How to Use TPS22918 Load Switch: Examples, Pinouts, and Specs

The TPS22918 is a high-performance load switch manufactured by Texas Instruments. It is designed to manage power distribution by controlling the flow of power to a load. With its low on-resistance, fast switching times, and integrated protection features, the TPS22918 is ideal for applications requiring efficient power management.

• Battery-powered devices (e.g., smartphones, tablets, wearables)
• Power distribution in embedded systems
• Portable medical devices
• Consumer electronics
• Industrial and IoT applications

The TPS22918 is a compact and efficient load switch with the following key specifications:

The TPS22918 is available in a 6-pin package. Below is the pinout and description:

1. Power Supply: Connect the input voltage (VIN) to the power source. Ensure the voltage is within the range of 1 V to 5.5 V.
2. Enable Pin: Use the ON pin to control the switch. Drive the ON pin high (above 1 V) to enable the switch and allow power to flow to the load. Drive it low (below 0.4 V) to disable the switch.
3. Output Connection: Connect the load to the VOUT pin. Ensure the load does not exceed the maximum continuous current of 2 A.
4. Ground: Connect the GND pin to the system ground.

• Input Capacitor: Place a 1 µF ceramic capacitor close to the VIN pin to stabilize the input voltage.
• Output Capacitor: Use a 0.1 µF to 10 µF capacitor at the VOUT pin to improve transient response and stability.
• Thermal Management: Ensure adequate thermal dissipation, especially in high-current applications.
• Enable Pin Control: Avoid floating the ON pin. Use a pull-down resistor if the pin is not actively driven.
• Protection Features: The TPS22918 includes over-current and thermal shutdown protection. Ensure the load does not exceed the rated current to avoid triggering these protections unnecessarily.

The TPS22918 can be controlled using a GPIO pin from an Arduino UNO. Below is an example circuit and code:

• Connect VIN to a 5 V power source.
• Connect VOUT to the load (e.g., an LED with a current-limiting resistor).
• Connect the ON pin to a digital GPIO pin on the Arduino (e.g., pin 7).
• Connect GND to the Arduino's ground.

// Define the GPIO pin connected to the ON pin of TPS22918
const int loadSwitchPin = 7;

void setup() {
  // Set the load switch pin as an output
  pinMode(loadSwitchPin, OUTPUT);

  // Turn off the load switch initially
  digitalWrite(loadSwitchPin, LOW);
}

void loop() {
  // Turn on the load switch
  digitalWrite(loadSwitchPin, HIGH);
  delay(5000); // Keep the load on for 5 seconds

  // Turn off the load switch
  digitalWrite(loadSwitchPin, LOW);
  delay(5000); // Keep the load off for 5 seconds
}

1. The load does not power on:

   • Verify that the ON pin is driven high (above 1 V).
   • Check the input voltage (VIN) to ensure it is within the specified range.
   • Ensure the load does not exceed the maximum current rating of 2 A.

2. The device shuts down unexpectedly:

   • Check if the thermal shutdown or over-current protection is triggered. Reduce the load current or improve thermal dissipation.
   • Verify that the input and output capacitors are properly connected.

3. High quiescent current:

   • Ensure the ON pin is not left floating. Use a pull-down resistor if necessary.

4. Slow switching times:

   • Verify the input capacitor value. A 1 µF capacitor is recommended for optimal performance.

Q: Can the TPS22918 handle reverse current?
A: No, the TPS22918 does not support reverse current blocking. Ensure the output voltage does not exceed the input voltage.

Q: What happens if the load exceeds 2 A?
A: The over-current protection feature will activate, shutting down the device to protect it from damage.

Q: Can I use the TPS22918 with a 3.3 V microcontroller?
A: Yes, the ON pin is compatible with logic levels as low as 1 V, making it suitable for 3.3 V systems.

Q: Is the TPS22918 suitable for high-frequency switching?
A: The TPS22918 is optimized for power management and not designed for high-frequency switching applications.