LTC2862/LTC2863/
LTC2864/LTC2865
±60V Fault Protected 3V to 5.5V
RS485/RS422 Transceivers
Features
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Description
Protected from Overvoltage Line Faults to ±60V
3V to 5.5V Supply Voltage
20Mbps or Low EMI 250kbps Data Rate
±15kV ESD Interface Pins, ±8kV All Other Pins
Extended Common Mode Range: ±25V
Guaranteed Failsafe Receiver Operation
High Input Impedance Supports 256 Nodes
1.65V to 5.5V Logic Supply Pin (VL) for Flexible
Digital Interface (LTC2865)
MP-Grade Option Available (–55°C to 125°C)
Fully Balanced Differential Receiver Thresholds for
Low Duty Cycle Distortion
Current Limited Drivers and Thermal Shutdown
Pin Compatible with LT1785 and LT1791
Available in DFN and Leaded Packages
The LTC®2862/LTC2863/LTC2864/LTC2865 are low power,
20Mbps or 250kbps RS485/RS422 transceivers operating
on 3V to 5.5V supplies that feature ±60V overvoltage fault
protection on the data transmission lines during all modes
of operation, including power-down. Low EMI slew rate
limited data transmission is available in a logic-selectable
250kbps mode in the LTC2865 and in 250kbps versions of
the LTC2862-LTC2864. Enhanced ESD protection allows
these parts to withstand ±15kV HBM on the transceiver
interface pins without latchup or damage.
Extended ±25V input common mode range and full failsafe operation improve data communication reliability in
electrically noisy environments and in the presence of
large ground loop voltages.
Product Selection Guide
Applications
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Supervisory Control and Data Acquisition (SCADA)
Industrial Control and Instrumentation Networks
Automotive and Transportation Electronics
Building Automation, Security Systems and HVAC
Medical Equipment
Lighting and Sound System Control
L, LT, LTC, LTM, Linear Technology the Linear logo and µModule are registered trademarks of
Linear Technology Corporation. All other trademarks are the property of their respective owners.
PART
NUMBER
DUPLEX
ENABLES
MAX DATA
RATE (bps)
VL PIN
LTC2862-1
HALF
YES
20M
NO
LTC2862-2
HALF
YES
250k
NO
LTC2863-1
FULL
NO
20M
NO
LTC2863-2
FULL
NO
250k
NO
LTC2864-1
FULL
YES
20M
NO
LTC2864-2
FULL
YES
250k
NO
LTC2865
FULL
YES
20M/250k
YES
Typical Application
LTC2865 Receiving 10Mbps ±200mV Differential
Signal with 1MHz ±25V Common Mode Sweep
RS485 Link With Large Ground Loop Voltage
LTC2862
LTC2862
VCC1
DI1
VCC2
R
RO1
RE1
DE1
R
Rt
RO2
RE2
DE2
Rt
D
D
GND1
V GROUND LOOP
≤25V PEAK
GND2
A,B
A,B
50V/DIV
2862345 TA01a
A-B
0.5V/DIV
A-B
DI2
RO
5V/DIV
RO
100ns/DIV
2862345 TA01b
2862345fc
For more information www.linear.com/LTC2862
1
LTC2862/LTC2863/
LTC2864/LTC2865
Absolute Maximum Ratings
(Note 1)
Supply Voltages
VCC............................................................. –0.3 to 6V
VL............................................................... –0.3 to 6V
Logic Input Voltages (RE, DE, DI, SLO)........... –0.3 to 6V
Interface I/O: A, B, Y, Z............................... –60V to +60V
Receiver Output (RO)
(LTC2862-LTC2864)....................–0.3V to (VCC+0.3V)
Receiver Output (RO)
(LTC2865) ...................................–0.3V to (VL + 0.3V)
Operating Ambient Temperature Range (Note 4)
LTC286xC................................................. 0°C to 70°C
LTC286xI..............................................–40°C to 85°C
LTC286xH........................................... –40°C to 125°C
LTC286xMP........................................ –55°C to 125°C
Storage Temperature Range................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec).................... 300°C
Pin Configuration
LTC2862-1, LTC2862-2
LTC2862-1, LTC2862-2
TOP VIEW
TOP VIEW
RO 1
8
VCC
RE 2
7
B
DE 3
6
A
DI 4
5
GND
S8 PACKAGE
8-LEAD (150mil) PLASTIC SO
TJMAX = 150°C, θJA = 150°C/W, θJC = 39°C/W
LTC2863-1, LTC2863-2
RO
1
RE
2
DE
3
DI
4
8 VCC
9
7 B
6 A
5 GND
DD PACKAGE
8-LEAD (3mm × 3mm) PLASTIC DFN
EXPOSED PAD (PIN 9) CONNECT TO PCB GND
TJMAX = 150°C, θJA = 43°C/W, θJC = 3°C/W
LTC2863-1, LTC2863-2
TOP VIEW
TOP VIEW
VCC 1
8
A
RO 2
7
B
DI 3
6
Z
GND 4
5
Y
S8 PACKAGE
8-LEAD (150mil) PLASTIC SO
TJMAX = 150°C, θJA = 150°C/W, θJC = 39°C/W
LTC2864-1, LTC2864-2
VCC
1
RO
2
DI
3
GND
4
8 A
9
7 B
6 Z
5 Y
DD PACKAGE
8-LEAD (3mm × 3mm) PLASTIC DFN
EXPOSED PAD (PIN 9) CONNECT TO PCB GND
TJMAX = 150°C, θJA = 43°C/W, θJC = 3°C/W
LTC2864-1, LTC2864-2
TOP VIEW
TOP VIEW
NC 1
14 VCC
RO
1
RO 2
13 NC
RE
2
RE 3
12 A
DE
3
11 B
DI
4
7 Z
GND
5
6 Y
DE 4
DI 5
10 Z
GND 6
9
Y
GND 7
8
NC
S PACKAGE
14-LEAD (150mil) PLASTIC SO
TJMAX = 150°C, θJA = 88°C/W, θJC = 37°C/W
10 VCC
9 A
11
8 B
DD PACKAGE
10-LEAD (3mm × 3mm) PLASTIC DFN
EXPOSED PAD (PIN 11) CONNECT TO PCB GND
TJMAX = 150°C, θJA = 43°C/W, θJC = 3°C/W
2862345fc
2
For more information www.linear.com/LTC2862
LTC2862/LTC2863/
LTC2864/LTC2865
PIN CONFIGURATION
LTC2865
LTC2865
TOP VIEW
RO
RE
DE
DI
VL
GND
1
2
3
4
5
6
13
TOP VIEW
12
11
10
9
8
7
VCC
A
B
Z
Y
SLO
MSE PACKAGE
12-LEAD PLASTIC MSOP
EXPOSED PAD (PIN 13) CONNECT TO PCB GND
TJMAX = 150°C, θJA = 40°C/W, θJC = 10°C/W
RO
1
12 VCC
RE
2
11 A
DE
3
DI
4
VL
GND
13
10 B
9
Z
5
8
Y
6
7
SLO
DE PACKAGE
12-LEAD (4mm × 3mm) PLASTIC DFN
EXPOSED PAD (PIN 13) CONNECT TO PCB GND
TJMAX = 150°C, θJA = 43°C/W, θJC = 4.3°C/W
Order Information
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC2862CS8-1#PBF
LTC2862CS8-1#TRPBF
28621
8-Lead (150mil) Plastic SO
0°C to 70°C
LTC2862IS8-1#PBF
LTC2862IS8-1#TRPBF
28621
8-Lead (150mil) Plastic SO
–40°C to 85°C
LTC2862HS8-1#PBF
LTC2862HS8-1#TRPBF
28621
8-Lead (150mil) Plastic SO
–40°C to 125°C
LTC2862CS8-2#PBF
LTC2862CS8-2#TRPBF
28622
8-Lead (150mil) Plastic SO
0°C to 70°C
LTC2862IS8-2#PBF
LTC2862IS8-2#TRPBF
28622
8-Lead (150mil) Plastic SO
–40°C to 85°C
LTC2862HS8-2#PBF
LTC2862HS8-2#TRPBF
28622
8-Lead (150mil) Plastic SO
–40°C to 125°C
