LTC490
Differential Driver and
Receiver Pair
FEATURES
DESCRIPTIO
n
Low Power: I = 300m A Typical The LTC 490 is a low power differential bus/line trans-
CC
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Designed for RS485 or RS422 Applications ceiver designed for multipoint data transmission standard
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Single 5V Supply RS485 applications with extended common mode range
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7V to 12V Bus Common Mode Range (12V to 7V). It also meets the requirements of RS422.
Permits 7V Ground Difference Between Devices
The CMOS design offers significant power savings over its
on the Bus
bipolar counterpart without sacrificing ruggedness against
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Thermal Shutdown Protection
overload or ESD damage.
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Power-Up/-Down Glitch-Free Driver Outputs Permit
Excessive power dissipation caused by bus contention or
Live Insertion or Removal of Package
n faults is prevented by a thermal shutdown circuit which
Driver Maintains High Impedance with the
forces the driver outputs into a high impedance state. The
Power Off
n receiver has a fail safe feature which guarantees a high
Combined Impedance of a Driver Output and
output state when the inputs are left open.
Receiver Allows up to 32 Transceivers on the Bus
n
70mV Typical Input Hysteresis
Both AC and DC specifications are guaranteed from 0 C to
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28ns Typical Driver Propagation Delays with
70 C and 4.75V to 5.25V supply voltage range.
5ns Skew for 2.5MB Operation
, LTC and LT are registered trademarks of Linear Technology Corporation.
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Pin Compatible with the SN75179
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Available in 8-Lead PDIP and SO Packages
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APPLICATIO S
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Low Power RS485/RS422 Transceiver
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Level Translator
TYPICAL APPLICATIO
LTC490 LTC490
5
3
120W 120W
D DRIVER RECEIVER R
6
4000 FT BELDEN 9841
8
2
120W 120W
R RECEIVER DRIVER D
7
4000 FT BELDEN 9841
LTC490 TA01
490fb
1
U
ULTC490
UUW
ABSOLUTE AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
(Note 1)
ORDER PART
Supply Voltage (V ) ............................................... 12V
TOP VIEW
CC
NUMBER
Driver Input Currents ........................... 25mA to 25mA
V 1 8 A
CC
R
Driver Input Voltages ...................... 0.5V to V + 0.5V
CC R 2 7 B LTC490CN8
Driver Output Voltages .......................................... 14V
D 3 6 Z LTC490CS8
D
Receiver Input Voltages ......................................... 14V
GND 5 Y
4 LTC490IN8
Receiver Output Voltages ............... 0.5V to V + 0.5V
CC LTC490IS8
N8 PACKAGE
8-LEAD PDIP
Operating Temperature Range
S8 PACKAGE S8 PART MARKING
LTC490C ................................................ 0 C to 70 C
8-LEAD PLASTIC SO
LTC490I............................................. 40 C to 85 C 490
T = 125 C, q = 100 C/ W (N8)
JMAX JA
T = 150 C, q = 150 C/W (S8)
JMAX JA
Storage Temperature Range ................. 65 C to 150 C 490I
Lead Temperature (Soldering, 10 sec).................. 300 C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
DC ELECTRICAL CHARACTERISTICS
The l denotes the specificatiions which apply over the full
operating temperature range, otherwise specifications are at T = 25 C. V = 5V 5%
A CC
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V Differential Driver Output Voltage (Unloaded) I = 0 l 5V
OD1 O
l
V Differential Driver Output Voltage (with Load) R = 50W (RS422) 2V
OD2
l
R = 27W (RS485) (Figure 1) 1.5 5 V
l
D V Change in Magnitude of Driver Differential Output R = 27W or R = 50W (Figure 1) 0.2 V
OD
Voltage for Complementary Output States
l
V Driver Common Mode Output Voltage R = 27W or R = 50W (Figure 1) 3V
OC
D V Change in Magnitude of Driver Common Mode R = 27W or R = 50W (Figure 1) l 0.2 V
OC
Output Voltage for Complementary Output States
l
V Input High Voltage (D) 2.0 V
IH
l
V Input Low Voltage (D) 0.8 V
IL
l Input Current (D) l 2 m A
IN1
l
l Input Current (A, B) V = 0V or 5.25V V = 12V 1mA
IN2 CC IN
l
V = 7V 0.8 mA
IN
V Differential Input Threshold Voltage for Receiver 7V V 12V l 0.2 0.2 V
TH CM
l
D V Receiver Input Hysteresis V = 0V 70 mV
TH CM
l
V Receiver Output High Voltage I = 4mA, V = 0.2V 3.5 V
OH O ID
V Receiver Output Low Voltage I = 4mA, V = 0.2V l 0.4 V
OL O ID
l
I Three-State Output Current at Receiver V = Max 0.4V V 2.4V 1 m A
OZR CC O
l
I Supply Current No Load; D = GND or V 300 500 m A
CC CC
l
R Receiver Input Resistance 7V V 12V 12 kW
IN O
l
I Driver Short-Circuit Current, V = High V = 7V 100 250 mA
OSD1 OUT O
l
I Driver Short-Circuit Current, V = Low V = 12V 100 250 mA
OSD2 OUT O
I Receiver Short-Circuit Current 0V V V l 785 mA
OSR O CC
l
I Driver Three-State Output Current V = 7V to 12V 2 200 m A
OZ O
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