FeaTures
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LTM2881
Complete Isolated
RS485/RS422 µModule
Transceiver + Power
DescripTion
The
LTM
®
2881
is a complete galvanically isolated full-du-
plex RS485/RS422 µModule
®
(micromodule) transceiver.
No external components are required. A single supply
powers both sides of the interface through an integrated,
isolated, low noise, efficient 5V output DC/DC converter.
Coupled inductors and an isolation power transformer
provide 2500V
RMS
of isolation between the line transceiver
and the logic interface. This device is ideal for systems
where the ground loop is broken allowing for large com-
mon mode voltage variation. Uninterrupted communica-
tion is guaranteed for common mode transients greater
than 30kV/μs.
Maximum data rates are 20Mbps or 250kbps in slew
limited mode. Transmit data, DI and receive data, RO, are
implemented with event driven low jitter processing. The
receiver has a one-eighth unit load supporting up to 256
nodes per bus. A logic supply pin allows easy interfacing
with different logic levels from 1.62V to 5.5V, independent
of the main supply.
Enhanced ESD protection allows this part to withstand up
to ±15kV (human body model) on the transceiver interface
pins to isolated supplies and ±10kV through the isolation
barrier to logic supplies without latch-up or damage.
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.
RS485/RS422 Transceiver: 2500V
RMS
for 1 Minute
UL-CSA Recognized
File #E151738
CSA Component Acceptance Notice 5A
Isolated DC Power: 5V at Up to 200mA
No External Components Required
20Mbps or Low EMI 250kbps Data Rate
High ESD: ±15kV HBM on Transceiver Interface
High Common Mode Transient Immunity: 30kV/μs
Integrated Selectable 120Ω Termination
3.3V (LTM2881-3) or 5.0V (LTM2881-5) Operation
1.62V to 5.5V Logic Supply Pin for Flexible Digital Interface
Maximum Continuous Working Voltage: 560V
PEAK
High Input Impedance Failsafe RS485 Receiver
Current Limited Drivers and Thermal Shutdown
Compatible with TIA/EIA-485-A and PROFIBUS
High Impedance Output During Internal Fault Condition
Low Current Shutdown Mode (< 10µA)
General Purpose CMOS Isolated Channel
15mm
×
11.25mm BGA and LGA Packages
applicaTions
n
n
n
n
Isolated RS485/RS422 Interface
Industrial Networks
Breaking RS485 Ground Loops
Isolated PROFIBUS-DP Networks
Typical applicaTion
Isolated Half-Duplex RS485 μModule Transceiver
3.3V (LTM2881-3)
5V (LTM2881-5)
V
CC
ISOLATION BARRIER
V
L
RO
RE
TE
DE
DI
GND
LTM2881
AVAILABLE CURRENT:
150mA (LTM2881-5)
100mA (LTM2881-3)
LTM2881 Operating Through 35kV/μs CM Transients
MULTIPLE SWEEPS
OF COMMON MODE
TRANSIENTS
PWR
V
CC2
A
B
5V
500V/DIV
DI
TWISTED-PAIR
CABLE
1V/DIV
1V/DIV
50ns/DIV
2881 TA01a
RO
Y
Z
GND2
2881 TA01
For more information
www.linear.com/LTM2881
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LTM2881
absoluTe MaxiMuM raTings
(Note 1)
pin conFiguraTion
TOP VIEW
1
A
B
C
D
E
F
G
H
J
K
L
D
IN
SLO
Y
Z
B
A
V
CC2
BGA PACKAGE
32-PIN (15mm
×
11.25mm
×
3.42mm)
T
JMAX
= 125°C,
θ
JA
= 32.2°C/W,
θ
JCTOP
= 27.2°C/W,
θ
JCBOTTOM
= 20.9°C/W,
θ
JB
= 26.4°C/W,
WEIGHT = 1g
LGA PACKAGE
32-PIN (15mm
