Index of the output resistance of the regulated power supply
Quality indicators of regulated power supply
The output voltage Uo of the voltage stabilizing circuit will be affected by three factors: input voltage UI, load current Io and ambient temperature T, namely
Uo=f (UI, Io, T) Therefore, the general expression of the change in the output voltage of the regulated power supply can be recorded as Uo=f (UI, Io, T). It can be seen that the four main indicators reflecting the quality of the DC regulated power supply It is Su, Ro, ST, Ur. The following are respectively explained as follows:
(1)Input adjustment quotation and voltage stabilization coefficient
We call the ratio of the change in the input voltage after rectification and filtering to the change in the output voltage caused by the input voltage regulation factor. In fact, the ratio of the relative change of the output voltage and the input voltage is often used to characterize the voltage stabilization performance of the power supply, which is called the voltage stabilization coefficient. By definition it can be recorded as
(2)Output resistance
When the input voltage and temperature remain unchanged, the ratio of the change in output voltage to the change in load current is defined as the output resistance, denoted as
The negative sign in the formula indicates that ΔUo and ΔIo change in opposite directions.
(3)Temperature coefficient
When the input voltage and load circuit remain unchanged, the change in output voltage caused by a unit temperature change is the temperature coefficient of the regulated power supply, or temperature drift, denoted as
(4)Ripple voltage
Under the rated operating current, the AC component value in the output voltage becomes the ripple voltage. The symbol of the effective value of the ripple voltage is Ur, and UIr can be regarded as the variation of the input voltage. Obviously, the voltage stabilizing circuit itself will suppress this change. So Ur≈SuUIr
Sometimes the ripple suppression ratio is often used to describe the size of the ripple voltage, written as 20lg (UIr/Ur) (dB). Obviously, the larger the ripple suppression ratio, the better.
For a high-performance voltage stabilizing circuit, the four indicators mentioned above are all as small as possible.
