Voltage Regulator Problem

[davyzhu]

lm317l lm317t noise psrr

Hello all,

I found these voltage regulators are quite frequently used in pcb design:
1) 7805
2) 29502
3) LM317
4) LT1753

I have read the spec. but I cannot make a intuitive conclusion on their usage region, and there difference, e.g. 12v->3.3v we can use either 29502 or LM317; 12v->1.5v we can use either 29502 or LT1753, but how about the difference?

BTW, how about the other good Voltage Regulators, for I am a newbie on this region.

Regards,

Davy Zhu

 

[staric]

voltage regulator problems

I think you can compare the range of input voltage, the variation of output voltage, the noise, the PSRR characteristic, line regulation, load regulation and so on. These spec. are very important for voltage regulator.

 

[exeiji]

Hi Davy:

Shown on google, LT1753 is a switching regulator so that's one big difference from LM317 and 7805. Both LM317 (aka LM117) and LM7805 are linear regulators that are less efficient compared to a switching regulators. However, switching regulators are more expensive than linear regulators.

Another key performance factor in linear regulator is the dropout voltage. From what I was told, regulators with less than 1.2V dropout are called LDO's and those with much less dropout are called Ultra-LDO or Super-LDO.

Other well-known regulator are 78L05 and 431. Both can be found on national's website.

 

[rajath]

Another problem with switching regulators is that they tend to be much more
noisy than their linear counterparts. So if noise is a consideration in your
design, better stick to the power hungry linear regulators.