LTC486
Quad Low Power
RS485 Driver
FEATURES
DESCRIPTION
n
n
The LTC®486 is a low power differential bus/line driver
designed for multipoint data transmission standard RS485
applications with extended common-mode range (12V to
–7V). It also meets RS422 requirements.
n
n
n
n
n
n
n
Very Low Power: ICC = 110µA Typ
Designed for RS485 or RS422 Applications
Single 5V Supply
–7V to 12V Bus Common-Mode Range Permits ±7V
GND Difference Between Devices on the Bus
Thermal Shutdown Protection
Power-Up/Down Glitch-Free Driver Outputs Permit
Live Insertion/Removal of Package
Driver Maintains High Impedance in Three-State or
with the Power Off
28ns Typical Driver Propagation Delays with 5ns
Skew
Pin Compatible with the SN75172, DS96172,
µA96172, and DS96F172
The CMOS design offers significant power savings over
its bipolar counterpart without sacrificing ruggedness
against overload or ESD damage.
The driver features three-state outputs, with the driver
outputs maintaining high impedance over the entire
common-mode range. Excessive power dissipation caused
by bus contention or faults is prevented by a thermal
shutdown circuit which forces the driver outputs into a
high impedance state.
Both AC and DC specifications are guaranteed from 0°C
to 70°C (Commercial), –40°C to 85°C (Industrial), over
the 4.75V to 5.25V supply voltage range.
APPLICATIONS
Low Power RS485/RS422 Drivers
Level Translator
n
L, LT, LTC, LTM, Linear Technology, µModule and the Linear logo are registered trademarks of
Linear Technology Corporation. All other trademarks are the property of their respective owners.
n
TYPICAL APPLICATION
RS485 Length Specification
EN
EN
4
DI
1
DRIVER
12
2
120Ω
120Ω
4000 FT BELDEN 9841
4
RECEIVER
1
3
RO
CABLE LENGTH (FT)
10k
1k
100
1/4 LTC488
1/4 LTC486
EN
486 TA01a
10
10k
100k
1M
2.5M
10M
DATA RATE (bps)
486 TA01b
* APPLIES FOR 24 GAUGE, POLYETHYLENE
DIELECTRIC TWISTED PAIR
486fc
1
LTC486
ABSOLUTE MAXIMUM RATINGS
PIN CONFIGURATION
(Note 1)
Supply Voltage (VCC).................................................12V
Control Input Voltages........................0.5V to VCC + 0.5V
Driver Input Voltages....................... –0.5V to VCC + 0.5V
Driver Output Voltages.............................................±14V
Control Input Currents..........................................±25mA
Driver Input Currents............................................±25mA
Operating Temperature Range
LTC486C................................................... 0°C to 70°C
LTC486I................................................ –40°C to 85°C
Storage Temperature Range.................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
TOP VIEW
DI1
1
16 VCC
DO1A
2
15 DI4
DO1B
3
14 DO4A
EN
4
13 DO4B
DO2B
5
12 EN
DO2A
6
11 DO3B
DI2
7
10 DO3A
GND
8
9
N PACKAGE
16-LEAD PLASTIC DIP
DI3
SW PACKAGE
16-LEAD PLASTIC SO
TJMAX = 125°C, θJA = 70°C/W (N)
TJMAX = 150°C, θJA = 95°C/W (SW)
Consult factory for Military grade parts.
