How to Use Dual-Channel Digital Isolator: Examples, Pinouts, and Specs

The ADuM1201 is a dual-channel digital isolator manufactured by Analog Devices Inc. It provides electrical isolation between two circuits while enabling the transmission of digital signals. This isolation is achieved using iCoupler® technology, which employs magnetic coupling to ensure robust performance and high-speed operation. The ADuM1201 is ideal for applications requiring protection from high voltages, noise immunity, and signal integrity across isolated domains.

• Microcontroller and sensor interface isolation
• Industrial automation and motor control
• Power supply and battery management systems
• Data communication in noisy environments
• Medical equipment requiring patient safety isolation

The ADuM1201 is available in an 8-lead SOIC package. The pinout and descriptions are as follows:

1. Power Supply: Connect VDD1 and VDD2 to separate power supplies (2.7 V to 5.5 V). Ensure that GND1 and GND2 are isolated from each other to maintain proper isolation.
2. Signal Connections:
   • Connect the digital input signals to IN1 and IN2.
   • The corresponding isolated outputs will appear on OUT1 and OUT2.
3. Bypass Capacitors: Place decoupling capacitors (e.g., 0.1 µF) close to VDD1 and VDD2 pins to reduce noise and ensure stable operation.
4. PCB Layout: Maintain sufficient spacing between the isolated sides to prevent breakdown and ensure compliance with isolation standards.

• Isolation Voltage: Do not exceed the rated isolation voltage of 2.5 kV RMS.
• Data Rate: Ensure the input signal frequency does not exceed the maximum data rate of 25 Mbps.
• Thermal Management: Operate within the specified temperature range (-40°C to +125°C) to avoid thermal stress.
• Signal Integrity: Use short and direct traces for input and output signals to minimize noise and signal degradation.

The ADuM1201 can be used to isolate an Arduino UNO from a high-voltage circuit. Below is an example of how to connect and program the ADuM1201 for isolating a digital signal.

• Connect VDD1 and GND1 to the Arduino's 5V and GND pins, respectively.
• Connect VDD2 and GND2 to the isolated circuit's power supply.
• Connect a digital output pin (e.g., D2) of the Arduino to IN1.
• OUT1 will provide the isolated signal to the high-voltage circuit.

// Example code to toggle a digital signal through the ADuM1201
const int signalPin = 2; // Arduino pin connected to IN1 of ADuM1201

void setup() {
  pinMode(signalPin, OUTPUT); // Set signalPin as an output
}

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

1. No Signal on Output Pins

   • Cause: Missing or incorrect power supply connections.
   • Solution: Verify that VDD1 and VDD2 are powered correctly and that GND1 and GND2 are isolated.

2. Signal Distortion or Noise

   • Cause: Insufficient decoupling or long signal traces.
   • Solution: Add bypass capacitors near the VDD pins and minimize trace lengths.

3. Exceeding Isolation Voltage

   • Cause: High voltage spikes or improper grounding.
   • Solution: Ensure the voltage across the isolation barrier does not exceed 2.5 kV RMS.

4. Overheating

   • Cause: Operating outside the specified temperature range or excessive current draw.
   • Solution: Check the operating conditions and ensure proper thermal management.

Q1: Can the ADuM1201 handle bidirectional communication?
A1: No, the ADuM1201 is designed for unidirectional communication. For bidirectional communication, consider using other isolators with dedicated bidirectional channels.

Q2: What is the maximum distance between the isolated sides?
A2: The maximum distance is determined by the PCB layout and isolation standards. Ensure sufficient spacing to maintain the rated isolation voltage.

Q3: Can I use the ADuM1201 for analog signals?
A3: No, the ADuM1201 is designed for digital signals only. For isolating analog signals, consider using analog isolators.

Q4: Is the ADuM1201 suitable for medical applications?
A4: Yes, the ADuM1201 can be used in medical applications, provided it meets the required isolation and safety standards for the specific use case.