LTC2862CDD-1#PBF
LTC2862CDD-1#TRPBF
LFXK
8-Lead (3mm × 3mm) Plastic DFN
0°C to 70°C
LTC2862IDD-1#PBF
LTC2862IDD-1#TRPBF
LFXK
8-Lead (3mm × 3mm) Plastic DFN
–40°C to 85°C
LTC2862HDD-1#PBF
LTC2862HDD-1#TRPBF
LFXK
8-Lead (3mm × 3mm) Plastic DFN
–40°C to 125°C
LTC2862CDD-2#PBF
LTC2862CDD-2#TRPBF
LFXM
8-Lead (3mm × 3mm) Plastic DFN
0°C to 70°C
LTC2862IDD-2#PBF
LTC2862IDD-2#TRPBF
LFXM
8-Lead (3mm × 3mm) Plastic DFN
–40°C to 85°C
LTC2862HDD-2#PBF
LTC2862HDD-2#TRPBF
LFXM
8-Lead (3mm × 3mm) Plastic DFN
–40°C to 125°C
LTC2863CS8-1#PBF
LTC2863CS8-1#TRPBF
28631
8-Lead (150mil) Plastic SO
0°C to 70°C
LTC2863IS8-1#PBF
LTC2863IS8-1#TRPBF
28631
8-Lead (150mil) Plastic SO
–40°C to 85°C
LTC2863HS8-1#PBF
LTC2863HS8-1#TRPBF
28631
8-Lead (150mil) Plastic SO
–40°C to 125°C
LTC2863CS8-2#PBF
LTC2863CS8-2#TRPBF
28632
8-Lead (150mil) Plastic SO
0°C to 70°C
LTC2863IS8-2#PBF
LTC2863IS8-2#TRPBF
28632
8-Lead (150mil) Plastic SO
–40°C to 85°C
LTC2863HS8-2#PBF
LTC2863HS8-2#TRPBF
28632
8-Lead (150mil) Plastic SO
–40°C to 125°C
LTC2863CDD-1#PBF
LTC2863CDD-1#TRPBF
LFXN
8-Lead (3mm × 3mm) Plastic DFN
0°C to 70°C
LTC2863IDD-1#PBF
LTC2863IDD-1#TRPBF
LFXN
8-Lead (3mm × 3mm) Plastic DFN
–40°C to 85°C
LTC2863HDD-1#PBF
LTC2863HDD-1#TRPBF
LFXN
8-Lead (3mm × 3mm) Plastic DFN
–40°C to 125°C
LTC2863CDD-2#PBF
LTC2863CDD-2#TRPBF
LFXP
8-Lead (3mm × 3mm) Plastic DFN
0°C to 70°C
LTC2863IDD-2#PBF
LTC2863IDD-2#TRPBF
LFXP
8-Lead (3mm × 3mm) Plastic DFN
–40°C to 85°C
LTC2863HDD-2#PBF
LTC2863HDD-2#TRPBF
LFXP
8-Lead (3mm × 3mm) Plastic DFN
–40°C to 125°C
2862345fc
For more information www.linear.com/LTC2862
3
LTC2862/LTC2863/
LTC2864/LTC2865
order information
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC2864CS-1#PBF
LTC2864CS-1#TRPBF
LTC2864S-1
14-Lead (150mil) Plastic SO
0°C to 70°C
LTC2864IS-1#PBF
LTC2864IS-1#TRPBF
LTC2864S-1
14-Lead (150mil) Plastic SO
–40°C to 85°C
LTC2864HS-1#PBF
LTC2864HS-1#TRPBF
LTC2864S-1
14-Lead (150mil) Plastic SO
–40°C to 125°C
LTC2864CS-2#PBF
LTC2864CS-2#TRPBF
LTC2864S-2
14-Lead (150mil) Plastic SO
0°C to 70°C
LTC2864IS-2#PBF
LTC2864IS-2#TRPBF
LTC2864S-2
14-Lead (150mil) Plastic SO
–40°C to 85°C
LTC2864HS-2#PBF
LTC2864HS-2#TRPBF
LTC2864S-2
14-Lead (150mil) Plastic SO
–40°C to 125°C
LTC2864CDD-1#PBF
LTC2864CDD-1#TRPBF
LFXQ
10-Lead (3mm × 3mm) Plastic DFN
0°C to 70°C
LTC2864IDD-1#PBF
LTC2864IDD-1#TRPBF
LFXQ
10-Lead (3mm × 3mm) Plastic DFN
–40°C to 85°C
LTC2864HDD-1#PBF
LTC2864HDD-1#TRPBF
LFXQ
10-Lead (3mm × 3mm) Plastic DFN
–40°C to 125°C
LTC2864CDD-2#PBF
LTC2864CDD-2#TRPBF
LFXR
10-Lead (3mm × 3mm) Plastic DFN
0°C to 70°C
LTC2864IDD-2#PBF
LTC2864IDD-2#TRPBF
LFXR
10-Lead (3mm × 3mm) Plastic DFN
–40°C to 85°C
LTC2864HDD-2#PBF
LTC2864HDD-2#TRPBF
LFXR
10-Lead (3mm × 3mm) Plastic DFN
–40°C to 125°C
LTC2865CMSE#PBF
LTC2865CMSE#TRPBF
2865
12-Lead Plastic MSOP
0°C to 70°C
LTC2865IMSE#PBF
LTC2865IMSE#TRPBF
2865
12-Lead Plastic MSOP
–40°C to 85°C
LTC2865HMSE#PBF
LTC2865HMSE#TRPBF
2865
12-Lead Plastic MSOP
–40°C to 125°C
LTC2865CDE#PBF
LTC2865CDE#TRPBF
2865
12-Lead (4mm × 3mm) Plastic DFN
0°C to 70°C
LTC2865IDE#PBF
LTC2865IDE#TRPBF
2865
12-Lead (4mm × 3mm) Plastic DFN
–40°C to 85°C
LTC2865HDE#PBF
LTC2865HDE#TRPBF
2865
12-Lead (4mm × 3mm) Plastic DFN
–40°C to 125°C
LTC2862MPS8-1#PBF
LTC2862MPS8-1#TRPBF
28621
8-Lead (150mm) Plastic SO
–55°C to 125°C
LTC2862MPS8-2#PBF
LTC2862MPS8-2#TRPBF
28622
8-Lead (150mm) Plastic SO
–55°C to 125°C
LTC2863MPS8-1#PBF
LTC2863MPS8-1#TRPBF
28631
8-Lead (150mm) Plastic SO
–55°C to 125°C
LTC2863MPS8-2#PBF
LTC2863MPS8-2#TRPBF
28632
8-Lead (150mm) Plastic SO
–55°C to 125°C
LTC2864MPS-1#PBF
LTC2864MPS-1#TRPBF
LTC2864S-1
14-Lead (150mm) Plastic SO
–55°C to 125°C
LTC2864MPS-2#PBF
LTC2864MPS-2#TRPBF
LTC2864S-2
14-Lead (150mm) Plastic SO
–55°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
Electrical
Characteristics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = VL = 3.3V unless otherwise noted. (Note 2)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Supplies
VCC
Primary Power Supply
VL
Logic Interface Power Supply
ICCS
ICCTR
l
3
5.5
V
LTC2865 Only
l
1.65
VCC
V
Supply Current in Shutdown Mode
(C-, I-Grade) (N/A LTC2863)
DE = 0V, RE = VCC = VL
l
0
5
µA
Supply Current in Shutdown Mode
(H-, MP-Grade) (N/A LTC2863)
DE = 0V, RE = VCC = VL
l
0
40
µA
Supply Current with Both Driver and
Receiver Enabled (LTC2862-1, LTC2863-1,
LTC2864-1, LTC2865 with SLO High)
No Load, DE = VCC = VL, RE = 0V
l
900
1300
µA
2862345fc
4
For more information www.linear.com/LTC2862
LTC2862/LTC2863/
LTC2864/LTC2865
Electrical
Characteristics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = VL = 3.3V unless otherwise noted. (Note 2)
SYMBOL
PARAMETER
CONDITIONS
ICCTRS
Supply Current with Both Driver and
Receiver Enabled (LTC2862-2, LTC2863-2,
LTC2864-2, LTC2865 with SLO Low)
No Load, DE = VCC = VL, RE = 0V
l
MIN
TYP
MAX
3.3
8
UNITS
mA
Driver
|VOD|
Differential Driver Output Voltage
R = ∞ (Figure 1)
l
1.5
VCC
V
R = 27Ω (Figure 1)
l
1.5
5
V
R = 50Ω (Figure 1)
l
2
VCC
V
Δ|VOD|
Change in Magnitude of Driver Differential
Output Voltage
R = 27Ω or 50Ω (Figure 1)
l
0.2
V
VOC
Driver Common-Mode Output Voltage
R = 27Ω or 50Ω (Figure 1)
l
3
V
Δ|VOC|
Change in Magnitude of Driver
Common-Mode Output Voltage
R = 27Ω or 50Ω (Figure 1)
l
0.2
V
IOSD
Maximum Driver Short-Circuit Current
–60V ≤ (Y or Z) ≤ 60V (Figure 2)
l
IOZD
Driver Three-State (High Impedance)
Output Current on Y and Z
DE = 0V, VCC = 0V or 3.3V, VO = –25V,
25V
Receiver Input Current (A,B)
(C-, I-Grade LTC2863, LTC2864, LTC2865)
±150
±250
mA
l
±30
µA
VCC = 0V or 3.3V, VIN = 12V (Figure 3)
l
125
µA
VCC = 0V or 3.3V, VIN = –7V (Figure 3)
l
Receiver Input Current (A,B)
(H-, MP-Grade LTC2863, LTC2864,
LTC2865; C-, I-, H-, MP-Grade LTC2862)
VCC = 0V or 3.3V, VIN = 12V (Figure 3)
l
VCC = 0V or 3.3V, VIN = –7V (Figure 3)
l
RIN
Receiver Input Resistance
