DS36C280_00 [NSC]
Slew Rate Controlled CMOS EIA-RS-485 Transceiver; 压摆率控制的CMOS EIA -RS - 485收发器型号: | DS36C280_00 |
厂家: | National Semiconductor |
描述: | Slew Rate Controlled CMOS EIA-RS-485 Transceiver |
文件: | 总9页 (文件大小:563K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
July 2000
DS36C280
Slew Rate Controlled CMOS EIA-RS-485 Transceiver
General Description
Features
n 100% RS-485 compliant
The DS36C280 is a low power differential bus/line trans-
ceiver designed to meet the requirements of RS-485 Stan-
dard for multipoint data transmission. In addition, it is com-
patible with TIA/EIA-422-B.
— Guaranteed RS-485 device interoperation
n Low power CMOS design: ICC 500 µA max
n Adjustable slew rate control
— Minimizes EMI affects
n Built-in power up/down glitch-free circuitry
— Permits live transceiver insertion/displacement
The slew rate control feature allows the user to set the driver
rise and fall times by using an external resistor. Controlled
edge rates can reduce switching EMI.
n SOIC packages
The CMOS design offers significant power savings over its
bipolar and ALS counterparts without sacrificing ruggedness
against ESD damage. The device is ideal for use in battery
powered or power conscious applications. ICC is specified at
500 µA maximum.
n Industrial temperature range: −40˚C to +85˚C
n On-board thermal shutdown circuitry
— Prevents damage to the device in the event of
excessive power dissipation
The driver and receiver outputs feature TRI-STATE® capa-
bility. The driver outputs operate over the entire common
mode range of −7V to +12V. Bus contention or fault situa-
tions are handled by a thermal shutdown circuit, which
forces the driver outputs into the high impedance state.
n Wide common mode range: −7V to +12V
n Receiver open input fail-safe (Note 1)
1
n
n
⁄
⁄
4
unit load (DS36C280): ≥128 nodes
unit load (DS36C280T): ≥64 nodes
1
2
n ESD (human body model): ≥2 kV
The receiver incorporates a fail safe circuit which guarantees
a high output state when the inputs are left open (Note 1) .
Connection and Logic Diagram
Truth Table
DRIVER SECTION
DE/RE*
DI
H
L
DO/RI
DO*/RI*
H
H
L
H
L
L
H
Z
X
Z
RECEIVER SECTION
DE/RE*
RI-RI*
RO
H
L
L
≥+0.2V
≤−0.2V
X
L
H
Z
01205201
Order Number DS36C280M, DS36C280TM
See NS Package Number M08A
L
OPEN (Note 1)
H
Note 1: Non-terminated, Open Inputs only
TRI-STATE® is a registered trademark of National Semiconductor Corporation.
© 2004 National Semiconductor Corporation
DS012052
www.national.com
Absolute Maximum Ratings (Note 2)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Storage Temperature Range
Lead Temperature
−65˚C to +150˚C
+260˚C
(Soldering 4 sec.)
Supply Voltage (VCC
Input Voltage (DE/RE*, & DI)
Common Mode (VCM
Driver Output/Receiver
Input
)
+12V
Recommended Operating
Conditions
−0.5V to (VCC +0.5V)
)
Min
Typ
Max
Units
Supply Voltage (VCC
Bus Voltage
)
+4.75 +5.0 +5.25
V
V
15V
−7
+12
Input Voltage (DO/RI,
DO*/RI*)
14V
Operating Free Air Temperature (TA)
Receiver Output Voltage
−0.5V to (VCC +0.5V)
DS36C280T
DS36C280
−40
0
+25
+25
+85
+70
˚C
˚C
@
Maximum Package Power Dissipation +25˚C
M Package 1190 mV,
derate
9.5 mW/˚C above +25˚C
Electrical Characteristics (Notes 3, 4)
Over Supply Voltage and Operating Temperature ranges, unless otherwise specified
Symbol
Parameter
Conditions
Reference
Min
Typ
Max Units
DIFFERENTIAL DRIVER CHARACTERISTICS
VOD1
VOD0
VOD0*
VOD2
Differential Output Voltage
Output Voltage
IO = 0 mA (No Load)
1.5
0
5.0
5.0
5.0
V
V
V
V
V
V
(422)
(485)
IO = 0 mA
Output Voltage
(Output to GND)
RL = 50Ω
0
Differential Output Voltage
(Termination Load)
(422)
(485)
(Note 5)
Figure 1
2.0
1.5
2.8
2.3
0.1
RL = 27Ω
5.0
∆VOD2
VOD3