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC486CN#PBF
LTC486CN#TRPBF
LTC486CN
16-Lead Plastic DIP
0°C to 70°C
LTC486CSW#PBF
LTC486CSW#TRPBF
LTC486CSW
16-Lead Plastic SO
0°C to 70°C
LTC486IN#PBF
LTC486IN#TRPBF
LTC486IN
16-Lead Plastic DIP
–40°C to 85°C
LTC486ISW#PBF
LTC486ISW#TRPBF
LTC486ISW
16-Lead Plastic SO
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
486fc
2
LTC486
DC ELECTRICAL CHARACTERISTICS
VCC = 5V ±5%, 0°C ≤ Temperature ≤ 70°C (Commercial), –40°C ≤ Temperature ≤ 85°C (Industrial) (Notes 2, 3)
SYMBOL
PARAMETER
CONDITIONS
MIN
VOD1
Differential Driver Output Voltage (Unloaded)
IOUT = 0
VOD2
Differential Driver Output Voltage (With Load)
R = 50Ω; (RS422)
Change in Magnitude of Driver Differential
Output Voltage for Complementary Output States
VOC
Driver Common-Mode Output Voltage
|VOC|
Change in Magnitude of Driver Common-Mode
Output Voltage for Complementary Output States
VIH
Input High Voltage
VIL
Input Low Voltage
IIN1
Input Current
ICC
Supply Current
No Load
IOSD1
Driver Short-Circuit Current, VOUT = High
IOSD2
Driver Short-Circuit Current, VOUT = Low
IOZ
High Impedance State Output Current
MAX
5
2
R = 27Ω; (RS485) (Figure 1)
VOD
TYP
V
V
1.5
R = 27Ω or R = 50Ω
(Figure 1)
DI, EN, EN
UNITS
5
V
0.2
V
3
V
0.2
V
2.0
V
0.8
V
±2
µA
110
110
200
200
µA
µA
VOUT = –7V
100
250
mA
VOUT = 12V
100
250
mA
VOUT = –7V to 12V
±10
±200
µA
Output Enabled
Output Disabled
SWITCHING CHARACTERISTICS
VCC = 5V ±5%, 0°C ≤ Temperature ≤ 70°C (Commercial), –40°C ≤ Temperature ≤ 85°C (Industrial) (Notes 2, 3)
SYMBOL
PARAMETER
CONDITIONS
tPLH
Driver Input to Output
tPHL
Driver Input to Output
RDIFF = 54Ω, CL1 = CL2 = 100pF
(Figures 2, 4)
MIN
TYP
MAX
10
30
50
tSKEW
Driver Output to Output
tr, tf
Driver Rise or Fall Time
tZH
Driver Enable to Output High
tZL
Driver Enable to Output Low
tLZ
tHZ
ns
10
30
50
ns
5
15
ns
5
15
25
ns
CL = 100pF (Figures 3, 5) S2 Closed
35
70
ns
CL = 100pF (Figures 3, 5) S1 Closed
35
70
ns
Driver Disable Time from Low
CL = 15pF (Figures 3, 5) S1 Closed
35
70
ns
Driver Disable Time from High
CL = 15pF (Figures 3, 5) S2 Closed
35
70
ns
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
UNITS
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 temperature = 25°C.
486fc
3
LTC486
SWITCHING TIME WAVEFORMS
DI
3V
f = 1MHz : t r < 10ns : t f < 10ns
1.5V
0V
t PLH
B
A
VO
–VO
1.5V
t PHL
VO
t SKEW
1/2 VO
80%
t SKEW
1/2 VO
90%
VDIFF = V(A) – V(B)
10%
20%
tf
tr
486 F01
Figure 1. Driver Propagation Delays
EN
3V
f = 1MHz : t r ≤ 10ns : t f ≤ 10ns
1.5V
0V
5V
A, B
VOL
t ZL
VOH
A, B
0V
1.5V
t LZ
2.3V
OUTPUT NORMALLY LOW
2.3V
OUTPUT NORMALLY HIGH
0.5V
0.5V
tHZ
tZH
486 F02
Figure 2. Driver Enable and Disable Times
486fc
4
LTC486
TYPICAL PERFORMANCE CHARACTERISTICS
Driver Output High Voltage
vs Output Current TA = 25°C
Driver Differential Output Voltage
