LTC2876CMS8E#PBF [Linear]
LTC2876 - ±60V Rugged PROFIBUS RS485 Transceivers; Package: MSOP; Pins: 8; Temperature Range: 0°C to 70°C;
| 型号： | LTC2876CMS8E#PBF |
| 厂家： | 
Linear |
| 描述： | LTC2876 - ±60V Rugged PROFIBUS RS485 Transceivers; Package: MSOP; Pins: 8; Temperature Range: 0°C to 70°C |
| 文件： | 总32页 (文件大小：1613K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC2876/LTC2877
±±60V RuugeVꢀ ꢁOFIBUV
U485VTranscgivgrs
FeaTures
DescripTion
The LTC®2876 and LTC2877 are PROFIBUS RS485
transceivers designed to meet the test specifications for
PROFIBUS-DP masters and PROFIBUS-DP slaves, fully
compatible with IEC 61158-2, type 3: medium attachment
unit (MAU). With operation up to 20Mbps, the LTC2876/
LTC2877supportsallPROFIBUSdataratesupto12Mbps.
n
PROFIBUS IEC 61158-2 Compliant
Protected from Overvoltage Line Faults to 6ꢀ0
52ꢁ0 ESꢂ Interface Pinsꢃ 15ꢁ0 All Otꢄer Pins
2ꢁ0 ꢅLevel ꢆ4 IEC61ꢀꢀꢀ-ꢆ-ꢆ Fast Transient Burst
250 ꢇorꢁing Common Mode Range
2ꢀMbps Maximum Baud Rate
1.650 to 5.50 Logic Supply Pin for Flexible ꢂigital
Interfacing ꢅLTC28774
5V Supply Can Operate Down to 3V for Low Power,
Low Swing Applications
Fully Balanced Differential Receiver Thresholds with
240mV Hysteresis for Superior Noise Tolerance and
Low Duty Cycle Distortion
Receiver Failsafe for Open, Shorted and Terminated
Conditions
n
n
n
n
n
n
TheLTC2876andLTC2877areexceptionallyrobust,toler-
ating 60V faults on the bus pins and protected to 52kV
ESD. These devices are suitable for harsh environments
or where 24V power might be inadvertently connected.
Extended 25V input common mode range and full fail-
safe operation improve data communication reliability in
noisy systems.
n
n
n
The LTC2876 and LTC2877 meet PROFIBUS and RS485
specifications with a supply voltage of 4.5V to 5.5V but
can operate down to 3V with reduced supply current.
n
n
Wide Operating Temperature Range: –40°C to 125°C
Available in Small DFN and MSOP Packages
Product Selection Guide
PART NUMBER
LTC2876
LOGIC SUPPLY PIN
PACKAGE
applicaTions
NO
DFN-8, MSOP-8
DFN-10, MSOP-10
n
LTC2877
YES
PROFIBUS-DP
Industrial Communication Networks
RS485 and RS422 Systems
n
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
n
n
3V Low Voltage Differential Signaling
Typical applicaTion
Eye ꢂiagram of 12Mbps Signal at
1.8V
5V
tꢄe Near and Far End of a 1ꢀꢀm
5V
PROFIBUS Cable ꢂriven by tꢄe
LTC2877 Using 28–1 PRBS Pattern
0.1µF
1µF
V
L
V
CC
LTC2877
390Ω
220Ω
390Ω
390Ω
PROFIBUS
CABLE
PB–PA
RO
NEAR END
2V/DIV
PB
PB
B´
RE
µC
220Ω
PA
SENSOR
DI
A´
PA
Z
= 150Ω
O
B´– A´
2V/DIV
FAR END
20ns/DIV
390Ω
DE
GND
28767 TA01b
28767 TA01a
28767fa
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For more information www.linear.com/LTC2876
LTC2876/LTC2877
absoluTe MaxiMuM raTings
ꢅNotes 1ꢃ 24
Supply Voltages (V , V )............................ –0.3V to 6V
Operating Ambient Temperature Range (Note 3)
CC
L
Logic Input Voltages (RE, DE, DI) ................ –0.3V to 6V
Line Interface I/O (PA, PB).......................... –60V to 60V
Line Interface I/O Difference (PB–PA) .....–120V to 120V
Receiver Output (RO)
LTC287xC ................................................ 0°C to 70°C
LTC287xI..............................................–40°C to 85°C
LTC287xH .......................................... –40°C to 125°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10sec)....................300°C
LTC2876 ......................................–0.3V to V + 0.3V
CC
LTC2877 ....................................... –0.3V to V + 0.3V
L
pin conFiguraTion
LTC2876
LTC2876
TOP VIEW
TOP VIEW
RO
RE
DE
DI
1
2
3
4
8
7
6
5
V
CC
RO
RE
DE
DI
1
2
3
4
8 V
CC
PA
7 PA
9
GND
9
GND
6 PB
5 GND
PB
GND
MS8E PACKAGE
8-LEAD PLASTIC MSOP
DD PACKAGE
8-LEAD (3mm × 3mm) PLASTIC DFN
T
= 150°C, θ = 40°C/W, θ = 10°C/W
JA JC
JMAX
EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB
T
= 150°C, θ = 43°C/W, θ = 5.5°C/W
JA JC
JMAX
EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB
LTC2877
LTC2877
TOP VIEW
TOP VIEW
RO
RE
DE
DI
1
2
3
4
5
10
9
V
CC
RO
RE
DE
DI
1
2
3
4
5
10
9
V
CC
PA
PA
11
11
GND
8
PB
NC
GND
8
PB
GND
7
6
7
NC
V
L
V
6
GND
L
MSE PACKAGE
10-LEAD PLASTIC MSOP
DD PACKAGE
T
= 150°C, θ = 40°C/W, θ = 10°C/W
JA JC
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB
JMAX
10-LEAD (3mm × 3mm) PLASTIC DFN
T
= 150°C, θ = 43°C/W, θ = 5.5°C/W
JA JC
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB
JMAX
28767fa
2
For more information www.linear.com/LTC2876
LTC2876/LTC2877
orDer inForMaTion ꢄttp://www.linear.com/product/LTC2876#orderinfo
Lead Free Finisꢄ
TUBE
TAPE ANꢂ REEL
PART MARKING
PACKAGE ꢂESCRIPTION
TEMPERATURE RANGE
LTC2876CMS8E#PBF
LTC2876IMS8E#PBF
LTC2876HMS8E#PBF
LTC2876CMS8E#TRPBF LTGTN
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
0°C to 70°C
LTC2876IMS8E#TRPBF LTGTN
LTC2876HMS8E#TRPBF LTGTN
–40°C to 85°C
–40°C to 125°C
LTC2876CDD#PBF
LTC2876IDD#PBF
LTC2876HDD#PBF
LTC2876CDD#TRPBF
LTC2876IDD#TRPBF
LTC2876HDD#TRPBF
LGTM
LGTM
LGTM
8-Lead Plastic DFN
8-Lead Plastic DFN
8-Lead Plastic DFN
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
LTC2877CMSE#PBF
LTC2877IMSE#PBF
LTC2877HMSE#PBF
LTC2877CMSE#TRPBF
LTC2877IMSE#TRPBF
LTC2877HMSE#TRPBF
LTGTQ
LTGTQ
LTGTQ
10-Lead Plastic MSOP
10-Lead Plastic MSOP
10-Lead Plastic MSOP
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
LTC2877CDD#PBF
LTC2877IDD#PBF
LTC2877HDD#PBF
LTC2877CDD#TRPBF
LTC2877IDD#TRPBF
LTC2877HDD#TRPBF
LGTP
LGTP
LGTP
10-Lead Plastic DFN
10-Lead Plastic DFN
10-Lead Plastic DFN
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on nonstandard 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/. Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
elecTrical characTerisTics Tꢄe l denotes tꢄe specifications wꢄicꢄ apply over tꢄe full operating
temperature rangeꢃ otꢄerwise specifications are at TA = 25°C. 0CC = 0L = 50 unless otꢄerwise noted.
SYMBOL
Supplies
PARAMETER
CONꢂITIONS
MIN
TYP
MAX
UNITS
l
l
l
l
l
l
V
Primary Power Supply
PROFIBUS, RS485
Low Voltage RS485 (Note 6)
LTC2877 Only
4.5
3.0
5.5
V
V
CC
V
L
Logic Interface Power Supply
1.65
V
CC
V
I
LTC2876 Supply Current in Shutdown DE = 0V, RE = V , DI = V
Mode
0
12
0
5
25
5
µA
µA
µA
CCS
CC
CC
DE = 0V, RE = V , DI = 0V
CC
LTC2877 Supply Current in Shutdown DE = 0V, RE = V = V , DI = 0V or V
L
Mode
L
CC
l
l
l
I
I
I
Supply Current with Only Receiver
Enabled
No Load, DE = 0V, RE = 0V
No Load, DE = RE = V = V
L
600
700
750
900
1100
1200
µA
µA
µA
CCR
Supply Current with Only Driver
Enabled
CCD
CC
Supply Current with Both Driver and
Receiver Enabled
No Load, DE = V = V , RE = 0V
CC L
CCDR
l
l
l
l
LTC2877 Logic Supply Current in
Shutdown Mode
DE = 0V, RE = V , DI = V
0
5
µA
µA
µA
µA
L
L
DE = 0V, RE = V , DI = 0V
12
30
65
25
L
LTC2877 Logic Supply Current with
Both Driver and Receiver Enabled
DE = V , RE = 0V, DI = V
60
L
L
DE = V , RE = 0V, DI = 0V
120
L
28767fa
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For more information www.linear.com/LTC2876
LTC2876/LTC2877
elecTrical characTerisTics Tꢄe l denotes tꢄe specifications wꢄicꢄ apply over tꢄe full operating
temperature rangeꢃ otꢄerwise specifications are at TA = 25°C. 0CC = 0L = 50 unless otꢄerwise noted.
