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Regulated vs Unregulated, and voltage ripple

Ricardo Pedro
Prodigy 80 points
Other Parts Discussed in Thread: DCR022405

Hi,

I need a isolated DC/DC for convert 24V to 5V with a great accuracy (is for analog measurement). My first question is: I must choose a regulated or unregulated converter? I selected the DCR022405. Theorically, the better is a regulated, right?

My second question is: the better documents for reduce voltage ripple is http://www.ti.com/lit/an/sbva013a/sbva013a.pdf and http://www.ti.com/lit/an/sbva012/sbva012.pdf, right?

Thank you for attention! 

  • 0
    Prodigy 140 points

    You may be confusing "regulated" with "linear".  You certainly do need a regulated supply for a reference, but the module you mention is a switching converter.  A linear regulator will be extremely inefficient dropping 24V to 5V (and many can't handle such a big drop), but a switching converter will have ripple (noise).  One option may be to use a switching regulator to drop the voltage to something like 7-8V and then use a linear regulator to supply 5V.  What specifically are you using the 5V for, and how much current do you need available?  Is it just a voltage reference?

    I do not think that sbva013a applies to the converter you mention, and sbva012 is 20 years old and does not appear to take into account advances in multilayer ceramic capacitors (MLCCs), which provide many benefits in DC/DC converters over older capacitor designs.

  • 0 in reply to chrylis
    Prodigy 80 points

    Hi,

    First, thanks for your answer.

    I didn´t confuse the regulated with linear; I use the switching converter because the voltage difference of input and ouput is big; but, there are two types of isolated switching converter: regulated and unregulated output. Right? For example, the http://www.ti.com/lit/ds/symlink/dcr022405.pdf and http://www.ti.com/product/dcp022405d . So, my question is: the best is the regulated, right?

    Thank you for your attention.