Power supply noise problem customized by power supply module

Power module customizationProduction has been developing for many years, but power supply noise is a serious problem that plagues most power supply module manufacturers.

The noise-free power supply is not designed by accident. A good power supply layout is to shorten the experiment time to a greater extent during design. It takes a few minutes or even hours to carefully check the power supply layout, and you can save days of troubleshooting time.

Power supply noise mainly comes from three places: error amplifier input and output, reference voltage, and slope. Careful electrical design and physical design of these nodes can help shorten the fault diagnosis time to a large extent. Generally speaking, noise will capacitively couple with these low-level circuits. An excellent design can ensure the tight layout of these low-level circuits and stay away from all switching waveforms. The ground layer also has a shielding effect.

The error amplifier input may be a more sensitive node in the power supply, because it usually has more connection components. If it is combined with the extremely high gain and high impedance of this stage, the troubles are endless. During the layout process, you must minimize the node length and place the feedback and input components as close as possible to the error amplifier. If there is a high-frequency integrating capacitor in the feedback network, you must place it close to the amplifier, and other feedback components will follow. In addition, the series resistor-capacitor may also form a compensation network. The ideal result is to place the resistor close to the input of the error amplifier, so that if a high-frequency signal is injected into the resistor-capacitor node, then the high-frequency signal has to withstand a higher resistance and impedance—and the capacitor has a higher resistance to the high-frequency signal. The impedance is very small.

Slope is another place that can potentially cause noise problems. The ramp is usually generated by charging the capacitor (voltage mode) or by sampling the current from the power switch (current mode). Generally, voltage mode ramping is not a problem because the capacitor has very little impedance to high-frequency injection signals. The current ramp is trickier because of the rising edge peak, relatively small ramp amplitude, and power level parasitics.

Nanjing Fulaixiang Electronics Co., Ltd. is mainly engaged in special power supply, military power supply module, military power supply module, ACDC power supply module, DCDC power supply module, customized power supply module and other products. There are thousands of models for each product.