SYMBOL
ꢂriver
PARAMETER
CONꢂITIONS
MIN
TYP
MAX
UNITS
V
Differential Bus Output Voltage (B´–A´) PROFIBUS LOAD (Figure 1)
OD(PP)
l
l
l
with PROFIBUS Load
R
R
R
= 0Ω, V = 4.5V to 5.5V
4
4
4
7
7
7
V
V
V
CABLE
CABLE
CABLE
CC
CC
P-P(DIFF)
P-P(DIFF)
P-P(DIFF)
= 5.5Ω, V = 4.5V to 5.5V
= 11Ω, V = 4.75V to 5.5V
CC
l
V
V
Single-Ended Bus Output Amplitude
All of the Conditions Above
All of the Conditions Above
Figure 2 with No Load
0.5
V
BPP-APP
Difference (B´ – A´
)
PP
PP
l
Single-Ended Bus Output Amplitude
Sum |B´ + A´
4
V
BPP+APP
|
PP
PP
l
l
l
l
l
l
l
|V
|
|
RS485 Differential Driver Output
Voltage, in Either Logic State
V
CC
V
V
V
V
V
V
V
OD(485)
R = 27Ω,V = 4.5V to 5.5V (Figure 2)
1.5
0.8
3.4
1.8
L
CC
R = 27Ω,V = 3.0V to 3.6V (Figure 2)
L
CC
|V
RS422 Differential Driver Output
Voltage, Either Logic State
Figure 2 with No Load
R = 50Ω,V = 4.5V to 5.5V (Figure 2)
V
CC
OD(422)
2
1
4
2
L
CC
R = 50Ω,V = 3.0V to 3.6V (Figure 2)
L
CC
Δ|V
Δ|V
|, RS485, RS422 Change in Magnitude of R = 27Ω (RS485) or
0.2
OD(485)
OD(422)
L
|
Driver Differential Output Voltage
R = 50Ω (RS422) (Figure 2)
L
l
l
l
V
V
,
RS485, RS422 Driver Common-Mode
Output Voltage
R = 27Ω (RS485) or
L
3
V
V
OC(485)
OC(422)
L
R = 50Ω (RS422) (Figure 2)
Δ|V
Δ|V
|, RS485, RS422 Change in Magnitude of R = 27Ω (RS485) or
0.2
250
OC(485)
OC(422)
L
|
Driver Common-Mode Output Voltage
R = 50Ω (RS422) (Figure 2)
L
I
Maximum Driver Short-Circuit Current –60V ≤ (PB or PA) ≤ 60V (Figure 3)
150
112
mA
OSD
Receiver
l
l
I
IN
Input Current (PA, PB)
Input Resistance
V
V
= 0V or 5V, V
= 0V or 5V, V
= 12V (Figure 4)
= –7V (Figure 4)
160
µA
µA
CC
CC
BUS
BUS
–100
75
l
l
R
V
= –25V or 25V (Figure 4)
135
25
kΩ
V
IN
BUS
V
V
V
Common Mode Input Voltage
(PA+PB)/2 for Data Reception
CM
l
l
+
Differential Input Signal Threshold
Voltage (PB–PA) Rising
–25V ≤ V ≤ 25V, Edge Rates > 100mV/µs
50
120
200
mV
mV
TS
TS
CM
(Note 5) (Figure 13)
–
Differential Input Signal Threshold
Voltage (PB–PA) Falling
–25V ≤ V ≤ 25V, Edge Rates > 100mV/µs
–50
–120
–200
CM
(Note 5) (Figure 13)
ΔV
Differential Input Signal Hysteresis
Edge Rates > 100mV/µs (Note 5) (Figure 13)
240
–75
mV
mV
TS
l
l
V
TFS
+
Differential Input Failsafe Threshold
Voltage (PB–PA) Rising
–25V ≤ V ≤ 25V, DC Bus Voltages
–20
–50
–200
–200
CM
(Figure 13)
V
TFS
–
Differential Input Failsafe Threshold
Voltage (PB–PA) Falling
–25V ≤ V ≤ 25V, DC Bus Voltages
–120
45
mV
CM
(Figure 13)
ΔV
TFS
Differential Input Failsafe Hysteresis
Receiver Output High Voltage
DC Bus Voltages (Figure 13)
mV
l
l
l
V
OH
V
≥ 4.5V, I(RO) = –3mA (LTC2876)
V – 0.4V
CC
V
V
V
CC
L
L
V ≥ 2.25V, I(RO) = –3mA (LTC2877)
V – 0.4V
L
V < 2.25V, I(RO) = –2mA (LTC2877)
V – 0.4V
L
l
l
V
OL
Receiver Output Low Voltage
V ≥ 1.65V, I(RO) = 3mA (LTC2877)
CC
0.4
0.4
V
V
L
V
≥ 3.0V, I(RO) = 3mA (LTC2876)
l
Receiver Three-State (High Impedance) RE = High, RO = 0V
–20
0
–40
µA
Output Current on RO
l
Receiver Three-State (High Impedance) RE = High, RO = V (LTC2876) or V
5
µA
CC
L
Output Current on RO
(LTC2877)
28767fa
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For more information www.linear.com/LTC2876
LTC2876/LTC2877
elecTrical characTerisTics Tꢄe l denotes tꢄe specifications wꢄicꢄ apply over tꢄe full operating
temperature rangeꢃ otꢄerwise specifications are at TA = 25°C. 0CC = 0L = 50 unless otꢄerwise noted.
SYMBOL
PARAMETER
CONꢂITIONS
MIN
TYP
MAX
UNITS
l
Receiver Short-Circuit Current
RE = Low, RO = 0V or V (LTC2876) or V
12
20
mA
CC
L
(LTC2877)
Logic
l
l
l
l
l
l
l
l
Low Level Input Voltage (DE, DI, RE)
High Level Input Voltage (DE, DI, RE)
LTC2876, 3.0 ≤ V ≤ 5.5V
0.25 • V
V
V
CC
CC
LTC2877, 1.65 ≤ V ≤ 5.5V
0.25 • V
L
L
LTC2876, 3.0 ≤ V ≤ 5.5V
0.75 • V
V
CC
CC
LTC2877, 1.65 ≤ V ≤ 5.5V
0.75 • V
V
L
L
Logic Input Current Low (DE)
Logic Input Current Low (DI, RE)
Logic Input Current High (DE)
Logic Input Current High (DI, RE)
DE = 0V
0
–10
10
0
–5
–20
20
5
µA
µA
µA
µA
DI or RE = 0V
–3
3
DE = V (LTC2876) or V (LTC2877)
CC
L
(DI, RE) = V (LTC2876) or V (LTC2877)
CC
L
ESꢂ ꢅNote ꢆ4
ESD Protection Level of Interface Pins Human Body Model to GND or V , or V ,
26
kV
CC
L
(PA, PB)
Powered or Unpowered
Human Body Model to GND, Unpowered
ESD Protection Level of All Other Pins Human Body Model
(DE, DI, RE, V , V )
52
15
kV
kV
CC
L
swiTching characTerisTics Tꢄe l denotes tꢄe specifications wꢄicꢄ apply over tꢄe full operating
temperature rangeꢃ otꢄerwise specifications are at TA = 25°C. 0CC = 0L = 50 unless otꢄerwise noted.
SYMBOL
PARAMETER
CONꢂITIONS
MIN
TYP
MAX
UNITS
l
f
Maximum Data Rate
(Note 4)
20
Mbps
MAX
ꢂriver
, t
l
l
t
Driver Input to Output
V
= 3.3V or 5V (Figure 5)
CC
13
2
50
9
ns
ns
PLHD PHLD
Δt
PD
Driver Input to Output Difference
(Figure 5)
|t
– t
PHLD
|
PLHD
l
l
l
t
t
Driver Output PB to Output PA
Driver Rise or Fall Time
(Figure 5)
9
15
ns
ns
ns
SKEWD
, t
RD FD
V
= 3.3V or 5V (Figure 5)
CC
4
t
t
, t
, t
,
Driver Enable or Disable Time
RE = 0V (Figure 6)
180
ZLD ZHD
LZD HZD
l
l
t
t
, t
Driver Enable from Shutdown
Time to Shutdown with DE
RE = High (Figure 6)
RE = High (Figure 6)
15
µs
ns
ZHSD ZLSD
SHDND
180
Receiver
, t
l
l
t
Receiver Input to Output
V
R
= 2.25V, (PB–PA) = 1.5V,
CM
50
2
70
14
ns
ns
PLHR PHLR
t and t < 4ns, V = 3.3V or 5V (Figure 7)
F
CC
Δt
PR
Receiver Input to Output Difference
(Figure 7)
|t
– t
PHLR
|
PLHR
l
l
t
, t
Receiver Output Rise or Fall Time
Receiver Enable/Disable Time
(Figure 7)
3
15
40
ns
ns
RR FR
t
t
, t
, t
,
DE = High (Figure 8)
ZLR ZHR
LZR HZR
l
l
t
t
, t
Receiver Enable from Shutdown
DE = 0V, (Figure 9)
DE = 0V, (Figure 9)
9
µs
ns
ZHSR ZLSR
SHDNR
Time to Shutdown with RE
40
28767fa
5
For more information www.linear.com/LTC2876
LTC2876/LTC2877
elecTrical characTerisTics
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 ꢆ: Not tested in production.
