DS75176B/DS75176BT
Multipoint RS-485/RS-422 Transceivers
General Description
The DS75176B is a high speed differential TRI-STATE®
bus/line transceiver designed to meet the requirements of
EIA standard RS485 with extended common mode range
(+12V to −7V), for multipoint data transmission. In addition, it
is compatible with RS-422.
The driver and receiver outputs feature TRI-STATE capabil-
ity, for the driver outputs over the entire common mode
range of +12V to −7V. Bus contention or fault situations that
cause excessive power dissipation within the device are
handled by a thermal shutdown circuit, which forces the
driver outputs into the high impedance state.
DC specifications are guaranteed over the 0 to 70˚C tem-
perature and 4.75V to 5.25V supply voltage range.
Features
nMeets EIA standard RS485 for multipoint bus
transmission and is compatible with RS-422.
nSmall Outline (SO) Package option available for
minimum board space.
n22 ns driver propagation delays.
nSingle +5V supply.
n−7V to +12V bus common mode range permits ±7V
ground difference between devices on the bus.
nThermal shutdown protection.
nHigh impedance to bus with driver in TRI-STATE or with
power off, over the entire common mode range allows
the unused devices on the bus to be powered down.
nPin out compatible with DS3695/A and SN75176A/B.
nCombined impedance of a driver output and receiver
input is less than one RS485 unit load, allowing up to 32
transceivers on the bus.
n70 mV typical receiver hysteresis.
Connection and Logic Diagram
TRI-STATE®is a registered trademark of National Semiconductor Corp.
DS008759-1
Top View
Order Number DS75176BN, DS75176BTN, DS75176BM or DS75176BTM
See NS Package Number N08E or M08A
July 1998
DS75176B/DS75176BT Multipoint RS-485/RS-422 Transceivers
© 1999 National Semiconductor Corporation DS008759 www.national.com
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage, V
CC
7V
Control Input Voltages 7V
Driver Input Voltage 7V
Driver Output Voltages +15V/ −10V
Receiver Input Voltages (DS75176B) +15V/ −10V
Receiver Output Voltage 5.5V
Continuous Power Dissipation @25˚C
for M Package 675 mW (Note 5)
for N Package 900 mW (Note 4)
Storage Temperature Range −65˚C to +150˚C
Lead Temperature
(Soldering, 4 seconds) 260˚C
Recommended Operating
Conditions
Min Max Units
Supply Voltage, V
CC
4.75 5.25 V
Voltage at Any Bus Terminal −7 +12 V
(Separate or Common Mode)
Operating Free Air Temperature T
A
DS75176B 0 +70 ˚C
DS75176BT −40 +85 ˚C
Differential Input Voltage,
VID (Note 6) −12 +12 V
Electrical Characteristics (Notes 2, 3)
0˚C ≤T
A
≤70˚C, 4.75V <V
CC
<5.25V unless otherwise specified
Symbol Parameter Conditions Min Typ Max Units
V
OD1
Differential Driver Output I
O
=0 5 V
Voltage (Unloaded)
V
OD2
Differential Driver Output (
Figure 1
) R=50Ω; (RS-422) (Note 7) 2 V
Voltage (with Load) R = 27Ω; (RS-485) 1.5 V
∆V
OD
Change in Magnitude of Driver
Differential Output Voltage For 0.2 V
Complementary Output States
V
OC
Driver Common Mode Output (
Figure 1
) R=27Ω3.0 V
Voltage
∆|V
OC
| Change in Magnitude of Driver
Common Mode Output Voltage 0.2 V
For Complementary Output
States
V
IH
Input High Voltage 2V
V
IL
Input Low Voltage DI, DE, 0.8
V
CL
Input Clamp Voltage RE , E I
IN
= −18 mA −1.5
I
IL
Input Low Current V
IL
= 0.4V −200 µA
I
IH
Input High Current V
IH
= 2.4V 20 µA
I
IN
Input DO/RI, DO/RI V
CC
= 0V or 5.25V V
IN
= 12V +1.0 mA
Current DE = 0V V
IN
= −7V −0.8 mA
V
TH
Differential Input Threshold −7V ≤V
CM
≤+ 12V −0.2 +0.2 V
Voltage for Receiver
∆V
TH
Receiver Input Hysteresis V
CM
=0V 70 mV
V
OH
Receiver Output High Voltage I
OH
= −400 µA 2.7 V
V
OL
Output Low Voltage RO I
OL
= 16 mA (Note 7) 0.5 V
I
OZR
OFF-State (High Impedance) V
CC
= Max ±20 µA
Output Current at Receiver 0.4V ≤V
O
≤2.4V
R
IN
Receiver Input Resistance −7V ≤V
CM
≤+12V 12 kΩ
I
CC
Supply Current No Load Driver Outputs Enabled 55 mA
(Note 7) Driver Outputs Disabled 35 mA
I
OSD
Driver Short-Circuit V
O
= −7V (Note 7) −250 mA
Output Current V
O
= +12V (Note 7) +250 mA
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Electrical Characteristics (Notes 2, 3) (Continued)
0˚C ≤T
A
≤70˚C, 4.75V <V
CC
<5.25V unless otherwise specified
Symbol Parameter Conditions Min Typ Max Units
I
OSR
Receiver Short-Circuit V
O
= 0V −15 −85 mA
Output Current
Note 1: “Absolute Maximum Ratings” are those beyond which the safety of the device cannot be guaranteed. They are not meant to imply that the device should
be operated at these limits. The tables of “Electrical Characteristics” provide conditions for actual device operation.