×
11.25mm
×
2.8mm)
T
JMAX
= 125°C,
θ
JA
= 31.1°C/W,
θ
JCTOP
= 27.3°C/W,
θ
JCBOTTOM
= 19.5°C/W,
θ
JB
= 25.1°C/W,
WEIGHT = 1g
GND2
GND
V
CC
2
3
4
5
6
7
8
D
OUT
TE
DI DE
RE
RO V
L
ON
V
CC
to GND .................................................. –0.3V to 6V
V
CC2
to GND2 ............................................... –0.3V to 6V
V
L
to GND .................................................... –0.3V to 6V
Interface Voltages
(A, B, Y, Z) to GND2 ........................ V
CC2
–15V to 15V
(A-B) with Terminator Enabled ..............................±6V
Signal Voltages ON, RO, DI, DE,
RE,
TE, D
OUT
to GND ......................... –0.3V to V
L
+0.3V
Signal Voltages
SLO,
D
IN
to GND2 ....................................–0.3V to V
CC2
+0.3V
Operating Temperature Range
LTM2881C ............................................... 0°C to 70°C
LTM2881I.............................................–40°C to 85°C
LTM2881H ......................................... –40°C to 105°C
LTM2881MP ...................................... –55°C to 105°C
Maximum Internal Operating Temperature ....... 125°C
Storage Temperature Range .................. –55°C to 150°C
Peak Package Body Reflow Temperature .............. 245°C
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For more information
www.linear.com/LTM2881
LTM2881
orDer inForMaTion
PART NUMBER
LTM2881CY-3#PBF
LTM2881IY-3#PBF
LTM2881HY-3#PBF
LTM2881HY-3
LTM2881MPY-3#PBF
LTM2881MPY-3
LTM2881CY-5#PBF
LTM2881IY-5#PBF
LTM2881HY-5#PBF
LTM2881HY-5
LTM2881MPY-5#PBF
LTM2881MPY-5
LTM2881CV-3#PBF
LTM2881IV-3#PBF
LTM2881HV-3#PBF
LTM2881CV-5#PBF
LTM2881IV-5#PBF
LTM2881HV-5#PBF
INPUT
VOLTAGE
http://www.linear.com/product/LTM2881#orderinfo
PART MARKING
DEVICE
FINISH CODE
e1
LTM2881Y-3
e0
e1
e0
e1
LTM2881Y-5
e0
e1
e0
3
PACKAGE
TYPE
MSL
RATING
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
–40°C to 105°C
–40°C to 105°C
–55°C to 105°C
–55°C to 105°C
0°C to 70°C
–40°C to 85°C
–40°C to 105°C
–40°C to 105°C
–55°C to 105°C
–55°C to 105°C
0°C to 70°C
–40°C to 85°C
–40°C to 105°C
0°C to 70°C
–40°C to 85°C
–40°C to 105°C
PAD OR BALL FINISH
SAC305 (RoHS)
3V to 3.6V
SnPb (63/37)
SAC305 (RoHS)
SnPb (63/37)
SAC305 (RoHS)
BGA
4.5V to 5.5V
SnPb (63/37)
SAC305 (RoHS)
SnPb (63/37)
3V to 3.6V
Au (RoHS)
4.5V to 5.5V
LTM2881V-3
e4
LTM2881V-5
LGA
•
Device temperature grade is indicated by a label on the shipping
container.
•
Pad or ball finish code is per IPC/JEDEC J-STD-609.
•
Terminal Finish Part Marking:
www.linear.com/leadfree
•
This product is not recommended for second side reflow. For more
information, go to:
www.linear.com/BGA-assy
•
Recommended BGA and LGA PCB Assembly and Manufacturing
Procedures:
www.linear.com/umodule/pcbassembly
•
LGA and BGA Package and Tray Drawings:
www.linear.com/packaging
•
This product is moisture sensitive. For more information, go to:
www.linear.com/umodule/pcbassembly
For more information
www.linear.com/LTM2881
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LTM2881
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. LTM2881-3 V
CC
= 3.3V, LTM2881-5 V
CC
= 5.0V, V
L
= 3.3V, GND = GND2
= 0V, ON = V
L
unless otherwise noted.
