DS36C279TN [NSC]
Low Power EIA-RS-485 Transceiver with Sleep Mode; 低功耗EIA -RS - 485收发器,睡眠模式型号: | DS36C279TN |
厂家: | National Semiconductor |
描述: | Low Power EIA-RS-485 Transceiver with Sleep Mode |
文件: | 总10页 (文件大小:173K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
July 1998
DS36C279
Low Power EIA-RS-485 Transceiver with Sleep Mode
General Description
Features
n 100% RS-485 compliant
The DS36C279 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 compat-
ible with TIA/EIA-422-B.
— Guaranteed RS-485 device interoperation
n Low power CMOS design: ICC 500 µA max
n Automatic sensing sleep mode
— Reduces ICC to 10 µA maximum
n Built-in power up/down glitch-free circuitry
The sleep mode feature automatically puts the device in a
power saving mode when both the driver and receiver are
††
disabled. The device is ideal for use in power conscious
— Permits live transceiver intersection/displacement
n DIP and SOIC packages available
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
n Wide common mode range: −7V to +12V
applications where the device may be disabled for extended
periods of time.
The driver and receiver outputs feature TRI-STATE® capabil-
ity. The driver outputs operate over the entire common mode
range of −7V to +12V. 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 a high impedance state.
n Receive open input fail-safe (Note 1)
1
n
n
⁄
⁄
4
unit load (DS36C279): ≥ 128 nodes
unit load (DS36C279T): ≥ 64 nodes
The receiver incorporates a fail safe circuit which guarantees
a high output state when the inputs are left open.
1
2
†
n ESD (Human Body Model): ≥ 2 kV
n Drop-in replacement for:
— LTC485 MAX485 DS75176 DS3695
The DS36C279T is fully specified over the industrial tem-
perature range (−40˚C to +85˚C).
Connection and Logic Diagram
Truth Table
DRIVER SECTION
RE*
X
DE
H
DI
H
L
DO/RI
DO*/RI*
H
L
L
H
Z
X
H
X
L
X
Z
RECEIVER SECTION
RE*
L
DE
L
RI-RI*
RO
DS012053-1
≥+0.2V
≤−0.2V
X
H
Order Number DS36C279M, DS36C279N,
DS36C279TM or DS36C279TN
See NS Package Number M08A or N08E
L
L
L
Z (Note 2)
H
H
L
L
L
OPEN (Note 1)
Note 1: Non-terminated, open input only
Note 2: Device enters sleep mode if enable conditions are held 600 ns
TRI-STATE® is a registered trademark of National Semiconductor Corporation.
© 1999 National Semiconductor Corporation
DS012053
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Absolute Maximum Ratings (Note 3)
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)
Recommended Operating
Conditions
Supply Voltage (VCC
Input Voltage (DE, RE*, & DI)
Common Mode (VCM
)
+12V
−0.5V to (VCC +0.5V)
)
Min
+4.75
−7
Typ
Max
+5.25
+12
Units
±
±
Driver Output/Receiver Input
Input Voltage (DO/RI, DO*/RI*)
Receiver Output Voltage
15V
14V
Supply Voltage (VCC
)
+5.0
V
V
Bus Voltage
−0.5V to (VCC +0.5V)
Operating Free Air Temperature (TA)
Maximum Package Power Dissipation
DS36C279T
DS36C279
−40
0
+25
+25
+85
+70
˚C
˚C
@
+25˚C
M Package 1190 mW, derate
N Package 744 mW, derate
9.5 mW/˚C above +25˚C
6.0 mW/˚C above +25˚C
Electrical Characteristics (Notes 4, 5)
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)
(422)
(485)
1.5
0
5.0
5.0
5.0
V
V
V
V
V
V
IO = 0 mA