Note 5: The dependency on edge rate is tested indirectly.
Note 6: Does not meet RS485 or PROFIBUS specifications. See the
Applications Information section for more information about running with
a 3V supply.
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: This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature exceeds 150°C when overtemperature protection is active.
Continuous operation above the specified maximum operating temperature
may result in device degradation or failure.
28767fa
6
For more information www.linear.com/LTC2876
LTC2876/LTC2877
Typical perForMance characTerisTics
TA = 25°C. VCC = VL = 5V, unless otherwise noted. (Note 2)
VCC Supply Current vs Voltage for
Various Modes, No Load
VCC Supply Current vs Temperature
for Various Modes, No Load
VCC Supply Current vs Data Rate
750
700
650
600
550
500
5
4
3
2
1
0
800
725
650
575
500
10k
50
40
30
20
10
0
RS485 54Ω/100pF Load (Fig. 5) V = 5V
CC
1k
I
I
CCDR
CCDR
PROFI 100m cable w/term (Fig.1) V = 5V
CC
100
10
1
I
CCD
I
CCD
I
(nA)
CCS
RS485 54Ω/100pF Load (Fig. 5) V = 3.3V
CC
I
(nA)
CCS
I
CCR
No Load, V = 5V
CC
I
CCR
No Load, V = 3.3V
CC
0.1
3
3.5
4
4.5
5
5.5
0
5
10
15
20
–50 –25
0
25 50 75 100 125 150
V
SUPPLY VOLTAGE (V)
DATA RATE (Mbps)
TEMPERATURE (°C)
CC
28767 G01
28767 G03
28767 G02
Driver Differential Output Voltage
vs Supply Voltage
Driver Differential Output Voltage
vs Temperature
VL Supply Current vs Data Rate
3.0
2.5
2.0
1.5
1.0
0.5
0
7
6
5
4
3
2
1
0
6
5
4
3
2
1
0
V
V
V
PROFIBUS LOADS (Fig. 1)
V
V
V
V
= 5V, C = 15pF
OD(PP)
OD(422)
OD(485)
L
L
L
L
RO
(Fig. 2, R = 50Ω)
= 5V, C = 0pF
L
RO
(Fig. 2, R = 27Ω)
V
V
V
V
V
PROFI LOAD (Fig. 1), V = 5V
= 1.65V, C = 15pF
L
OD(PP)
CC
RO
(Fig. 2, R = 50Ω), V = 5V
= 1.65V, C = 0pF
OD(422)
OD(485)
OD(422)
OD(485)
L
L
CC
CC
CC
CC
RO
(Fig. 2, R = 27Ω), V = 5V
(Fig. 2, R = 50Ω), V = 3.3V
L
(Fig. 2, R = 27Ω), V = 3.3V
L
0
5
10
15
20
3
3.5
4
4.5
(V)
5
5.5
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
DATA RATE (Mbps)
V
CC
28767 G04
28767 G05
28767 G06
Driver Output Low/High Voltage
vs Output Current
Driver Output Short-Circuit
Current vs Voltage
Driver and Receiver Propagation
Delay vs VCC
5
4
3
2
1
0
160
120
80
60
V
OH
(V = 5.0V)
CC
RECEIVER
50
40
30
20
10
0
OUTPUT LOW
40
V
(V = 3.3V)
CC
OH
0
–40
–80
–120
–160
DRIVER
V
(V = 3.3V)
CC
OL
OUTPUT HIGH
V
(V = 5.0V)
CC
OL
0
10
20
30
40
50
–60
–40
–20
0
20
40
60
3
3.5
4
4.5
5
5.5
OUTPUT CURRENT (mA)
OUTPUT VOLTAGE (V)
V
CC
28767 G07
28767 G08
28767 G09
28767fa
7
For more information www.linear.com/LTC2876
LTC2876/LTC2877
Typical perForMance characTerisTics
TA = 25°C. VCC = VL = 5V, unless otherwise noted. (Note 2)
Driver Propagation Delay
vs Temperature
Driver Output Skew
vs Temperature
Driver Output Propagation Delay
Difference vs Temperature
30
27
24
21
18
15
12
9
5
4
5
4
3
3
2
2
V
= 5V
CC
V
= 3.3V
CC
1
1
V
= 5V
CC
0
0
V
CC
= 5V
–1
–2
–3
–4
–5
–1
–2
–3
–4
–5
V
= 3.3V
CC
V
CC
= 3.3V
6
3
0
–50 –25
0
25 50 75 100 125 150
–50 –25
0
25 50 75 100 125 150
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
28767 G10
28767 G12
28767 G11
Receiver Propagation Delay
vs Temperature
Receiver Propagation Delay
Difference vs Temperature
Receiver Output Voltage
vs Output Current (Source and Sink)
5
4
60
55
50
45
40
6
5
4
3
2
1
0
V
L
= 5.5V
3
2
V
= 3.3V
CC
V
= 5V
CC
1
V
V
= 3.3V
L
0
V
= 5V
CC
V
= 3.3V
CC
–1
–2
–3
–4
–5
= 2.25V
L
V
L
= 1.65V
V
L
= 1.65V TO 5.5V
2
–50 –25
0
25 50 75 100 125 150
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
0
4
6
8
TEMPERATURE (°C)
OUTPUT CURRENT (ABSOLUTE VALUE, mA)
28767 G14
28767 G13
28767 G15
Receiver Output Voltage
vs VL Voltage (LTC2877)
PROFIBUS Operation at 12Mbps
VCC = 5V
RS4 85 Operation at 20Mbps
VCC = 3.3V
400
300
200
100
0
V
for I(RO) = +2mA
OL
DI
DI
V –V
for I(RO) = –2mA
for I(RO) = +3mA
for I(RO) = –3mA
L
OH
2V/DIV
5V/DIV
V
OL
V –V
L
OH
PB
1V/DIV
PB
0.5V/DIV
PA
1V/DIV
PA
0.5V/DIV
DOUBLE PROFIBUS TERMINATION
R
LDIFF
= 54Ω; C =100pF (Fig. 5)
L
R
CABLE
= 0Ω (Fig. 1)
28767 G17
28767 G18
50ns/DIV
20ns/DIV
1.5
2.5
3.5
(V)
4.5
5.5
V
L
28767 G16
28767fa
8
For more information www.linear.com/LTC2876
LTC2876/LTC2877
pin FuncTions (LTC2876/LTC2877)
RO (Pin 1): Receiver Output. Supplied by V in the
V (NA/Pin 5): Logic supply: 1.65V ≤ V ≤ V . Powers
L L CC
CC
LTC2876 or V in the LTC2877. If the receiver is enabled
RO, RE, DE, and DI on LTC2877 only. Bypass with 0.1µF
L
(RE low) and PB–PA > 200mV, then RO will be high. If
PB–PA <–200mV,thenROwillbelow.Ifthereceiverinputs
are open, shorted, or terminated without being driven for
more than about 1.5µs, RO will be high. Integrated 250k
pull-up resistor to supply.
ceramic capacitor to GND.
GND (Pin 5, 9/Pin 6,11): Ground
NC (NA/Pin 7): Not Internally Connected.
PB (Pin 6/Pin 8): PROFIBUS B. Non-inverting receiver
input and non-inverting driver output. Connect this to
the B wire (positive) in a PROFIBUS network. In most
non-PROFIBUS applications, this should connect to the
A terminal. See the Applications Information section for
more information on A vs B naming conventions.
RE(Pin2):ReceiverEnable.LogiclevelsdefinedbytheV
CC
supply in the LTC2876 or the V supply in the LTC2877.
L
A low input enables the receiver. A high input forces the
receiver output into a high impedance state. If RE is high
withDElow,thedeviceentersalowpowershutdownstate.
Integrated 500k pull-up resistor to supply.
PA (Pin 7/Pin 9): PROFIBUS A. Inverting receiver input
and inverting driver output. Connect this to the A wire
(negative)inaPROFIBUSnetwork.Inmostnon-PROFIBUS
applications, this should connect to the B terminal. See
the ApplicationsInformationsectionformoreinformation
on A vs B naming conventions.
DE (Pin 3): Driver Enable. Logic levels defined by the V
CC
supply in the LTC2876 or the V supply in the LTC2877.
L
A high input on DE enables the driver. A low input forces
the driver outputs into a high impedance state. If DE is
low with RE high, the device enters a low power shutdown
state. Integrated 500k pull-down resistor to ground.
V
(Pin 8/Pin 10): Power Supply. 4.5V ≤ V ≤ 5.5V for
CC
CC
PROFIBUS and RS485 compliant applications; 3.0V ≤ V
DI (Pin 4 ): Driver Input. Logic levels defined by the V
CC
CC
≤ 5.5V for a wide range of usage. See 3.3V Operation in
the Applications Information section for details. Bypass
with 1µF ceramic capacitor to GND.
supply in the LTC2876 or the V supply in the LTC2877.
