DS3695A/DS3695AT/DS3696A
Multipoint RS485/RS422 Transceivers
General Description
The DS3695A and DS3696A are high speed differential
TRI-STATE
bus/line transceivers designed to meet the re-
quirements of EIA standard RS485 with extended common
mode range (+12V to -7V), for multipoint data transmission.
In addition they are compatible with requirements of RS-422.
The driver and receiver outputs feature TRI-STATE capabil-
ity. The driver outputs remain in TRI-STATE over the entire
common mode range of +12V to -7V. Bus faults that cause
excessive power dissipation within the device trigger a ther-
mal shutdown circuit, which forces the driver outputs into the
high impedance state. The DS3696A provides an output pin
(TS) which reports the thermal shutdown of the device. TS is
an "open collector" pin with an internal 10 k
pull-up resistor.
This allows the TS outputs of several devices to be wire
OR-ed.
Both AC and DC specifications are guaranteed over the 0C
to 70C temperature and 4.75V to 5.25V supply voltage
range.
Features
n
Meets EIA standard RS485 for multipoint bus
transmission and is compatible with RS-422
n
10 ns driver propagation delays (typical)
n
Single +5V supply
n
-7V to +12V bus common mode range permits
7V
ground difference between devices on the bus
n
Thermal shutdown protection
n
High 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
n
Combined impedance of a driver output and receiver
input is less than one RS485 unit load, allowing up to 32
transceivers on the bus
n
70 mV typical receiver hysteresis
n
Available in SOIC packaging
Connection and Logic Diagram
TRI-STATE
is a registered trademark of National Semiconductor Corporation.
Molded Package, Small Outline (M)
DS005272-1
Top View
DS005272-2
TS was LF (Line Fault) on previous datasheets, TS goes low upon thermal shutdown.
Top View
Order Number DS3695AM, DS3695ATM or DS3696AM
See NS Package Number M08A
February 1996
DS3695A/DS3695A
T/DS3696A
Multipoint
RS485/RS422
T
ransceivers
1998 National Semiconductor Corporation
DS005272
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
+15V/-10V
Receiver Output Voltage
5.5V
Continuous Power Dissipation 25C
M Package
630 mW (Note 4)
Storage Temp. Range
-65C to +150C
Lead Temp. (Soldering 4 seconds)
260C
Recommended Operating
Conditions
Min
Max
Units
Supply Voltage, V
CC
4.75
5.25
V
Bus Voltage
-7
+12
V
Operating Free Air Temp. (T
A
)
Commercial (DS3695AM)
0
+70
C
Industrial (DS3695ATM)
-40
+85
C
Commercial (DS3696AM)
0
+70
C
Electrical Characteristics
(Notes 2, 3)
0C
T
A
70C, 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
R = 50
; (RS-422) (Note 5)
2
V
Voltage (with Load)
R = 27
; (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
Voltage
R = 27
3.0
V
|V
OC
|
Change in Magnitude of Driver
Common Mode Output Voltage
0.2
V
For Complementary Output States
V
IH
Input High Voltage
2
V
V
IL
Input Low Voltage
DI, DE,
0.8
V
V
CL
Input Clamp Voltage
RE , RE /DE
I
IN
= -18 mA
-1.5
V
I
IL
Input Low Current
V
IL
= 0.4V
-200
A
I
IH
Input High Current
V
IH
= 2.4V
20
A
I
IN
Input Current
DO/RI, DO /RI
V
CC
= 0V or 5.25V
V
IN
= 12V
+1.0
mA
RI, RI
DE or RE /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 A
2.4
V
V
OL
Output Low Voltage
RO
I
OL
= 16 mA (Note 5)
0.5
V
TS
I
OL
= 8 mA
0.45
V
I
OZR
OFF-State (High Impedance)
V
CC
= Max
20
A
Output Current at Receiver
0.4V
V
O
2.4V
R
IN
Receiver Input Resistance
-7V
V
CM
+12V
12
k
I
CC
Supply Current
No Load
Driver Outputs Enabled
42
60
mA
(Note 5)
Driver Outputs Disabled
27
40
mA
I
OSD
Driver Short-Circuit
V
O
= -7V (Note 5)
-250
mA
Output Current
V
O
= +12V (Note 5)
+250
mA
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.
www.national.com
2
Electrical Characteristics
(Notes 2, 3) (Continued)
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 V
CC
= 5V and T
A
= 25C.
