How to Use SN75175: Examples, Pinouts, and Specs

The SN75175 is a quad differential line driver designed for high-speed data transmission over twisted-pair cables. It is widely used in communication systems due to its ability to provide robust and reliable data transfer in noisy environments. The component is compliant with RS-485 and RS-422 standards, making it ideal for industrial automation, networking, and other applications requiring long-distance, high-speed communication.

• RS-485 and RS-422 communication systems
• Industrial automation and control systems
• Networking equipment
• Data acquisition systems
• Long-distance data transmission over twisted-pair cables

• Supply Voltage (Vcc): 4.75V to 5.25V
• Input Voltage Range: -7V to +12V
• Output Voltage Range: -7V to +12V
• Data Rate: Up to 10 Mbps
• Operating Temperature Range: 0°C to 70°C
• Power Consumption: Low power design
• Differential Output Voltage: ±2V minimum
• Short-Circuit Protection: Yes
• Compliance Standards: RS-485, RS-422

The SN75175 is available in a 16-pin DIP (Dual Inline Package). Below is the pinout and description:

1. Power Supply: Connect the Vcc pin (Pin 16) to a regulated 5V power supply and the GND pin (Pin 9) to ground.
2. Input Signals: Provide differential input signals to the A and B pins of each driver (e.g., A1 and B1 for Driver 1).
3. Output Signals: The corresponding differential outputs (Y and Z pins) will provide the amplified signals for transmission over twisted-pair cables.
4. Termination Resistors: For RS-485 applications, use termination resistors at the ends of the twisted-pair cable to minimize signal reflections.
5. Enable/Disable Drivers: Ensure proper control of the input signals to enable or disable the drivers as needed.

• Use decoupling capacitors (e.g., 0.1 µF) close to the Vcc pin to reduce noise and stabilize the power supply.
• Ensure the input voltage levels are within the specified range (-7V to +12V) to avoid damage to the device.
• For long-distance communication, use twisted-pair cables with proper shielding to minimize electromagnetic interference (EMI).
• Avoid exceeding the maximum data rate of 10 Mbps to ensure reliable operation.

The SN75175 can be used with an Arduino UNO for RS-485 communication. Below is an example of how to send data using the SN75175:

• Connect the Arduino's digital output pin (e.g., D2) to the A1 pin of the SN75175.
• Connect the corresponding B1 pin to ground.
• Connect the Y1 and Z1 pins to the twisted-pair cable for data transmission.
• Connect Vcc and GND of the SN75175 to a 5V power supply and ground, respectively.

// Example code to send data using SN75175 with Arduino UNO
const int dataPin = 2; // Pin connected to A1 of SN75175

void setup() {
  pinMode(dataPin, OUTPUT); // Set data pin as output
}

void loop() {
  digitalWrite(dataPin, HIGH); // Send a HIGH signal
  delay(1000); // Wait for 1 second
  digitalWrite(dataPin, LOW); // Send a LOW signal
  delay(1000); // Wait for 1 second
}

1. No Output Signal:

   • Cause: Incorrect power supply or loose connections.
   • Solution: Verify that Vcc is connected to a 5V regulated power supply and GND is properly grounded.

2. Signal Distortion:

   • Cause: Missing or incorrect termination resistors.
   • Solution: Add 120-ohm termination resistors at both ends of the twisted-pair cable.

3. Overheating:

   • Cause: Short circuit on the output pins.
   • Solution: Check for short circuits and ensure proper wiring.

4. Low Data Rate:

   • Cause: Excessive cable length or poor cable quality.
   • Solution: Use high-quality twisted-pair cables and ensure the cable length is within RS-485 specifications.

Q1: Can the SN75175 be used for single-ended signals?
A1: No, the SN75175 is designed for differential signaling and is not suitable for single-ended signals.

Q2: What is the maximum cable length supported by the SN75175?
A2: The maximum cable length depends on the data rate and cable quality. For RS-485, it typically supports up to 1200 meters at lower data rates.

Q3: Is the SN75175 compatible with 3.3V systems?
A3: No, the SN75175 requires a 5V power supply. Use a level shifter if interfacing with 3.3V systems.

Q4: Can I use the SN75175 for bidirectional communication?
A4: No, the SN75175 is a line driver and does not support bidirectional communication. Use an RS-485 transceiver for bidirectional communication.