What does power ripple mean? How big is the DDR power ripple requirement?

What does power ripple mean?

    The power supply ripple index is a very important parameter of the switching power supply module or DC/DC.

    Power ripple can be understood as the fluctuation of the output voltage of the power module including VRM, which has nothing to do with the complex power supply network, or the fluctuation of the voltage at the source end of the power supply output. It is a periodic signal that fluctuates up and down around the output DC voltage, but the period and amplitude are not fixed, but change with time, and the ripple waveforms of different power supplies are also different.

What is the DDR power supply ripple requirement?

    Generally it does not exceed 1%. DDR3 is generally 1.5V, so the ripple cannot exceed 15mV and so on. If it is too high, it will not reach high frequency!

    What is Ripple?

The output of a switching power supply is not truly constant, and there is periodic jitter in the output, which looks like water ripples and is called ripple. The ripple can be voltage ripple or current ripple.

    Power ripple

    Low-frequency ripple: It comes from the cycle of AC input. The power supply’s rejection ratio to input is not perfect. When the input changes, the output will also change.

    High-frequency ripple: It comes from the switching cycle. The switching power supply does not output energy linearly and continuously, but transmits the energy in packets. Therefore, there will be ripples corresponding to the switching cycle.