vs Output Current TA = 25°C
64
–48
–24
1
2
3
48
32
16
0
4
OUTPUT VOLTAGE (V)
0
1
2
3
486 G01
60
40
20
0
4
OUTPUT VOLTAGE (V)
TTL Input Threshold
vs Temperature
0
1
2
3
OUTPUT VOLTAGE (V)
486 G02
4
486 G03
Driver Skew vs Temperature
1.63
5
1.61
4
TIME (ns)
INPUT THRESHOLD VOLTAGE (V)
1.59
3
2
1.57
1.55
–50
0
50
1
–50
100
TEMPERATURE (°C )
50
100
486 G05
Driver Differential Output Voltage
vs Temperature RO = 54Ω
Supply Current vs Temperature
2.3
130
120
110
100
90
–50
0
TEMPERATURE (°C )
486 G04
DIFFERENTIAL VOLTAGE (V)
0
80
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
–72
SUPPLY CURRENT (µA)
OUTPUT CURRENT (mA)
–96
0
Driver Output Low Voltage
vs Output Current TA = 25°C
0
50
TEMPERATURE (°C )
2.1
1.9
1.7
1.5
–50
100
486 G06
0
50
TEMPERATURE (°C )
100
486 G07
486fc
5
LTC486
FUNCTION TABLE
INPUT
ENABLES
OUTPUTS
DI
EN
EN
OUTA
OUTB
H
L
H
L
X
H
H
X
X
L
X
X
L
L
H
H
L
H
L
Z
L
H
L
H
Z
H: High Level
L: Low Level
X: Irrelevant
Z: High Impedance (Off)
PIN FUNCTIONS
DI1 (Pin 1): Driver 1 Input. If Driver 1 is enabled, then a
low on DI1 forces the driver outputs DO1A low and DO1B
high. A high on DI1 with the driver outputs enabled will
force DO1A high and DO1B low.
GND (Pin 8): Ground Connection.
DO1A (Pin 2): Driver 1 Output.
DO3B (Pin 11): Driver 3 Output.
DO1B (Pin 3): Driver 1 Output.
EN (Pin 12): Driver Outputs Disabled. See Function Table
for details.
EN (Pin 4): Driver Outputs Enabled. See Function Table
fordetails.
DI3 (Pin 9): Driver 3 Input. Refer to DI1.
DO3A (Pin 10): Driver 3 Output.
DO4B (Pin 13): Driver 4 Output.
DO2B (Pin 5): Driver 2 Output.
DO4A (Pin 14): Driver 4 Output.
DO2A (Pin 6): Driver 2 Output.
DI4 (Pin 15): Driver 4 Input. Refer to DI1.
DI2 (Pin 7): Driver 2 Input. Refer to DI1
VCC (Pin 16): Positive Supply; 4.75V < VCC < 5.25V
486fc
6
LTC486
TEST CIRCUITS
A
R
VOD
R
B
VOC
486 F03
Figure 3. Driver DC Test Load
EN
CI1
A
DI
DRIVER
RDIFF
B
CI2
486 F04
EN
Figure 4. Driver Timing Test Circuit
S1
VCC
OUTPUT
UNDER TEST
500Ω
CL
S2
486 F05
Figure 5. Driver Timing Test Load #2
486fc
7
LTC486
APPLICATIONS INFORMATION
EN
EN
4
DX
1
SHIELD
SHIELD
3
2
120Ω
DX
120Ω
4
3
RX
2
RX
1
12
12
EN
1/4 LTC486
DX
1
EN
EN
4
4
3
1
DX
EN
1/4 LTC488
3
RX
2
2
12
EN
1/4 LTC486
RX
12
EN
1/4 LTC488
486 F06
Figure 6. Typical Connection
Typical Application
Cable and Data Rate
A typical connection of the LTC486 is shown in Figure 6.
A twisted pair of wires connect up to 32 drivers and
receivers for half duplex data transmission. There are no
restrictions on where the chips are connected to the wires,
and it isn’t necessary to have the chips connected at the
ends. However, the wires must be terminated only at the
ends with a resistor equal to their characteristic impedance,
typically 120Ω. The optional shields around the twisted
pair help reduce unwanted noise, and are connected to
GND at one end.
