Accuracy-of dc-dc converter

Hi,

How would you define setpoint accuracy for DC-DC converter ?
.Is it the margin to adjust voltage ?

-D

It is the peak to peak ripple as it jumps about the DC voltage it is supposed to output (the voltage point it is set to, hence setpoint).

If a DC to DC converter has an error amplifier, a voltage reference and negative feedback then its output voltage can be very accurate. You can make its output voltage adjustable if you want.

Firstly start with the accuarcy of the reference. For example in a boost converter, you normally have 2 feedback resistors providing a potential divider back to a comparator, the other side of the comparator is connected to an internal reference. If this reference drifts by, say 10mV, your output will drift by a multiple of 10mV, according to your feedback resistors.

For an output of 10V and a reference of 1V, you have a 'gain' of 10. Your reference drifts by 10mV and your output will drift by 100mV.

You then need to think about the accuracy of your feedback resistors to add to the inaccuracies of the system.

Ripple (as mentioned in a previous post) is another issue, but not related to reference drift

Who mentioned drift? Why are you confusing “accuracy” with “initial accuracy”? Once the output of a DC-DC has been trimmed, it's "accuracy" will be very good. That all of course assumes all conditions remain the same. Start changing line, load, temperature...etc. and that's a different matter. The original post only asked about "accuracy". At best a DC-DC can only adjust itself on a cycle by cycle basis. In the case of a flyback, your a cycle behind.