Output Voltage
(Output to GND)
RL = 50Ω
0
Differential Output Voltage
(Termination Load)
Balance of VOD2
(422)
(485)
(Note 6)
Figure 1
2.0
1.5
−0.2
2.8
2.3
0.1
RL = 27Ω
5.0
∆VOD2
VOD3
VOC
RL = 27Ω or 50Ω
+0.2
|VOD2 − VOD2*
|
(422, 485)
Figure 2
Differential Output Voltage
(Full Load)
R1 = 54Ω, R2 = 375Ω
VTEST = −7V to +12V
RL = 27Ω
1.5
2.0
5.0
V
Driver Common Mode
Output Voltage
(485)
(422)
(Note 6)
(422, 485)
Figure 1
0
0
3.0
3.0
V
V
V
RL = 50Ω
∆VOC
Balance of VOC
RL = 27Ω or
RL = 50Ω
−0.2
+0.2
|VOC − VOC*
|
IOSD
Driver Output Short-Circuit
Current
VO = +12V
(485) Figure 4
(485)
200
+250
mA
mA
VO = −7V
−190 −250
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 7)
(422, 485)
VTL
Differential Input Low
Threshold Voltage
−0.2 −0.035
VHST
RIN
Hysteresis
(Note 8)
70
mV
kΩ
kΩ
mA
mA
mA
mA
mA
mA
mA
mA
mV
V
Input Resistance
−7V ≤ VCM ≤ +12V
DS36C279T
DS36C279
DS36C279
24
48
0
68
68
IIN
Line Input Current
(Note 9)
Other Input = 0V,
VIN = +12V
VIN = −7V
0.19
−0.1
0.19
−0.1
0.19
−0.1
0.19
−0.1
0.25
−0.2
0.5
DE = VIL, RE* = VIL
VCC = 4.75 to 5.25
or 0V
,
0
DS36C279T
DS36C279
DS36C279T
VIN = +12V
VIN = −7V
0
0
−0.4
0.25
−0.2
0.5
IING
Line Input Current Glitch
(Note 9)
Other Input = 0V,
VIN = +12V
VIN = −7V
0
DE = VIL, RE* = VIL
,
0
VCC = +3.0V or 0V,
TA = 25˚C
VIN = +12V
VIN = −7V
0
0
−0.4
±
IB
Input Balance Test
RS = 500Ω
(422) (Note 12)
400
VOH
VOL
High Level Output Voltage
Low Level Output Voltage
IOH = −4 mA, VID = +0.2V
IOL = +4 mA, VID = −0.2V
RO
Figure 11
3.5
4.6
0.3
0.5
V
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2
Electrical Characteristics (Notes 4, 5) (Continued)
Over Supply Voltage and Operating Temperature ranges, unless otherwise specified
Symbol
Parameter
Conditions
Reference
Min
Typ
Max Units
RECEIVER CHARACTERISTICS
IOSR
IOZR
Short Circuit Current
VO = GND
RO
7
35
85
mA
µA
±
1
TRI-STATE Leakage
Current
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
DE,
RE*,
DI
2.0
VCC
0.8
2
V
GND
V
VIH = VCC
µA
µA
µA
µA
µA
µA
µA
IIL
VCC = 5V
VIL = 0V
−2
VCC = +3.0V
−2
ICC
Power Supply Current
(No Load)
Driver and Receiver ON
200
200
200
0.2
500
500
500
10
ICCR
ICCD
ICCX
Driver OFF, Receiver ON
Driver ON, Receiver OFF
Sleep Mode
VCC
Switching Characteristics (Notes 5, 10)
Over Supply Voltage and Operating Temperature ranges, unless otherwise specified
Symbol
Parameter
Conditions
Reference
Min
Typ
39
40
1
Max
Units
ns
DRIVER CHARACTERISTICS
tPHLD
tPLHD
tSKD
Differential Propagation
Delay High to Low
RL = 54Ω, CL = 100 pF
10
10
0
80
80
10
Differential Propagation
Delay Low to High
ns
Figures 5, 6
Differential Skew
ns
|tPHLD − tPLHD
Rise Time
Fall Time
|
tr
3
3
25
25
80
80
50
65
98
50
ns
ns
ns
ns
ns
ns
ns
tf
50
tPHZ
tPLZ
tPZH
tPZL
tPSH
Disable Time High to Z
Disable Time Low to Z
Enable Time Z to High
Enable Time Z to Low
Driver Enable from Sleep
Mode to Output High
Driver Enble from Sleep
Mode to Output Low
CL = 15 pF
RE* = L
Figures 7, 8
Figures 9, 10
Figures 7, 8
Figures 9, 10
Figures 7, 8
200
200
200
200
250
CL = 100 pF
RE* = L
CL = 100 pF
(Note 11)
70
70
tPSL
CL = 100 pF
(Note 11)
Figures 9, 10
Figures 12, 13
98
250
ns
RECEIVER CHARACTERISTICS
tPHL
Propagation Delay
