RECEIVER INPUT RESISTANCE (k) VCC = 5.25V 200 OUTPUT HIGH SHORT TO -7V 25
150
100
OUTPUT LOW SHORT TO 10V
50
0 -55 -35 -15
5 25 45 65 85 105 125 TEMPERATURE (C)
1690 G29
6
UW
Driver Output High Voltage vs Output Current
-100 TA = 25C VCC = 5V 100 90 80 70 60 50 40 30 20 10 0 0 0 1 2 3 4 DRIVER OUTPUT HIGH VOLTAGE (V)
1690 G23
Driver Output Low Voltage vs Output Current
TA = 25C VCC = 5V
-60
-40
-20
0
0.5 1 1.5 2 2.5 DRIVER OUTPUT LOW VOLTAGE (V)
3
1690 G24
Driver Skew vs Temperature
30 VCC = 5V 25 20 15 10 5 0
Driver Propagation Delay vs Supply Voltage
tPHL tPLH
1.0 -55 -35 -15
5 25 45 65 85 105 125 TEMPERATURE (C)
1690 G26
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)
1690 G27
Receiver Input Resistance vs Temperature
VCC = 5V 24
23
VCM = 12V
22
VCM = -7V
21
20 -55 -35 -15
5 25 45 65 85 105 125 TEMPERATURE (C)
1690 G30
LTC1690
PIN FUNCTIONS
VCC (Pin 1): Positive Supply. 4.75V < VCC < 5.25V. 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. Y (Pin 5): Driver Output. Z (Pin 6): Driver Output. B (Pin 7): Receiver Input. A (Pin 8): Receiver Input.
TEST CIRCUITS
Y R VOD2 R Z
1690 F01
VOC
Figure 1. Driver DC Test Load #1
SWITCHI G TI E WAVEFOR S
3V D 0V VO -VO Z VO Y t SKEW 1/2 VO t SKEW
1690 F04
1.5V
f = 1MHz, t r 10ns, t f 10ns tPLH 90% tr 90%
1.5V tPHL
50% 10%
VO = V(A) - V(B)
tf
Figure 4. Driver Propagation Delays
FUNCTION TABLES
Driver
D 1 0 Z 0 1 Y 1 0
W
W
U
U
U
U
U
U
+
375 Y
D Y RDIFF Z
CL1
A R
VOD3
60 375
VTST -7V TO 12V
1690 F02
+
CL2
B
+
15pF
Z
1690 F03
Figure 2. Driver DC Test Load #2
Figure 3. Driver/Receiver Timing Test Load
VOD2 A-B -VOD2 5V R VOL
0V
f = 1MHz, t r 10ns, t f 10ns INPUT tPHL 1.5V OUTPUT
0V tPLH 1.5V
1690 F05
50% 10%
NOTE: tSKD = |tPHL - tPLH|
Figure 5. Receiver Propagation Delays
Receiver
A-B - 0.01V - 0.20V Inputs Open Inputs Shorted R 1 0 1 1
Note: Table valid with or without termination resistors.
7
LTC1690
APPLICATIONS INFORMATION
A typical application is shown in Figure 6. Two twisted pair wires connect two driver/receiver pairs for full duplex data transmission. Note that the driver and receiver outputs are 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 connected to the ends of the wire. However, the wires must be terminated at the ends with a resistor equal to their characteristic impedance, typically 120. 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. 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. 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 logic 1 state when the receiver inputs are left floating or shorted together. This is achieved without external components 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/s, 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 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 100 or 120 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.
5V 1 LTC1690 5 D 3 DRIVER 6 SHIELD 120 7 8 RECEIVER 2 R LTC1690 1
0.01F 7 R 2 RECEIVER 120 8 5 SHIELD 6 DRIVER 3 D
4
1690 F06
Figure 6. Typical Application
8
U
W
U
U
5V
0.01F
4
LTC1690
APPLICATIONS INFORMATION
Fault Protection 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 maximum. 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. 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 to VCC, the current will be limited to a maximum of 250mA. If the die temperature rises above 150C, the thermal shutdown circuit three-states the driver outputs to open the current path. When the die cools down to about 130C, the driver outputs are taken out of three-state. If the short persists, the part will heat again and the cycle will repeat. This thermal oscillation occurs at about 10Hz and protects the part from excessive power dissipation. The average fault current drops as the driver cycles between active and three-state. When the short is removed, the part will return to normal operation. 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 shutdown circuit will not prevent contention faults when two drivers are active on the bus at the same time.
