RS485/422 transceivers operating on 5V supplies. The
receiver includes a logic-selectable 120Ω termination,
one-eighth unit load supporting up to 256 nodes per bus,
and a failsafe feature that guarantees a high output state
under conditions of floating or shorted inputs.
The driver features a logic-selectable low-EMI 250kbps
operating mode, and maintains a high output impedance
over the entire common mode range when disabled or
when the supply is removed. Excessive power dissipation
caused by bus contention or a fault is prevented by current
limiting all outputs and by a thermal shutdown.
Enhanced ESD protection allows the LTC2859 and LTC2861
to withstand ±15kV (human body model) on the transceiver
interface pins without latchup or damage.
■
■
■
■
■
■
Integrated, Logic-Selectable 120Ω Termination
Resistor
20Mbps Max Data Rate
No Damage or Latchup to ESD: ±15kV HBM
High Input Impedance Supports 256 Nodes
250kbps Low-EMI Mode
Guaranteed Failsafe Receiver Operation Over the
Entire Common Mode Range
Current Limited Drivers and Thermal Shutdown
Delayed Micropower Shutdown (5μA Max)
Power Up/Down Glitch-Free Driver Outputs
Low Operating Current (900μA Max in Receive Mode)
Meets All TIA/EIA-485-A Specifications
Available in 10-Pin 3mm
×
3mm DFN, 12-Pin
4mm
×
3mm DFN and 16-Pin SSOP Packages
APPLICATIONS
■
■
■
Low Power RS485/RS422 Transceiver
Level Translator
Backplane Transceiver
PRODUCT SELECTION GUIDE
PART NUMBER
LTC2859
LTC2861
DUPLEX
Half
Full
PACKAGE
DFN-10
SSOP-16, DFN-12
L,
LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
LTC2859
RO
RE
TE
DE
DI
SLO
2859/61 TA01
LTC2859
R
RO
RE
TE
DE
Y
D
DI
SLO
LTC2859
120Ω
2V/DIV
20ns/DIV
Z
Y–Z
R
LTC2859 at 20Mbps
DI
120Ω
D
120Ω
285961 TA02
R
D
RO
RE
TE DE
DI
SLO
285961fb
1
LTC2859/LTC2861
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Supply Voltage (V
CC
) ................................... –0.3V to 7V
Logic Input Voltages (RE, DE, DI, TE,
SLO)
... –0.3V to 7V
Interface I/O:
A, B, Y, Z ...................................... (V
CC
–15V) to +15V
(A-B) or (B-A) with Terminat or Enabled .................6V
Receiver Output Voltage (RO) ........ –0.3V to (V
CC
+0.3V)
Operating Temperature (Note 4)
LTC2859C, LTC2861C .............................. 0°C to 70°C
LTC2859I, LTC2861I ............................. –40°C to 85°C
Storage Temperature Range................... –65°C to 125°C
Lead Temperature (Soldering, 10 sec)
GN Package ...................................................... 300°C
PIN CONFIGURATION
TOP VIEW
TOP VIEW
RO
RO
RE
DE
DI
TE
1
2
3
4
5
11
10 V
CC
9 B
8 A
7
SLO
6 GND
RE
DE
DI
TE
GND
DD PACKAGE
10-LEAD (3mm
×
3mm) PLASTIC DFN
