What to Do When TPS61021ADSGR Has Unstable Outputs

What to Do When TPS61021ADSGR Has Unstable Outputs

The TPS61021ADSGR is a boost converter designed to step up the input voltage to a higher, regulated output voltage. If you are experiencing unstable outputs with the TPS61021ADSGR, it's important to address the issue step by step to identify and resolve the problem.

Common Causes of Unstable Outputs:

Insufficient Input Voltage: If the input voltage is too low, the boost converter may not be able to generate a stable output. The TPS61021ADSGR typically requires a minimum input voltage, depending on the output voltage setting.

Improper or Faulty Capacitors : Boost converters rely on external capacitor s to maintain stability. If the input or output capacitors are missing, damaged, or have incorrect values, they can cause instability in the output voltage.

Load Instability: If the load connected to the boost converter is highly dynamic or fluctuating, the TPS61021ADSGR might struggle to maintain a stable output voltage.

Overheating or Thermal Shutdown: Overheating can lead to thermal shutdown, causing the boost converter to stop functioning correctly. Excessive heat can be generated due to high current demands, poor PCB design, or insufficient cooling.

Faulty Inductor: The inductor used in the boost converter is a crucial component. If it is not correctly selected or damaged, it could cause irregular behavior in the output voltage.

Incorrect Feedback Network: The feedback loop, which controls the output voltage, could have incorrect components or wiring, leading to instability in the output voltage.

Improper Layout: A poor PCB layout can introduce noise, lead to high parasitic inductance, and cause the boost converter to operate erratically.

Step-by-Step Troubleshooting and Solution:

Step 1: Verify Input Voltage Check the input voltage to ensure it meets the minimum required for the desired output. The TPS61021ADSGR typically requires a minimum input voltage of 0.8V above the output voltage to function correctly. Use a multimeter to measure the input voltage at the converter’s VIN pin. If the voltage is too low, consider increasing the input voltage or using a higher capacity power supply. Step 2: Inspect Capacitors Check all capacitors (input and output) for correct values and condition. Ensure the input capacitor is within the recommended range (typically 10µF to 22µF, low ESR). Verify the output capacitor (typically 22µF to 47µF). Ensure they are not damaged or leaking. Replace any capacitors that appear faulty or do not meet the required specifications. Step 3: Check Load Conditions If the load is highly dynamic or fluctuating, try connecting a more stable load to see if the output becomes more stable. If the instability is load-dependent, consider using additional filtering or adjusting the load to reduce the current spikes. Step 4: Examine Thermal Conditions Check the temperature of the boost converter. Ensure it’s not overheating. If it is, check the PCB design and thermal management (e.g., adding heatsinks or improving ventilation). If the device is too hot, the TPS61021ADSGR may enter thermal shutdown, causing instability. Step 5: Inspect the Inductor Ensure that the inductor is of the correct value and type (usually, a 10µH to 22µH inductor is used). Check if the inductor is properly rated for the current required by your application. Replace the inductor if you suspect it is faulty. Step 6: Verify Feedback Network Check the feedback loop and resistors that set the output voltage. Ensure there are no broken connections and the resistors are properly placed according to the datasheet. Verify that the feedback pin (FB) is correctly connected to the output and input. Step 7: Optimize PCB Layout Ensure that the PCB layout follows the recommendations in the TPS61021ADSGR datasheet, particularly: Keep the input and output capacitor placement as close as possible to the pins. Ensure a solid ground plane to minimize noise and parasitic inductance. Place the inductor and feedback components away from high-frequency noise sources.

Conclusion:

By following these steps, you should be able to identify and resolve the issue of unstable outputs in the TPS61021ADSGR. Most often, the problem will be linked to input voltage, faulty capacitors, load instability, or poor PCB layout. Addressing these components should stabilize the output and restore proper operation of the boost converter.