The transmission line of choice for RS485 applications is
a twisted pair. There are coaxial cables (twinaxial) made
for this purpose that contain straight pairs, but these are
less flexible, more bulky, and more costly than twisted
pairs. Many cable manufacturers offer a broad range of
120Ω cables designed for RS485 applications.
The LTC486 has a thermal shutdown feature which protects
the part from excessive power dissipation. If the outputs
of the driver are accidently shorted to a power supply or
low impedance source, up to 250mA can flow through
the part. The thermal shutdown circuit disables the driver
outputs when the internal temperature reaches 150°C and
turns them back on when the temperature cools to 130°C.
If the outputs of two or more LTC486 drivers are shorted
directly, the driver outputs cannot supply enough current
to activate the thermal shutdown. Thus, the thermal shutdown circuit will not prevent contention faults when two
drivers are active on the bus at the same time.
10
LOSS PER 100 FT (dB)
Thermal Shutdown
Losses in a transmission line are a complex combination of
DC conductor loss, AC losses (skin effect), leakage, and AC
losses in the dielectric. In good polyethylene cables such
as the Belden 9841, the conductor losses and dielectric
losses are of the same order of magnitude, with relatively
low overall loss (Figure 7).
1
0.1
0.1
1
10
100
FREQUENCY (MHz)
486 F07
Figure 7. Attenuation vs Frequency for Belden 9841
486fc
8
LTC486
APPLICATIONS INFORMATION
When using low loss cables, Figure 8 can be used as a
guideline for choosing the maximum line length for a given
data rate. With lower quality PVC cables, the dielectric loss
factor can be 1000 times worse. PVC twisted pairs have
terrible losses at high data rates (>100kbs) and greatly
reduce the maximum cable length. At low data rates however, they are acceptable and much more economical.
CABLE LENGTH (FT)
10k
1k
100
Cable Termination
10
10k
100k
1M
2.5M
10M
DATA RATE (bps)
486 F08
Figure 8. Cable Length vs Data Rate
PROBE HERE
DX
Rt
DRIVER
RECEIVER
RX
Rt = 120Ω
Rt = 47Ω
Rt = 470Ω
486 F09
Figure 9. Termination Effects
The proper termination of the cable is very important. If
the cable is not terminated with its characteristic impedance, distorted waveforms will result. In severe cases,
distorted (false) data and nulls will occur. A quick look
at the output of the driver will tell how well the cable is
terminated. It is best to look at a driver connected to the
end of the cable, since this eliminates the possibility of
getting reflections from two directions. Simply look at the
driver output while transmitting square wave data. If the
cable is terminated properly, the waveform will look like
a square wave (Figure 9).
If the cable is loaded excessively (e.g., 47Ω), the signal
initially sees the surge impedance of the cable and jumps
to an initial amplitude. The signal travels down the cable
and is reflected back out of phase because of the mistermination. When the reflected signal returns to the driver,
the amplitude will be lowered. The width of the pedestal
is equal to twice the electrical length of the cable (about
1.5ns/ft). If the cable is lightly loaded (e.g., 470Ω), the
signal reflects in phase and increases the amplitude at the
driver output. An input frequency of 30kHz is adequate for
tests out to 4000 ft. of cable.
AC Cable Termination
120Ω
C
RECEIVER
RX
C = LINE LENGTH (FT) × 16.3pF
486 F10
Figure 10. AC Coupled Termination
Cable termination resistors are necessary to prevent unwanted reflections, but they consume power. The typical
differential output voltage of the driver is 2V when the
cable is terminated with two 120Ω resistors. When no
data is being sent 33mA of DC current flows in the cable.
This DC current is about 220 times greater than the supply
current of the LTC486. One way to eliminate the unwanted
current is by AC coupling the termination resistors as
shown in Figure 10.
