How to Use sn75173N: Examples, Pinouts, and Specs

The SN75173N, manufactured by Texas Instruments (TI), is a quad differential line driver designed for high-speed data transmission. It is widely used in RS-485 and RS-422 communication systems, offering robust and reliable data transfer over long distances. The component is engineered to provide excellent noise immunity, making it ideal for industrial, automotive, and telecommunications applications.

• RS-485 and RS-422 communication networks
• Industrial automation and control systems
• Long-distance data transmission
• Motor control and robotics
• Telecommunications equipment

• Supply Voltage (Vcc): 4.75V to 5.25V
• Input Voltage Range: -0.5V to Vcc + 0.5V
• Output Voltage Range: -0.5V to 6V
• Differential Output Voltage: ±6V (maximum)
• Data Rate: Up to 10 Mbps
• Operating Temperature Range: 0°C to 70°C
• Power Dissipation: 1W (maximum)
• Package Type: 16-pin DIP (Dual Inline Package)

The SN75173N is a 16-pin IC. Below is the pinout and description:

1. Power Supply:

   • Connect the Vcc pin (Pin 12) to a regulated 5V power supply.
   • Connect the GND pin (Pin 4) to the ground of the circuit.

2. Input Signals:

   • Provide the input signals to the A pins (1A, 2A, 3A, 4A).
   • Ensure the input voltage levels are within the specified range (-0.5V to Vcc + 0.5V).

3. Enable Pin:

   • The ENABLE pin (Pins 8 and 16) must be set HIGH to activate the drivers.
   • If the ENABLE pin is LOW, all outputs will be in a high-impedance state.

4. Output Connections:

   • Connect the differential outputs (Y and Z pins) to the corresponding RS-485 or RS-422 bus lines.
   • Use proper termination resistors at the ends of the bus to minimize signal reflections.

5. Termination Resistors:

   • For RS-485 applications, use a 120-ohm resistor between the Y and Z lines at each end of the bus.

• Avoid exceeding the maximum voltage ratings to prevent damage to the IC.
• Use decoupling capacitors (e.g., 0.1 µF) near the Vcc pin to filter noise from the power supply.
• Ensure proper grounding to minimize noise and improve signal integrity.
• For long-distance communication, use twisted-pair cables to reduce electromagnetic interference (EMI).

The SN75173N can be used with an Arduino UNO to drive an RS-485 communication bus. Below is an example circuit and code:

• Connect the Arduino's digital pins to the A inputs of the SN75173N (e.g., Pin 2 to 1A, Pin 3 to 2A).
• Connect the ENABLE pin to a digital pin on the Arduino (e.g., Pin 4).
• Connect the Y and Z outputs to the RS-485 bus lines.
• Power the SN75173N with a 5V supply and connect the GND pin to the Arduino's ground.

// Example code to control the SN75173N with an Arduino UNO
const int enablePin = 4;  // Pin to control the ENABLE pin
const int driver1A = 2;   // Pin connected to 1A input
const int driver2A = 3;   // Pin connected to 2A input

void setup() {
  pinMode(enablePin, OUTPUT);  // Set ENABLE pin as output
  pinMode(driver1A, OUTPUT);   // Set Driver 1A as output
  pinMode(driver2A, OUTPUT);   // Set Driver 2A as output

  digitalWrite(enablePin, HIGH);  // Enable the SN75173N
}

void loop() {
  // Send a HIGH signal on Driver 1A
  digitalWrite(driver1A, HIGH);
  delay(1000);  // Wait for 1 second

  // Send a LOW signal on Driver 1A
  digitalWrite(driver1A, LOW);
  delay(1000);  // Wait for 1 second

  // Toggle Driver 2A
  digitalWrite(driver2A, HIGH);
  delay(500);  // Wait for 0.5 seconds
  digitalWrite(driver2A, LOW);
  delay(500);  // Wait for 0.5 seconds
}

1. No Output Signal:

   • Ensure the ENABLE pin is set HIGH.
   • Verify that the input signals are within the specified voltage range.
   • Check the power supply connections and ensure Vcc is 5V.

2. Distorted Output Signal:

   • Verify the termination resistors on the RS-485 bus.
   • Use twisted-pair cables for the differential lines to reduce noise.
   • Check for proper grounding in the circuit.

3. Overheating of the IC:

   • Ensure the output load does not exceed the maximum current rating.
   • Verify that the supply voltage is within the specified range.

4. High-Impedance Outputs:

   • Check if the ENABLE pin is LOW. Set it HIGH to activate the drivers.

Q: Can the SN75173N be used for single-ended communication?
A: No, the SN75173N is designed for differential communication (e.g., RS-485, RS-422). For single-ended communication, consider using a standard line driver.

Q: What is the maximum cable length supported by the SN75173N?
A: The maximum cable length depends on the data rate and cable type. For RS-485, it typically supports up to 1200 meters at lower data rates.

Q: Can I use the SN75173N with a 3.3V microcontroller?
A: The SN75173N requires a 5V supply for proper operation. Use level shifters to interface with 3.3V logic.

Q: Is the SN75173N suitable for multi-drop communication?
A: Yes, the SN75173N supports multi-drop communication in RS-485 networks. Ensure proper termination and biasing resistors are used.