DS3695A [NSC]
Multipoint RS485/RS422 Transceivers; 多点RS485 / RS422收发器
| 型号： | DS3695A |
| 厂家： | 
National Semiconductor |
| 描述： | Multipoint RS485/RS422 Transceivers |
| 文件： | 总8页 (文件大小：112K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
February 1996
DS3695A/DS3695AT/DS3696A
Multipoint RS485/RS422 Transceivers
General Description
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
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.
±
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
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 kΩ pull-up resistor.
This allows the TS outputs of several devices to be wire
OR-ed.
n 70 mV typical receiver hysteresis
n Available in SOIC packaging
Both AC and DC specifications are guaranteed over the 0˚C
to 70˚C temperature and 4.75V to 5.25V supply voltage
range.
Connection and Logic Diagram
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
TRI-STATE® is a registered trademark of National Semiconductor Corporation.
© 1998 National Semiconductor Corporation
DS005272
www.national.com
Absolute Maximum Ratings (Note 1)
Lead Temp. (Soldering 4 seconds)
260˚C
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Recommended Operating
Conditions
Supply Voltage, VCC
7V
Min
Max
5.25
+12
Units
Control Input Voltages
Driver Input Voltage
7V
7V
Supply Voltage, VCC
4.75
−7
V
V
Bus Voltage
Driver Output Voltages
Receiver Input Voltages
Receiver Output Voltage
Continuous Power Dissipation 25˚C
M Package
+15V/−10V
+15V/−10V
5.5V
Operating Free Air Temp. (TA)
Commercial (DS3695AM)
Industrial (DS3695ATM)
Commercial (DS3696AM)
0
−40
0
+70
+85
+70
˚C
˚C
˚C
630 mW (Note 4)
−65˚C to +150˚C
Storage Temp. Range
Electrical Characteristics (Notes 2, 3)
<
<
0˚C ≤ TA ≤ 70˚C, 4.75V VCC 5.25V unless otherwise specified
Symbol
Parameter
Differential Driver Output
Voltage (Unloaded)
Conditions
Min Typ Max Units
VOD1
VOD2
∆VOD
IO = 0
5
V
Differential Driver Output
Voltage (with Load)
R = 50Ω; (RS-422) (Note 5)
R = 27Ω; (RS-485)
2
V
V
1.5
Change in Magnitude of Driver
Differential Output Voltage For
Complementary Output States
0.2
3.0
0.2
V
V
V
VOC
Driver Common Mode Output
Voltage
R = 27Ω
∆|VOC
|
Change in Magnitude of Driver
Common Mode Output Voltage
For Complementary Output States
Input High Voltage
VIH
VIL
VCL
IIL
2
V
V
Input Low Voltage
DI, DE,
0.8
−1.5
−200
20
Input Clamp Voltage
RE , RE /DE
IIN = −18 mA
VIL = 0.4V
VIH = 2.4V
V
Input Low Current
µA
µA
mA
mA
V
IIH
Input High Current
IIN
Input Current
DO/RI, DO /RI VCC = 0V or 5.25V VIN = 12V
+1.0
−0.8
RI, RI
DE or RE /DE = 0V VIN = −7V
VTH
Differential Input Threshold
Voltage for Receiver
−7V ≤ VCM ≤ +12V
−0.2
2.4
+0.2
∆VTH
VOH
VOL
Receiver Input Hysteresis
Receiver Output High Voltage
VCM = 0V
70
mV
V
IOH = −400 µA
IOL = 16 mA (Note 5)
IOL = 8 mA
Output Low Voltage
RO
TS
0.5
V
0.45
V
IOZR
OFF-State (High Impedance)
Output Current at Receiver
Receiver Input Resistance
Supply Current
VCC = Max
±
20
µA
0.4V ≤ VO ≤ 2.4V
−7V ≤ VCM ≤ +12V
RIN
ICC
12
kΩ
mA
mA
mA
mA
mA
No Load
Driver Outputs Enabled
Driver Outputs Disabled
42
27
60
(Note 5)
40
IOSD
Driver Short-Circuit
Output Current
VO = −7V (Note 5)
VO = +12V (Note 5)
VO = 0V
−250
+250
−85
IOSR
Receiver Short-Circuit
Output Current
−15
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.
