1.62V to 5.5V Logic Supply Pin for Flexible Digital Interface
Common Mode 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
Small, Low Profile (15mm
×
11.25mm)
Surface Mount BGA and LGA Packages
The LTM
®
2881 is a complete galvanically isolated full-
duplex RS485/RS422 μModule
®
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.
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
PWR
LTM2881 Operating Through 35kV/μs CM Transients
MULTIPLE SWEEPS
OF COMMON MODE
TRANSIENTS
LTM2881
V
CC2
A
B
5V
AVAILABLE CURRENT:
150mA (LTM2881-5)
100mA (LTM2881-3)
500V/DIV
DI
TWISTED-PAIR
CABLE
1V/DIV
1V/DIV
50ns/DIV
2881 TA01a
RO
Y
Z
GND2
2881 TA01
2881fe
1
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
GND2
GND
V
CC
2
3
4
5
6
7
8
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 125°C
Peak Package Body Reflow Temperature .............. 245°C
D
OUT
TE
BGA PACKAGE
32-PIN (15mm 11.25mm 3.42mm)
T
JMAX
= 125°C,
JA
= 32.2°C/W,
JCTOP
= 27.2°C/W,
JCBOTTOM
= 20.9°C/W,
JB
= 26.4°C/W,
WEIGHT = 1g
LGA PACKAGE
32-PIN (15mm 11.25mm 2.8mm)
T
JMAX
= 125°C,
JA
= 31.1°C/W,
JCTOP
= 27.3°C/W,
JCBOTTOM
= 19.5°C/W,
JB
= 25.1°C/W,
WEIGHT = 1g
ORDER INFORMATION
LEAD FREE FINISH
LTM2881CY-3#PBF
LTM2881IY-3#PBF
LTM2881HY-3#PBF
LTM2881MPY-3#PBF
LTM2881CY-5#PBF
LTM2881IY-5#PBF
LTM2881HY-5#PBF
LTM2881MPY-5#PBF
LTM2881CV-3#PBF
LTM2881IV-3#PBF
LTM2881HV-3#PBF
LTM2881CV-5#PBF
LTM2881IV-5#PBF
LTM2881HV-5#PBF
TRAY
LTM2881CY-3#PBF
LTM2881IY-3#PBF
LTM2881HY-3#PBF
LTM2881MPY-3#PBF
LTM2881CY-5#PBF
LTM2881IY-5#PBF
LTM2881HY-5#PBF
LTM2881MPY-5#PBF
LTM2881CV-3#PBF
LTM2881IV-3#PBF
LTM2881HV-3#PBF
LTM2881CV-5#PBF
LTM2881IV-5#PBF
LTM2881HV-5#PBF
PART MARKING*
LTM2881Y-3
LTM2881Y-3
LTM2881Y-3
LTM2881Y-3
LTM2881Y-5
LTM2881Y-5
LTM2881Y-5
LTM2881Y-5
LTM2881V-3
LTM2881V-3
LTM2881V-3
LTM2881V-5
LTM2881V-5
LTM2881V-5
PACKAGE DESCRIPTION
32-Pin (15mm
×
11.25mm
×
3.42mm) BGA
32-Pin (15mm
×
11.25mm
×
3.42mm) BGA
32-Pin (15mm
×
11.25mm
×
3.42mm) BGA
32-Pin (15mm
×
11.25mm
×
3.42mm) BGA
32-Pin (15mm
×
11.25mm
×
3.42mm) BGA
32-Pin (15mm
×
11.25mm
×
3.42mm) BGA
32-Pin (15mm
×
11.25mm
×
3.42mm) BGA
32-Pin (15mm
×
11.25mm
×
3.42mm) BGA
32-Pin (15mm
×
11.25mm
×
2.8mm) LGA
32-Pin (15mm
×
11.25mm
×
2.8mm) LGA
32-Pin (15mm
×
11.25mm
×
2.8mm) LGA
32-Pin (15mm
×
11.25mm
×
2.8mm) LGA
32-Pin (15mm
×
11.25mm
×
2.8mm) LGA
32-Pin (15mm
×
11.25mm
×
2.8mm) LGA
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
–40°C to 105°C
–55°C to 105°C
0°C to 70°C
–40°C to 85°C
–40°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
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
This product is only offered in trays. For more information go to:
http://www.linear.com/packaging/
2881fe
2
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
PARAMETER
V
CC
Supply Voltage
V
L
Supply Voltage
V
CC
Supply Current in Off Mode
V
CC
Supply Current in On Mode
ON = 0V
LTM2881-3 DE = 0V,
RE
= V
L
, No Load
LTM2881-5 DE = 0V,
RE
= V
L
, No Load
LTM2881-5, H/MP-Grade
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
l
ELECTRICAL CHARACTERISTICS
CONDITIONS
LTM2881-3
LTM2881-5
Power Supply
MIN
l
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
25
19
20
UNITS
V
V
V
μA
mA
mA
mA
V
V
V
3.0
4.5
1.62
V
CC2
Regulated V
CC2
Output Voltage,
Loaded
4.75
4.75
4.75
4.8
5.0
5.0
5.0
62
250
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
|
Differential Driver Output Voltage
V
CC2
Short-Circuit Current
V
%
mA
V
V
V
V
2.1
2.1
Δ|V
OD
|
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)
