PMP8944: New input requirement changes

Sarumathi R

Intellectual 480 points

Part Number: PMP8944

Hi Team,

PMP8944 has the input range of 18VDc to 30VDC.

If we extend the input voltage upto 32VDC, is there any changes in transformer and any other thing?

over 5 years ago

0 Sonal Singh over 5 years ago

TI__Expert 6080 points

Hello Sarumathi,

In this design, the turns ratio of the transformer is based on the minimum input voltage.

I do not see any issues in running this board at 32Vdc input, the only thing to keep in mind is the additional stress at the power stage switches and diodes. they seem to be rated sufficiently to cope with the 32VDc input.

Regards,

Sonal

0 Sarumathi R over 5 years ago in reply to Sonal Singh

Intellectual 480 points

Hi Sonal,

I have calculated output indcutor value with the following formula taken from http://www.ti.com/lit/an/slua535a/slua535a.pdf?ts=1588056439329(refer page no 10)

I got calculated value greater than 12uH. But in reference design 15uH is used.

Can you please justify on this?

0 Sarumathi R over 5 years ago in reply to Sarumathi R

Intellectual 480 points

Sorry , there is a correction in previous post.

I got calculated value greater than 15uH. But in reference design 15uH is used.

0 Sarumathi R over 5 years ago in reply to Sarumathi R

Intellectual 480 points

Hi any update on this?

0 Sonal Singh over 5 years ago in reply to Sarumathi R

TI__Expert 6080 points

Hello,

May you please share your selection for the Min_switching frequency and duty cycle? how much inductor ripple is allowable in your spec?

If you have the PMP8944 and it works for the designed input range it should not require any changes for increasing the high line voltage by 2V.

Regards,

Sonal

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PMP8944: New input requirement changes