Why Your TPS61230DRCR is Generating Excessive Ripple and How to Solve It
The TPS61230DRCR is a highly efficient buck-boost converter designed for power regulation, often used in applications requiring low voltage, such as portable electronics. However, excessive ripple can occur, leading to instability or reduced performance. Let’s walk through the reasons behind this issue and the steps to resolve it.
Common Causes of Excessive Ripple:
Improper capacitor Selection: The output ripple can be caused by using inappropriate Capacitors . The TPS61230DRCR’s performance is highly dependent on the type and quality of capacitors used in the design. Low-quality or incorrect value capacitors may not filter the ripple efficiently.
Inadequate Inductor Selection: If the inductor's value is not well-matched to the application or is too small, it may not store and release energy as smoothly, leading to high ripple at the output. The inductor's saturation current rating also needs to be sufficient for the power load.
High Output Load: When the power load is high or fluctuates rapidly, it can lead to excessive ripple. If the load exceeds the design specifications, the converter struggles to maintain stable voltage, generating ripple.
Inappropriate PCB Layout: Poor PCB layout can introduce noise and ripple. High current paths should be kept short and wide, while sensitive signal paths should be isolated from noisy switching components. Ground planes and proper decoupling are crucial.
Switching Frequency Issues: An incorrect or fluctuating switching frequency can cause instability and excessive ripple. Ensuring the switching frequency is set correctly and is stable is essential to avoid ripple problems.
Incorrect Feedback Network: The feedback network plays a critical role in maintaining a stable output voltage. A malfunction or misconfiguration in the feedback circuit, like improper resistor values, can lead to instability and ripple.
Steps to Solve Excessive Ripple:
Check and Upgrade Capacitors: Ensure the capacitors used meet the recommended values and specifications outlined in the datasheet (e.g., low ESR, high quality). Use ceramic capacitors for high-frequency filtering, especially for the output capacitor, to reduce ripple. Consider using higher-value capacitors to improve stability. Review Inductor Specifications: Verify the inductor’s value and saturation current rating against the recommended values. Use a larger inductor if necessary to smooth out energy fluctuations. Check for inductor quality, ensuring it has low core losses and minimal resistance. Reduce Load Variability: Ensure that the load is within the specifications of the power converter. Use load transient suppression techniques such as additional bulk capacitors if the load fluctuates significantly. Optimize PCB Layout: Use a solid ground plane to reduce noise and minimize ripple. Keep power traces as short and wide as possible to minimize inductance and resistance. Place input and output capacitors as close as possible to the IC to reduce parasitic inductances and resistances. Check and Adjust Switching Frequency: Verify that the switching frequency is within the recommended range. If the frequency is too low or too high, adjust it to the optimal level as specified in the datasheet. Adjust Feedback Network: Review the feedback network to ensure correct resistor values and stability. Make sure the feedback loop is properly compensated to avoid oscillations and excessive ripple. Check for External Noise: Ensure that no external sources of EMI (electromagnetic interference) are affecting the converter. Shielding or using ferrite beads can help reduce the impact of external noise.Final Thoughts:
Excessive ripple from the TPS61230DRCR can arise from several causes, such as poor component selection, layout issues, or incorrect feedback configurations. By carefully reviewing the design, choosing the right components, and following best practices for layout and noise management, you can significantly reduce ripple and improve the converter’s performance.
