LM2676S-ADJ and ripple

[Scarr]

Hi all,

I have a power supply problem, I am powering a GM862 with a LM2676 but it fails to power up correctly, I am pretty sure this is due to the ripple (logged at >700mv) from the regulator can anyone look at my design and advise how I can improve it to reduce this ripple so it works reliably across 8v-40v and max 2.5A

Input voltage = 8v-38v
Output Voltage = 3.8v
IOut Max = 2.5A

 

[Scarr]

Am I asking the wrong question?

I see some people have looked at my post but not replied, is my post understandable?

Thx

Steve

 

[Sebi]

I've tried the Webench, and give same value (22uH,100uF), but i always use 47..100uH (what i found...) and 470uF without any problem. Sometimes need an additional filter for fussy circuits.
Anyway the GM-47 engine need 2200uF capacitor nearby the socket...