ADP5074 will not turn on

Hi DTipple,

1. Please increase EN voltage (R432, R420) to meet 2.8V rising threshold

2. COMP pin values of -15V circuit: have values close to recommended in Table 9 of datasheet

I increased the enable voltage to 5V and still  neither P/S will start

Can you try start-up while both outputs are at no load? The output load may be too much or there is too much capacitance at the load other than your schematic. Take note that the datasheet current you see is not the output current but inductor current. This is higher than the output current. If issue persists, can you give me scope shot of VIN, VOUT and VSW?

The parts on the #1 board are both BAD.  I powered up board #@ and both parts are working.  here are the waveforms

ch1 -yellow V_in 12V

CH2 Blue Vout

CH4 green Vsw

there is a little "noise" on the switch/output but nothing like what I expect from the switching waveform.

Thanks for your help

If the other boards are working, its a good sign that you don't have issue with design. It must be manufacturing issue. Make sure that everything is properly mounted specially the IC. You may want to troubleshoot using meter  several nodes impedance and compare with a good board.

The waveforms I asked was assuming you had issue with design. Everything is flat in the steady-state. It means IC is not even responding and not enabled. Waveforms during start-up may also help in the analysis. But I think what you have is board issue and should be addressed by basic troubleshooting methods.