Document
LTC487 Quad Low Power
RS485 Driver
Features
n Very Low Power: ICC = 110µA Typ n Designed for RS485 or RS422 Applications n Single 5V Supply n – 7V to 12V Bus Common Mode Range Permits ±7V
GND Difference Between Devices on the Bus n Thermal Shutdown Protection n Power-Up/Down Glitch-Free Driver Outputs Permit
Live Insertion/Removal of Package n Driver Maintains High Impedance in Three-State or
with the Power Off n 28ns Typical Driver Propagation Delays with
5ns Skew n Pin Compatible with the SN75174, DS96174,
µA96174, and DS96F174
Applications
n Low Power RS485/RS422 Drivers n Level Translator
Description
The LTC®487 is a low power differential bus/line driver designed for multipoint data transmission standard RS485 applications with extended common mode range (– 7V to 12V). It also meets RS422 requirements. 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) and over the 4.75V to 5.25V supply voltage range.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.
Typical Application
EN 12
4 2
DI 1 DRIVER
3
1/4 LTC487
120Ω
120Ω
4000 FT BELDEN 9841
EN 12
4 2
RECEIVER
3 RO
1 1/4 LTC489
LTC487 TA01
CABLE LENGTH (FT)
RS485 Cable Length Specification*
10k
1k
100
10 10k
100k
1M 2.5M 10M
DATA RATE (bps)
LTC487 TA09
* APPLIES FOR 24 GAUGE, POLYETHYLENE DIELECTRIC TWISTED PAIR
487fc
LTC487
Absolute Maximum Ratings
(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
Commercial.............................................. 0°C to 70°C Industrial..............................................–40°C to 85°C Storage Temperature Range................... –65°C to 150°C Lead Temperature (Soldering, 10 sec.).................. 300°C
Pin Configuration
DI1 1 DO1A 2 DO1B 3 EN12 4 DO2B 5 DO2A 6
DI2 7 GND 8
TOP VIEW
16 VCC 15 DI4 14 DO4A 13 DO4B 12 EN34 11 DO3B 10 DO3A 9 DI3
N PACKAGE
SW PACKAGE
16-LEAD PLASTIC DIP 16-LEAD PLASTIC SO
TJMAX = 125°C, θJA = 70°C/W (N) TJMAX = 150°C, θJA = 95°C/W (S)
Consult factory for Military grade parts.
Order Information
LEAD FREE FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
LTC487CN#PBF
LTC487CN#TRPBF
LTC487CN
16-Lead Plastic DIP
LTC487CSW#PBF
LTC487CSW#TRPBF
LTC487CSW
16-Lead Plastic SO
LTC487IN#PBF
LTC487IN#TRPBF
LTC487IN
16-Lead Plastic DIP
LTC487ISW#PBF
LTC487IS#TRPBF
LTC487ISW
16-Lead Plastic SO
Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based finish parts.
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/
TEMPERATURE RANGE 0°C to 70°C 0°C to 70°C –40°C to 85°C –40°C to 85°C
487fc
LTC487
D C Electrical Characteristics VCC = 5V ±5%, 0°C ≤ TA ≤ 70°C (Commercial), –40°C ≤ TA ≤ 85°C
(Industrial) (Notes 2, 3)
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX UNITS
VOD1 Differential Driver Output Voltage (Unloaded) IO = 0
VOD2
Differential Driver Output Voltage (With Load)
R = 50Ω; (RS422)
2
5V V
R = 27Ω; (RS485) (Figure 3)
1.5
5V
VOD Change in Magnitude of Driver Differential
R = 27Ω or R = 50Ω
Output Voltage for Complementary Output States (Figure 3)
0.2 V
VOC VOC
Driver Common Mode Output Voltage Change in Magnitude of Driver Common Mode Output Voltage for Complementary Output States
3V 0.2 V
VIH Input High Voltage VIL Input Low Voltage IIN1 Input Current ICC Supply Current
DI, EN12, EN34
No Load Output Enabled Output Enabled
2.0 V 0.8 ±2
110 200 110 200
V µA µA µA
IOSD1 IOSD2 IOZ
Driver Short-Circuit Current, VOUT = High Driver Short-Circuit Current, VOUT = Low High Impedance State Output Current
VO = – 7V VO = 12V VO = –7V to 12V
100 250 100 250 ±10 ±200
mA mA µA
S witching Characteristics VCC = 5V ± 5%, 0°C ≤ TA ≤ 70°C (Notes 2, 3)
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX UNITS
tPLH tPHL tSKEW tr, tf tZH tZL tLZ tHZ
Driver Input to Output Driver Input to Output Driv.