Output resistance index of the power source with regulation
Quality indicators of regulated power supply
The output voltage Uo of the voltage stabilizing circuit is influenced by three factors: input voltage UI, load current Io, and ambient temperature T
Uo=f (UI, Io, T)
Therefore, the general expression for the variation of the output voltage of a regulated power supply can be written as Uo=f (UI, Io, T)
It can be seen that the four main indicators reflecting the quality of DC regulated power supply are Su, Ro, ST, Ur. The following are the explanations:
(1) Input adjustment citation and voltage stabilization coefficient
We refer to the ratio of the change in input voltage after rectification and filtering to the change in output voltage caused by it as the input voltage regulation factor. In fact, the ratio of the relative change in output voltage to input voltage is often used to characterize the voltage stabilization performance of a power supply, which is called the voltage stabilization coefficient. By definition, it can be recorded as
(2) Output resistance
The ratio of the change in output voltage to the change in load current, with constant input voltage and temperature, is defined as the output resistance, denoted as
The negative sign in the equation represents Δ Uo and Δ Io changes in the opposite direction.
(3) Temperature coefficient
The change in output voltage caused by a unit temperature change, while both the input voltage and the load circuit remain unchanged, is the temperature coefficient or temperature drift of the regulated power supply, denoted as
(4) Ripple voltage
Under the rated working 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 change in input voltage. Obviously, the voltage stabilizing circuit itself will suppress this variation. So Ur ≈ SuUIr
Sometimes the ripple suppression ratio is also commonly used to indicate the magnitude of the ripple voltage, written as 20lg (UIr/Ur) (dB). Obviously, the larger the ripple suppression ratio, the better.
For a high-performance voltage regulator circuit, the four indicators mentioned above are as small as possible
