The output voltage of the switching power supply is unstable

Generally speaking, the reasons for the unstable output voltage of a switching power supply are complex, but they can be identified from the following starting points:

1. The VDD ripple of the control circuit is too large or unstable, exceeding the operating conditions of the control IC. You can adjust the power supply voltage or add filtering capacitors accordingly to select the appropriate decoupling capacitor.

2. Given that the bias current given to the reference circuit is less than the requirement for normal operation, the reference is unstable. You can investigate the waveform of the benchmark and compare existing parameter adjustment loops to meet the working conditions of the benchmark.

3. When the parameters of the reaction circuit are unreasonable, the negative reaction circuit reacts with positive values at a specific frequency, leading to circuit shock. You can reduce the loop speed and gain first, and then investigate whether the bird diagram adjustment loop is satisfied with the dynamic response requirements until the loop stops stably.

4. Partial maintenance circuit errors triggered, such as overvoltage, overcurrent, overcurrent, etc. Investigate the control nodes of each maintenance circuit to determine which parts are not working properly. The number of parameters required for parameter adjustment. Attention: Circuit maintenance can also refer to 1, 2 above and below.

5. Due to power disturbance, the control circuit is unstable. For example, current sampling, voltage sampling circuit (comparator output), etc. Check the circuit wiring. Sensitive circuits use maintenance lines that avoid interference factors and form signal pairs (i.e. parallel wiring as close as possible to the ground wire).

6. The input voltage range exceeds the conditions for the switching power converter to maintain output (such as too low or too high). Ensure that the preceding circuit has output stability. If the input is within the range, it may be necessary to adjust the transformer design.

Article source: Jiangmen LED Switching Power Supply http://www.gddpdz.com/