LTC1690 5 D 3 DRIVER 6 DATA OUT
R
2
RECEIVER
U
W
U
U
8 120 7 DATA IN
1690 F07
Figure 7. Line Repeater
9
LTC1690
APPLICATIONS INFORMATION
Cables and Data Rate 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 120 cables designed for RS485 applications. 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). When using low loss cable, Figure 9 can be used as a guideline for choosing the maximum length for a given data rate. With lower quality PVC cables, the dielectric loss 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 terminations as well as common low cost residential telephone wire. ESD PROTECTION The ESD performance of the LTC1690 driver outputs (Z, Y) and the receiver inputs (A, B) is as follows: a) Meets 15kV Human Body Model (100pF, 1.5k). b) Meets IEC1000-4-2 Level 4 (8kV) contact mode specifications. c) Meets IEC1000-4-2 Level 3 (8kV) air discharge specifications. This level of ESD performance means that external voltage 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 protected to 2kV per the Human Body Model. 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
LOSS PER 100 FT (dB)
CABLE LENGTH (FT)
0.1 1.0 10 100
1690 F08
1.0
0.1 FREQUENCY (MHz)
Figure 8. Attenuation vs Frequency for Belden 9841
10
U
W
U
U
10k
1k
100
10 10k
100k
1M
2.5M
10M
1690 F09
DATA RATE (bps)
Figure 9. RS485 Cable Length Recommended. Applies for 24 Gauge, Polyethylene Dielectric Twisted Pair
LTC1690
PACKAGE DESCRIPTION
0.007 (0.18) 0.021 0.006 (0.53 0.015)
0 - 6 TYP SEATING PLANE 0.012 (0.30) 0.0256 REF (0.65) BSC 0.193 0.006 (4.90 0.15) 0.118 0.004** (3.00 0.102)
* 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
0.300 - 0.325 (7.620 - 8.255)
0.009 - 0.015 (0.229 - 0.381)
0.065 (1.651) TYP 0.125 (3.175) 0.020 MIN (0.508) MIN 0.018 0.003 (0.457 0.076)
(
+0.035 0.325 -0.015 8.255 +0.889 -0.381
)
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)
0.010 - 0.020 x 45 (0.254 - 0.508) 0.008 - 0.010 (0.203 - 0.254) 0- 8 TYP
0.053 - 0.069 (1.346 - 1.752)
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
0.016 - 0.050 (0.406 - 1.270)
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.
U
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)
0.040 0.006 (1.02 0.15)
0.034 0.004 (0.86 0.102)
8
76
5
0.006 0.004 (0.15 0.102)
MSOP (MS8) 1098
1
23
4
N8 Package 8-Lead PDIP (Narrow 0.300)
(LTC DWG # 05-08-1510)
0.400* (10.160) MAX 8 7 6 5
0.045 - 0.065 (1.143 - 1.651)
0.130 0.005 (3.302 0.127)
0.255 0.015* (6.477 0.381)
1
2
3
4
0.100 (2.54) BSC
N8 1098
S8 Package 8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 - 0.197* (4.801 - 5.004) 8 0.004 - 0.010 (0.101 - 0.254) 0.228 - 0.244 (5.791 - 6.197) 0.150 - 0.157** (3.810 - 3.988) 7 6 5
0.050 (1.270) BSC
1
2
3
4
SO8 1298
11
LTC1690
TYPICAL APPLICATIONS
Receiver with Low Fail-Safe Output
5V 1.2k
120
RECEIVER
1.2k
1690 TA02
RELATED PARTS
PART NUMBER LTC485 LTC1480 LTC1481 LTC1482 LTC1483 LTC1484 LTC1485 LTC1487 LTC490 LTC491 LTC1535 LTC1685 LTC1686/LTC1687 LT1785/LT1791 DESCRIPTION 5V Low Power RS485 Interface Transceiver 3.3V Ultralow Power RS485 Transceiver with Shutdown 5V Ultralow Power RS485 Transceiver with Shutdown 5V Low Power RS485 Transceiver with Carrier Detect Output 5V Ultralow Power RS485 Low EMI Transceiver with Shutdown 5V Low Power RS485 Transceiver with Fail-Safe Receiver Circuit 5V RS485 Transceiver 5V Ultralow Power RS485 with Low EMI, Shutdown and High Input Impedance 5V Differential Driver and Receiver Pair 5V Low Power RS485 Full-Duplex Transceiver Isolated RS485 Transceiver 52Mbps, RS485 Fail-Safe Transceiver 52Mbps, RS485 Fail-Safe Driver/Receiver 60V Fault Protected RS485 Half-/Full-Duplex Transceiver COMMENTS Low Power Lower Supply Voltage Lowest Power Low Power, High Output State when Inputs are Open, Shorted or Terminated, 15kV ESD Protection Low EMI, Lowest Power Low Power, High Output State when Inputs are Open, Shorted or Terminated, 15kV ESD Protection High Speed, 10Mbps Highest Input Impedance, Low EMI, Lowest Power Low Power, Pin Compatible with LTC1690 Low Power 2500VRMS Isolation, Full Duplex Pin Compatible with LTC485 Pin Compatible with LTC490/LTC491 15kV ESD Protection
12
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com
U
RS232 Receiver
2.7k RS232 IN
RX
2.7k
RECEIVER
RX
1690 TA03
1690f LT/TP 0400 4K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1998

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