LM317A: LM317Aに供給する電源について

Hello,

It looks like your input supply is a 12W, 24V output capable of providing up to 0.5A.  This is feeding into the LM317A, where you wish to generate an output voltage of 5V at 1.5A load. 

If this is the situation then unfortunately it will not work as expected.  Linear regulators simply pass current from the input to the output, thus the 1.5A on the output will be drawn from the input as 1.5A.  The 24V input supply must be capable of supplying 1.5A to the LM317A if 1.5A is the load of the linear regulator.  I would also be concerned with thermal performance, as the LM317 will dissipate a significant amount of power (24V - 5V)*1.5A = 28.5W.  This will require active cooling to manage the heat.

You may wish to use the TPSM84205, a switching converter that can replace the LM317. 

https://www.ti.com/lit/ds/symlink/tpsm84203.pdf

Thanks,

Stephen