SYMBOL
V
CC
V
L
I
CCPOFF
I
CCS
V
CC2
PARAMETER
V
CC
Supply Voltage
V
L
Supply Voltage
V
CC
Supply Current in Off Mode
V
CC
Supply Current in On Mode
Regulated V
CC2
Output Voltage,
Loaded
ON = 0V
LTM2881-3 DE = 0V,
RE
= V
L
, No Load
LTM2881-5 DE = 0V,
RE
= V
L
, No Load
LTM2881-3 DE = 0V,
RE
= V
L
, I
LOAD
= 100mA
LTM2881-5 DE = 0V,
RE
= V
L
, I
LOAD
= 150mA
LTM2881-3, H/MP-Grade, I
LOAD
= 90mA
DE = 0V,
RE
= V
L
, No Load
I
CC2
= 100mA, LTM2881-5 (Note 2)
DE = 0V,
RE
= V
L
, V
CC2
= 0V
R = ∞ (Figure 1)
R = 27Ω (RS485) (Figure 1)
R = 50Ω (RS422) (Figure 1)
l
l
l
l
elecTrical characTerisTics
CONDITIONS
LTM2881-3
LTM2881-5
Power Supply
MIN
l
l
l
l
l
l
l
l
l
TYP
3.3
5.0
0
20
15
MAX
3.6
5.5
5.5
10
30
25
UNITS
V
V
V
µA
mA
mA
V
V
V
3.0
4.5
1.62
4.75
4.75
4.75
4.8
5.0
5.0
5.0
62
200
V
CC2
V
CC2
V
CC2
0.2
5.35
V
CC2NOLOAD
Regulated V
CC2
Output Voltage,
No Load
Efficiency
I
CC2S
Driver
|V
OD
|
∆|V
OD
|
V
OC
∆|V
OC
|
I
OZD
I
OSD
Receiver
R
IN
R
TE
I
IN
Receiver Input Resistance
Differential Driver Output Voltage
V
CC2
Short-Circuit Current
V
%
mA
V
V
V
V
2.1
2.1
Difference in Magnitude of Driver R = 27Ω or R = 50Ω (Figure 1)
Differential Output Voltage for
Complementary Output States
Driver Common Mode Output
Voltage
R = 27Ω or R = 50Ω (Figure 1)
l
l
3
0.2
V
V
Difference in Magnitude of Driver R = 27Ω or R = 50Ω (Figure 1)
Common Mode Output Voltage
for Complementary Output States
Driver Three-State (High
Impedance) Output Current on
Y and Z
Maximum Driver Short-Circuit
Current
DE = 0V, (Y or Z) = –7V, +12V
DE = 0V, (Y or Z) = –7V, +12V, H/MP-Grade
– 7V ≤ (Y or Z) ≤ 12V (Figure 2)
l
l
l
±10
±50
– 250
250
µA
µA
mA
RE
= 0V or V
L
, V
IN
= –7V, –3V, 3V, 7V, 12V (Figure 3)
RE
= 0V or V
L
, V
IN
= –7V, –3V, 3V, 7V, 12V (Figure 3),
H/MP-Grade
TE = V
L
, V
AB
= 2V, V
B
= – 7V, 0V, 10V (Figure 8)
ON = 0V V
CC2
= 0V or 5V, V
IN
= 12V (Figure 3)
ON = 0V V
CC2
= 0V or 5V, V
IN
= 12V (Figure 3), H/MP-Grade
ON = 0V V
CC2
= 0V or 5V, V
IN
= –7V (Figure 3)
ON = 0V V
CC2
= 0V or 5V, V
IN
= –7V (Figure 3), H/MP-Grade
l
l
l
l
l
l
l
l
96
48
108
125
125
120
156
125
250
kΩ
kΩ
Ω
µA
µA
0.2
V
mV
0
V
Receiver Termination Resistance
Enabled
Receiver Input Current (A, B)
–100
–145
–0.2
25
–0.2
–0.05
V
TH
∆V
TH
Receiver Differential Input
Threshold Voltage (A-B)
–7V ≤ B ≤ 12V
Receiver Input Failsafe Hysteresis B = 0V
Receiver Input Failsafe Threshold B = 0V
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For more information
www.linear.com/LTM2881
LTM2881
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. LTM2881-3 V
CC
= 3.3V, LTM2881-5 V
CC
= 5.0V, V
L
= 3.3V, GND = GND2
= 0V, ON = V
L
unless otherwise noted.