L
If the driver outputs are enabled (DE high), then a low on
DI drives a negative differential voltage between PB and
PA. A high on DI, with the driver outputs enabled, drives a
positivedifferentialvoltagebetweenPBandPA.Integrated
500k pull-up resistor to supply.
Exposed Pad (Pin 9/Pin 11): Must be connected to GND.
28767fa
9
For more information www.linear.com/LTC2876
LTC2876/LTC2877
block DiagraM
3V TO 5.5V
LTC2876
V
CC
V
CC
V
CC
RO
RE
DE
DI
RECEIVER
PB
MODE
CONTROL
PA
V
CC
DRIVER
GND
28767 BD1
3V TO 5.5V
LTC2877
V
CC
1.65V TO V
CC
V
L
V
CC
RO
RECEIVER
RE
PB
MODE
CONTROL
PA
DE
V
CC
DI
DRIVER
GND
28767 BD2
28767fa
10
For more information www.linear.com/LTC2876
LTC2876/LTC2877
TesT circuiTs
V
CC
B´
PP
V
V
CC
A´
PP
CC
LTC2876/LTC2877
B´
RO
A´
390Ω
220Ω
390Ω
390Ω
220Ω
390Ω
0
R
CABLE
PB
B´
RE
HIGH
B´– A´
V
DE
OD(PP)
0
HIGH
R
CABLE
PA
A´
DI
V
V
= |B´ – A´ |
PP PP
BPP–APP
BPP+APP
= B´ + A´
PP
+
–
PP
MEASUREMENTS TAKEN AT STEADY STATE
28767 F01
Figure 1. Driver Differential Output Voltages for PROFIBUS Load
+
V
OD(485)
V
CC
–
V
OD(485)
∆|V
OC(485)
|
PB
CM
PA
LTC2876/LTC2877
RO
PB
RE
R
L
HIGH
CM
PB–PA
V
= PB–PA
V
OD(485)
DE
OD(485)
HIGH
PA
0
R
L
DI
V
OC(485)
+
–
+
–
∆|V
OD(485)
| = |V
– V
|
OD(485)
OD(485)
FOR RS422 MEASUREMENTS, SUBSTITUTE 485 WITH 422 IN THIS FIGURE.
MEASUREMENTS TAKEN AT STEADY STATE
28767 F02
Figure 2. Driver Output Voltages in RS4 85 and RS4 22 Configurations
V
CC
LTC2876/LTC2877
RO
RE
HIGH
PB
I
OSD
DE
HIGH
PA
+
–
–60V TO +60V
DI
HIGH OR LOW
28767 F03
Figure 3. Drive Output Short-Circuit Current
28767fa
11
For more information www.linear.com/LTC2876
LTC2876/LTC2877
TesT circuiTs
V
CC
LTC2876/LTC2877
RO
RE
HIGH OR LOW
PB
I
IN
DE
LOW
PA
+
V
BUS
DI
–
LOW
V
I
BUS
R
IN
=
IN
28767 F04
Figure 4 . Receiver Input Current and Input Resistance
V
CC
V
*
CC
LTC2876/LTC2877
t
t
PHLD
PLHD
DI
0V
RO
t
SKEWD
PA
½V
O
V
PB
O
RE
100pF
54Ω
100pF
HIGH
PB
DE
HIGH
90%
90%
PA
PB–PA
0
0
DI
10%
10%
t
RD
t
FD
*FOR THE LTC2877, SUBSTITUTE V FOR V
L
CC
28767 F05
Figure 5. Driver Timing Measurement
28767fa
12
For more information www.linear.com/LTC2876
LTC2876/LTC2877
TesT circuiTs
V
CC
V
*
CC
DE
½V
*
CC
LTC2876/LTC2877
t
t
,
0V
ZLD
t
LZD
ZLSD
RO
V
WHEN
V
CC
CC
500Ω
PB
DI LOW
½V
CC
PA OR PB
GND WHEN
DI HIGH
0.5V
RE
LOW OR
HIGH
V
OL
50pF
DE
V
OH
0.5V
500Ω
PA
½V
CC
PB OR PA
GND WHEN
DI LOW
CC
DI HIGH
DI
LOW OR
HIGH
0V
t
t
,
t
t
,
50pF
ZHD
HZD
SHDND
V
WHEN
ZHSD
*FOR THE LTC2877, SUBSTITUTE V FOR V
L
CC
28767 F06
Figure 6. Driver Enable, Disable and Shutdown Timing Measurements
V
CC
∆t = |t
– t
|
PR
PLHR PHLR
LTC2876/LTC2877
1.5V
PB–PA
RO
0V
PB
–1.5V
± ±(PB(A)/2
15pF
t
t
PHLR
PLHR
RE
V
*
CC
LOW
V
CM
90%
10%
90%
10%
RO
½V
*
½V *
CC
PA
DE
CC
LOW
± ±(PB(A)/2
0
t
RR
t
FR
DI
LOW
*FOR THE LTC2877, SUBSTITUTE V FOR V
L
CC
28767 F07
Figure 7. Receiver Propagation Delay Measurements
28767fa
13
For more information www.linear.com/LTC2876
LTC2876/LTC2877
TesT circuiTs
V
CC
V
*
CC
1k
t
½V
*
CC
ZLR
RE
V
FOR DI LOW
CC
GND FOR DI HIGH
LTC2876/LTC2877
0V
15pF
t
LZR
V
CC
RO
½V
*
CC
RO
0.5V
V
OL
RE
PB
V
OH
0.5V
DE
PA
HIGH
½V
*
CC
RO
0V
DI
LOW OR
HIGH
t
t
HZR
ZHR
*FOR THE LTC2877, SUBSTITUTE V FOR V
L
CC
28767 F08
Figure 8. Receiver Enable and Disable Timing Measurements
V
CC
V
*
CC
1k
V
FOR CASE1
CC
t
ZLSR
½V
*
CC
RE
GND FOR CASE2
LTC2876/LTC2877
0V
15pF
t
SHDNR
RO
V
*
CC
CASE 1 CASE 2
½V
*
CC
RO
0.5V
RE
V
OL
PB
0V
V
CC
V
DE
OH
0.5V
LOW
PA
V
0V
½V
*
CC
CC
RO
DI
0V
LOW
t
t
ZHSR
SHDNR
*FOR THE LTC2877, SUBSTITUTE V FOR V
L
CC
28767 F09
Figure 9. Receiver Shutdown Timing Measurements
28767fa
14
For more information www.linear.com/LTC2876
LTC2876/LTC2877
applicaTions inForMaTion
Note:Specificationsinthissectionrepresenttypicalvalues
unless otherwise noted.
be compliant to PROFIBUS requirements. The LTC2876/
LTC2877wasdesignedspecificallytomeetPROFIBUSand
RS485requirementsandistestedinawaythatensuresthis.
PROFIBUS-DP AND RS4 85
Cable and Termination Differences from RS485
PROFIBUS-DP can communicate over a variety of media,
including copper wires, fiber optics, and even air in an
infrared communicator. By far, the most commonly used
media is a twisted pair of wires connecting devices that
communicate with TIA/EIA-485-A (RS485) transceivers.
The cable and termination network used for PROFIBUS is
different than for RS485 as illustrated in Figure 10. The
PROFIBUS network includes bus biasing resistors that
are used in conjunction with the differential termination
resistors on each end of the bus. The cable is a shielded
twisted pair with an impedance of 150Ω. Oddly enough,
theeffectivedifferentialresistanceofthespecifiedtermina-
tion network is 172Ω, which is not a perfect match for the
150Ω cable, resulting in a slightly underdamped network.
This manifests itself as a small bump, or increase in the
signal voltage, at the receiving end of the cable, lasting
twice as long as the cable propagation delay.
RS485 offers high speed differential signaling that is
robust for communication between multiple devices over
long distances in noisy environments such as factory
applications.
Not All RS4 85 Transceivers Are Suitable for PROFIBUS
Although the PROFIBUS standard specifies the use of
RS485 devices at the physical layer, there are differences
in the cable, termination, and driver requirements from
RS485. A device meeting RS485 specifications may not
In contrast, the RS485 network shows the preferred
configuration with only differential termination resistors
at each end of the bus, matching the 120Ω characteristic
impedance of the cable.
Profibus Multi-Node Network
Twisted Pair Cable (Z = 150Ω)
O
5V
5V
390Ω
220Ω
390Ω
390Ω
220Ω
390Ω
PROFIBUS
MASTER
PROFIBUS
STATION
PROFIBUS
STATION
PROFIBUS
STATION
RS485 Multi-Node Network
Twisted Pair Cable (Z = 120Ω)
O
RS485
MASTER
RS485
NODE
120Ω
120Ω
RS485
NODE
RS485
NODE
28767 F10
Figure 10. Cable and Termination Differences in RS4 85 and PROFIBUS Multi-Node Networks.
PROFIBUS Type A Cable and Termination Shown in PROFIBUS Example (Top)
28767fa
15
For more information www.linear.com/LTC2876
LTC2876/LTC2877
applicaTions inForMaTion
Driver Output Requirement Differences from RS485
DRIVER OPERATION
The driver requirements for PROFIBUS are specified dif-
ferently than how the RS485 standard specifies them. A
The driver is enabled when the LTC2876/LTC2877 is
powered up, DE is high, and there are no thermal faults.
