Is Your UCC28910DR Overvoltage Protection Triggering_ Here’s Why

Is Your UCC28910DR Overvoltage Protection Triggering? Here’s Why

Is Your UCC28910DR Overvoltage Protection Triggering? Here’s Why and How to Fix It

If your UCC28910DR, a popular integrated controller for Power supplies, is triggering overvoltage protection unexpectedly, it can cause unwanted shutdowns or interruptions in your system. Understanding the reasons behind this trigger and knowing how to resolve it is crucial for smooth operation. Let's break down the causes and step-by-step solutions to fix this issue.

1. Understanding the Overvoltage Protection Mechanism

Before diving into potential causes, it's important to understand how the UCC28910DR's overvoltage protection (OVP) works. The UCC28910DR monitors the output voltage through a feedback loop. If the output voltage exceeds a preset threshold (OVP threshold), it activates protection mechanisms to prevent damage to the power supply and connected components.

2. Common Causes of OVP Triggering

Several factors could trigger overvoltage protection on the UCC28910DR:

a. Incorrect Feedback Network Configuration

The feedback resistor network or optocoupler can be improperly set, causing incorrect voltage feedback to the controller. This misconfiguration may lead to the controller falsely detecting an overvoltage condition.

b. Faulty Voltage Divider Resistor

In many cases, a malfunctioning or out-of-tolerance resistor in the voltage divider used for the feedback loop can cause an erroneous overvoltage reading, triggering the protection.

c. capacitor Issues

An issue with the output filter Capacitors , such as increased ESR (Equivalent Series Resistance ) or degraded capacitors, can result in voltage overshoots that cause the overvoltage protection to activate.

d. Transient Voltage Spikes

If there are sudden transient voltage spikes or noise from the AC line or other parts of the circuit, the controller might detect these as overvoltage conditions and trigger protection.

e. Power Supply Design

Inadequate power supply design, such as improper component selection or poor layout, can lead to instability or noise, affecting the voltage feedback and causing false OVP triggers.

3. How to Solve the Overvoltage Protection Triggering

Let’s walk through the steps to resolve the overvoltage protection issue:

Step 1: Verify Feedback Network Configuration Action: Double-check the feedback resistor values and configuration against the UCC28910DR datasheet. Ensure the resistors and optocoupler are correctly chosen to set the desired voltage threshold. Why: Incorrect resistor values can cause erroneous voltage feedback, leading to OVP activation. Step 2: Inspect the Voltage Divider Resistor Action: Measure the resistance values of the voltage divider resistors. If the resistors are out of tolerance or damaged, replace them with the correct values. Why: A faulty resistor can cause incorrect voltage feedback, leading to false overvoltage detection. Step 3: Check the Output Capacitors Action: Measure the ESR of the output capacitors and check for any signs of wear or degradation. If the ESR is high or the capacitors are old, replace them with suitable new capacitors. Why: Degraded capacitors can cause voltage spikes, triggering the OVP. Step 4: Examine for Transient Spikes Action: Use an oscilloscope to check for any transient voltage spikes on the output or input lines. If spikes are detected, add appropriate filtering or snubbing components, such as capacitors or transient voltage suppression diodes. Why: Voltage transients can trigger the OVP function, so eliminating or reducing them can prevent unwanted triggering. Step 5: Review Power Supply Design and Layout Action: Examine your power supply design and PCB layout to ensure there are no issues like poor grounding, excessive noise, or incorrect component placements. Why: Poor design and layout can cause noise or instability in the feedback loop, triggering false OVP alarms. Step 6: Adjust OVP Threshold (if needed) Action: If the above steps don’t resolve the issue, consider adjusting the OVP threshold by modifying the feedback loop components. Why: Sometimes, fine-tuning the threshold can help the system better handle small fluctuations without triggering unnecessary protection.

4. Conclusion

The UCC28910DR’s overvoltage protection can be triggered by various factors, including incorrect feedback configuration, faulty resistors, degraded capacitors, transient voltage spikes, and poor power supply design. By following the steps above and systematically checking each potential cause, you can pinpoint the issue and restore normal operation.

Remember, the key to solving this problem is thorough troubleshooting and ensuring that your feedback network is correctly configured and your components are in good condition. With careful attention to these factors, your UCC28910DR should operate without unnecessary interruptions.