How to Use USB Load Switch: Examples, Pinouts, and Specs

The TPS2024P is a USB load switch manufactured by Texas Instruments. It is designed to control power delivery to USB devices, offering features such as overcurrent protection, thermal shutdown, and controlled power switching. This component is ideal for applications requiring reliable power management and protection for USB ports.

• USB power distribution in consumer electronics
• Overcurrent protection for USB ports
• Power management in embedded systems
• Enabling/disabling USB power in portable devices
• Controlled power delivery in industrial systems

The TPS2024P is a robust and versatile USB load switch with the following key specifications:

• Input Voltage Range: 2.7V to 5.5V
• Continuous Output Current: 0.5A per channel (dual-channel device)
• Overcurrent Protection Threshold: 0.8A (typical)
• Quiescent Current: 0.5mA (typical)
• Enable Input Logic Levels:
  • High: 2V (min)
  • Low: 0.8V (max)
• Thermal Shutdown Protection: Yes
• Operating Temperature Range: -40°C to 85°C
• Package Type: 8-pin PDIP (Plastic Dual In-line Package)

The TPS2024P is an 8-pin device with the following pinout:

1. Power Supply: Connect a regulated power supply (2.7V to 5.5V) to the IN1 and IN2 pins. Ensure the supply voltage matches the requirements of the connected USB devices.
2. Load Connection: Connect the USB device or load to the OUT1 and OUT2 pins.
3. Enable Control: Use the EN1 and EN2 pins to control the power delivery to each channel. Drive these pins high (≥2V) to enable the corresponding channel or low (≤0.8V) to disable it.
4. Fault Monitoring: Connect the FAULT pin to a microcontroller or LED to monitor overcurrent or thermal shutdown events. The pin is active low and requires a pull-up resistor.
5. Bypass Capacitors: Place a 0.1µF ceramic capacitor close to each IN pin to stabilize the input voltage and reduce noise.

• Thermal Management: Ensure adequate heat dissipation, especially when operating near the maximum current rating.
• Overcurrent Protection: The device automatically limits current to protect the load. Avoid connecting loads that exceed the overcurrent threshold.
• Fault Handling: Use the FAULT pin to detect and respond to fault conditions in your system.
• Decoupling Capacitors: Use decoupling capacitors on the input and output pins to minimize voltage fluctuations and improve stability.

The following example demonstrates how to use the TPS2024P to control power delivery to a USB device using an Arduino UNO.

• Connect IN1 to the 5V pin of the Arduino.
• Connect OUT1 to the USB device.
• Connect EN1 to a digital output pin (e.g., D7) of the Arduino.
• Connect the FAULT pin to another digital input pin (e.g., D8) for fault monitoring.

// Define pin connections
const int enablePin = 7;  // Pin connected to EN1
const int faultPin = 8;   // Pin connected to FAULT

void setup() {
  pinMode(enablePin, OUTPUT);  // Set EN1 as an output
  pinMode(faultPin, INPUT);    // Set FAULT as an input
  digitalWrite(enablePin, LOW); // Start with the load switch disabled
  Serial.begin(9600);          // Initialize serial communication
}

void loop() {
  // Enable the load switch
  digitalWrite(enablePin, HIGH);
  delay(1000);  // Wait for 1 second

  // Check for faults
  if (digitalRead(faultPin) == LOW) {
    Serial.println("Fault detected! Overcurrent or thermal shutdown.");
    digitalWrite(enablePin, LOW); // Disable the load switch
  } else {
    Serial.println("Load switch is operating normally.");
  }

  delay(1000);  // Wait for 1 second
}

1. No Power Output on OUT Pins:

   • Ensure the EN pin is driven high (≥2V) to enable the channel.
   • Verify the input voltage is within the specified range (2.7V to 5.5V).
   • Check for a fault condition by monitoring the FAULT pin.

2. Frequent Fault Conditions:

   • Ensure the load current does not exceed the overcurrent protection threshold (0.8A).
   • Verify proper heat dissipation to prevent thermal shutdown.

3. Noise or Voltage Fluctuations:

   • Add decoupling capacitors (0.1µF) close to the IN and OUT pins.
   • Ensure the power supply is stable and free from excessive noise.

Q1: Can the TPS2024P handle USB 3.0 devices?
A1: The TPS2024P is designed for USB 2.0 power requirements. It may not support the higher current demands of USB 3.0 devices.

Q2: What happens during an overcurrent event?
A2: The TPS2024P limits the current to protect the load and triggers the FAULT pin. The device may also enter thermal shutdown if the condition persists.

Q3: Can I use only one channel of the TPS2024P?
A3: Yes, you can use a single channel by leaving the unused channel's IN, OUT, and EN pins unconnected.

This concludes the documentation for the TPS2024P USB load switch.