The polarity of PB–PA follows that of DI. That is, when DI
is high, PB drives to a voltage that is greater than PA. If DI
is low, PA is higher than PB. When the driver is disabled
with DE low, both outputs are high impedance and the
overall pin resistance is dominated by the receiver inputs
sharing pins PA and PB.
keydifferenceistheterminateddriveroutputvoltage,V ,
OD
as described below.
The PROFIBUS driver output levels are required to meet
the following condition as stated in the “Test Specification
for PROFIBUS DP Masters” and “Test Specification for
PROFIBUS DP Slaves”:
• The differential voltage between A- and B-line shall be
a minimum of 4V and a maximum of 7V, peak-to-peak
differential.
DRIVER OVERVOLTAGE AND OVERCURRENT
PROTECTION
The driver outputs PA and PB are protected from short
circuitstoanyvoltagewithintheabsolutemaximumrange
of –60V to +60V, with a maximum differential voltage
of –120V to +120V. The maximum short-circuit current
to any voltage within this range is 250mA. The driver
includes a progressive foldback current limiting circuit
that continuously reduces the driver current limit with
increasing output short circuit voltage to better manage
power dissipation and heating effects.
• This measurement shall be taken at the far end of the
cable in use, with termination at each end.
On the other hand, RS485 specifies the following:
• The differential voltage between A- and B-line shall be
a minimum of 1.5V and a maximum of 5V, peak dif-
ferential.
• This measurement shall be taken at the driver terminals
with a 54Ω resistor between A and B.
The LTC2876/LTC2877 also features thermal shutdown
protection that disables the driver and receiver in case of
excessive power dissipation (see Note 3).
Clearly, these requirements are quite different. A common
misunderstandingisthatifanRS485driverdevelopsmore
than 2.1V across a 54Ω RS485 resistive load, then it will
meet PROFIBUS requirements when used with a PRO-
FIBUS termination network. This is not always the case.
Furthermore, the strength of the driver can be too high,
exceeding the upper limit of the PROFIBUS Specification
RECEIVER
The receiver provides full PROFIBUS and RS485 compat-
ibility. When enabled, the state of RO reflects the polarity
of (PB–PA). When the receiver is disabled, the output is
high impedance and RO weakly pulled high through an
internal 250k pull-up resistor.
(7V ). The best way to ensure PROFIBUS compliance
P-P
is to test the device with a PROFIBUS load.
TheLTC2876andLTC2877aretestedwithaPROFIBUSload
and with extra resistance added to represent cable losses
for 100m and 200m to ensure they meet the PROFIBUS
High Receiver Input Resistance Permits 200 Nodes
The RS485 and PROFIBUS specifications allows for up to
32 receivers, each contributing one unit load, to be con-
nected together in one network. The input resistance of
the LTC2876/LTC2877 is guaranteed to be at least 6.25
times higher, and drawing proportionally less current,
than a standard RS485 load, permitting a total of 200
receivers per contiguous network. The input load of the
receiver is unaffected by enabling/disabling the receiver
V
requirement. The devices are also fully tested with
OD
RS485 loads to ensure they meet RS485 specifications.
See the Electrical Characteristics section for details.
or by powering/depowering the device.
28767fa
16
For more information www.linear.com/LTC2876
LTC2876/LTC2877
applicaTions inForMaTion
Balanced Signal Threshold
LTC2876, LTC2877 - BALANCED THRESHOLDS
+200mV
The LTC2876/LTC2877 differential threshold is 120mV
for rising input signals and –120mV for falling signals.
This constitutes 240mV of hysteresis, which offers a high
rejection to signal noise that can otherwise falsely trip
a receiver. Since these thresholds are centered around
zero volts (i.e. “balanced”), the duty cycle is preserved
for small amplitude signals with slewed edges—typical
of what is observed at the end of a long cable. Figure 11
illustrates this point.
+120mV
V
+
TS
0
(PB–PA)
–120mV
V
–
TS
–200mV
RO
28767 F11
Figure 11. The LTC2876/LTC2877 Balanced Signal Threshold
Voltages Preserve the Duty Cycle of an Incoming Signal. The
Differential Signal Received (Top) Has a Duty Cycle of 50%,
and Is Reflected In the Receiver Output, RO (Bottom)
In contrast to this, some RS485 receivers have an un-
balanced receiver threshold, used to address failsafe
conditions (more on this below). That is, the rising and
falling differential signal thresholds are both negative.
Figure12illustratesanexamplewheretherisingthreshold
is –75mV and falling threshold is –120mV. This has two
disadvantages. First, the hysteresis is only 45mV in this
example, reducing the tolerance to noise, compared to the
240mV of hysteresis in the LTC2876/LTC2877. Secondly,
these unbalanced thresholds cause a duty cycle or pulse
width distortion at the receiver output relative to the input
signal. Figure 12 illustrates how a competitor part, using
the negative thresholds in this example introduces a duty
cycle distortion that becomes increasingly worse with low
input signal levels and slow input edge rates.
UNBALANCED THRESHOLDS
+200mV
(PB–PA)
0
–75mV
–120mV
V
V
+
–
TS
TS
–200mV
RO
28767 F12
Figure 12. Typical Competitor Unbalanced Signal Threshold
Voltages Distort the Duty Cycle of an Incoming Signal. Input Is
50% Duty Cycle (Top) But the Receiver Output Is Not 50% Duty
Cycle (Bottom)
Failsafe Operation
The LTC2876 and LTC2877 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 1.5µs. This
failsafe feature is guaranteed to work for inputs spanning
the entire common mode range of –25V to +25V.
Failsafe operation is performed with a window compara-
tor to determine when the differential input voltage falls
between the rising and falling signal thresholds (V +,
TS
and V –). If this condition persists for more than about
TS
1.5µs then the receiver switches over to using the failsafe
ManyRS485receiverssimplyemployanegativethreshold
(forrisingandfallingsignals)toachievefailsafeoperation.
If the inputs are shorted together (0V differential), the
receiver produces a high output, consistent with failsafe.
However, this asymmetrical threshold comes with the
disadvantages of pulse width distortion and sensitivity to
signal noise as described in the section above.
thresholds (V –, V +), as illustrated in Figure 13 and
TFS
TFS
Figure14.Thedelayallowsnormaldatasignalstotransition
through the threshold region without being interpreted as
a failsafe condition, and thus maintaining the benefits of a
balancedthresholdreceiver. However,forfaultconditions
(e.g., shorted, open, or undriven lines) that persist for
more than 1.5µs, the failsafe thresholds are engaged and
the receiver output drives high, indicating this condition.
The failsafe delay also prevents unwanted receiver output
The LTC2876/LTC2877 achieves full failsafe operation,
whilereapingthebenefitsofabalancedreceiverthreshold.
28767fa
17
For more information www.linear.com/LTC2876
LTC2876/LTC2877
applicaTions inForMaTion
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.
∆V
TS
∆V
TFS
RO
This shutdown mode delay does not affect the outputs of
the transmitter and receiver, which start to switch to the
highimpedancestateuponthereceptionoftheirrespective
(PB–PA)
V
–,V
TFS
–
V
+
V
+
TS
TFS
TS
–200mV –120mV –75mV
0
+120mV +200mV
disable signals as defined by the parameters t
and
SHDND
28767 F13
t
. The shutdown mode delay affects only the time
SHDNR
Figure 13. The LTC2876/LTC2877 Signal Thresholds (VTS–, VTS+)
and Failsafe Thresholds (VTFS–, VTFS+)
when all the internal circuits that draw DC power from
are turned off.
V
CC
+200mV
POWER-UP/DOWN GLITCH-FREE OUTPUTS
+120mV
V
+
TS
TheLTC2876andLTC2877employanundervoltagedetec-
tioncircuittocontroltheactivationoftheon-chipcircuitry.
During power-up, PB, PA, and RO are undriven, until the
(PB–PA) 0
–75mV
V
V
+
TFS
–, V
–
TFS
–120mV
TS
–200mV
2
3
V
supply reaches a voltage sufficient to reliably operate
CC
1
4
the chip. In this mode, only the internal pull-up resistor
on RO and the receiver input resistance to ground on PA
and PB offer weak conduction paths at those pins. As the
supplyvoltagerisesabovetheundervoltagethreshold,and
if the device is configured for drive mode, the PB and PA
pins become active and are driven to a state that reflects
the input condition on DI. Likewise, if the device is config-
ured for receive mode, the RO pin is driven high or low to
reflect the state of the differential voltage across PB–PA.
RO
28767 F14
Figure 14 . LTC2876/LTC2877 Receiver Operation. Event 1: Signal
Rises into Region Between Signal Thresholds, Resulting in the
RO Transitioning to a Failsafe Condition After a Fixed Delay of
About 1.5µs. Event 2: Input Signal Falls Below Negative Signal
Threshold, Resulting in an Immediate Fall on RO. Event 3:
Signal Glitches into the Region Between Signal Thresholds for a
Period Less Than the Failsafe Delay Time (~1.5µs), Resulting in
an Unchanged Output. Event 4 : Signal Transitions Above Rising
Signal Threshold, Resulting in an Immediate Rise in RO
During power down, the reverse occurs; the supply un-
dervoltage detection circuit senses low supply voltage
and immediately puts the chip into shutdown. The driver
and receiver outputs go to the undriven state. RO is pulled
up through the internal 250k pull-up resistor and PA, PB
are pulled low through the 125k receiver input resistors.
glitches resulting from receiver inputs that momentarily
cross into the region between the signal rising and falling
thresholds as illustrated in Figure 14, event 3.