VOC
Balance of VOD2
RL = 27Ω or 50Ω
−0.2
+0.2
|VOD2 − VOD2*
|
(422, 485)
Differential Output Voltage
(Full Load)
R1 = 54Ω, R2 = 375Ω
VTEST = −7V to +12V
RL = 27Ω
Figure 2
1.5
2.0
5.0
V
Driver Common Mode
Output Voltage
(485)
(422)
(Note 5)
Figure 1
0
0
3.0
3.0
V
V
V
RL = 50Ω
∆VOC
IOSD
Balance of VOC
RL = 27Ω or
RL = 50Ω
−0.2
+0.2
|VOC − VOC*
|
(422, 485)
(485) Figure 4
(485)
Driver Output Short-Circuit
Current
VO = +12V
200
+250
−250
mA
mA
VO = −7V
−190
RECEIVER CHARACTERISTICS
VTH
Differential Input High
Threshold Voltage
VO = VOH, IO = −0.4 mA
−7V ≤ VCM ≤ +12V
VO = VOL, IO = 0.4 mA
−7V ≤ VCM ≤ +12V
VCM = 0V
+0.035 +0.2
V
V
(Note 6)
(422, 485)
VTL
Differential Input Low
Threshold Voltage
−0.2 −0.035
VHST
RIN
RIN
IIN
Hysteresis
70
mV
kΩ
Input Resistance
Input Resistance
Line Input Current
(Note 8)
−7V ≤ VCM ≤ +12V
−7V ≤ VCM ≤ +12V
DS36C280T
DS36C280
VIN = +12V
VIN = −7V
24
48
0
68
68
kΩ
Other Input = 0V
DE = VIL, RE* = VIL
VCC = 4.75 to 5.25
or 0V
DS36C280
0.19
−0.1
0.19
−0.1
0.19
−0.1
0.19
−0.1
0.25
−0.2
0.5
mA
mA
mA
mA
mA
mA
mA
mA
mV
0
DS36C280T VIN = +12V
0
VIN = −7V
VIN = +12V
VIN = −7V
0
−0.4
0.25
−0.2
0.5
IING
Line Input Current
Glitch (Note 8)
Other Input = 0V
DE = VIL, RE* = VIL
VCC = +3.0V
DS36C280
0
0
DS36C280T VIN = +12V
VIN = −7V
0
or 0V TA = 25˚C
RS = 500Ω
0
−0.4
400
IB
Input Balance Test
(422) (Note 10)
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2
Electrical Characteristics (Notes 3, 4) (Continued)
Over Supply Voltage and Operating Temperature ranges, unless otherwise specified
Symbol
Parameter
Conditions
Reference
Min
3.5
7
Typ
Max Units
RECEIVER CHARACTERISTICS
VOH
VOL
IOSR
IOZR
High Level Output Voltage
Low Level Output Voltage
Short Circuit Current
TRI-STATE Leakage
Current
IOH = −4 mA, VID = +0.2V
IOL = +4 mA, VID = −0.2V
VO = GND
RO
4.6
0.3
35
V
Figure 11
0.5
85
1
V
RO
mA
µA
VO = 0.4V to 2.4V
DEVICE CHARACTERISTICS
VIH
VIL
IIH
High Level Input Voltage
Low Level Input Voltage
High Level Input Current
Low Level Input Current
2.0
VCC
0.8
2
V
V
GND
DE/RE*,
DI
VIH = VCC
µA
µA
µA
mA
µA
µA
IIL
VCC = 5.0V
−2
VIL = 0V
VCC = +3.0V
−2
SR = 0V
SR
−1
ICCR
ICCD
Power Supply Current
(No Load)
Driver OFF, Receiver ON
Driver ON, Receiver OFF
200
200
500
500
VCC
Switching Characteristics (Notes 4, 9, 11)
Over Supply Voltage and Operating Temperature ranges, unless otherwise specified
Symbol
Parameter
Conditions
Reference
Min
10
10
0
Typ
Max
Units
ns
DRIVER CHARACTERISTICS
tPHLD
tPLHD
tSKD
Differential Propagation
Delay High to Low
RL = 54Ω, CL = 100 pF
Figures 5, 6
399
400
1
1000
1000
10
Differential Propagation
Delay Low to High
ns
Differential Skew
ns
|tPHLD − tPLHD
Rise Time
Fall Time
|
tr
SR = Open
SR = 100 kΩ
SR = Short
CL = 15 pF
CL = 100 pF
2870
3070
1590
1640
337
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
tf
tr
Rise Time
Fall Time
tf
tr
Rise Time
Fall Time
100
100
1000
1000
2000
800
tf
348
tPHZ
tPLZ
tPZH
tPZL
Disable Time High to Z
Disable Time Low to Z
Enable Time Z to High
Enable Time Z to Low
Figures 7, 8
Figures 9, 10
Figures 7, 8
Figures 9, 10
1100
500
300
500
300
500
RECEIVER CHARACTERISTICS
tPHL
tPLH
Propagation Delay
High to Low
CL = 15 pF
30
30
0
210
190
400
400
ns
ns
Propagation Delay
Low to High
Figures 12, 13
tSK
Skew, |tPHL − tPLH
|
20
50
55
40
45
50
ns
ns
ns
ns
ns
tPLZ
tPHZ
tPZL
tPZH
Output Disable Time
CL = 15 pF
150
150
150
150
Figures 14, 15, 16
Output Enable Time
Note 2: “Absolute Maximum Ratings” are those values beyond which the safety of the device cannot be guaranteed. They are not meant to imply that the devices
should be operated at these limits. The table of “Electrical Characteristics” specifies conditions of device operation.