0 ≤ VCC ≤ 5.5V, VIN = –25V or 25V
(Figure 3)
VCM
Receiver Common Mode Input Voltage
(A + B)/2
VTH
Differential Input Signal Threshold
Voltage (A – B)
–25V ≤ VCM ≤ 25V
ΔVTH
Differential Input Signal Hysteresis
VCM = 0V
Differential Input Failsafe Threshold Voltage
–25V ≤ VCM ≤ 25V
Differential Input Failsafe Hysteresis
VCM = 0V
VOH
Receiver Output High Voltage
I(RO) = –3mA (Sourcing)
VL ≥ 2.25V, I(RO) = –3mA (LTC2865)
VL < 2.25V, I(RO) = –2mA (LTC2865)
l
l
l
VOL
Receiver Output Low Voltage
I(RO) = 3mA (Sinking)
l
0.4
V
IOZR
Receiver Three-State (High Impedance)
Output Current on RO
RE = High, RO = 0V or VCC
RO = 0V or VL (LTC2865)
l
±5
µA
IOSR
Receiver Short-Circuit Current
RE = Low, RO = 0V or VCC
RO = 0V or VL (LTC2865)
l
±20
mA
Receiver
IIN
µA
–100
143
µA
–100
112
l
–25
kΩ
25
±200
l
150
l
–200
µA
V
mV
mV
–50
0
25
mV
mV
VCC –0.4V
VL –0.4V
VL –0.4V
V
Logic (LTC2862, LTC2863, LTC2864)
VTH
Input Threshold Voltage (DE, DI, RE)
3.0 ≤ VCC ≤ 5.5V
l
IINL
Logic Input Current (DE, DI, RE)
0 ≤ VIN ≤ VCC
l
0.33 • VCC
0
0.67 • VCC
V
±5
µA
Logic (LTC2865)
VTH
Input Threshold Voltage (DE, DI, RE, SLO)
1.65V ≤ VL ≤ 5.5V
l
IINL
Logic Input Current (DE, DI, RE, SLO)
0 ≤ VIN ≤ VL
l
0.33 • VL
0
0.67 • VL
V
±5
µA
2862345fc
For more information www.linear.com/LTC2862
5
LTC2862/LTC2863/
LTC2864/LTC2865
Switching
Characteristics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = VL = 3.3V unless otherwise noted. (Note 2)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Driver – High Speed (LTC2862-1, LTC2863-1, LTC2864-1, LTC2865 with SLO High)
fMAX
Maximum Data Rate
(Note 3)
l
20
Mbps
tPLHD, tPHLD
Driver Input to Output
RDIFF = 54Ω, CL = 100pF (Figure 4)
l
25
50
ns
ΔtPD
Driver Input to Output Difference
|tPLHD – tPHLD|
RDIFF = 54Ω, CL = 100pF (Figure 4)
l
2
9
ns
tSKEWD
Driver Output Y to Output Z
RDIFF = 54Ω, CL = 100pF (Figure 4)
l
±10
ns
tRD, tFD
Driver Rise or Fall Time
RDIFF = 54Ω, CL = 100pF (Figure 4)
l
15
ns
tZLD, tZHD,
tLZD, tHZD
Driver Enable or Disable Time
RL = 500Ω, CL = 50pF, RE = 0V
(Figure 5)
l
180
ns
tZHSD, tZLSD
Driver Enable from Shutdown
RL =500Ω, CL = 50pF, RE = High
(Figure 5)
l
9
µs
tSHDND
Time to Shutdown
RL = 500Ω, CL = 50pF, RE = High
(Figure 5)
l
180
ns
4
Driver – Slew Rate Limited ( LTC2862-2, LTC2863-2, LTC2864-2, LTC2865 with SLO Low)
fMAX
Maximum Data Rate
(Note 3)
l
tPLHD, tPHLD
Driver Input to Output
RDIFF = 54Ω, CL = 100pF (Figure 4)
l
250
850
1500
ns
ΔtPD
Driver Input to Output Difference
|tPLHD – tPHLD|
RDIFF = 54Ω, CL = 100pF (Figure 4)
l
50
500
ns
tSKEWD
Driver Output Y to Output Z
RDIFF = 54Ω, CL = 100pF (Figure 4)
l
±500
ns
tRD, tFD
Driver Rise or Fall Time
RDIFF = 54Ω, CL =100pF (Figure 4)
l
1200
ns
tZLD, tZHD
Driver Enable Time
RL = 500Ω, CL = 50pF, RE = 0V
(Figure 5)
l
1200
ns
tLZD, tHZD
Driver Disable Time
RL = 500Ω, CL = 50pF, RE = 0V
(Figure 5)
l
180
ns
tZHSD, tZLSD
Driver Enable from Shutdown
RL = 500Ω, CL = 50pF, RE = High
(Figure 5)
l
10
µs
tSHDND
Time to Shutdown
RL =500Ω, CL = 50pF, RE = High
(Figure 5)
l
180
ns
tPLHR, tPHLR
Receiver Input to Output
CL = 15pF, VCM = 1.5V, |VAB| = 1.5V,
tR and tF < 4ns (Figure 6)
l
50
65
ns
tSKEWR
Differential Receiver Skew
|tPLHR – tPHLR|
CL = 15pF (Figure 6)
2
9
ns
tRR, tFR
Receiver Output Rise or Fall Time
CL = 15pF (Figure 6)
l
3
12.5
ns
tZLR, tZHR,
tLZR, tHZR
Receiver Enable/Disable Time
RL = 1k, CL = 15pF, DE = High (Figure 7)
l
40
ns
tZHSR, tZLSR
Receiver Enable from Shutdown
RL = 1k, CL = 15pF, DE = 0V, (Figure 7)
l
9
µs
tSHDNR
Time to Shutdown
RL = 1k, CL = 15pF, DE = 0V, (Figure 7)
l
100
ns
500
kbps
800
Receiver
Note 1. Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
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. Maximum data rate is guaranteed by other measured parameters
and is not tested directly.
Note 4. This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 150ºC when overtemperature protection is active.
Continuous operation above the specified maximum operating temperature
may result in device degradation or failure.
2862345fc
6
For more information www.linear.com/LTC2862
LTC2862/LTC2863/
LTC2864/LTC2865
Typical Performance Characteristics
3.0
2.5
2.0
1.5
10
1
3.0
4.0
4.5
VCC (V)
3.5
0.1
–50
5.5
5.0
ICCS
2862345 G01
80
0.0
60
–0.5
40
SLEW LIMITED
20
–1.0
50
100
TEMPERATURE (°C)
DRIVER DELAY (NON SLEW LIMITED) (ns)
DRIVER SKEW (NON SLEW LIMITED) (ns)
0.5
0
0
150
1000
SLEW LIMITED
30
800
NON SLEW LIMITED
20
–50
0
50
100
TEMPERATURE (°C)
700
150
VOH
2.3
VOD (V)
2.0
1.5
10
20
30
40
OUTPUT CURRENT (mA)
50
0
–50
–100
OUTPUT HIGH
–150
–200
–60
–40
–20
0
20
OUTPUT VOLTAGE (V)
2.1
1.9
1.7
2862345 G07
1.5
–50
0
50
100
TEMPERATURE (°C)
150
2862345 G08
60
VL Supply Current vs Data Rate
CL (RO) = 15pF
VCC = 5V
VL = 5V
400
VL = 3.3V
300
200
100
50
40
2862345 G06
500
RDIFF = 100Ω
RDIFF = 54Ω
VOL
OUTPUT LOW
100
600
1.0
0
60
45
50
55
40
SUPPLY CURRENT (mA)
150
2.5
0
35
200
Driver Differential Output Voltage
vs Temperature
2.5
0.0
30
2862345 G05
3.5
DRIVER OUTPUT VOLTAGE (V)
900
25
Driver Output Low/High Voltage
vs Output Current
0.5
50
4
Driver Output Short-Circuit
Current vs Voltage
RDIFF = 54Ω
CL = 100pF
2862345 G04
3.0
NON SLEW LIMITED
2862345 G03
DRIVER DELAY (SLEW LIMITED) (ns)
100
NON SLEW LIMITED
–1.5
–50
35
120
DRIVER SKEW (SLEW LIMITED) (ns)
1.0
100
8
Driver Propagation Delay vs
Temperature
RDIFF = 54Ω
CL = 100pF
150
12
2862345 G02
Driver Skew vs Temperature
1.5
200
SLEW LIMITED
150
50
100
TEMPERATURE (°C)
250
RDIFF = 54Ω
CL = 100pF
16
0
0
VL SUPPLY CURRENT (µA)
0
100
ICCTR
0.5
ICCTR
OUTPUT CURRENT (mA)
1.0
ICCTRS
1000
SUPPLY CURRENT (µA)
SUPPLY CURRENT (mA)
ICCTRS
3.5
20
DATA RATE (SLEW LIMITED) (kbps)
4.0
Supply Current vs Data Rate
Supply Current vs Temperature
10000
4.5
DATA RATE (NON SLEW LIMITED) (Mbps)
Supply Current vs VCC
TA = 25°C, VCC = VL = 3.3V, unless otherwise noted.
