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5 V, 0.8 mA PROFIBUS
RS-485 Transceiver
ADM1486
FEATURES
Meets and exceeds EIA RS-485 and EIA RS-422 standards
30 Mbps data rate
Recommended for PROFIBUS applications
2.1 V minimum differential output with 54 Ω termination
Low power 0.8 mA I
CC
Thermal shutdown and short-circuit protection
0.5 ns skew driver and receiver
Driver propagation delay: 11 ns
Receiver propagation delay: 12 ns
High impedance outputs with drivers disabled or power off
Superior upgrade for SN65ALS1176
Available in standard 8-lead SOIC package
FUNCTIONAL BLOCK DIAGRAM
ADM1486
RO
1
R
8
V
CC
RE
2
7
B
DE
3
6
A
DI
4
D
5
GND
02603-001
APPLICATIONS
Industrial field equipment
Figure 1.
GENERAL DESCRIPTION
The ADM1486 is a differential line transceiver suitable for high
speed bidirectional data communication on multipoint bus
transmission lines. It is designed for balanced data transmission,
complies with EIA Standards RS-485 and RS-422, and is recom-
mended for PROFIBUS applications. The part contains a
differential line driver and a differential line receiver. Both the
driver and the receiver may be enabled independently. When
disabled or powered down, the driver outputs are high impedance.
The ADM1486 operates from a single 5 V power supply.
Excessive power dissipation caused by bus contention or output
shorting is prevented by short-circuit protection and thermal
circuitry. Short-circuit protection circuits limit the maximum
output current to ±200 mA during fault conditions. A thermal
shutdown circuit senses if the die temperature rises above
150°C and forces the driver outputs into a high impedance state
under this condition.
Up to 50 transceivers may be connected simultaneously on a
bus, but only one driver should be enabled at a time. Therefore,
it is important that the remaining disabled drivers do not load
the bus.
To ensure this, the ADM1486 driver features high output
impedance when disabled and when powered down. This
minimizes the loading effect when the transceiver is not being
used. The high impedance driver output is maintained over the
entire common-mode voltage range from −7 V to +12 V.
The receiver contains a fail-safe feature that results in a logic
high output state if the inputs are unconnected (floating).
The ADM1486 is fabricated on BiCMOS, an advanced mixed
technology process combining low power CMOS with fast
switching bipolar technology. All inputs and outputs contain
protection against ESD; all driver outputs feature high source
and sink current capability. An epitaxial layer is used to guard
against latch-up.
The ADM1486 features extremely fast and closely matched
switching, enable, and disable times. Minimal driver propaga-
tion delays permit transmission at data rates up to 30 Mbps
while low skew minimizes EMI interference.
The part is fully specified over the commercial and industrial
temperature range and is available in an 8-lead SOIC package.
Rev. A
Information furnished by Analog Devices is believed to be accurate and reliable.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
© 2005 Analog Devices, Inc. All rights reserved.
ADM1486
TABLE OF CONTENTS
Specifications..................................................................................... 3
Timing Specifications....................................................................... 4
Absolute Maximum Ratings............................................................ 5
ESD Caution.................................................................................. 5
Pin Configuration and Function Descriptions............................. 6
Test Circuits....................................................................................... 7
Switching Characteristics ................................................................ 8
Typical Performance Characteristics ............................................. 9
Applications Information .............................................................. 13
Differential Data Transmission ................................................ 13
Cable and Data Rate................................................................... 13
Thermal Shutdown .................................................................... 13
Propagation Delay ...................................................................... 13
Receiver Open-Circuit Fail-Safe............................................... 13
Outline Dimensions ....................................................................... 15
Ordering Guide .......................................................................... 15
REVISION HISTORY
3/05—Rev. 0 to Rev. A
Updated Format..................................................................Universal
Added PROFIBUS Logo .................................................................. 1
Updated Outline Dimensions ....................................................... 15
Changes to Ordering Guide .......................................................... 15
11/02—Revision 0: Initial Version
Rev. A | Page 2 of 16
ADM1486
SPECIFICATIONS
V
CC
= 5 V ±5%. All specifications T
MIN
to T
MAX
, unless otherwise noted.
Table 1.