SHUTDOWN MODE DELAY
If the LTC2876/LTC2877 is powered or depowered when
configured for shutdown (RE = 0V and DE = V (LTC2877)
The LTC2876 and LTC2877 feature a low power shutdown
mode that is entered when both the driver and receiver
are simultaneously disabled (pin DE low and RE high).
A shutdown mode delay of approximately 250ns (not
tested in production) is imposed after the state is received
before the chip enters shutdown. If either DE goes high
L
or V (LTC2876) then RO, PB, and PA will remain in the
CC
undriven state, without glitching high or low during the
supply transition. This allows the powering and depower-
ing of the LTC2876/LTC2877 when connected onto a live
network without disturbing the lines.
28767fa
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60V FAULT PROTECTION
technology. The naturally high breakdown voltage of this
technology provides protection in powered off and high
impedance conditions. Figure 15 further illustrates how
thedriverandreceiverinputstoleratelargevoltagesabove
the supply and below ground without excessive device
currents. As shown, the driver outputs are reverse-diode
TIA/EIA-485-A specifies that ground shifts between two
devices on a network can be as large as –7V to +12V
during operation. Most RS485 transceivers cannot safely
tolerate voltages on their interface pins that are much
higher than this range. However, industrial installations
may encounter voltages much greater than this, causing
damage to the devices.
protected from voltages back-driven above V or below
CC
ground. The receiver inputs use resistive dividers that
toleratelargepositiveandnegativevoltages.TheLTC2876/
LTC2877 is protected from 60V bus faults even with the
This requirement means that a driver and receiver sharing
communication on a network must be able to operate with
a signal common mode voltage difference of –7V to 12V.
Competing PROFIBUS transceivers can be damaged by
pin voltages exceeding these levels by only a few volts.
The limited overvoltage tolerance makes implementation
of effective external protection networks difficult without
interferingwithproperdatanetworkperformance.Replac-
ing standard RS485 transceivers with the LTC2876 or
LTC2877 can eliminate field failures due to overvoltage
faults without using costly external protection devices.
loss of GND or V .
CC
25V EXTENDED COMMON MODE RANGE
TheLTC2876/LTC2877receiverfeaturesanextendedcom-
monmoderangeof–25Vto+25V.Thewidecommonmode
increases the reliability of operation in environments with
high common mode voltages created by electrical noise
or local ground potential differences due to ground loops.
This extended common mode range allows the LTC2876/
LTC2877 to transmit and receive under conditions that
would cause data errors or possible device damage in
competing products.
The 60V fault protection of the LTC2876/LTC2877 is
achievedbyusingahighvoltageBiCMOSintegratedcircuit
PB PA
LTC2876/LTC2877
SIMPLIFIED DRIVER
OUTPUT STAGE
LTC2876/LTC2877
SIMPLIFIED RECEIVER
INPUT STAGE
V
CC
20:1
DIVIDE
V
CC
TO RO
OUTPUT CIRCUITS
FROM DI
INPUT CIRCUITS
20:1
DIVIDE
28767 F15
Figure 15. Internal Circuit Structure at PA/PB Pins That Tolerates Large Positive and Negative Voltages
28767fa
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ELECTRICAL OVERSTRESS PROTECTION
charge on one object, and discharged onto another in
close proximity. The LTC2876/LTC2877 features excep-
tionally robust ESD protection. The bus interface pins
(PB and PA) are protected to 52kV human body model
(HBM) with respect to GND when unpowered and 26kV
Equipment used in industrial environments is often ex-
posed to extremely high levels of electrical overstress
due to phenomena such as electrostatic discharges (ESD)
from personnel or equipment, electrical fast transients
(EFT) from switching high current inductive loads, and
even lightning surges. The LTC2876/LTC2877 has been
designed to thrive in these adverse conditions.
with respect to GND, V , or V when powered, without
CC
L
latchup or damage, in any mode of operation. Every other
pin on the device is protected to 15kV ESD (HBM) for
all-around robustness. Figure 16 shows an unprotected
LTC2876 struck repeatedly with 26kV from an ESD gun
using air discharge to illustrate the strike energy. The
device continues to function normally after the strikes,
without damage or cycling the power.
ESD
Perhaps the most common exposure to electrical over-
stress is ESD, which results from the build-up of electrical
Figure 16. This Single Exposure Image Captures the Striking Robustness of an Unprotected LTC2876 Hit Repeatedly with 26kV ESD
Discharges While Operating without Damage or Circuit Latchup
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The IEC standard for ESD, IEC 61000-4-2, specifies a very
fast (sub-nanosecond) edge transient stimulus intended
forsystemlevelESDtestingandnotspecifiedatthedevice
level. However, if it is applied directly to the bus interface
pins,withoutanyexternalprotectiondevices,theLTC2876/
LTC2877isprotectedto4kVIECwhenusedinatypicalap-
plication, powered or unpowered, and terminated with the
standard PROFIBUS load. This is not tested in production.
the transceiver bus, allowing operation at full data rate.
The LTC2876/LTC2877’s 60V pin rating makes it easy
to find protection devices meeting these requirements.
Figure 21 shows a solution providing 4kV protection of
the bus Interface pins (PA and PB) for all three IEC 61000
standards as follows:
IEC 61000-4-5 2nd Ed. 2005-11 Surge Level 4: 4kV
(line to GND, 8/20µs waveform, each line coupled to
generator through 80Ω resistor per Figure 14 of the
standard)
EFT
Electrical fast transients can result from arcing contacts
in switches and relays, common when switching induc-
tive loads. The IEC standard for EFT is IEC61000-4-4 and
specifiesarepetitive burstpattern lasting 60seconds. The
LTC2876/LTC2877 is robust to EFT events and passes the
highest level recognized in the IEC standard: level 4, 2kV
on the PA and PB pins, without any external protection.
IEC 61000-4-4 2nd Ed. 2004-07 EFT Level 4: 4kV
(line to GND, 5kHz repetition rate, 15ms burst duration
every 300ms, 60s test duration, discharge coupled to
bus pins through 100pF capacitor per paragraph 7.3.2
of the standard)
IEC 61000-4-2 2nd Ed. 2008-12 ESD Level 3: 4kV
contact (line to GND, direct discharge to bus pins with
transceiver and standard PROFIBUS resistor load and
protection circuit mounted on a ground referenced test
card per Figure 4 of the standard)
Auxiliary Protection for Surge
Surge events represent the most severe transient condi-
tions caused by such things as load switching in power
distribution systems, high current short circuit faults,
and lighting strikes. These are addressed in standard IEC
61000-4-5, which specifies repetitive voltage and current
waveformsusedtodeliverhighpowerstimuluslastingtens
ofmicrosecondseach.TheLTC2876/LTC2877isdesigned
for high robustness against ESD and EFT, but the on-chip
protectionisnotabletoabsorbtheenergyassociatedwith
the IEC 61000-4-5 surge transients. External protection is
necessary to achieve a high level of surge protection, and
can also extend the ESD and EFT protection to extremely
high levels.
The TVS devices in Figure 21 have a typical clamp voltage
ofabout36V,comfortablybeyondtheLTC2876/LTC2877’s
common mode operating range of 25V and well below
the 60Vrating. SincetheLTC2876/LTC2877buspinsare
rated for 60V, the clamping device must maintain volt-
ages less than this when conducting peak current during
the overstress event. This relatively wide voltage window
permits the use of smaller, more resistive clamps, which
generally also have less capacitance.
Two of these TVS devices are used in an antiparallel con-
figuration because each can only protect in one polarity.
Thebenefitoftheseuni-directionalTVS devicesistheirlow
capacitance, offering a total load of only about 50pF to the
signal lines in this configuration, permitting the LTC2876/
LTC2877 to communicate at maximum data rates with no
significant performance degradation.
Inadditiontoprovidingtransientprotection,externallycon-
nected devices must preserve the ability of the LTC2876/
LTC2877 to operate over a wide common mode voltage
and yet safely clamp the pin voltage low enough to avoid
damageduringtheoverstressevent.Theaddedprotection
must be low in capacitance to avoid excessively loading
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BUS PINS PA & PB NAMING CONVENTION
Table 1. PROFIBUS Type-A Cable Properties
PROPERTY
VALUE
PROFIBUScommunicateswithRS485signalingthrougha
differential signal interface. These wires are labeled A and
B. The PROFIBUS standard specifies that the bus wire B
takes on a positive value with respect to bus wire A when
no station is transmitting data (during the idle periods).
However, the polarity convention of most RS485 devices
uses the opposite convention. That is, with no transmis-
sion on the bus, the receiver reports a logic value that
would result if A were higher than B—in this case a high
on RO. From a practical standpoint, this means that if a
general RS485 transceiver is connected to a PROFIBUS
network, the transceiver’s A pin must connect to the B
wire and the B pin connect to the A wire. Certainly this
can be confusing!
Impedance
135Ω to 165Ω
< 30pF/m
Capacitance
Loop Resistance
Conductor Area
< 110Ω/km
2
≥ 0.34mm
Color of Sheath (Non-IS)
Color of Inner Conductor A
Color of Inner Conductor B
Violet
Green
Red
The three resistors that make up the termination network
should be placed at both ends of the bus and must be
powered during operation. If there are multiple nodes
communicating on the bus, only the nodes at the ends
should be terminated.