486fc
9
LTC486
APPLICATIONS INFORMATION
The coupling capacitor allows high frequency energy to flow
to the termination, but blocks DC and low frequencies. The
dividing line between high and low frequency depends on
the length of the cable. The coupling capacitor must pass
frequencies above the point where the line represents an
electrical one-tenth wavelength. The value of the coupling
capacitor should therefore be set at 16.3pF per foot of cable
length for 120Ω cables. With the coupling capacitors in
place, power is consumed only on the signal edges, not
when the driver output is idling at a 1 or 0 state. A 100nF
capacitor is adequate for lines up to 4000 feet in length.
Be aware that the power savings start to decrease once
the data rate surpasses 1/(120Ω × C).
5V
110Ω
130Ω
110Ω
130Ω
RECEIVER
RX
5V
140Ω
RECEIVER
RX
RECEIVER
RX
1.5k
C
100k
120Ω
486 F11
Figure 11. Forcing “0” When All Drivers Are Off
Y
DRIVER
Some data encoding schemes require that the output of
the receiver maintains a known state (usually a logic 1)
when the data is finished transmitting and all drivers on
the line are forced into three-state. All LTC RS485 receivers
have a fail-safe feature which guarantees the output to be
in a logic 1 state when the receiver inputs are left floating
(open-circuit). However, when the cable is terminated with
120Ω, the differential inputs to the receiver are shorted
together, not left floating.
If the receiver output must be forced to a known state, the
circuits of Figure 11 can be used.
The termination resistors are used to generate a DC bias
which forces the receiver output to a known state, in this
case a logic 0. The first method consumes about 208mW
and the second about 8mW. The lowest power solution is to
use an AC termination with a pull-up resistor. Simply swap
the receiver inputs for data protocols ending in logic 1.
Fault Protection
1.5k
5V
Receiver Open-Circuit Fail-Safe
120Ω
Z
All of LTC’s RS485 products are protected against ESD
transients up to ±2kV using the human body model
(100pF, 1.5kΩ). However, some applications need greater
protection. The best protection method is to connect a
bidirectional TransZorb from each line side pin to ground
(Figure 12).
A TransZorb is a silicon transient voltage suppressor that
has exceptional surge handling capabilities, fast response
time, and low series resistance. They are available from
General Semiconductor Industries and come in a variety
of breakdown voltages and prices. Be sure to pick a breakdown voltage higher than the common-mode voltage
required for your application (typically 12V). Also, don’t
forget to check how much the added parasitic capacitance
will load down the bus.
486 F12
Figure 12. ESD Protection
486fc
10
LTC486
PACKAGE DESCRIPTION
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
N Package
16-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510 Rev I)
.770*
(19.558)
MAX
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
.255 ±.015*
(6.477 ±0.381)
.300 – .325
(7.620 – 8.255)
.008 – .015
(0.203 – 0.381)
(
+.035
.325 –.015
+0.889
8.255
–0.381
NOTE:
1. DIMENSIONS ARE
)
.130 ±.005
(3.302 ±0.127)
.045 – .065
(1.143 – 1.651)
.020
(0.508)
MIN
.065
(1.651)
TYP
.120
(3.048)
MIN
.100
(2.54)
BSC
.018 ±.003
(0.457 ±0.076)
N16 REV I 0711
INCHES
MILLIMETERS
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)
486fc
11
LTC486
PACKAGE DESCRIPTION
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
SW Package
16-Lead Plastic Small Outline (Wide .300 Inch)
(Reference LTC DWG # 05-08-1620)
.050 BSC .045 ±.005
.030 ±.005
TYP
.398 – .413
(10.109 – 10.490)
NOTE 4
16
N
15
14
13
12
11
10
9
N
.325 ±.005
.420
MIN
.394 – .419
(10.007 – 10.643)
NOTE 3
1
2
3
N/2
N/2
RECOMMENDED SOLDER PAD LAYOUT
1
.005
(0.127)
RAD MIN
.009 – .013
(0.229 – 0.330)
NOTE:
1. DIMENSIONS IN
.291 – .299
(7.391 – 7.595)
NOTE 4
.010 – .029 × 45°
(0.254 – 0.737)
2
3
4
5
6
.093 – .104
(2.362 – 2.642)
7
8
.037 – .045
(0.940 – 1.143)
0° – 8° TYP
NOTE 3
.016 – .050
(0.406 – 1.270)
.050
(1.270)
BSC
.014 – .019
(0.356 – 0.482)
TYP
INCHES
(MILLIMETERS)
