• State TI Thinks Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 40 subscribers
  • Views 958 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TIDA-00173: Using the optional Vaux as stated in TIDU-412A

ahsan tipu
Prodigy 250 points
Part Number: TIDA-00173
Other Parts Discussed in Thread: LM5001

Hi,

I have designed a power supply with three phase input for my VFD, as detailed in TIDU-412A (TIDA-00173). I originally wanted an isolated 24 V supply plus a non-isolated 24V supply (sharing the same ground as PGND). The design provides an isolated 24 V supply but only provides 16V non-isolated supply (Vaux). So I have decided to use a boost switching converter to convert the non-isolated 16V to 24V. My questions are as follows:-

1) The 16V non-isolated supply (Vaux) has been derived from Vfb which is also being used as feedback to the controller. Will using Vaux, in any way disrupt the feedback being sent to the controller through Vfb?

2) Secondly, I am going to use a switching converter to boost Vax=16V to 24V. I have the attached the datasheet of the converter. Will using this converter, which is basically a high speed switching device (1.5 MHz), introduce any further complications in the overall supply design? AP3012.pdf  

  • 0
    Prodigy 250 points

    Any updates? Anyone?

  • 0 in reply to ahsan tipu
    TI__Genius 12990 points
    Hi Ahsan,

    Thanks for your question about this TIDA and sorry for the late reply! I hope to answer all of your questions!!

    1) Vaux output is capable of 15W. At 16V this allows for less than 1A which seems to come from the 120uF cap C11. As long as the VS pin stays around 4.05V the feedback will remain stable.

    2) There are alot of considerations that go along with this. A big factor will be stability or frequency response of your system and EMI of your current loops. What is your allowed component size, do you require 1.5Mhz? targeted load? max ripple? why have you chosen this boost? If you want more overhead the LM5001 is a Wide Vin, 1A Current Mode Non-Synchronous switching regulator that has selectable switching frequency, wide EA BW, 1.5% VOUT accuracy, etc.

    Thanks,