High to Low
CL = 15 pF
30
30
0
210
190
400
400
ns
ns
tPLH
Propagation Delay
Low to High
tSK
Skew, |tPHL − tPLH
|
20
50
55
40
45
97
50
ns
ns
ns
ns
ns
ns
tPLZ
tPHZ
tPZL
tPZH
tPSH
Output Disable Time
CL = 15 pF
DE = H
150
150
150
150
250
Figures 14, 15,
16
Output Enable Time
Receiver Enable from Sleep
Mode to Output High
CL = 15 pF
(Note 11)
Figures 14, 16
Figures 14, 15
70
70
tPSL
Receiver Enable from Sleep
CL = 15 pF
95
250
ns
3
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Switching Characteristics (Notes 5, 10) (Continued)
Over Supply Voltage and Operating Temperature ranges, unless otherwise specified
Symbol
Parameter
Conditions
Reference
Min
Typ
Max
Units
RECEIVER CHARACTERISTICS
Mode to Output Low
(Note 11)
Note 3: “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.
Note 4: 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
OD1
and V .
OD2
Note 5: All typicals are given for: V
CC
= +5.0V, T = + 25˚C.
A
Note 6: Delta |V | and Delta |V
OD2
| are changes in magnitude of V
OC
and V
, respectively, that occur when input changes state.
OC
OD2
Note 7: Threshold parameter limits specified as an algebraic value rather than by magnitude.
Note 8: Hysteresis defined as V = V − V
.
HST TH TL
Note 9:
I
includes the receiver input current and driver TRI-STATE leakage current.
C includes probe and jig capacitance.
L
IN
Note 10:
Note 11: For enable from sleep mode delays DE = L and RE* = H for greater than 600 ns prior to test (device is in sleep mode).
Note 12: For complete details of test, see RS-485.
Parameter Measurement Information
DS012053-3
DS012053-2
FIGURE 3. Driver VOH and VOL
FIGURE 1. Driver VOD2 and VOC
DS012053-4
Vtest = −7V to +12V
FIGURE 4. Driver IOSD
DS012053-17
FIGURE 2. Driver VOD3
DS012053-5
FIGURE 5. Driver Differential Propagation Delay Test Circuit
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4
Parameter Measurement Information (Continued)
DS012053-6
FIGURE 6. Driver Differential Propagation Delays and Differential Rise and Fall Times
DS012053-10
FIGURE 10. TRI-STATE and Sleep Mode Waveforms
(tPZL, (tPSL), tPLZ
)
DS012053-7
FIGURE 7. TRI-STATE and Sleep Mode Test Circuit
(tPZH, (tPSH), tPHZ
)
DS012053-11
DS012053-8
FIGURE 11. Receiver VOH and VOL
FIGURE 8. TRI-STATE and Sleep Mode Waveforms
(tPZH, (tPSH), tPHZ
)
DS012053-12
FIGURE 12. Receiver Differential Propagation Delay
Test Circuit
DS012053-9
FIGURE 9. TRI-STATE and Sleep Mode Test Circuit
(tPZL, (tPSL), tPLZ
)
5
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Parameter Measurement Information (Continued)
DS012053-13
FIGURE 13. Receiver Differential Propagation Delay Waveforms
DS012053-14
FIGURE 14. Receiver TRI-STATE and Sleep Mode Test Circuit
DS012053-15
FIGURE 15. Receiver Enable and Disable Waveforms (tPLZ, tPZL, (tPSL))
DS012053-16
FIGURE 16. Receiver Enable and Disable Waveforms (tPHZ, tPZH, (tPSH))
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6
Parameter Measurement Information (Continued)
DS012053-19
FIGURE 17. Entering Sleep Mode Conditions
Typical Application Information
DS012053-18
FIGURE 18. Typical RS-485 Bus Interface
TABLE 1. Device Pin Descriptions
Description
Pin
No.
