Sinrace Power Supply Technology (Shenzhen) Co., Ltd.

Our ultimate aim is to adjust output ripple to a tolerable level. Achieving this goal, the most fundamental solution is to minimize the generation of the ripple.

 First we must know the type of switching power supply ripple and causes.
With SWITCH switches, inductor current in L is in the output current RMS fluctuating along a figure. Therefore, the output will appear with the frequency of a ripple with SWITCH. In general, it is the ripple. It is with the output capacitor while ESR is related. The switching power supply ripples’ frequency and the same for the tens to hundreds of KHz.

In addition, SWITCH is generally used in bipolar transistor, or MOSFET, no matter how, in their on and off, that they will have a rise time and fall time. This time in the circuit will be a rise and fall with the SWITCH same time or odd harmonic frequency noise, typically tens of MHz. Reverse recovery diode D in the same instant, the equivalent circuit for the resistance and capacitance and inductance in series, will cause resonance frequency of noise generated by tens of MHz. The two noises generally called high-frequency noise; the amplitude is usually much larger than the ripple.

If it is AC / DC converter, in addition to the two ripples (noises), there are AC noise, which frequency is the frequency of the input AC power for about 50 ~ 60Hz. There is also a common mode noise, which is due to many switching power supply power devices use the shell as a heat sink, as a result, the equivalent capacitance due.

Measurement of switching power supply ripple

Basic requirements: AC coupled oscilloscope, 20MHz bandwidth limits, unplug the probe's ground

1, AC coupling is to remove the DC voltage superimposed to obtain an accurate waveform.

2, open 20MHz bandwidth limit is to prevent the interference of high frequency noise and to prevent erroneous results during measuring. For the reason of the larger the amplitude of high frequency components, the time of measuring should be removed.

3, Unplug the oscilloscope probe ground clip and the use of ground loop measurement is to reduce the interference.

Another point is to use the 50Ω termination. The information on Yokogawa oscilloscopes, said, 50Ω module is to remove DC components and to accurate measurement of AC components.

Our ultimate aim is to adjust output ripple to a tolerable level. Achieving this goal, the most fundamental solution is to minimize the generation of the ripple.

First we must know the type of switching power supply ripple and causes.
With SWITCH switches, inductor current in L is in the output current RMS fluctuating along a figure. Therefore, the output will appear with the frequency of a ripple with SWITCH. In general, it is the ripple. It is with the output capacitor while ESR is related. The switching power supply ripples’ frequency and the same for the tens to hundreds of KHz.

In addition, SWITCH is generally used in bipolar transistor, or MOSFET, no matter how, in their on and off, that they will have a rise time and fall time. This time in the circuit will be a rise and fall with the SWITCH same time or odd harmonic frequency noise, typically tens of MHz. Reverse recovery diode D in the same instant, the equivalent circuit for the resistance and capacitance and inductance in series, will cause resonance frequency of noise generated by tens of MHz. The two noises generally called high-frequency noise; the amplitude is usually much larger than the ripple.

If it is AC / DC converter, in addition to the two ripples (noises), there are AC noise, which frequency is the frequency of the input AC power for about 50 ~ 60Hz. There is also a common mode noise, which is due to many switching power supply power devices use the shell as a heat sink, as a result, the equivalent capacitance due.

Measurement of switching power supply ripple

Basic requirements: AC coupled oscilloscope, 20MHz bandwidth limits, unplug the probe's ground

1, AC coupling is to remove the DC voltage superimposed to obtain an accurate waveform.

2, open 20MHz bandwidth limit is to prevent the interference of high frequency noise and to prevent erroneous results during measuring. For the reason of the larger the amplitude of high frequency components, the time of measuring should be removed.

3, Unplug the oscilloscope probe ground clip and the use of ground loop measurement is to reduce the interference.

Another point is to use the 50Ω termination. The information on Yokogawa oscilloscopes, said, 50Ω module is to remove DC components and to accurate measurement of AC components.