0
VL = 1.8V
0
5
VL = 2.5V
10
15
DATA RATE (Mbps)
20
2862345 G09
2862345fc
For more information www.linear.com/LTC2862
7
LTC2862/LTC2863/
LTC2864/LTC2865
TYPICAL PERFORMANCE Characteristics
58
VL = 5.5V
5.0
56
RECEIVER DELAY (ns)
RECEIVER OUTPUT VOLTAGE (V)
6.0
Receiver Propagation Delay
vs Temperature
4.0
VL = 3.3V
3.0
2.0
VL = 2.25V
VL = 1.65V
Receiver Skew vs Temperature
–1.6
VAB = 1.5V
CL = 15pF
54
52
50
1.0
48
VL = 1.65V TO 5.5V
0.0
4.0
6.0
0.0
8.0
2.0
OUTPUT CURRENT (ABSOLUTE VALUE) (mA)
46
–50
VAB = 1.5V
CL = 15pF
–1.8
RECEIVER SKEW (ns)
Receiver Output Voltage vs
Output Current (Source and Sink)
TA = 25°C, VCC = VL = 3.3V, unless otherwise noted.
–2.0
–2.2
–2.4
0
50
100
TEMPERATURE (°C)
2862345 G10
150
–2.6
–50
0
50
100
TEMPERATURE (°C)
150
2862345 G12
2862345 G11
Pin Functions
PIN NUMBER
PIN
NAME
LTC2862
LTC2863
LTC2864
(DFN)
LTC2864
(SO)
LTC2865
DESCRIPTION
RO
1
2
1
2
1
RE
2
-
2
3
2
DE
3
-
3
4
3
DI
4
3
4
5
4
VL
-
-
-
-
5
GND
Exposed Pad
SLO
5
9
-
4
9
-
5
11
-
6, 7
-
6
13
7
Y
-
5
6
9
8
Z
-
6
7
10
9
B
7
7
8
11
10
A
6
8
9
12
11
VCC
NC
8
1
10
14
1, 8, 13
12
Receiver Output. If the receiver output is enabled (RE low) and A–B > 200mV,
then RO will be high. If A–B < –200mV, then RO will be low. If the receiver
inputs are open, shorted, or terminated without a signal, RO will be high.
Receiver Enable. A low input enables the receiver. A high input forces the
receiver output into a high impedance state. If RE is high with DE low, the part
will enter a low power shutdown state.
Driver Enable. A high input on DE enables the driver. A low input will force the
driver outputs into a high impedance state. If DE is low with RE high, the part
will enter a low power shutdown state.
Driver Input. If the driver outputs are enabled (DE high), then a low on DI
forces the driver noninverting output Y low and inverting output Z high. A high
on DI, with the driver outputs enabled, forces the driver noninverting output Y
high and inverting output Z low.
Logic Supply: 1.65V ≤ VL ≤ VCC. Bypass with 0.1µF ceramic capacitor. Powers
RO, RE, DE, DI and SLO interfaces on LTC2865 only.
Ground.
Connect the exposed pads on the DFN and MSOP packages to GND
Slow Mode Enable. A low input switches the transmitter to the slew rate
limited 250kbps max data rate mode. A high input supports 20Mbps.
Noninverting Driver Output for LTC2863, LTC2864, LTC2865.
High-impedance when driver disabled or unpowered.
Inverting Driver Output for LTC2863, LTC2864, LTC2865.
High-impedance when driver disabled or unpowered.
Inverting Receiver Input (and Inverting Driver Output for LTC2862).
Impedance is > 96kΩ in receive mode or unpowered.
Noninverting Receiver Input (and Noninverting Driver Output for LTC2862).
Impedance is > 96kΩ in receive mode or unpowered.
Power Supply. 3V < VCC < 5.5V. Bypass with 0.1µF ceramic capacitor to GND.
Unconnected Pins. Float or connect to GND.
2862345fc
8
For more information www.linear.com/LTC2862
LTC2862/LTC2863/
LTC2864/LTC2865
FUNCTION Tables
LTC2862
LOGIC INPUTS
DE
RE
0
0
0
1
1
0
1
1
LTC2864, LTC2865:
MODE
A, B
RO
Receive
Shutdown
Transceive
Transmit
RIN
RIN
Active
Active
Active
High-Z
Active
High-Z
LOGIC INPUTS
DE
RE
0
0
0
1
1
0
1
1
MODE
A, B
Y, Z
RO
Receive
Shutdown
Transceive
Transmit
RIN
RIN
RIN
RIN
High-Z
High-Z
Active
Active
Active
High-Z
Active
High-Z
Block Diagrams
LTC2862
LTC2863
VCC
VCC
A*
RO
RO
RECEIVER
B*
A*
RE
DE
RECEIVER
MODE CONTROL
LOGIC
B*
Z*
DI
DRIVER
Y*
DI
DRIVER
GND
2862345 BDb
*15kV ESD
GND
2862345 BDa
*15kV ESD
LTC2864
LTC2865
VCC
VL
VCC
A*
A*
RO
RE
DE
RECEIVER
RO
DE
DRIVER
MODE CONTROL
LOGIC
Z*
DI
DRIVER
Y*
Y*
SLO
GND
GND
2862345 BDc
*15kV ESD
B*
RE
MODE CONTROL
LOGIC
Z*
DI
RECEIVER
B*
2862345 BDd
*15kV ESD
2862345fc
For more information www.linear.com/LTC2862
9
LTC2862/LTC2863/
LTC2864/LTC2865
Test Circuits
Y**
Y**
GND
OR DI
VCC*
+
VOD
–
DRIVER
R
+
VOC
–
R
Z**
IOSD
GND
OR DI
VCC*
DRIVER
+
–
Z**
–60V TO 60V
2862345 FO2
2862345 FO1
*LTC2865 ONLY: SUBSTITUTE VL FOR VCC
**LTC2862 ONLY: SUBSTITUTE A, B FOR Y, Z
*LTC2865 ONLY: SUBSTITUTE VL FOR VCC
**LTC2862 ONLY: SUBSTITUTE A, B FOR Y, Z
Figure 1. Driver DC Characteristics
Figure 2. Driver Output Short-Circuit Current
IIN
VIN
+
–
A OR B
B OR A
RECEIVER
2862345 FO3
V
RIN = IN
IIN
Figure 3. Receiver Input Current and Input Resistance
VCC*
Y**
DI
CL
DI
RDIFF
DRIVER
CL
Z**
tPLHD
0V
Y, Z
tPHLD
tSKEWD
VO
2862345 FO4
(Y–Z)
1/2 VO
90%
10%
0
0
tRD
**LTC2862 ONLY: SUBSTITUTE A, B FOR Y, Z
90%
10%
tFD
2862345 F04b
*LTC2865 ONLY: SUBSTITUTE VL FOR VCC
Figure 4. Driver Timing Measurement
2862345fc
10
For more information www.linear.com/LTC2862
LTC2862/LTC2863/
LTC2864/LTC2865
TEST CIRCUITS
GND
OR
VCC
RL
Y**
CL
VCC*
OR DI
GND
VCC*
DE
0V
DRIVER
tZLD,
tZLSD
VCC
RL
DE
1/2 VCC*
Z**
Y OR Z
VCC
OR
GND
CL
Z OR Y
tLZD
1/2 VCC
VOL
VOH
0.5V
0.5V
1/2 VCC
0V
tZHD,
tZHSD
*LTC2865 ONLY: SUBSTITUTE VL FOR VCC
**LTC2862 ONLY: SUBSTITUTE A, B FOR Y, Z
2862345 FO5
2862345 F05b
tHZD,
tSHDN
*LTC2865 ONLY: SUBSTITUTE VL FOR VCC
Figure 5. Driver Enable and Disable Timing Measurements
tSKEWR = |tPLHR – tPHLR|
VAB
±VAB/2
VCM
RO
RECEIVER
B
VCC*
CL
±VAB/2
0
A–B
–VAB
A
RO
0
2862345 FO6a
tPLHR
tPHLR
90%
1/2 VCC*
10%
90%
1/2 VCC*
10%
tRR
tFR
2862345 F06b
*LTC2865 ONLY: SUBSTITUTE VL FOR VCC
Figure 6. Receiver Propagation Delay Measurements
0V OR VCC
VCC OR 0V
DI = 0V OR VCC*
A
B
RECEIVER
RL
RO
CL
VCC*
OR
GND
VCC*
RE
0V
tZLR,
tZLSR
1/2 VCC*
tLZR
VCC*
RO
RE
RO
1/2 VCC*
VOL
VOH
0.5V
0.5V
1/2 VCC*
0V
tZHR,
tZHSR
2862345 FO7a
*LTC2865 ONLY: SUBSTITUTE VL FOR VCC
tHZR,
tSHDNR
2862345 F07b
*LTC2865 ONLY: SUBSTITUTE VL FOR VCC
Figure 7. Receiver Enable/Disable Time Measurements
2862345fc
For more information www.linear.com/LTC2862
11
LTC2862/LTC2863/
LTC2864/LTC2865
Applications Information
±60V Fault Protection
±25V Extended Common Mode Range
The LTC2862-LTC2865 devices answer application needs
for overvoltage fault-tolerant RS485/RS422 transceivers
operating from 3V to 5.5V power supplies. Industrial
installations may encounter common mode voltages
between nodes far greater than the –7V to 12V range
specified by the RS485 standards. Standard RS485
transceivers can be damaged by voltages above their typical
absolute maximum ratings of –8V to 12.5V. The limited
overvoltage tolerance of standard RS485 transceivers
makes implementation of effective external protection
networks difficult without interfering with proper data
network performance within the –7V to 12V region of
RS485 operation. Replacing standard RS485 transceivers
with the rugged LTC2862-LTC2865 devices may eliminate
field failures due to overvoltage faults without using costly
external protection devices.