1
Name
RO
Receiver Output: When 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
4
RE*
DE
DI
Receiver Output Enable: When RE* is LOW the receiver output is enabled. When RE* is HIGH, the
receiver output is in TRI-STATE (OFF). When RE* is HIGH and DE is LOW, the device will enter a
low-current sleep mode after 600 ns.
Driver Output Enable: When DE is HIGH, the driver outputs are enabled. When DE is LOW, the
driver outputs are in TRI-STATE (OFF). When RE* is HIGH and DE is LOW, the device will enter a
low-current sleep mode after 600 ns.
Driver Input: When DE (Driver Enable) is HIGH, 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.
5
6
7
8
GND
DO/RI
DO*/RI*
VCC
Ground Connection.
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.
Unit Load
A unit load for an RS-485 receiver is defined by the input cur-
rent 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 de-
fined as one unit load. Likewise, the bottom border extending
from +5V at 0 mA to −7V at −0.8 mA is also defined as one
unit load (see Figure 19). An RS-485 driver is capable of
driving up to 32 unit loads. This allows up to 32 nodes on a
single bus. Although sufficient for many applications, it is
sometimes desirable to have even more nodes. For ex-
ample, an aircraft that has 32 rows with 4 seats per row
would benefit from having 128 nodes on one bus. This would
7
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Unit Load (Continued)
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.
The DS36C278, the DS36C279, and the DS36C280 all have
1
1
4
⁄ unit load and ⁄ unit load (UL) options available. These
2
devices will allow up to 64 nodes or 128 nodes guaranteed
over temperature depending upon which option is selected.
1
The
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
1
⁄
4
First, for a 1
⁄2
DS012053-20
Figure 19 are scaled. Both 0 mA reference points at +5V and
−3V stay the same. The other reference points are +12V at
FIGURE 19. Input Current vs Input Voltage
Operating Range
+0.5 mA for the top border and −7V at −0.4 mA for the bot-
1
tom border (see Figure 19). Second, for a
⁄4 UL device the
The DS36C279 and DS36C280 have an additional feature
which offers more advantages. The DS36C279 has an auto-
matic sleep mode function for power conscious applications.
The DS36C280 has a slew rate control for EMI conscious
applications. 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.
top and bottom borders shown in Figure 19 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 19).
1
1
The advantage of the
⁄ UL and ⁄ UL devices is the in-
2
4
creased number of nodes on one bus. In a single master
multi-slave type of application where 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.
Sleep Mode
The DS36C279 features an automatic shutdown mode that
allows the device to save power when not transmitting data.
Since the shutdown mode is automatic, no external compo-
nents are required. It may be used as little or as much as the
application requires. The more the feature is utilized, the
more power it saves.
The sleep mode is automatically entered when both the
driver and receiver are disabled. This occurs when both the
DE pin is asserted to a logic low and the RE* pin is asserted
to a logic high. Once both pins are asserted the device will
enter sleep mode typically in 50 ns. The DS36C279 is guar-
anteed to go into sleep mode within 600 ns after both pins
are asserted. The device wakes up (comes out of sleep
mode) when either the DE pin is asserted to a logic high
and/or the RE* pin is asserted to a logic low. After the device
enters sleep mode it will take longer for the device to wake
up than it does for the device to enable from TRI-STATE. Re-
fer to datasheet specifications tPSL and tPSH and compare
with tPZL and tPZH for timing differences.
The benefit of the DS36C279 is definitely its power savings.
When active the device has a maximum ICC of 500 µA.
When in sleep mode the device has a maximum ICC of only
10 µA, which is 50 times less power than when active. The
I
CC when the device is active is already very low but when in
sleep mode the ICC is ultra low.
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8
Physical Dimensions inches (millimeters) unless otherwise noted
8-Lead (0.150" Wide) Molded Small Outline Package, JEDEC
Order Number DS36C279M or DS36C279TM
NS Package Number M08A
8-Lead (0.300" Wide) Molded Dual-In-Line Package
Order Number DS36C279N or DS36C279TN
NS Package Number N08E
9
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LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DE-
VICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMI-
CONDUCTOR CORPORATION. As used herein:
1. Life support devices or systems are devices or sys-
tems which, (a) are intended for surgical implant into
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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Corporation
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Tel: 1-800-272-9959
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