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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 = 25˚C.
A
Note 4: Derate linearly at 6.5 mW/˚C to 337 mW at 70˚C.
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
(−40˚C ≤ T ≤ +85˚C).
A
Switching Characteristics
<
<
0˚C ≤ TA ≤ 70˚C, 4.75V VCC 5.25V unless otherwise specified (Note 3)
Receiver Switching Characteristics
(Figures 1, 2 and Figure 3)
Symbol
Conditions
Min
15
15
0
Typ
28
28
3
Max
42
Units
ns
tPLH
CL = 15 pF
S1 and S2
Closed
tPHL
42
ns
|tPLH–tPHL
|
ns
tPLZ
CL = 15 pF, S2 Open
CL = 15 pF, S1 Open
CL = 15 pF, S2 Open
CL = 15 pF, S1 Open
5
29
12
15
15
35
16
28
20
ns
tPHZ
5
ns
tPZL
7
ns
tPZH
7
ns
Driver Switching Characteristics
Symbol
Conditions
Min
Typ
Max
Units
SINGLE ENDED CHARACTERISTICS (Figures 4, 5 and Figure 7)
tPLH
tPHL
SKEW|tPLH–tPHL
RLDIFF = 60Ω
9
9
15
15
2
22
22
8
ns
ns
ns
ns
ns
ns
ns
CL1 = CL2 = 100 pF
t
|
0
tPLZ
tPHZ
tPZL
tPZH
CL = 15 pF, S2 Open
CL = 15 pF, S1 Open
CL = 100 pF, S2 Open
CL = 100 pF, S1 Open
7
15
15
35
35
30
30
50
50
7
30
30
DIFFERENTIAL SWITCHING CHARACTERISTICS (Figure 7)
tr, tf
RLDIFF = 60Ω
CL1 = CL2 = 100 pF
6
10
18
ns
AC Test Circuits and Switching Waveforms
DS005272-6
FIGURE 1. Receiver Propagation Delay Test Circuit
3
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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
DS005272-10
DS005272-9
Unless otherwise specified the switches are closed.
FIGURE 4. Driver Propagation Delay Test Circuits
DS005272-11
t
and t
PHL
are measured to the respective 50% points. t is the difference between propagation delays of the complementary outputs.
SKEW
PLH
FIGURE 5. Driver Input-to-Output Propagation Delay Timing (Single-Ended)
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4
AC Test Circuits and Switching Waveforms (Continued)
DS005272-12
FIGURE 6. Driver Enable/Disable Propagation Delay Timing
DS005272-13
FIGURE 7. Driver Differential Transition Timing
Function Tables
DS3695A/DS3696A Transmitting
Inputs
Line
Condition
No Fault
No Fault
X
Outputs
TS * (DS3696A Only)
RE
X
DE
1
DI
1
DO
0
DO
1
H
H
H
L
X
1
0
1
0
X
0
X
X
Z
Z
X
1
Fault
Z
Z
DS3695A/DS3696A Receiving
Inputs
Output
RE
0
DE
0
RI–RI
≥+0.2V
RO
1
TS * (DS3696A Only)
H
H
H
H
0
0
≤−0.2V
0
0
0
Inputs Open**
X
1
1
0
Z
X
Z
—
—
Don’t care condition
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 kΩ pull-up resistor.
** This is a fail safe condition
5
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Typical Application
DS005272-18
Repeater control logic not shown. See AN-702.
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6
7
Physical Dimensions inches (millimeters) unless otherwise noted
Molded SOIC Package (M)
Order Number DS3695AM, DS3695ATM or DS3696AM
NS Package Number M08A
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NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DE-
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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 in 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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