Powering Zynq-7000 from 28VDC
Good practice in most of applications is to use switcher with combination with LDO. First you use adjustable step-down switcher that goes up to that voltage; 28V in your example and than switch it to lower voltage.  Switchers are known to make a lot of noise if they are not designed right. So because of that we add LDO in the output.
For your example you can use simple switcher as LT8609S, simulated it in LT spice. At output of your switcher you connect your LDO; LM1117 is very popular. LM117 comes in different already defined voltage level as 1V8, 3V3, 5V or you can choose adjustable one and define your preferred voltage level with simple resistor divider. But be careful the LDOs have some voltage drop, so you need to design your switcher in that way you will have at least voltage drop of the LDO bigger voltage on the output of your switcher. For example, if you need to have steady 5V power you need at least 6.2 Von the output of the switcher, if the voltage drop of LDO is 1.2V. After that you add some decoupling capacitors and you are done.
I am attaching picture of my 12V design that you can re-engineer it.