EXPOSED PAD (PIN 11) PCB GND CONNECTION
T
JMAX
= 125°C,
θ
JA
= 43°C/W
θ
JC
= 3°C/W
1
2
3
4
5
6
13
12 V
CC
11 A
10 B
9
8
7
Z
Y
SLO
RO
RE
DE
DI
TE
GND
NC
NC
1
2
3
4
5
6
7
8
TOP VIEW
16 V
CC
15 A
14 B
13 Z
12 Y
11
SLO
10 NC
9
NC
DE PACKAGE
12-LEAD (4mm
×
3mm) PLASTIC DFN
EXPOSED PAD (PIN 13) PCB GND CONNECTION
T
JMAX
= 125°C,
θ
JA
= 43°C/W
θ
JC
= 4.3°C/W
GN PACKAGE
16-LEAD (NARROW 0.150) PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 110°C/W
θ
JC
= 40°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC2861CDE#PBF
LTC2861IDE#PBF
LTC2861CGN#PBF
LTC2861IGN#PBF
LTC2859CDD#PBF
LTC2859IDD#PBF
LEAD BASED FINISH
LTC2861CDE
LTC2861IDE
LTC2861CGN
LTC2861IGN
TAPE AND REEL
LTC2861CDE#TRPBF
LTC2861IDE#TRPBF
LTC2861CGN#TRPBF
LTC2861IGN#TRPBF
LTC2859CDD#TRPBF
LTC2859IDD#TRPBF
TAPE AND REEL
LTC2861CDE#TR
LTC2861IDE#TR
LTC2861CGN#TR
LTC2861IGN#TR
PART MARKING*
2861
2861
2861
2861I
LBNX
LBNX
PART MARKING*
2861
2861
2861
2861I
PACKAGE DESCRIPTION
12-Lead (4mm
×
3mm) Plastic DFN
12-Lead (4mm
×
3mm) Plastic DFN
16-Lead Plastic SSOP
16-Lead Plastic SSOP
10-Lead (3mm
×
3mm) Plastic DFN
10-Lead (3mm
×
3mm) Plastic DFN
PACKAGE DESCRIPTION
12-Lead (4mm
×
3mm) Plastic DFN
12-Lead (4mm
×
3mm) Plastic DFN
16-Lead Plastic SSOP
16-Lead Plastic SSOP
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°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/
285961fb
2
LTC2859/LTC2861
ELECTRICAL CHARACTERISTICS
SYMBOL
Driver
|V
OD
|
Differential Driver Output Voltage
R = ∞, I
O
= 0mA, V
CC
= 4.5V (Figure 1)
R = 27Ω (RS485), V
CC
= 4.5V (Figure 1)
R = 50Ω (RS422), V
CC
= 4.5V (Figure 1)
R = 27Ω or R = 50Ω (Figure 1)
●
●
●
●
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C, V
CC
= 5V unless otherwise noted (Note 2).
PARAMETER
CONDITIONS
MIN
TYP
MAX
V
CC
V
CC
V
CC
0.2
UNITS
V
V
V
V
1.5
2.0
Δ|V
OD
|
Change in Magnitude of Driver
Differential Output Voltage for
Complementary Output States
Driver Common Mode Output Voltage
Change in Magnitude of Driver
Common Mode Output Voltage for
Complementary Output States
Driver Three-State (High Impedance)
Output Current on Y and Z
Maximum Driver Short-Circuit Current
Receiver Input Current (A, B)
V
OC
Δ|V
OC
|
R = 27Ω or R = 50Ω (Figure 1)
R = 27Ω or R = 50Ω (Figure 1)
●
●
3.0
0.2
V
V
I
OZD
I
OSD
Receiver
I
IN2
DE = OV, V
O
= –7V, +12V
(LTC2861 Only)
–7V ≤ (Y or Z) ≤ 12 (Figure 2)
DE = TE = 0V, V
CC
= 0V or 5V, V
A
or V
B
=
12V, Other at 0V
DE = TE = 0V, V
CC
= 0V or 5V, V
A
or V
B
=
–7V, Other at 0V
●
●
±10
±120
±250
125
–100
±0.2
25
μA
mA
μA
μA
V
mV
V
●
●
●
V
TH
ΔV
TH
V
OH
V
OL
I
OZR
R
IN
R
TERM
Logic
V
IH
V
IL
I
IN1
Supplies
I
SHDN
I
CCR
I
CCT
I
CCTS
I
CCL
I
CCRT