2. DRAWING NOT TO SCALE
3. PIN 1 IDENT, NOTCH ON TOP AND CAVITIES ON THE BOTTOM OF PACKAGES ARE THE MANUFACTURING OPTIONS.
THE PART MAY BE SUPPLIED WITH OR WITHOUT ANY OF THE OPTIONS
4. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
.004 – .012
(0.102 – 0.305)
S16 (WIDE) 0502
486fc
12
LTC486
REVISION HISTORY
(Revision history begins at Rev C)
REV
DATE
DESCRIPTION
C
11/12
Order Information: corrected Package Descriptions
PAGE NUMBER
2
Added Related Parts section
14
486fc
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
13
LTC486
TYPICAL APPLICATION
RS232 to RS485 Level Translator with Hysteresis
R = 220k
Y
10k
RS232 IN
120Ω
DRIVER
5.6k
1/4 LTC486
Z
19k
|VY - VZ|
HYSTERESIS = 10k × ———— ≈ ——
R
R
486 TA14
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC487
Low Power RS485 Quad Drivers
10Mbps, ±4kV ESD, Two DE Pins, SO(W)-16 or DIP-16 Package
LTC1688/LTC1689
High Speed RS485 Quad Drivers
100Mbps, ±4kV ESD, One-Half DE Pins, SO-16 Package
RS485 Quad Drivers
RS485 Quad Receivers
LTC1518/LTC1519
High Speed RS485 Quad Receivers
52Mbps, ±4kV ESD, SO-16 Package
LTC1520
Precision RS485 Quad Receivers
50Mbps, 18ns Propagation Delay, SO-16 Package
LTC488/LTC489
Low Power RS485 Quad Receivers
10Mbps, ±10kV ESD, One-Half DE Pins, SO(W)-16 or DIP-16 Package
Fault Protected 3V to 5.5V RS485 Transceivers
LTC2862
±60V Fault Protected RS485 Transceiver Half Duplex, 20Mbps or 250kbps, ±25kV Common Mode Range, ±15kV, Enable Pins,
SO-8 or 3mm × 3mm DFN-8 Package
LTC2863
±60V Fault Protected RS485 Transceiver Full Duplex, 20Mbps or 250kbps, ±25kV Common Mode Range, ±15kV,
SO-8 or 3mm × 3mm DFN-8 Package
LTC2864
±60V Fault Protected RS485 Transceiver Full Duplex, 20Mbps or 250kbps, ±25kV Common Mode Range, ±15kV, Enable Pins,
SO-14 or 3mm × 3mm DFN-10 Package
LTC2865
±60V Fault Protected RS485 Transceiver Full Duplex, Selectable 20Mbps or 250kbps, ±25kV Common Mode Range, ±15kV,
Enable Pins, Logic Supply, MSOP-12 or 4mm × 3mm DFN-12
Isolated RS485 Transceivers
LTM2881
Complete Isolated RS485 µModule®
Transceiver + Power
±2500VRMS Isolation, 3.3V or 5V Supply, No External Components, 1W DC/DC Converter,
Switchable Termination, 20Mbps, 30kV/µs Common Mode, ±15kV ESD, 15mm × 11.25mm
LGA or BGA Package
LTC1535
Isolated RS485 Transceiver
5V Supply, 250kbps, ±8kV ESD, SO(W)-28
486fc
14 Linear Technology Corporation
LT 1112 REV C • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
LINEAR TECHNOLOGY CORPORATION 1994
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湘ICP备2023018690号
