viper06 buck mode to generate 3.3V. output voltage =1.24V

[LROCH.11]

I use the viper06HS to generate +3.3V. i follow the reference design provided by eDesignSuite.

When i turn on my system. the viper06HS provide 1.24V

do you idea?

I attach my schematic

[Peter BENSCH]

The VIPER06HS is actually intended for isolated converters, but can also be used for non-isolated converters. Unfortunately you confused pin 1 (GND) with neutral, which leads to several errors:

• C4.1 should not connect to L3.1, but to D4.2
• C3.2 should not connect to D4.1, but to D4.2 as well
• the capacitor between IC1.5 and D4.2 is missing (shown as Cp in eDesignSuite)

Regards

/Peter

[LRoch.1]

I have made the modification on my design. but i have 1.5V on the output

[Peter BENSCH]

Can you please update the schematic?

Have you got a layout and/or photo for review?

/Peter

[LRoch.1]

i update my schematic. for the layout . i put some wires on PCB

[Peter BENSCH]

Hmm, just wires on a PCB doesn't sound like optimal wiring for a switching regulator.

Please make sure the FB wire is as short as possible and not below the inductors.

Also minimize the length of the wires between pin 1 (GND), D4.1 and L3.1. The connection between D4.2, C6 (-) and the output should also be minimized.

BTW: I forgot to mention one additional error - the compensation network C5 and C? should not be connected to D4.1, but to D4.2.

/Peter

[LRoch.1]

I know the wire is not optimal but for the moment I try to solve my problem.

the feedback Wire is near viper on my design.

it is strange that the modifications do not correspond with the reference diagram

for example, i have the reference design of steval-blueplug on the schematic is very different 

[LROCH.11]

I have make all modification but i have always 1.5V

[LROCH.11 · Accepted solution]

I have modify my first schematic to generate +4V with VIPER06. 

I have changed the value R2 by 100K and i have add a resistor of 470K to D4.1 and now it is works.

thanks for your help