Note 4: Derate linearly at 6.5 mW/C to 337 mW at 70C.
Note 5: All limits for which Note 5 is applied must be derated by 10% for DS3695AT. Other parameters remain the same for this extended temperature range device
(-40C
T
A
+85C).
Switching Characteristics
0C
T
A
70C, 4.75V
<
V
CC
<
5.25V unless otherwise specified (Note 3)
Receiver Switching Characteristics
(
Figures 1, 2 and Figure 3)
Symbol
Conditions
Min
Typ
Max
Units
t
PLH
C
L
= 15 pF
15
28
42
ns
t
PHL
S1 and S2
15
28
42
ns
|t
PLH
t
PHL
|
Closed
0
3
ns
t
PLZ
C
L
= 15 pF, S2 Open
5
29
35
ns
t
PHZ
C
L
= 15 pF, S1 Open
5
12
16
ns
t
PZL
C
L
= 15 pF, S2 Open
7
15
28
ns
t
PZH
C
L
= 15 pF, S1 Open
7
15
20
ns
Driver Switching Characteristics
Symbol
Conditions
Min
Typ
Max
Units
SINGLE ENDED CHARACTERISTICS (
Figures 4, 5 and Figure 7)
t
PLH
R
LDIFF
= 60
9
15
22
ns
t
PHL
C
L1
= C
L2
= 100 pF
9
15
22
ns
t
SKEW
|t
PLH
t
PHL
|
0
2
8
ns
t
PLZ
C
L
= 15 pF, S2 Open
7
15
30
ns
t
PHZ
C
L
= 15 pF, S1 Open
7
15
30
ns
t
PZL
C
L
= 100 pF, S2 Open
30
35
50
ns
t
PZH
C
L
= 100 pF, S1 Open
30
35
50
ns
DIFFERENTIAL SWITCHING CHARACTERISTICS (
Figure 7)
t
r
, t
f
R
LDIFF
= 60
C
L1
= C
L2
= 100 pF
6
10
18
ns
AC Test Circuits and Switching Waveforms
DS005272-6
FIGURE 1. Receiver Propagation Delay Test Circuit
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3
AC Test Circuits and Switching Waveforms
(Continued)
DS005272-7
Differential input voltage may be realized by grounding RI and pulsing RI between +2.5V and -2.5V
FIGURE 2. Receiver Input-to-Output Propagation Delay Timing
DS005272-8
FIGURE 3. Receiver Enable/Disable Propagation Delay Timing
DS005272-9
Unless otherwise specified the switches are closed.
DS005272-10
FIGURE 4. Driver Propagation Delay Test Circuits
DS005272-11
t
PLH
and t
PHL
are measured to the respective 50% points. t
SKEW
is the difference between propagation delays of the complementary outputs.
FIGURE 5. Driver Input-to-Output Propagation Delay Timing (Single-Ended)
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4
AC Test Circuits and Switching Waveforms
(Continued)
Function Tables
DS3695A/DS3696A Transmitting
Inputs
Line
Outputs
RE
DE
DI
Condition
DO
DO
TS * (DS3696A Only)
X
1
1
No Fault
0
1
H
X
1
0
No Fault
1
0
H
X
0
X
X
Z
Z
H
X
1
X
Fault
Z
Z
L
DS3695A/DS3696A Receiving
Inputs
Output
RE
DE
RIRI
RO
TS * (DS3696A Only)
0
0
+0.2V
1
H
0
0
-0.2V
0
H
0
0
Inputs Open**
1
H
1
0
X
Z
H
X -- Don't care condition
Z -- High impedance state
Fault -- Improper line conditions causing excessive power dissipation in the driver, such as shorts or bus contention situations
* TS is an "open collector" output with an on-chip 10 k
pull-up resistor.
** This is a fail safe condition
DS005272-12
FIGURE 6. Driver Enable/Disable Propagation Delay Timing
DS005272-13
FIGURE 7. Driver Differential Transition Timing
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5
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