SYMBOL
Logic
V
IL
V
IH
Logic Input High Voltage
Logic Input Low Voltage
1.62V ≤ V
L
≤ 5.5V
D
IN
SLO
DI, TE, DE, ON,
RE:
V
L
≥ 2.35V
1.62V ≤ V
L
< 2.35V
(Note 2)
Output High, I
LOAD
= –4mA
(Sourcing), 5.5V ≥ V
L
≥ 3V
Output High, I
LOAD
= –1mA
(Sourcing), 1.62V ≤ V
L
< 3V
Output Low, I
LOAD
= 4mA
(Sinking), 5.5V ≥ V
L
≥ 3V
Output High, I
LOAD
= 1mA
(Sinking), 1.62V ≤ V
L
< 3V
RE
= V
L
, 0V ≤ RO ≤ V
L
0V ≤ (RO or D
OUT
) ≤ V
L
l
l
l
l
l
l
l
l
l
l
l
l
elecTrical characTerisTics
PARAMETER
CONDITIONS
MIN
TYP
MAX
0.4
UNITS
V
V
V
V
V
0.67•V
CC2
2
0.67•V
L
0.75•V
L
0
150
V
L
–0.4
V
L
–0.4
0.4
0.4
±1
±85
±1
I
INL
V
HYS
V
OH
Logic Input Current
Logic Input Hysteresis
Output High Voltage
µA
mV
V
V
V
V
µA
mA
V
OL
Output Low Voltage
I
OZR
I
OSR
Three-State (High Impedance)
Output Current on RO
Short-Circuit Current
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. LTM2881-3 V
CC
= 3.3V, LTM2881-5 V
CC
= 5.0V, V
L
= 3.3V, GND = GND2
= 0V, ON = V
L
unless otherwise noted.
SYMBOL
f
MAX
t
PLHD
t
PHLD
∆t
PD
t
SKEWD
t
RD
t
FD
t
ZLD
, t
ZHD
,
t
LZD
, t
HZD
f
MAX
t
PLHD
t
PHLD
∆t
PD
t
SKEWD
t
RD
t
FD
PARAMETER
Maximum Data Rate
Driver Input to Output
Driver Input to Output Difference
|t
PLHD
– t
PHLD
|
Driver Output Y to Output Z
Driver Rise or Fall Time
Driver Output Enable or Disable
Time
Maximum Data Rate
Driver Input to Output
Driver Input to Output Difference
|t
PLHD
– t
PHLD
|
Driver Output Y to Output Z
Driver Rise or Fall Time
CONDITIONS
(Note 3)
R
DIFF
= 54Ω, C
L
= 100pF
(Figure 4)
R
DIFF
= 54Ω, C
L
= 100pF
(Figure 4)
R
DIFF
= 54Ω, C
L
= 100pF
(Figure 4)
R
DIFF
= 54Ω, C
L
= 100pF
(Figure 4)
R
L
= 500Ω, C
L
= 50pF
(Figure 5)
(Note 3)
R
DIFF
= 54Ω, C
L
= 100pF
(Figure 4)
R
DIFF
= 54Ω, C
L
= 100pF
(Figure 4)
R
DIFF
= 54Ω, C
L
= 100pF
(Figure 4)
R
DIFF
= 54Ω, C
L
= 100pF
(Figure 4)
l
l
l
l
l
l
swiTching characTerisTics
Driver
SLO
= V
CC2
MIN
20
TYP
MAX
UNITS
Mbps
60
1
1
4
85
8
±8
12.5
170
ns
ns
ns
ns
ns
Driver
SLO
= GND2
250
1
50
±200
0.9
1.55
500
±500
1.5
kbps
µs
ns
ns
µs
For more information
www.linear.com/LTM2881
5
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