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: All typicals are given for VCC = 5V and TA= 25˚C.
Note 4: Derate linearly at 5.56 mW/˚C to 650 mW at 70˚C.
Note 5: Derate linearly 6.11 mW/˚C to 400 mW at 70˚C.
Note 6: Differential - Input/Output bus voltage is measured at the noninverting terminal A with respect to the inverting terminal B.
Note 7: All worst case parameters for which note 7 is applied, must be increased by 10%for DS75176BT. The other parameters remain valid for −40˚C <TA
<+85˚C.
Switching Characteristics
V
CC
= 5.0V, T
A
= 25˚C
Symbol Parameter Conditions Min Typ Max Units
t
PLH
Driver Input to Output R
LDIFF
=60Ω12 22 ns
t
PHL
Driver Input to Output C
L1
=C
L2
= 100 pF 17 22 ns
t
r
Driver Rise Time R
LDIFF
=60Ω18 ns
t
f
Driver Fall Time C
L1
=C
L2
= 100 pF 18 ns
(
Figure 3
and
Figure 5
)
t
ZH
Driver Enable to Output High C
L
= 100 pF (
Figure 4
and
Figure 6
)S1
Open 29 100 ns
t
ZL
Driver Enable to Output Low C
L
= 100 pF (
Figure 4
and
Figure 6
)S2
Open 31 60 ns
t
LZ
Driver Disable Time from Low C
L
=15pF(
Figure 4
and
Figure 6
)S2
Open 13 30 ns
t
HZ
Driver Disable Time from High C
L
=15pF(
Figure 4
and
Figure 6
)S1
Open 19 200 ns
t
PLH
Receiver Input to Output C
L
=15pF(
Figure 2
and
Figure 7
)3037ns
t
PHL
Receiver Input to Output S1 and S2 Closed 32 37 ns
t
ZL
Receiver Enable to Output Low C
L
=15pF(
Figure 2
and
Figure 8
)S2
Open 15 20 ns
t
ZH
Receiver Enable to Output High C
L
=15pF(
Figure 2
and
Figure 8
)S1
Open 11 20 ns
t
LZ
Receiver Disable from Low C
L
=15pF(
Figure 2
and
Figure 8
)S2
Open 28 32 ns
t
HZ
Receiver Disable from High C
L
=15pF(
Figure 2
and
Figure 8
)S1
Open 13 35 ns
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AC Test Circuits
Switching Time Waveforms
DS008759-2
FIGURE 1.
DS008759-3
Note: S1 and S2 of load circuit are closed except as otherwise mentioned.
FIGURE 2.
DS008759-4
FIGURE 3.
DS008759-5
Note: Unless otherwise specified the switches are closed.
FIGURE 4.
DS008759-6
FIGURE 5. Driver Propagation Delays and Transition Times
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Switching Time Waveforms (Continued)
Function Tables
DS75176B Transmitting
Inputs Line Outputs
RE DE DI Condition DO DO
X 1 1 No Fault 0 1
X 1 0 No Fault 1 0
X0X X ZZ
X 1 X Fault Z Z
DS008759-7
FIGURE 6. Driver Enable and Disable Times
DS008759-8
Note: Differential input voltage may may be realized by grounding RI and pulsing RI between +2.5V and −2.5V
FIGURE 7. Receiver Propagation Delays
DS008759-9
FIGURE 8. Receiver Enable and Disable Times
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Function Tables (Continued)
DS75176B Receiving
Inputs Outputs
RE DE RI-RI RO
00 ≥+0.2V 1
00 ≤−0.2V 0
0 0 Inputs Open** 1
10 X Z
X — Don’t care condition
Z — High impedance state
Fault — Improper line conditons causing excessive power dissipation in the driver, such as shorts or bus contention
situations
**This is a fail safe condition
Typical Application
DS008759-11
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Physical Dimensions inches (millimeters) unless otherwise noted
Lit. # 103669
Molded Dual-In-Line Package (N)
Order Number DS75176BN or DS75176BTN
NS Package Number N08E
www.national.com7
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the body, or (b) support or sustain life, and whose fail-
ure to perform when properly used in accordance
with instructions for use provided in the labeling, can
be reasonably expected to result in a significant injury
to the user.
2. A critical component is any component of a life support
device or system whose failure to perform can be rea-
sonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
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DS75176B/DS75176BT Multipoint RS-485/RS-422 Transceivers
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.