3
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Switching Characteristics (Notes 4, 9, 11) (Continued)
Note 3: Current into device pins is defined as positive. Current out of device pins is defined as negative. All voltages are referenced to ground except V
and
OD1
V
.
OD2
Note 4: All typicals are given for: V
= +5.0V, T = + 25˚C.
A
CC
Note 5: Delta |V
| and Delta |V | are changes in magnitude of V
and V , respectively, that occur when input changes state.
OD2 OC
OD2
OC
Note 6: Threshold parameter limits specified as an algebraic value rather than by magnitude.
Note 7: Hysteresis defined as V = V − V
.
TL
HST
TH
Note 8: I includes the receiver input current and driver TRI-STATE leakage current.
IN
Note 9: C includes probe and jig capacitance.
L
Note 10: For complete details of test, see RS-485.
Note 11: SR = GND for all Switching Characteristics unless otherwise specified.
Parameter Measurement Information
01205202
FIGURE 1. Driver VOD2 and VOC
01205205
FIGURE 5. Driver Differential
Propagation Delay Test Circuit
01205218
FIGURE 2. Driver VOD3
01205203
FIGURE 3. Driver VOH and VOL
01205206
FIGURE 6. Driver Differential Propagation Delays
and Differential Rise and Fall Times
01205204
Vtest = −7V to +12V
FIGURE 4. Driver IOSD
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4
Parameter Measurement
Information (Continued)
01205210
FIGURE 10. TRI-STATE Waveforms (tPZL, tPLZ
)
01205207
FIGURE 7. TRI-STATE Test Circuit (tPZH , tPHZ
)
01205211
FIGURE 11. Receiver VOH and VOL
01205208
FIGURE 8. TRI-STATE Waveforms (tPZH, tPHZ
)
01205212
FIGURE 12. Receiver Differential
Propagation Delay Test Circuit
01205209
FIGURE 9. TRI-STATE Test Circuit (tPZL, tPLZ
)
01205213
FIGURE 13. Receiver Differential Propagation Delay Waveforms
5
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Parameter Measurement Information (Continued)
01205214
FIGURE 14. Receiver TRI-STATE Test Circuit
01205215
FIGURE 15. Receiver Enable and Disable Waveforms (tPLZ, tPZL
)
01205216
FIGURE 16. Receiver Enable and Disable Waveforms (tPHZ, tPZH
)
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6
Typical Application Information
01205217
FIGURE 17. Typical Pin Connection
TABLE 1. Device Pin Descriptions
Description
Pin
#
Name
1
RO
Receiver Output: When DE/RE* (Receiver Enable) is LOW, the receiver is enabled (ON), if DO/RI ≥
DO*/RI* by 200 mV, RO will be HIGH. If DO/RI ≤ DO*/RI* by 200 mV, RO will be LOW. Additionally RO will
be HIGH for OPEN (Non-terminated) inputs.
2
3
SR
Slew Rate Control: A resistor connected to Ground controls the Driver Output rising and falling edge rates.
Combined Driver and Receiver Output Enable: When signal is LOW the receiver output is enabled and the
driver outputs are in TRI-STATE (OFF). When signaI is HlGH, the receiver output is in TRI-STATE (OFF)
and the driver outputs are enabled.