Since the LTC2876/LTC2877 was designed specifically
for PROFIBUS applications, the pin naming convention
was made to match the PROFIBUS specification. To avoid
confusion with other RS485 transceivers, the prefix “P”
was added, meaning “PROFIBUS.” If driver and receiver
are enabled, a high level on DI, will drive the bus lines so
that PB is higher than PA and the receiver will report a
high level on RO.
The cable shield helps to improve electromagnetic com-
patibility (EMC). It is recommended to ground both ends
of the shield, through the case of the connector, to the
chassis of the connected station. In applications where
ground potential differences exist between stations, for
example long distance transmission between buildings,
theshieldshouldbegroundedonlyatoneendofthecable.
If the potential difference exceeds several volts, galvanic
isolation is recommended at one or more of the con-
nectedstations.Inthiscase,considerusingtheLTM®2892
In PROFIBUS installations, connect PB to the B wire (red)
and PA to the A wire (green). For non-PROFIBUS RS485
applications,thePBpinshouldbeconnectedtotheAsignal
and PA pin should be connect to the B signal to match the
convention of most other RS485 devices.
µModuleisolator(see3500V
IsolatedPROFIBUSNode
RMS
with Termination on the last page).
If the shield cannot be grounded through the connector
case, pin 1 of the D-sub connector can be used as an
alternative, although the added inductance makes this
sub-optimal. In such a case, it is better to bare the cable
shield at an appropriate point and ground it with a short
cable or clamp to the metallic structure of the station.
PROFIBUS CABLES
It is recommended that PROFIBUS installations use cable
designed for PROFIBUS applications. Typically, Type A
cable and termination is used. This is a shielded twisted
pair with the following properties:
Unshielded cable can be used in PROFIBUS installations
if there is no severe electromagnetic interference (EMI).
Do not use cables that are untwisted pairs.
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MAXIMUM PROFIBUS CABLE LENGTH
The D-sub connector is specified for use up to 12Mbps.
Inductors are often built into the cable connectors to
reduce unwanted ringing and reflections at data rates
above1.5Mbits/s.Cableconnectorsarealsoavailablewith
termination resistors that can be switched in/out.
The following table gives the maximum cable segment
lengths at PROFIBUS baud rates, as specified in IEC
61158-2:
Table 2. PROFIBUS Maximum Cable Length
Table 3. Pin Designation For D-Sub and M12 Connectors.
(Connections in Bold are Mandatory)
BAUD RATE (kbits/s)
MAX. SEGMENT LENGTH (m)
9.6
19.2
1200
1200
1200
1200
1000
400
PIN NUMBER
9-PIN D-Sub
M12
CONNECTION
Cable Shield
45.45
93.75
187.5
500
1, Case
Thread
2
3
4
GND for 24V Supply
PB (B – Red Wire)
4
CNTR-P
(Repeater Direction Control)
1500
3000
6000
12000
200
100
5
6
7
8
9
3
1
GND for Bus Termination
100
V
(+5V) for Bus Termination
+24V Supply
CC
100
2
PA (A – Green Wire)
CNTR-N
(Repeater Direction Control)
CONNECTORS
5
Not Used
The PROFIBUS standard only specifies the use of a 9-pin
D-sub connector for stations and cables. A commonly
used alternative is the 5-pin “B-coded” M12 circular con-
nectors (IEC 947-5-2). In all cases, the female side of the
connector is located in the station, while the cable uses
the male end. Connector diagrams are shown in Figure 17
and pin designations are shown in Table 3.
OPERATION IN RS4 85 AND RS4 22 SYSTEMS
The LTC2876 and LTC2877 are completely compatible
with standard RS485 and RS422 networks. In these in-
stallations, the PB pin should be treated as the A pin for
compatibilitywithmostRS485transceivers. Likewise, the
PA pin should be matched up with the B signal in RS485.
Furtherdiscussionaboutthiscanbefoundinsection“Bus
Pins PA and PB Naming Convention.”
2
4
3
1
3
1
Twistedpaircableswithcharacteristicimpedanceof120Ω
or 100Ω can be used. Shielded cable is recommended
for the highest electromagnetic compatibility (EMC), but
unshielded cable like CAT-5e works well. Untwisted pair
cables (UTP) should be avoided. Both ends of a cable
should be terminated differentially with resistors that
match the cable’s impedance, as illustrated in Figure 10.
4
5
5
2
M12 PLUG
M12 SOCKET
1
2
3
4
5
6
7
8
9
9-PIN D-SUB
28767 F16
Sometimes bus biasing resistors are used for non-
PROFIBUS RS485 installations to introduce a high level
(IDLE state) on the bus when nothing is driving it. An
Figure 17. Connector Pin Allocations
1
example of such a network is shown in Figure 18 . Here
the three resistors (620Ω, 130Ω, and 620Ω) replace the
single 120Ω differential resistor in one location only.
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5V
due to the overvoltage-tolerant design of the LTC2876/
LTC2877, as illustrated in Figure 15.
620Ω
LTC2876
OR
LTC2877
LTC2876
OR
LTC2877
One advantage to using a lower supply voltage is reduced
130Ω
120Ω
V
current draw. V supply currents are roughly pro-
CC
CC
portionaltotheappliedsupplyvoltagewhentheLTC2876/
LTC2877 is driving loads. The Typical Characteristics
section shows the typical power supply currents versus
transmission rates for 3.3V and 5V supplies.
28767 F17
BUS BIAS
RESISTORS
AT ONE END
620Ω
Figure 18. Using the LTC2876/LTC2877 in an RS4 85 Network
(Not PROFIBUS) with Optional Bus Bias Resistors
PROFIBUS installations that use the LTC2876/LTC2877
with supply voltages less than 4.5V, may fall out of com-
pliance to the PROFIBUS specification.
Unlike PROFIBUS, the biasing network is not part of the
RS485 standard. Although the LTC2876 and LTC2877
are compatible with this biasing arrangement, the inter-
nal failsafe feature eliminates the need for it, since an
undriven bus triggers a failsafe condition. In extremely
noisy environments the resistor biasing helps reinforce
the failsafe condition.
HIGH SPEED CONSIDERATIONS
A ground plane layout with a 1µF bypass capacitor placed
less than 7mm away from V is recommended. The PC
CC
board traces connected to signal PB and PA 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.
V LOGIC SUPPLY
L
A separate logic supply pin V allows the LTC2877 to
L
interface with any logic signal from 1.65V to 5.5V. All
logic I/Os use V as their high supply. It is recommended
L
that V does not exceed V during operation. If V does
L
CC
L
Care should be taken to route the outputs away from the
sensitive inputs to reduce feedback effects that might
cause noise, jitter, and even oscillations. For example, DI
and RO should not be routed next to each other or next
to PB and PA.
exceedV ,nodamagewilloccurbuttheV supplycurrent
CC
L
could increase about 300µA, depending on the operating
configuration and the state of the device. If V is not con-
L
nected to V , bypass V with a 0.1µF capacitor to GND.
CC
L
The driver is disabled and pins PB and PA are undriven
when V or V is grounded or disconnected.
Logic inputs have a typical hysteresis of about 150mV to
provide noise immunity. Fast edges on the outputs can
causeglitchesinthegroundandpowersupplieswhichare
exacerbated by capacitive loading. If a logic input is held
L
CC
3.3V OPERATION
The LTC2876 and LTC2877 can be used with a supply
voltage as low as 3.0V in RS485 installations. Reducing
the supply voltage reduces the driver output signal swing
below what is specified in the RS485 standard but still
produces signals much larger than the 200mV minimum
signal swing required at the receiver input. A plot in the
Typical Characteristics section shows the driver output
signal for 3.3V and 5V supply voltages.
near its threshold (typically V /2 or V /2), a noise glitch
CC
L
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 termi-
nation also reduces glitches caused by driver transitions.
3.3V-powered LTC2876/LTC2877 devices can be mixed
withotherRS485transceiversrunningfrom5Vonthesame
network as shown in Figure 20. There is no concern for
the higher voltage of a 5V node overdriving the 3.3V node
REFERENCES
1
“Application Guidelines for TIA/EIA-485-A”: TSB-89-A,
TIA Telecommunications System Bulletin, January 2006.