Parameter
DRIVER
Differential Output Voltage, V
OD
Min
Typ
Max
5.0
5.0
5.0
5.0
0.2
3.0
0.2
200
200
0.8
±1.0
−0.2
20
70
30
0.6
−0.35
±1.0
0.4
4.0
7
85
±1.0
1.2
0.8
2.0
1.5
+0.2
Unit
V
V
V
V
V
V
V
mA
mA
V
V
µA
V
mV
kΩ
mA
mA
µA
V
V
mA
µA
mA
mA
Test Conditions/Comments
R = Infinity, see Figure 3
V
CC
= 5 V, R = 50 Ω (RS-422), see Figure 3
R = 27 Ω (RS-485), see Figure 3
V
TST
= −7 V to +12 V, see Figure 4
R = 27 Ω or 50 Ω, see Figure 3
R = 27 Ω or 50 Ω, see Figure 3
R = 27 Ω or 50 Ω
−7 V ≤ V
O
≤ +12 V
−7 V ≤ V
O
≤ +12 V
V
OD3
∆| V
OD
| for Complementary Output States
Common-Mode Output Voltage V
OC
∆| V
OC
| for Complementary Output States
Output Short-Circuit Current (V
OUT
= High)
Output Short-Circuit Current (V
OUT
= Low)
CMOS Input Logic Threshold Low, V
INL
CMOS Input Logic Threshold High, V
INH
Logic Input Current (DE, DI)
RECEIVER
Differential Input Threshold Voltage, V
TH
Input Voltage Hysteresis, ∆V
TH
Input Resistance
Input Current (A, B)
Logic Enable Input Current (RE)
CMOS Output Voltage Low, V
OL
CMOS Output Voltage High, V
OH
Short-Circuit Output Current
Three-State Output Leakage Current
POWER SUPPLY CURRENT
I
CC
(Outputs Enabled)
I
CC
(Outputs Disabled)
2.1
2.1
2.1
60
60
2.0
−7 V ≤ V
CM
≤ +12 V
V
CM
= 0 V
−7 V ≤ V
CM
≤ +12 V
V
IN
= +12 V
V
IN
= −7 V
I
OUT
= +4.0 mA
I
OUT
= −4.0 mA
V
OUT
= GND or V
CC
0.4 V ≤ V
OUT
≤ 2.4 V
Outputs unloaded, digital inputs = GND or V
CC
Outputs unloaded, digital inputs = GND or V
CC
Rev. A | Page 3 of 16
ADM1486
TIMING SPECIFICATIONS
V
CC
= 5 V ±5%. All specifications T
MIN
to T
MAX
, unless otherwise noted.
Table 2.
Parameter
DRIVER
Propagation Delay Input to Output t
PLH
, t
PHL
Driver O/P to O/P t
SKEW
Driver Rise/Fall Time t
R
, t
F
Driver Enable to Output Valid t
ZH
, t
ZL
Driver Disable Timing t
HZ
, t
LZ
Matched Enable Switching
| t
AZH
− t
BZL
|, | t
BZH
− t
AZL
|
Matched Disable Switching
| t
AHZ
− t
BLZ
|, | t
BHZ
− t
ALZ
|
RECEIVER
Propagation Delay Input to Output t
PLH
, t
PHL
Skew | t
PLH
− t
PHL
|
Receiver Enable t
ZH
, t
ZL
Receiver Disable t
HZ
, t
LZ
1
Min
4
Typ
11
11
0.5
8
9
9
1
2
Max
17
13
2
15
15
15
3
5
20
2
13
13
Unit
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
Test Conditions/Comments
R
LDIFF
= 54 Ω, C
L1
= C
L2
= 100 pF, see Figure 5
R
LDIFF
= 54 Ω, C
L1
= C
L2
= 100 pF @ T
A
= 25°C
R
LDIFF
= 54 Ω, C
L1
= C
L2
= 100 pF, see Figure 5
1
R
LDIFF
= 54 Ω, C
L1
= C
L2
= 100 pF, see Figure 5
R
L
= 110 Ω, C
L
= 50 pF, see Figure 6
R
L
= 110 Ω, C
L
= 50 pF, see Figure 6
R
L
= 110 Ω, C
L
= 50 pF, see Figure 6
R
L
= 110 Ω, C
L
= 50 pF, see Figure 6
C
L
= 15 pF, see Figure 7
C
L
= 15 pF
1
, see Figure 7
C
L
= 15 pF, R
L
= 1 kΩ, see Figure 8
C
L
= 15 pF, R
L
= 1 kΩ, see Figure 8
6
12
0.4
7
7
Guaranteed by characterization.
Rev. A | Page 4 of 16
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