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ldo [2019/04/07 17:41] gongyu |
ldo [2019/04/07 17:53] (当前版本) gongyu [电源抑制比] |
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| * 由于负载电流的突变、输出电容以及等效的串行阻抗对输出电压的影响 | * 由于负载电流的突变、输出电容以及等效的串行阻抗对输出电压的影响 | ||
| - | ### 电源抑制比 | + | #### 电源抑制比PSRR |
| - | PSRR refers to the LDO's ability to reject ripple it sees at its input.[11] As part of its regulation, the error amplifier and bandgap attenuate any spikes in the input voltage that deviate from the internal reference to which it is compared.[12] In an ideal LDO, the output voltage would be solely composed of the DC frequency. However, the error amplifier is limited in its ability to gain small spikes at high frequencies. PSRR is expressed as follows:[11] | + | PSRR指的就是LDO抑制输入端纹波的能力，作为稳压的一部分，误差放大器和bandgap会衰减掉输入电压与用于比较的内部参考电压偏离的所有毛刺。对于一个理想的LDO，其输出电压仅仅包含直流频率，然而误差放大器在高频的时候其抑制小毛刺的能力就会下降，PSRR可以用下面的公式来表示： |
| PSRR = 20 \times log \frac{Ripple_{IN}}{Ripple_{OUT}} | PSRR = 20 \times log \frac{Ripple_{IN}}{Ripple_{OUT}} | ||