28767fa
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V
V
L
V
CC
CC
V
V
CC
4.5V to 5.5V
1.65V to 5.5V
4.5V to 5.5V
CC
9-PIN D-SUB
CONNECTOR
(FEMALE)
9-PIN D-SUB
CONNECTOR
(FEMALE)
1µF
0.1µF
1µF
V
V
L
V
CC
CC
LTC2876
RO
LTC2877
RO
1
1
PB
PB
PB
PB
6
6
RE
DI
RE
DI
µC
µC
3
3
SENSOR
SENSOR
PA
PA
8
8
PA
PA
5
5
DE
DE
GND
GND
GND
GND
(a)
(b)
PROFIBUS CABLE
(Z = 150Ω)
390Ω
390Ω
1
3
5
1
3
5
O
6
6
B
220Ω
220Ω
8
8
A
SHIELD
390Ω
390Ω
TERMINATION RESISTOR STRINGS
SWITCHED IN TO SIGNAL LINES
IF LOCATED AT BUS END
9-PIN D-SUB
CONNECTOR
(MALE)
9-PIN D-SUB
CONNECTOR
(MALE)
(c)
28767 F18
Figure 19. Complete Configuration for PROFIBUS Operation Using the (a) LTC2876, or (b) LTC2877 and
(c) the Cable with Termination Resistors
28767fa
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3V TO 5.5V
3V TO 5.5V
V
CC
PB
A
3.3V OR 5V
RS485
NODE
LTC2876/
LTC2877
120Ω
120Ω
B
PA
28767 F19
Figure 20. LTC2876/LTC2877 Operation as Low as 3V is Compatible with Other RS4 85
Devices, but with Reduced Output Signal Swing
TVS
TVS
PB
PB
LTC2876/
LTC2877
PA
PA
TVS
TVS
TVS: LITTLEFUSE SACB30
28767 F21
Figure 21. Exceptionally Robust, Low-Capacitance, 30V Tolerant, 4 ꢀV ꢁEC 61000
Bus Protection Against Surge, EFT, and ESD. (See Auxiliary Protection for Surge,
EFT, and ESD in the Applications ꢁnformation Section for More Details)
28767fa
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LTC2876/LTC2877
package DescripTion
Please refer to http://www.linear.com/product/LTC2876#pacꢀaging for the most recent pacꢀage drawings.
DD Pacꢀage
8-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1698 Rev C)
0.70 ±0.05
3.5 ±0.05
2.10 ±0.05 (2 SIDES)
1.65 ±0.05
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
R = 0.125
0.40 ±0.10
TYP
5
8
3.00 ±0.10
(4 SIDES)
1.65 ±0.10
(2 SIDES)
PIN 1
TOP MARK
(NOTE 6)
(DD8) DFN 0509 REV C
4
1
0.25 ±0.05
0.75 ±0.05
0.200 REF
0.50 BSC
2.38 ±0.10
BOTTOM VIEW—EXPOSED PAD
0.00 – 0.05
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
28767fa
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LTC2876/LTC2877
package DescripTion
Please refer to http://www.linear.com/product/LTC2876#pacꢀaging for the most recent pacꢀage drawings.
DD Pacꢀage
10-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1699 Rev C)
0.70 ±0.05
3.55 ±0.05
2.15 ±0.05 (2 SIDES)
1.65 ±0.05
PACKAGE
OUTLINE
0.25 ±0.05
0.50
BSC
2.38 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
R = 0.125
0.40 ±0.10
TYP
6
10
3.00 ±0.10
(4 SIDES)
1.65 ±0.10
(2 SIDES)
PIN 1 NOTCH
R = 0.20 OR
PIN 1
TOP MARK
(SEE NOTE 6)
0.35 × 45°
CHAMFER
(DD) DFN REV C 0310
5
1
0.25 ±0.05
0.50 BSC
0.75 ±0.05
0.200 REF
2.38 ±0.10
(2 SIDES)
0.00 – 0.05
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
28767fa
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LTC2876/LTC2877
package DescripTion
Please refer to http://www.linear.com/product/LTC2876#pacꢀaging for the most recent pacꢀage drawings.
MS8E Pacꢀage
8-Lead Plastic MSOP, Exposed Die Pad
(Reference LTC DWG # 05-08-1662 Rev K)
BOTTOM VIEW OF
EXPOSED PAD OPTION
1.88
(.074)
1
0.29
REF
1.88 ±0.102
(.074 ±.004)
1.68
(.066)
0.889 ±0.127
(.035 ±.005)
0.05 REF
DETAIL “B”
5.10
(.201)
MIN
3.20 – 3.45
(.126 – .136)
1.68 ±0.102
(.066 ±.004)
CORNER TAIL IS PART OF
THE LEADFRAME FEATURE.
FOR REFERENCE ONLY
DETAIL “B”
8
NO MEASUREMENT PURPOSE
3.00 ±0.102
(.118 ±.004)
(NOTE 3)
0.65
(.0256)
BSC
0.52
(.0205)
REF
0.42 ±0.038
(.0165 ±.0015)
8
7 6 5
TYP
RECOMMENDED SOLDER PAD LAYOUT
3.00 ±0.102
(.118 ±.004)
(NOTE 4)
4.90 ±0.152
(.193 ±.006)
DETAIL “A”
0.254
(.010)
0° – 6° TYP
GAUGE PLANE
1
2
3
4
0.53 ±0.152
(.021 ±.006)
1.10
(.043)
MAX
0.86
(.034)
REF
DETAIL “A”
0.18
(.007)
SEATING
PLANE
0.22 – 0.38
(.009 – .015)
TYP
0.1016 ±0.0508
(.004 ±.002)
0.65
(.0256)
BSC
MSOP (MS8E) 0213 REV K
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.
28767fa
29
For more information www.linear.com/LTC2876
LTC2876/LTC2877
package DescripTion
Please refer to http://www.linear.com/product/LTC2876#pacꢀaging for the most recent pacꢀage drawings.
MSE Pacꢀage
10-Lead Plastic MSOP, Exposed Die Pad
(Reference LTC DWG # 05-08-1664 Rev I)
BOTTOM VIEW OF
EXPOSED PAD OPTION
1.88
(.074)
1.88 ±0.102
(.074 ±.004)
0.889 ±0.127
(.035 ±.005)
1
0.29
REF
1.68
(.066)
0.05 REF
5.10
(.201)
MIN
1.68 ±0.102
3.20 – 3.45
DETAIL “B”
(.066 ±.004) (.126 – .136)
CORNER TAIL IS PART OF
THE LEADFRAME FEATURE.
FOR REFERENCE ONLY
DETAIL “B”
10
NO MEASUREMENT PURPOSE
0.50
(.0197)
BSC
0.305 ± 0.038
(.0120 ±.0015)
TYP
3.00 ±0.102
(.118 ±.004)
(NOTE 3)
0.497 ±0.076
(.0196 ±.003)
10 9
8
7 6
RECOMMENDED SOLDER PAD LAYOUT
REF
3.00 ±0.102
(.118 ±.004)
(NOTE 4)
4.90 ±0.152
(.193 ±.006)
DETAIL “A”
0.254
(.010)
0° – 6° TYP
1
2
3
4 5
GAUGE PLANE
0.53 ±0.152
(.021 ±.006)
0.86
(.034)
REF
1.10
(.043)
MAX
DETAIL “A”
0.18
(.007)
SEATING
PLANE
0.17 – 0.27
(.007 – .011)
TYP
0.1016 ±0.0508
(.004 ±.002)
0.50
(.0197)
BSC
MSOP (MSE) 0213 REV I
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.
28767fa
30
For more information www.linear.com/LTC2876
LTC2876/LTC2877
revision hisTory
REV
DATE
DESCRꢁPTꢁON
PAGE NUMBER
A
08/16 Changed test condition for t
and t
5
PLHR
PHLR
28767fa
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 representa-
31
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
LTC2876/LTC2877
Typical applicaTion
3500VRMS Isolated PROFIBUS Node with Termination
ISOLATED
5V
LTM2892-S
IN
A6
A5
A4
B1
B2
B3
A3
A2
A1
B4
B5
B6
8
3V TO
5.5V
J6
J5
J4
J1
J2
J3
H3
H2
H1
H4
H5
H6
V
LTC2876
CC
V
V
ON1
OUTD
OUTE
OUTF
INC
INB
INA
V
CC2
V
L2
ON2
IND
INE
CC1
L1
390Ω
1
RO
4
RO
PB
6
3
2
RE
1
INF
220Ω
OUTC
OUTB
OUTA
EOUTA
GND2
GND2
7
D R
2
M12
CONNECTOR
(FEMALE)
4
DI
DI
PA
390Ω
EOUTD
GND1
GND1
3
DE
5
GND
ISOLATED
GROUND
28767 TA02
relaTeD parTs
PART NUMBER
DESCRIPTION
COMMENTS
LTC2862/LTC2863/ 60V Fault Protected 3V to 5.5V RS485/RS422 Transceivers
LTC2864/LTC2865
60V Tolerant, 15kV ESD, 250kbps or 20Mbps
15kV ESD, 250kbps or 20Mbps
15kV ESD
LTC2856/LTC2857/ 5V 20Mbps and Slew Rate Limited 15kV RS485/RS422
LTC2858
Transceivers
LTC2850/LTC2851/ 3.3V 20Mbps RS485 Transceivers
LTC2852
LTC2854/LTC2855 3.3V 20Mbps RS485 Transceivers with Integrated Switchable
Termination
25kV ESD (LTC2854), 15kV ESD (LTC2855)
15kV ESD
LTC2859, LTC2861 5V 20Mbps and Slew Rate Limited RS485 Transceivers
LTM2881
Complete 3.3V or 5V Isolated RS485 µModule Transceiver +
Power, and Switchable Integrated Termination Resistor
2500V
Isolation, with Integrated Isolated DC/DC Converter,
RMS
1W Power, Low EMI, 15kV ESD, 30kV/µs Transient Immunity
LTM2892
3500V
6-Channel Digital Isolator
3500V Isolation in a Small Package with Temperature Ratings
RMS
RMS
Up to 125°C
28767fa
LT 0816 REV A • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
32
(408)432-1900 FAX: (408) 434-0507 www.linear.com/LTC2876
●
●
LINEAR TECHNOLOGY CORPORATION 2016
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