LTC490 RS485/RS422 Differential Line Transceiver IC – 5V, Full-Duplex, DIP-8
The LTC490 is a low-power differential line transceiver integrated circuit designed for reliable serial data communication over long cable distances in industrial and embedded electronic systems.
Supporting RS485 and RS422 communication standards, the LTC490 combines one differential line driver and one differential line receiver in a single IC, allowing full-duplex communication over separate transmit and receive differential pairs.
Featuring a 5V power supply, low-power CMOS design, and built-in protection features, the LTC490 is suitable for industrial automation, PLC communication, instrumentation, and microcontroller-based serial communication projects.
Key Features
-
Model: LTC490
- RS485 and RS422 compatible differential transceiver
- Full-duplex communication
- One differential driver and one differential receiver
- Low-power CMOS design
- 5V DC operating supply
- Supports multipoint RS485 communication networks
- Extended receiver common-mode range
- Thermal shutdown protection for the driver
- Driver short-circuit protection
- Receiver fail-safe behavior for open inputs
- Suitable for industrial serial communication
- Standard 8-pin IC configuration
Technical Specifications
| Parameter |
Specification |
| Model |
LTC490 |
| Component Type |
Differential Line Transceiver |
| Communication Standards |
RS485 / RS422 |
| Communication Mode |
Full-Duplex |
| Driver Channels |
1 |
| Receiver Channels |
1 |
| Supply Voltage |
4.75V to 5.25V DC |
| Nominal Supply Voltage |
5V DC |
| Logic Interface |
TTL/CMOS-Compatible |
| Maximum Data Rate |
Up to 2.5Mbps, Typical LTC490 Specification |
| Receiver Common-Mode Range |
-7V to +12V |
| Driver Output |
Differential |
| Receiver Output |
Digital Logic |
| Driver Protection |
Short-Circuit and Thermal Shutdown |
| Receiver Fail-Safe |
Open-Input Fail-Safe |
| Operating Temperature |
0°C to +70°C for Standard Commercial Grade |
| Number of Pins |
8 |
| Package |
DIP-8 or SO-8, Depending on Version |
| Mounting Type |
Through-Hole or Surface-Mount, Depending on Package |
Note: Electrical specifications depend on the manufacturer and exact LTC490 ordering code. Confirm the package and temperature grade of the supplied IC.
Pin Configuration
The LTC490 uses the following standard 8-pin configuration.
| Pin |
Name |
Function |
| 1 |
VCC |
Positive 5V Power Supply |
| 2 |
R |
Receiver Logic Output |
| 3 |
D |
Driver Logic Input |
| 4 |
GND |
Ground |
| 5 |
Y |
Non-Inverting Driver Output |
| 6 |
Z |
Inverting Driver Output |
| 7 |
B |
Inverting Receiver Input |
| 8 |
A |
Non-Inverting Receiver Input |
How It Works
The LTC490 converts standard digital logic signals into differential signals suitable for transmission over twisted-pair cables.
Transmitter
The driver accepts a digital logic signal at the D input and produces a differential output across the Y and Z terminals.
Receiver
The receiver monitors the differential signal across the A and B terminals and converts it into a digital signal at the R output.
Full-Duplex Communication
Because the transmitter and receiver use separate differential pairs, the LTC490 can transmit and receive data simultaneously.
A typical full-duplex connection uses:
- One twisted pair for transmission
- One twisted pair for reception
- A suitable signal reference or grounding arrangement
Arduino Compatibility
The LTC490 can be used with Arduino development boards to create RS485 or RS422 serial communication interfaces.
Example Connection with Arduino Uno
| LTC490 Pin |
Arduino Uno |
| VCC (Pin 1) |
5V |
| R (Pin 2) |
RX or SoftwareSerial RX |
| D (Pin 3) |
TX or SoftwareSerial TX |
| GND (Pin 4) |
GND |
| Y / Z |
Differential Transmit Pair |
| A / B |
Differential Receive Pair |
Important: The LTC490 provides the physical communication interface. It does not independently implement Modbus or other communication protocols.
For a full-duplex link, the transmit pair of one device connects to the receive pair of the other device, with polarity matched correctly.
ESP32 Compatibility
The LTC490 operates from a 5V supply, while ESP32 GPIO pins use 3.3V logic.
The driver input may recognize a 3.3V HIGH signal, depending on the specified input thresholds. However, the receiver output can reach 5V and must not be connected directly to an ESP32 GPIO.
Use a suitable logic-level interface or select a 3.3V-compatible RS485 transceiver for direct integration.
Applications
- Industrial RS485 Communication
- RS422 Serial Communication
- PLC Communication Interfaces
- Industrial Automation
- Modbus RTU Physical Interfaces
- Data Acquisition Systems
- Remote Instrumentation
- Serial Communication Networks
- Arduino Communication Projects
- Embedded Control Systems
- Industrial Monitoring Equipment
- Electronic Prototyping
Important Notes
-
The LTC490 is a full-duplex transceiver, not a half-duplex RS485 transceiver.
- It requires separate differential pairs for transmitting and receiving.
- The device operates from a nominal 5V supply.
- It is not directly suitable for 3.3V-only GPIO interfaces without checking logic-level compatibility.
- The LTC490 is not an isolated transceiver; additional isolation may be required in industrial environments.
- Use appropriate termination resistors at the ends of the communication cable.
- Receiver biasing may be necessary depending on the network design and required idle-state behavior.
- The built-in fail-safe feature applies to open receiver inputs; it does not guarantee a defined output for every possible idle or terminated-bus condition.
- Do not connect RS485/RS422 differential lines directly to microcontroller UART pins.
- Observe the manufacturer's voltage, temperature, and current limits.
- Add appropriate surge and ESD protection for electrically demanding installations.
Package Includes
1 × LTC490 RS485/RS422 Differential Line Transceiver IC