Receiver Differential Input Threshold
Voltage
Receiver Input Hysteresis
Receiver Output HIGH Voltage
Receiver Output LOW Voltage
Receiver Three-State (High Impedance)
Output Current on RO
Receiver Input Resistance
Receiver Input Terminating Resistor
–7V ≤ V
CM
≤ 12
V
CM
= 0V
I
0
= –4mA, V
ID
= 200mV, V
CC
= 4.5V
I
0
= 4mA, V
ID
= –200mV, V
CC
= 4.5V
RE
= 5V, 0V ≤ V
O
≤ V
CC
RE
= 5V or 0V, DE = TE = 0V
–7V ≤ V
A
= V
B
≤ 12V
TE = 5V, V
AB
= 2V, V
B
= –7, 0, 10V
(Figure 7)
DE, DI,
RE,
TE,
SLO,
V
CC
= 4.5V
DE, DI,
RE,
TE,
SLO,
V
CC
= 4.5V
DE, DI,
RE,
TE,
SLO
DE = 0V,
RE
= V
CC
, TE = 0V
No Load, DE = 0V,
RE
= 0V, TE = 0V
No Load, DE = V
CC
,
RE
= V
CC
,
SLO
= V
CC
,
TE = 0V
No Load, DE = V
CC
,
RE
= V
CC
,
SLO
= 0V,
TE = 0V
●
●
●
●
2.4
0.4
±1
96
108
125
120
156
V
μA
kΩ
Ω
●
Logic Input High Voltage
Logic Input Low Voltage
Logic Input Current
Supply Current in Shutdown Mode
Supply Current in Receive Mode
Supply Current in Transmit Mode
Supply Current in Transmit SLO Mode
●
●
●
2
0.8
0
0
540
630
670
660
640
±10
5
900
1000
1100
1100
1180
V
V
μA
μA
μA
μA
μA
μA
μA
●
●
●
●
●
●
Supply Current in Loopback Mode (Both No Load, DE = V
CC
,
RE=
0V,
SLO
= V
CC
, TE
Driver and Receiver Enabled)
= 0V
Supply Current in Termination Mode
DE = 0V,
RE
= V
CC
, TE = V
CC
,
SLO
= V
CC
285961fb
3
LTC2859/LTC2861
SWITCHING CHARACTERISTICS
SYMBOL
f
MAX
t
PLHD
, t
PHLD
Δt
PD
t
SKEWD
t
RD
, t
FD
t
ZLD
, t
ZHD
, t
LZD
,
t
HZD
t
ZHSD
, t
ZLSD
t
SHDN
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 Enable or Disable Time
Driver Enable from Shutdown
Time to Shutdown
Driver in Normal Mode (SLO HIGH)
Note 3
R
DIFF
= 54Ω, C
L
= 100pF (Figure 3)
R
DIFF
= 54Ω, C
L
= 100pF (Figure 3)
R
DIFF
= 54Ω, C
L
= 100pF (Figure 3)
R
DIFF
= 54Ω, C
L
= 100pF (Figure 3)
R
L
= 500Ω, C
L
= 50pF
RE
= 0 (Figure 4)
,
R
L
= 500Ω, C
L
= 50pF
RE
= V
CC
(Figure 4)
,
(DE =
↓,
RE
= V
CC
) or (DE = 0,
RE
↑)
(Figure 4)
Note 3
R
DIFF
= 54Ω, C
L
= 100pF (Figure 3)
R
DIFF
= 54Ω, C
L
= 100pF (Figure 3)
R
DIFF
= 54Ω, C
L
= 100pF (Figure 3)
R
DIFF
= 54Ω, C
L
= 100pF (Figure 3)
R
L
= 500Ω, C
L
= 50pF
RE
= 0 (Figure 4)
,
R
L
= 500Ω, C
L
= 50pF
RE
= 0 (Figure 4)
,
R
L
= 500Ω, C
L
= 50pF
RE
= V
CC
(Figure 4)
,
(DE = 0,
RE
=
↑)
or (DE =
↓,
RE
= V
CC
)
(Figure 4)
C
L
= 15pF V
CM
= 1.5V, |V
AB
| = 1.5V, t
R
and
,
t
F
< 4ns (Figure 5)
C
L
= 15pF (Figure 5)
C
L
= 15pF (Figure 5)
R
L
= 1kΩ, C
L
=15pF DE = V
CC
(Figure 6)
,
DI = 0 or V
CC
R
L
= 1kΩ, C
L
= 15pF DE = 0V (Figure 6)
,
DI = 0 or V
CC
V
B
= 0V, V
AB
= 2V,
RE
= V
CC
, DE = 0V
(Figure 7)
●
●
●
●
●
●
●
●
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C, V
CC
= 5V, T
E
= 0 unless otherwise noted (Note 2).