To further increase the reliability of operation and extend
functionality in environments with high common mode
voltages due to electrical noise or local ground potential
differences due to ground loops, the LTC2862-LTC2865
devices feature an extended common mode operating
range of –25V to 25V. This extended common mode
range allows the LTC2862-LTC2865 devices to transmit
and receive under conditions that would cause data errors
and possible device damage in competing products.
The ±60V fault protection of the LTC2862 series is
achieved by using a high-voltage BiCMOS integrated circuit
technology. The naturally high breakdown voltage of this
technology provides protection in powered-off and highimpedance conditions. The driver outputs use a progressive
foldback current limit design to protect against overvoltage
faults while still allowing high current output drive.
The LTC2862 series is protected from ±60V faults even with
GND open, or VCC open or grounded. Additional precautions
must be taken in the case of VCC present and GND open.
The LTC2862 series chip will protect itself from damage,
but the chip ground current may flow out through the ESD
diodes on the logic I/O pins and into associated circuitry.
The system designer should examine the susceptibility
of the associated circuitry to damage if the condition of a
GND open fault with VCC present is anticipated.
The high voltage rating of the LTC2862 series makes it
simple to extend the overvoltage protection to higher
levels using external protection components. Compared
to lower voltage RS485 transceivers, external protection
devices with higher breakdown voltages can be used, so
as not to interfere with data transmission in the presence
of large common mode voltages. The Typical Applications
section shows a protection network against faults up to
±360V peak, while still maintaining the extended ±25V
common mode range on the signal lines.
12
±15kV ESD Protection
The LTC2862 series devices feature exceptionally robust
ESD protection. The transceiver interface pins (A,B,Y,Z)
feature protection to ±15kV HBM with respect to GND
without latchup or damage, during all modes of operation
or while unpowered. All the other pins are protected to ±8kV
HBM to make this a component capable of reliable operation
under severe environmental conditions.
Driver
The driver provides full RS485/RS422 compatibility. When
enabled, if DI is high, Y–Z is positive for the full-duplex
devices (LTC2863-LTC2865) and A–B is positive for the
half-duplex device (LTC2862).
When the driver is disabled, both outputs are highimpedance. For the full-duplex devices, the leakage on
the driver output pins is guaranteed to be less than 30µA
over the entire common mode range of –25V to 25V. On
the half-duplex LTC2862, the impedance is dominated by
the receiver input resistance, RIN.
Driver Overvoltage and Overcurrent Protection
The driver outputs are protected from short circuits to any
voltage within the Absolute Maximum range of –60V to
60V. The maximum current in a fault condition is ±250mA.
The driver includes a progressive foldback current limiting
circuit that continuously reduces the driver current limit
with increasing output fault voltage. The fault current is
less than ±15mA for fault voltages over ±40V.
All devices also feature thermal shutdown protection that
disables the driver and receiver in case of excessive power
dissipation (see Note 4).
2862345fc
For more information www.linear.com/LTC2862
LTC2862/LTC2863/
LTC2864/LTC2865
Applications Information
Full Failsafe Operation
When the absolute value of the differential voltage between
the A and B pins is greater than 200mV with the receiver
enabled, the state of RO will reflect the polarity of (A–B).
These parts have a failsafe feature that guarantees the
receiver output will be in a logic 1 state (the idle state)
when the inputs are shorted, left open, or terminated but
not driven, for more than about 3µs. The delay allows
normal data signals to transition through the threshold
region without being interpreted as a failsafe condition. This
failsafe feature is guaranteed to work for inputs spanning
the entire common mode range of –25V to 25V.
Most competing devices achieve the failsafe function by a
simple negative offset of the input threshold voltage. This
causes the receiver to interpret a zero differential voltage
as a logic 1 state. The disadvantage of this approach is
the input offset can introduce duty cycle asymmetry at the
receiver output that becomes increasingly worse with low
input signal levels and slow input edge rates.
Other competing devices use internal biasing resistors to
create a positive bias at the receiver inputs in the absence
of an external signal. This type of failsafe biasing is
ineffective if the network lines are shorted, or if the network
is terminated but not driven by an active transmitter.
the positive and negative thresholds. If this condition
persists for more than about 3µs the failsafe condition is
asserted and the RO pin is forced to the logic 1 state. This
circuit provides full failsafe operation with no negative
impact to receiver duty cycle symmetry, as shown in
Figure 8. The input signal in Figure 8 was obtained by
driving a 10Mbps RS485 signal through 1000 feet of cable,
thereby attenuating it to a ±200mV signal with slow rise
and fall times. Good duty cycle symmetry is observed at
RO despite the degraded input signal.
Enhanced Receiver Noise Immunity
An additional benefit of the fully symmetric receiver
thresholds is enhanced receiver noise immunity. The
differential input signal must go above the positive
threshold to register as a logic 1 and go below the
negative threshold to register as a logic 0. This provides
a hysteresis of 150mV (typical) at the receiver inputs for
any valid data signal. (An invalid data condition such as
a DC sweep of the receiver inputs will produce a different
observed hysteresis due to the activation of the failsafe
circuit.) Competing devices that employ a negative offset
of the input threshold voltage generally have a much
smaller hysteresis and subsequently have lower receiver
noise immunity.
RS485 Network Biasing
A, B
200mV/DIV
A–B
200mV/DIV
RO
1.6V/DIV
40ns/DIV
2862345 F08
Figure 8. Duty Cycle of Balanced Receiver with ±200mV
10Mbps Input Signal
The LTC2862 series uses fully symmetric positive and
negative receiver thresholds (typically ±75mV) to maintain
good duty cycle symmetry at low signal levels. The failsafe
operation is performed with a window comparator to
determine when the differential input voltage falls between
RS485 networks are usually biased with a resistive divider
to generate a differential voltage of ≥200mV on the data
lines, which establishes a logic 1 state (the idle state)
when all the transmitters on the network are disabled. The
values of the biasing resistors are not fixed, but depend
on the number and type of transceivers on the line and
the number and value of terminating resistors. Therefore,
the values of the biasing resistors must be customized to
each specific network installation, and may change if nodes
are added to or removed from the network.
The internal failsafe feature of the LTC2862-LTC2865
eliminates the need for external network biasing resistors
provided they are used in a network of transceivers with
similar internal failsafe features. The LTC2862-LTC2865
transceivers will operate correctly on biased, unbiased,
or under-biased networks.
