problem with a switcher and LDO. lmr62014 + LT1761

[ahgu]

I have a circuit that require 15Vdc, I used LMR62014 (1.6MHz) initially. The circuit run okay, except the noise a little high.
so I put a LT1761 after LMR62014. Changed the LMR62014 Vout to 16vdc, and LT1761-byp to 15v.

I notice the LT1761 Voutput has ripple triangular voltage, several hundred hertz, magnitude about several hundred millivolts.

I thought it is the LDO issue, changed the bypass cap to tantalum, added 0.5ohm in series with the output, but nothing helped.

Anyway, I need 15vdc with 10mA of low noise voltage supply, I don't have to use the above switcher, anyone please recommend.

thank you
ahgu

 

[Roaburn]

What is your input voltage limited to? Why not use a LM7815. Its voltage regulation is at least better than the several hundred millivolts you said your getting now. Plus you can clean it up a bit after the fact... I guess I'd need a bit more information, such as your input source, output requirements (amps, etc.), and maybe an idea what application this is going to be used for.

 

[ahgu]

input is 5vdc
output is 15vdc
current needed is less than 10mA.