PTR08100W: Reduce ripple

Hi Kevin,

I wan to begin by ensuring we are looking at the proper output noise measurement before considering the use of any post filtering or recommendations.

What do I mean by that? Well, the placement of the probes and ground connection is critical for a proper output noise measurement. Improper measurement techniques can exaggerate the output noise. Take a look at the image below which shows the difference between an improper (left) and proper (right) measurement technique. The extra long ground loop formed from the scope probe can act like an antenna and pollute the actual output ripple measurements with externally coupled noise. Reducing the ground lead by implementing a smaller ground connection (image used pigtail ground connection method) results in a proper and more accurate measurement.

Can you please provide the following measurement result when using the technique demonstrated on the right of image below? (assuming you measured differently than the recommended)

Thanks,
Alejandro

Hi  sir,

Yes, I will let test engineer to re- measure  using the good method.

I would like to know which bead can reduce  ripple below 20mv.

Can you recommend the bead?

Unfortunately, I do not have an exact recommendation. Selecting the correct Ferrite Bead filter varies through applications. But, below I have provided some technical documentations in which I believe can be very helpful if you are planning on implementing a bead filter onto your design.

• slyt740.pdf
• slyt782.pdf
• snva698.pdf
• snva871.pdf

There are various ways to filter output noise. However, if you must use a bead, it is important to first gather EMI Measurements before designing  pi-filter to attenuate noise.

Hi sir,

We would like to use the other power module to replace PTR08100W and almost

the same power up time or small power up time, but the output ripple(0.8v) is about 10~15mv.

Can you recommend such power module?

Because we need to revise the board as soon as possible. Thanks a lot.

What are your application requirements? Vin? Iout? Vout is 0.8V?
What about packaging? Does it need to be through-hole?

Hi sir,

Vin  is  12v,vout  is  0.8v, I  out  is  10A or 5A.

SMD  or DIP  are both  OK..