V
OC
Δ|V
OC
|
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
Receiver Input Resistance
DE = 0V, (Y or Z) = –7V, +12V
DE = 0V, (Y or Z) = –7V, +12V, H/MP-Grade
– 7V ≤ (Y or Z) ≤ 12V (Figure 2)
I
OZD
l
l
l
±10
±50
– 250
250
μA
μA
mA
I
OSD
Receiver
R
IN
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
R
TE
I
IN
Receiver Termination Resistance
Enabled
Receiver Input Current (A, B)
–100
–145
–0.2
25
–0.2
–0.05
V
TH
ΔV
TH
Receiver Differential Input
Threshold Voltage (A-B)
–7V ≤ B ≤ 12V
Receiver Input Failsafe Hysteresis B = 0V
Receiver Input Failsafe Threshold B = 0V
2881fe
3
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
LO AD
= 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
Δt
PD
t
SKEWD
t
RD
t
FD
t
ZLD
, t
ZHD
,
t
LZD
, t
HZD
f
MAX
t
PLHD
t
PHLD
Δt
PD
t
SKEWD
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
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)
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
1.55
500
±500
kbps
μs
ns
ns
2881fe
4
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
t
RD
t
FD
t
ZLD
, t
ZHD
,
t
LZD
, t
HZD
Receiver
t
PLHR
t
PHLR
t
SKEWR
t
RR
t
FR
t
ZLR
, t
ZHR
,
t
LZR
, t
HZR
t
RTEN
, t
RTZ
Receiver Input to Output
Differential Receiver Skew
|t
PLHR
- t
PHLR
|
C
L
= 15pF, V
CM
= 2.5V, |V
AB
| = 1.4V,
t
R
and t
F
< 4ns, (Figure 6)
C
L
= 15pF
(Figure 6)
l
l
l
l
l
SWITCHING CHARACTERISTICS
PARAMETER
Driver Rise or Fall Time
Driver Output Enable or Disable
Time
CONDITIONS
MIN
l
l
TYP
0.9
MAX
1.5
400
UNITS
μs
ns
R
DIFF
= 54Ω, C
L
= 100pF
(Figure 4)
R
L
= 500Ω, C
L
= 50pF
(Figure 5)
100
1
3
140
8
12.5
50
100
ns
ns
ns
ns
μs
Receiver Output Rise or Fall Time C
L
= 15pF
(Figure 6)
Receiver Output Enable Time
Termination Enable or Disable
Time
D
IN
to D
OUT
Input to Output
R
L
=1kΩ, C
L
= 15pF
(Figure 7)
RE
= 0V, DE = 0V, V
AB
= 2V, V
B
= 0V (Figure 8)
Generic Logic Input
t
PLHL1
t
PHLL1
C
L
= 15pF,
t
R
and t
F
< 4ns
ON
V
L
, No Load
l
60
100
ns
Power Supply Generator
V
CC2
–GND2 Supply Start-Up
Time
(0V to 4.5V)
l
325
800
μs
ISOLATION CHARACTERISTICS
otherwise noted.
SYMBOL
V
ISO
PARAMETER
Rated Dielectric Insulation Voltage
Common Mode Transient Immunity
V
IORM
Maximum Working Insulation Voltage
Partial Discharge
Input to Output Resistance
Input to Output Capacitance
Creepage Distance
T
A
= 25°C, LTM2881-3 V
CC
= 3.3V, LTM2881-5 V
CC
= 5.0V, V
L
= 3.3V unless
MIN
2500
±4400
±30
560
400
5
10
9
6
9.48
TYP
MAX
UNITS
V
RMS
V
DC
kV/μs
V
PEAK
V
RMS
pC
Ω
pF
mm
CONDITIONS
1 Minute (Derived from 1 Second Test)
1 Second (Note 5)
LTM2881-3 V
CC
= 3.3V, LTM2881-5 V
CC
= 5V,
V
L
= ON = 3.3V, V
CM
= 1kV, Δt = 33ns (Note 2)
(Notes 2, 5)
V
PR
= 1050 V
PEAK
(Note 2)
(Notes 2, 5)
(Notes 2, 5)
(Notes 2, 5)
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:
Guaranteed by design and not subject to production test.
Note 3:
Maximum Data rate is guaranteed by other measured parameters
and is not tested directly.
Note 4:
This μModule transceiver includes overtemperature protection that
is intended to protect the device during momentary overload conditions.
Junction temperature will exceed 125°C when overtemperature protection
is active. Continuous operation above specified maximum operating
junction temperature may result in device degradation or failure.
Note 5:
Device considered a 2-terminal device. Pin group A1 through B8
shorted together and pin group K1 through L8 shorted together.
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