2 19VDC laptop chargers in series

[Daniel_LaFleur]

Originally Posted by jason701802

While this is true for linear power supplies, it is not true for switching power supplies unless they are specifically designed for it. Because the output voltage of a switching power supply is actively controlled, any minute differences in output voltage will result in the supplies fighting each other. It will work for supplies that are well matched, but because they will use some current fighting each other, the available current will be less than combined rating and should only be done temporarily when there are no other options.

Jason,
While this is true, a simple fix for parallel switchers is 'OR'ing diodes. This will cause the 2 supplies to droop share.


Ether,
Traditional switching supplies are isolated so running them in series is usually fine. Adding a steering diode should give you protection from reverse biasing the supply. I'd also suggest powering the downstream supply first (for the same reverse bias reason ... although it should not matter).