2862345fc
For more information www.linear.com/LTC2862
13
LTC2862/LTC2863/
LTC2864/LTC2865
Applications Information
Hi-Z State
The receiver output is internally driven high (to VCC or VL)
or low (to GND) with no external pull-up needed. When the
receiver is disabled the RO pin becomes Hi-Z with leakage
of less than ±5μA for voltages within the supply range.
High Receiver Input Resistance
The receiver input load from A or B to GND for the LTC2863,
LTC2864, and LTC2865 is less than one-eighth unit load,
permitting a total of 256 receivers per system without
exceeding the RS485 receiver loading specification. All
grades of the LTC2862 and the H- and MP-grade devices
of the LTC2863, LTC2864, and LTC2865 have an input
load less than one-seventh unit load over the complete
temperature range of –40°C to 125°C. The increased input
load specification for these devices is due to increased
junction leakage at high temperature and the transmitter
circuitry sharing the A and B pins on the LTC2862. The
input load of the receiver is unaffected by enabling/disabling
the receiver or by powering/unpowering the part.
Supply Current
The unloaded static supply currents in these devices
are low —typically 900μA for non slew limited devices
and 3.3mA for slew limited devices. In applications
with resistively terminated cables, the supply current is
dominated by the driver load. For example, when using two
120Ω terminators with a differential driver output voltage
of 2V, the DC load current is 33mA, which is sourced by
the positive voltage supply. Power supply current increases
with toggling data due to capacitive loading and this term
can increase significantly at high data rates. A plot of
the supply current vs data rate is shown in the Typical
Performance Characteristics of this data sheet.
During fault conditions with a positive voltage larger than
the supply voltage applied to the transmitter pins, or during
transmitter operation with a high positive common mode
voltage, positive current of up to 80mA may flow from the
transmitter pins back to VCC. If the system power supply
or loading cannot sink this excess current, a 5.6V 1W
1N4734 Zener diode may be placed between VCC and GND
to prevent an overvoltage condition on VCC.
There are no power-up sequence restrictions on the
LTC2865. However, correct operation is not guaranteed for
VL > VCC.
Shutdown Mode Delay
The LTC2862, LTC2864, and LTC2865 feature a low power
shutdown mode that is entered when both the driver and
the receiver are simultaneously disabled (pin DE low and
RE high). A shutdown mode delay of approximately 250ns
(not tested in production) is imposed after this state is
received before the chip enters shutdown. If either DE goes
high or RE goes low during this delay, the delay timer is
reset and the chip does not enter shutdown. This reduces
the chance of accidentally entering shutdown if DE and
RE are driven in parallel by a slowly changing signal or if
DE and RE are driven by two independent signals with a
timing skew between them.
This shutdown mode delay does not affect the outputs of
the transmitter and receiver, which start to switch to the
high impedance state upon the reception of their respective disable signals as defined by the parameters tSHDND
and tSHDNR. The shutdown mode delay affects only the
time when all the internal circuits that draw DC power
from VCC are turned off.
High Speed Considerations
A ground plane layout with a 0.1µF bypass capacitor placed
less than 7mm away from the VCC pin is recommended. The
PC board traces connected to signals A/B and Z/Y should
be symmetrical and as short as possible to maintain good
differential signal integrity. To minimize capacitive effects,
the differential signals should be separated by more than
the width of a trace and should not be routed on top of
each other if they are on different signal planes.
Care should be taken to route outputs away from any
sensitive inputs to reduce feedback effects that might
cause noise, jitter, or even oscillations. For example, in
the full-duplex devices, DI and A/B should not be routed
near the driver or receiver outputs.
The logic inputs have a typical hysteresis of 100mV to
provide noise immunity. Fast edges on the outputs can
cause glitches in the ground and power supplies which are
2862345fc
14
For more information www.linear.com/LTC2862
LTC2862/LTC2863/
LTC2864/LTC2865
Applications Information
exacerbated by capacitive loading. If a logic input is held
near its threshold (typically VCC/2 or VL/2), a noise glitch
from a driver transition may exceed the hysteresis levels on
the logic and data input pins, causing an unintended state
change. This can be avoided by maintaining normal logic
levels on the pins and by slewing inputs faster than 1V/
μs. Good supply decoupling and proper driver termination
also reduce glitches caused by driver transitions.
RS485 Cable Length vs Data Rate
Many factors contribute to the maximum cable length
that can be used for RS485 or RS422 communication,
including driver transition times, receiver threshold, duty
cycle distortion, cable properties and data rate. A typical
curve of cable length versus maximum data rate is shown
in Figure 9. Various regions of this curve reflect different
performance limiting factors in data transmission.
At frequencies below 100kbps, the maximum cable length is
determined by DC resistance in the cable. In this example,
a cable longer than 4000ft will attenuate the signal at the
far end to less than what can be reliably detected by the
receiver.
For data rates above 100kbps the capacitive and inductive
properties of the cable begin to dominate this relationship.
The attenuation of the cable is frequency and length
dependent, resulting in increased rise and fall times at
the far end of the cable. At high data rates or long cable
lengths, these transition times become a significant part
of the signal bit time. Jitter and intersymbol interference
aggravate this so that the time window for capturing valid
data at the receiver becomes impossibly small.
The boundary at 20Mbps in Figure 9 represents the
guaranteed maximum operating rate of the LTC2862
series. The dashed vertical line at 10Mbps represents the
specified maximum data rate in the RS485 standard. This
boundary is not a limit, but reflects the maximum data
rate that the specification was written for.
It should be emphasized that the plot in Figure 9 shows
a typical relation between maximum data rate and
cable length. Results with the LTC2862 series will vary,
depending on cable properties such as conductor gauge,
characteristic impedance, insulation material, and solid
versus stranded conductors.
Low EMI 250kbps Data Rate
The LTC2862-2, LTC2863-2, and the LTC2864-2 feature
slew rate limited transmitters for low electromagnetic
interference (EMI) in sensitive applications. In addition,
the LTC2865 has a logic-selectable 250kbps transmit rate.
The slew rate limit circuit maintains consistent control of
transmitter slew rates across voltage and temperature to
ensure low EMI under all operating conditions. Figure 10
demonstrates the reduction in high frequency content
achieved by the 250kbps mode compared to the 20Mbps
mode.
20
100
LOW EMI
MODE
SLO = GND
RS485
STANDARD
SPEC
10
10k
100k
1M
10M
DATA RATE (bps)
0
Y–Z (NON SLEW LIMITED) (dB)
1k
80
–20
40
–40
20
–60
0
–80
–20
–100
100M
–120
–40
SLEW LIMITED
0
2
4
6
8
FREQUENCY (MHz)
10
–60
12
2862345 F10
2862345 F09
Figure 9. Cable Length vs Data Rate (RS485/RS422 Standard
Shown in Vertical Solid Line)
60
NON SLEW LIMITED
Y–Z (SLEW LIMITED) (dB)
CABLE LENGTH (FT)
10k
Figure 10. High Frequency EMI Reduction of Slew Limited
250kbps Mode Compared to Non Slew Limited 20Mbps Mode
2862345fc
For more information www.linear.com/LTC2862
15
LTC2862/LTC2863/
LTC2864/LTC2865
Applications Information
The 250kbps mode has the added advantage of reducing
signal reflections in an unterminated network, and thereby increasing the length of a network that can be used
without termination. Using the rule of thumb that the rise
time of the transmitter should be greater than four times
the one-way delay of the signal, networks of up to 140
feet can be driven without termination.
cable to attenuate the transmitted signal to meet the
PROFIBUS upper limit of 7V while still providing enough
drive strength to meet the lower limit of 4V.
4. The LTC2865 family transceiver should be powered by
a 5% tolerance 5V supply (4.75V to 5.25V) to ensure
that the PROFIBUS VOD tolerances are met.
Auxiliary Protection For IEC Surge, EFT and ESD
PROFIBUS Compatible Interface
PROFIBUS is an RS485-based field bus. In addition
to the specifications of TIA/EIA-485-A, the PROFIBUS
specification contains additional requirements for cables,
interconnects, line termination, and signal levels. The
following discussion applies to the PROFIBUS Type A cables
with associated connectors and termination. The Type A
cable is a twisted pair shielded cable with a characteristic
impedance of 135Ω to 165Ω and a loop resistance of
< 110Ω/km.
The LTC2865 family of RS485 transceivers may be used
in PROFIBUS compatible equipment if the following
considerations are implemented. (Please refer to the
schematic of the PROFIBUS Compatible Interface in the
Typical Applications Section.)