CONDITIONS
MIN
20
10
1
1
4
50
6
±6
12.5
70
8
100
TYP
MAX
UNITS
Mbps
ns
ns
ns
ns
ns
μs
ns
Driver in SLO Mode (SLO LOW)
f
MAXS
t
PLHDS,
t
PHLDS
Δt
PDS
t
SKEWDS
t
RDS,
t
FDS
t
ZHDS,
t
ZLDS
t
LZDS,
t
HZDS
t
ZHSDS,
t
ZLSDS
t
SHDNS
Receiver
t
PLHR
, t
PHLR
t
SKEWR
t
RR
, t
FR
t
ZLR
, t
ZHR
, t
LZR
,
t
HZR
t
ZHSR
, t
ZLSR
t
RTEN
, t
RTZ
Receiver Input to Output
Differential Receiver Skew
|t
PLHR
-t
PHLR
|
Receiver Output Rise or Fall Time
Receiver Enable/Disable
Receiver Enable from Shutdown
Termination Enable or Disable Time
●
●
●
●
●
●
Maximum Data Rate
Driver Input to Output
Driver Input to Output Difference
|t
PLHR
-t
PHLR
|
Driver Output A to Output B
Driver Rise or Fall Time
Driver Enable Time
Driver Disable Time
Driver Enable from Shutdown
Time to Shutdown
●
●
●
●
●
●
●
●
●
250
0.95
50
200
0.9
1.5
500
±500
1.5
300
70
8
500
kbps
μs
ns
ns
μs
ns
ns
μs
ns
50
1
3
70
6
12.5
50
8
100
ns
ns
ns
ns
μs
μs
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 125°C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may result in device degradation or failure.
285961fb
4
LTC2859/LTC2861
TEST CIRCUITS
Y
GND
DI
OR
V
CC
DRIVER
Z
+
V
OD
–
Y
GND
OR
DI
V
CC
I
OSD
DRIVER
Z
R
R
+
V
OC
–
+
–
2859/61 F01-2
–7V to +12V
Figure 1. Driver DC Characteristics
Figure 2. Driver Output Short-Circuit Current
Y
DI
C
L
DRIVER
Z
R
DIFF
C
L
DI
V
CC
OV
t
PLHD
,
t
PLHDS
t
SKEWD
, t
SKEWDS
V
O
1/2 V
O
t
PHLD
,
t
PHLDS
Y, Z
(Y-Z)
90%
10%
0
t
RD
,
t
RDS
0
90%
10%
t
FD
,
t
FDS
2859/61 F03
Figure 3. Driver Timing Measurement
R
L
Y
V
CC
OR DI
GND
DRIVER
Z
DE
C
L
R
L
C
L
GND
OR
V
CC
V
CC
DE
1/2 V
CC
OV
V
CC
Y or Z
V
O
V
OL
V
OH
t
ZLD
,
t
ZLDS
,
t
ZLSD
,
t
ZLSDS
1/2 V
CC
t
LZD
,
t
LZDS
0.5V
0.5V
t
HZD
,
t
HZDS,
t
SHDN,
t
SHDNS
2859/61 F04
V
CC
OR
GND
Z or Y
1/2 V
CC
OV
t
ZHD
,
t
ZHDS
,
t
ZHSD
,
t
ZHSDS
Figure 4. Driver Enable and Disable Timing Measurement
京公网安备 11010802033920号
EEWORLD