DE/RE*
4
DI
Driver Input: When DE/RE* is HlGH, the driver is enabled, if DI is LOW, then DO/RI will be LOW and
DO*/RI* will be HIGH. If DI is HIGH, then DO/RI is HIGH and DO*/RI* is LOW.
Ground Connection
5
6
7
8
GND
DO/RI
DO*/RI*
VCC
Driver Output/Receiver Input, 485 Bus Pin.
Driver Output/Receiver Input, 485 Bus Pin.
Positive Power Supply Connection: Recommended operating range for VCC is +4.75V to +5.25V.
−3V stay the same. The other reference points are +12V at
+0.5 mA for the top border and −7V at −0.4 mA for the
Unit Load
A unit load for a RS-485 receiver is defined by the input
current versus the input voltage curve. The gray shaded
region is the defined operating range from −7V to +12V. The
top border extending from −3V at 0 mA to +12V at +1 mA is
defined as one unit load. Likewise, the bottom border ex-
tending from +5V at 0 mA to −7V at −0.8 mA is also defined
as one unit load (see Figure 18 ). A RS-485 driver is capable
of driving up to 32 unit loads. This allows upto 32 nodes on
a single bus. Although sufficient for many applications, it is
sometime desirable to have even more nodes. For example
an aircraft that has 32 rows with 4 seats per row could
benefit from having 128 nodes on one bus. This would allow
signals to be transferred to and from each individual seat to
1 main station. Usually there is one or two less seats in the
last row of the aircraft near the restrooms and food storage
area. This frees the node for the main station.
1
bottom border (see Figure 18 ). Second, for a ⁄ UL device
4
the top and bottom borders shown in Figure 18 are scaled
also. Again, both 0 mA reference points at +5V and −3V stay
the same. The other reference points are +12V at +0.25 mA
for the top border and −7V at −0.2 mA for the bottom border
(see Figure 18 ).
1
1
The advantage of the
⁄ UL and ⁄ UL devices is the
2
4
increased number of nodes on one bus. In a single master
multi-slave type of application were the number of slaves
exceeds 32, the DS36C278/279/280 may save in the cost of
extra devices like repeaters, extra media like cable, and/or
extra components like resistors.
The DS36C279 and DS36C280 have addition feature which
offer more advantages. The DS36C279 has an automatic
sleep mode function for power conscious applications. The
DS36C280 has a slew rate control for EMI conscious appli-
cations. Refer to the sleep mode and slew rate control
portion of the application information section in the corre-
sponding datasheet for more information on these features.
The DS36C278, the DS36C279, and the DS36C280 all have
1
1
4
⁄2 unit load and ⁄ unit load (UL) options available. These
devices will allow upto 64 nodes or 128 nodes guaranteed
over temperature depending upon which option is selected.
1
The
⁄
2
UL option is available in industrial temperature and
UL is available in commercial temperature.
UL device the top and bottom borders shown in
Figure 18 are scaled. Both 0 mA reference points at +5V and
1
the ⁄
4
First, for a 1⁄
2
7
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tion fixed edge rate devices. The slew rate control may be
adjusted with or without any external components. The
DS36C280 offers both low power (ICC 500 µA max) and low
EMI for an RS-485 interface.
Unit Load (Continued)
The slew rate control is located at pin two of the device and
only controls the driver output edges. The slew rate control
pin (SR) may be left open or shorted to ground, with or
without a resistor. When the SR pin is shorted to ground
without a resistor, the driver output edges will transition
typically 350 ns. When the SR pin is left open, the driver
output edges will transition typically 3 µs. When the SR pin is
shorted to ground with a resistor, the driver output edges will
transition between 350 ns and 3 µs depending on the resis-
tor value. Refer to the slew rate versus resistor value curve
in this datasheet for determining resistor values and ex-
pected typical slew rate value. Please note, when slowing
the edge rates of the device (see Figure 19 ) will decrease
the maximum data rate also.
01205219
FIGURE 18. Input Current vs Input Voltage
Operating Range
Slew Rate Control
The DS36C280 features an adjustable slew rate control.
This feature allows more control over EMl levels than tradi-
Differential Rise/Fall Time
vs Slew Rate Resistor
01205220
FIGURE 19. Slew Rate Resistor
vs Rise/Fall Time
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8
Physical Dimensions inches (millimeters) unless otherwise noted
8-Lead (0.150" Wide) Molded Small Outline Package, JEDEC
Order Number DS36C280M or DS36C280TM
NS Package Number M08A
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.
For the most current product information visit us at www.national.com.
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