1. The polarity of the PROFIBUS signal is opposite to the
polarity convention used in this data sheet. The PROFIBUS B wire is driven by a non-inverted signal, while
the A wire is driven by an inverted signal. Therefore,
it is necessary to swap the output connections from
the transceiver. Pin A is connected to the PROFIBUS B
wire, and Pin B is connected to the PROFIBUS A wire.
2. Each end of the PROFIBUS line is terminated with a
220Ω resistor between B and A, a 390Ω pull-up resistor between B and VCC, and a 390Ω pull-down resistor
be-tween A and GND. This provides suitable termination
for the 150Ω twisted pair transmission cable.
3. The peak to peak differential voltage VOD received at
the end of a 100m cable with the cable and terminations described above must be greater than 4V and less
than 7V. The LTC2865 family produces signal levels in
excess of 7V when driving this network directly. 8.2Ω
resistors may be inserted between the A and B pins of
the transceiver and the B and A pins of the PROFIBUS
An interface transceiver used in an industrial setting
may be exposed to extremely high levels of electrical
overstress due to phenomena such as lightning surge,
electrical fast transient (EFT) from switching high current
inductive loads, and electrostatic discharge (ESD) from
the discharge of electrically charged personnel or equipment. Test methods to evaluate immunity of electronic
equipment to these phenomenon are defined in the IEC
standards 61000-4-2, 61000-4-4, and 61000-4-5, which
address ESD, EFT, and surge, respectively. The transients produced by the EFT and particularly the surge tests
contain much more energy than the ESD transients. The
LTC2865 family is designed for high robustness against
ESD, but the on-chip protection is not able to absorb the
energy associated with the 61000-4-5 surge transients.
Therefore, a properly designed external protection network
is necessary to achieve a high level of surge protection,
and can also extend the ESD and EFT performance of the
LTC2865 family to extremely high levels.
In addition to providing surge, EFT and ESD protection,
an external network should preserve or extend the ability
of the LTC2865 family to withstand overvoltage faults,
operate over a wide common mode, and communicate
at high frequencies. In order to meet the first two
requirements, protection components with suitably high
conduction voltages must be chosen. A means to limit
current must be provided to prevent damage in case
a secondary protection device or the ESD cell on the
LTC2865 family fires and conducts. The capacitance of
these components must be kept low in order to permit high
frequency communication over a network with multiple
nodes. Meeting the requirements for conducting very high
energy electrical transients while maintaining high hold-off
voltages and low capacitance is a considerable challenge.
2862345fc
16
For more information www.linear.com/LTC2862
LTC2862/LTC2863/
LTC2864/LTC2865
Applications Information
A protection network shown in the Typical Applications
section (network for IEC level 4 protection against surge,
EFT and ESD) meets this challenge. The network provides
the following protection:
The gas discharge tubes (GDTs) provide the primary protection against electrical surges. These devices provide a
very low impedance and high current carrying capability
when they fire, safely discharging the surge current to
GND. The transient blocking units (TBUs) are solid state
devices that switch from a low impedance pass through
state to a high impedance current limiting state when a
specified current level is reached. These devices limit the
current and power that can pass through to the secondary
protection. The secondary protection consists of a
bidirectional thyristor, which triggers above 35V to protect
the bus pins of the LTC2865 family transceiver. The high
trigger voltage of the secondary protection maintains the
full ±25V common mode range of the receivers. The final
component of the network is the metal oxide varistors
(MOVs) which are used to clamp the voltage across the
TBUs to protect them against fast ESD and EFT transients
which exceed the turn-on time of the GDT.
• IEC 61000-4-2 ESD Level 4: ±30KV contact, ±30kV air
(line to GND, direct discharge to bus pins with transceiver
and protection circuit mounted on a ground referenced
test card per Figure 4 of the standard)
• IEC 61000-4-4 EFT Level 4: ±5KV (line to GND, 5kHz
repetition rate, 15ms burst duration, 60 second test
duration, discharge coupled to bus pins through 100pF
capacitor per paragraph 7.3.2 of the standard)
• IEC 61000-4-5 Surge Level 4: ±5KV (line to GND, line to
line, 8/20µs waveform, each line coupled to generator
through 80Ω resistor per Figure 14 of the standard)
This protection circuit adds only ~8pF of capacitance per
line (line to GND), thereby providing an extremely high level
of protection without significant impact to the performance
of the LTC2865 family transceivers at high data rates.
The high performance of this network is attributable to
the low capacitance of the GDT and thyristor primary
and secondary protection devices. The high capacitance
MOV floats on the line and is shunted by the TBU, so it
contributes no appreciable capacitive load on the signal.
Typical Applications
PROFIBUS Compatible Line Interface
VCC
(4.75V TO 5.25V)
VCC
LTC2862-1
RO
A*
8.2Ω
B*
8.2Ω
RE
VCC
390Ω
B WIRE
390Ω
B WIRE
100m
220Ω
220Ω
5.5Ω/WIRE
DI
VOD
A WIRE
390Ω
390Ω
A WIRE
DE
GND
4VP-P ≤ VOD ≤ 7VP-P AT 12Mbps
* THE POLARITY OF A AND B IN THIS DATA SHEET IS OPPOSITE THE POLARITY DEFINED BY PROFIBUS.
2862345 TA02
2862345fc
For more information www.linear.com/LTC2862
17
LTC2862/LTC2863/
LTC2864/LTC2865
Typical Applications
Bidirectional ±60V 20Mbps Level Shifter/Isolator
C
LTC2863-1
LTC2863-1
R1
A
VCC
Y
RO
DATA OUT 2
DI
R2
R1
B
VCC
DATA IN 2
Z
C
C
R1
Y
DI
DATA IN 1
VCC
A
RO
R2
R1
Z
GND
B
C
GND
DATA OUT 1
VCC
±60V
2862345 TA03
R1 = 100k 1%. PLACE R1 RESISTORS NEAR A AND B PINS.
R2 = 10k
C = 47pF, 5%, 50 WVDC. MAY BE OMITTED FOR DATA RATES ≤ 100kbps.
Failsafe O Application (Idle State = Logic O)
5V
I1
RO
RO
LTC2862
R
DI
A
DE
DE
I2
DI/
VCC
B
D
“A”
“B”
GND
2862345 TA04
2862345fc
18
For more information www.linear.com/LTC2862
LTC2862/LTC2863/
LTC2864/LTC2865
Package Description
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610 Rev G)
.189 – .197
(4.801 – 5.004)
NOTE 3
.045 ±.005
.050 BSC
8
.245
MIN
.160 ±.005
.010 – .020
× 45°
(0.254 – 0.508)
2
.053 – .069
(1.346 – 1.752)
0°– 8° TYP
.016 – .050
(0.406 – 1.270)
5
.150 – .157
(3.810 – 3.988)
NOTE 3
1
RECOMMENDED SOLDER PAD LAYOUT
.008 – .010
(0.203 – 0.254)
6
.228 – .244
(5.791 – 6.197)
.030 ±.005
TYP
NOTE:
1. DIMENSIONS IN
7
.014 – .019
(0.355 – 0.483)
TYP
INCHES
(MILLIMETERS)
2. DRAWING NOT TO SCALE
3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
4. PIN 1 CAN BE BEVEL EDGE OR A DIMPLE
3
4
.004 – .010
(0.101 – 0.254)
.050
(1.270)
BSC
SO8 REV G 0212
2862345fc
For more information www.linear.com/LTC2862
19
LTC2862/LTC2863/
LTC2864/LTC2865
Package Description
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
DD Package
8-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1698 Rev C)
0.70 ±0.05
3.5 ±0.05
1.65 ±0.05
2.10 ±0.05 (2 SIDES)
PACKAGE
OUTLINE
0.25 ± 0.05
0.50
BSC
2.38 ±0.05
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
PIN 1
TOP MARK
(NOTE 6)
0.200 REF
3.00 ±0.10
(4 SIDES)
R = 0.125
TYP
5
0.40 ± 0.10
8
1.65 ± 0.10
(2 SIDES)
0.75 ±0.05
4
0.25 ± 0.05
1
(DD8) DFN 0509 REV C
0.50 BSC
2.38 ±0.10
0.00 – 0.05
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-1)
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION
ON TOP AND BOTTOM OF PACKAGE
2862345fc
20
For more information www.linear.com/LTC2862
LTC2862/LTC2863/
LTC2864/LTC2865
Package Description
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
S Package
14-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610 Rev G)
.337 – .344
(8.560 – 8.738)
NOTE 3
.045 ±.005
.050 BSC
14
N
12
11
10
9
8
N
.245
MIN
.160 ±.005
.228 – .244
(5.791 – 6.197)
1
.030 ±.005
TYP
13
2
3
N/2
N/2
RECOMMENDED SOLDER PAD LAYOUT
1
.010 – .020
× 45
(0.254 – 0.508)
.008 – .010
(0.203 – 0.254)
2
3
4
5
.053 – .069
(1.346 – 1.752)
NOTE:
1. DIMENSIONS IN
.014 – .019
(0.355 – 0.483)
TYP
INCHES
(MILLIMETERS)
2. DRAWING NOT TO SCALE
3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
4. PIN 1 CAN BE BEVEL EDGE OR A DIMPLE
7
.004 – .010
(0.101 – 0.254)
0° – 8° TYP
.016 – .050
(0.406 – 1.270)
6
.150 – .157
(3.810 – 3.988)
NOTE 3
.050
(1.270)
BSC
S14 REV G 0212
2862345fc
For more information www.linear.com/LTC2862
21
LTC2862/LTC2863/
LTC2864/LTC2865
Package Description
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
DD Package
DD Package
10-Lead
DFN×(3mm
10-Lead
PlasticPlastic
DFN (3mm
3mm)× 3mm)
(Reference
LTC
DWG # 05-08-1699
(Reference
LTC DWG
# 05-08-1699
Rev C) Rev C)
0.70 ±0.05
3.55 ±0.05
1.65 ±0.05
2.15 ±0.05 (2 SIDES)
PACKAGE
OUTLINE
0.25 ± 0.05
0.50
BSC
2.38 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
3.00 ±0.10
(4 SIDES)
R = 0.125
TYP
6
0.40 ± 0.10
10
1.65 ± 0.10
(2 SIDES)
PIN 1 NOTCH
R = 0.20 OR
0.35 × 45°
CHAMFER
PIN 1
TOP MARK
(SEE NOTE 6)
0.200 REF
0.75 ±0.05
0.00 – 0.05
5
1
(DD) DFN REV C 0310
0.25 ± 0.05
0.50 BSC
2.38 ±0.10
(2 SIDES)
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2).
CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
2862345fc
22
For more information www.linear.com/LTC2862
LTC2862/LTC2863/
LTC2864/LTC2865
Package Description
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
DE/UE Package
12-Lead Plastic DFN (4mm × 3mm)
(Reference LTC DWG # 05-08-1695 Rev D)
0.70 ±0.05
3.60 ±0.05
2.20 ±0.05
3.30 ±0.05
1.70 ± 0.05
PACKAGE OUTLINE
0.25 ± 0.05
0.50 BSC
2.50 REF
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
4.00 ±0.10
(2 SIDES)
7
R = 0.115
TYP
0.40 ± 0.10
12
R = 0.05
TYP
PIN 1
TOP MARK
(NOTE 6)
0.200 REF
3.30 ±0.10
3.00 ±0.10
(2 SIDES)
1.70 ± 0.10
0.75 ±0.05
6
0.25 ± 0.05
1
PIN 1 NOTCH
R = 0.20 OR
0.35 × 45°
CHAMFER
(UE12/DE12) DFN 0806 REV D
0.50 BSC
2.50 REF
0.00 – 0.05
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING PROPOSED TO BE A VARIATION OF VERSION
(WGED) IN JEDEC PACKAGE OUTLINE M0-229
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION
ON THE TOP AND BOTTOM OF PACKAGE
2862345fc
For more information www.linear.com/LTC2862
23
LTC2862/LTC2863/
LTC2864/LTC2865
Package Description
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
MSE Package
MSE
Package
12-Lead Plastic
MSOP
, Exposed Die Pad
12-Lead
Plastic
MSOP,
ExposedRev
DieG)Pad
(Reference
LTC DWG
# 05-08-1666
(Reference LTC DWG # 05-08-1666 Rev G)
BOTTOM VIEW OF
EXPOSED PAD OPTION
2.845 ±0.102
(.112 ±.004)
5.10
(.201)
MIN
2.845 ±0.102
(.112 ±.004)
0.889 ±0.127
(.035 ±.005)
6
1
1.651 ±0.102
(.065 ±.004)
1.651 ±0.102 3.20 – 3.45
(.065 ±.004) (.126 – .136)
12
0.65
0.42 ±0.038
(.0256)
(.0165 ±.0015)
BSC
TYP
RECOMMENDED SOLDER PAD LAYOUT
0.254
(.010)
0.35
REF
4.039 ±0.102
(.159 ±.004)
(NOTE 3)
0.12 REF
DETAIL “B”
CORNER TAIL IS PART OF
DETAIL “B” THE LEADFRAME FEATURE.
FOR REFERENCE ONLY
7
NO MEASUREMENT PURPOSE
0.406 ±0.076
(.016 ±.003)
REF
12 11 10 9 8 7
DETAIL “A”
0° – 6° TYP
3.00 ±0.102
(.118 ±.004)
(NOTE 4)
4.90 ±0.152
(.193 ±.006)
GAUGE PLANE
0.53 ±0.152
(.021 ±.006)
DETAIL “A”
1.10
(.043)
MAX
0.18
(.007)
SEATING
PLANE
0.22 – 0.38
(.009 – .015)
TYP
1 2 3 4 5 6
0.650
(.0256)
BSC
NOTE:
1. DIMENSIONS IN MILLIMETER/(INCH)
2. DRAWING NOT TO SCALE
3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
6. EXPOSED PAD DIMENSION DOES INCLUDE MOLD FLASH. MOLD FLASH ON E-PAD SHALL
NOT EXCEED 0.254mm (.010") PER SIDE.
0.86
(.034)
REF
0.1016 ±0.0508
(.004 ±.002)
MSOP (MSE12) 0213 REV G
2862345fc
24
For more information www.linear.com/LTC2862
LTC2862/LTC2863/
LTC2864/LTC2865
Revision History
REV
DATE
DESCRIPTION
A
03/13
Added MP-Grade to Data Sheet
PAGE NUMBER
B
01/14
Updated S8 and S Package
Changed ICCS for H-/MP-Grade.
03/14
17, 19
4
Added VL Supply Current vs Data Rate graph.
7
Added Shutdown Mode Delay section.
14
Added PROFIBUS Compatible Interface section, Auxiliary protection For IEC Surge, EFT and ESD section, and
PROFIBUS Compatible Line Interface schematic.
C
2, 4
16, 17
Replaced RS485 Network with 120V AC Line Fault Protection schematic with Network for IEC Level 4 Protection
Against Surge, EFT and ESD Plus 360V Overvoltage Protection schematic.
26
Changed part marking for DE package
4
2862345fc
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 representaFor more
information
www.linear.com/LTC2862
tion that the interconnection
of its circuits
as described
herein will not infringe on existing patent rights.
25
LTC2862/LTC2863/
LTC2864/LTC2865
Typical Application
Network for IEC Level 4 Protection Against Surge, EFT and ESD
Plus 360V Overvoltage Protection
MOV
RS485 A
(EXTERNAL)
VCC
DE
TBU
GDT
LTC2862-1
RO
R
A
SCR
GND
GDT
TBU
SCR
DI
T
B
RE
GND
RS485 B
(EXTERNAL)
2862345 TA05
MOV
GDT: BOURNS 2031-42T-SM; 420V GAS DISCHARGE TUBE
TBU: BOURNS TBU-CA085-300-WH; 850V TRANSIENT BLOCKING UNIT
MOV: BOURNS MOV-7D391K; 390V 25J METAL OXIDE VARISTOR
SCR: BOURNS TISP4P035L1NR-S; 35V BIDIRECTIONAL THYRISTOR
Related Parts
PART NUMBER
DESCRIPTION
COMMENTS
LT1785, LT1791
±60V Fault Protected RS485/RS422 Transceivers
±60V Tolerant, ±15kV ESD, 250kbps
LTC2850-53
3.3V 20Mbps ±15kV RS485 Transceivers
Up to 256 Transceivers Per Bus
LTC2854, LTC2855 3.3V 20Mbps RS485 Transceivers with Integrated Switchable Termination
±25kV ESD (LTC2854), ±15kV ESD (LTC2855)
LTC2856-1 Family
±15kV ESD
5V 20Mbps and Slew Rate Limited RS485 Transceivers
LTC2859, LTC2861 5V 20Mbps RS485 Transceivers with Integrated Switchable Termination
±15kV ESD
LTC1535
Isolated RS485 Transceiver
2500VRMS Isolation, Requires External Transceiver
LTM2881
Complete 3.3V Isolated RS485/RS422 μModule® Transceiver + Power
2500VRMS Isolation with Integrated Isolated DC/DC
Converter, 1W Power, Low EMI, ±15kV ESD, 30kV/µs
Common Mode Transient Immunity
2862345fc
26 Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
For more information www.linear.com/LTC2862
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com/LTC2862
LT 0314 REV C • PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 2011
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