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Help in choosing DC - DC converter

Ashish Sharma69
Prodigy 30 points
Other Parts Discussed in Thread: LM3478, LM3481, LM5022, LM3488, LM5175, TL1451

I'm Ashish Sharma from Traana Technologies, Bangalore. We specialize in Sensor communication and embedded system design. We are working on IRDE techno-commercial bid, for that i am looking for information regarding power ICs : requirements mentioned below. Please suggest suitable ICs.

Please provide me below details ASAP :
Input Voltage Range : 9V - 18V
Nominal Voltage : 12V
Output 1 : 5V , 3A 
Output 2 : 12V, 2A (Ripple should be <= 10mV)
Output 3 : 12V, 2A (Ripple should be <= 10mV)
Output 4 : 12V, 2A (Ripple should be <= 10mV)
For any clarification please contact.
  • 0
    TI__Guru**** 191445 points
    Output 1 is a simple buck converter. We will have many devices that can provide that output. Outputs 2, 3, and 4 will require a buck boost converter. LM3478, LM3481, LM3488, LM5175 or LM5022 can support that. I would recommend using our Webench design center to help you make your selections:

    www.ti.com/.../tools-software.page

    One other thing I may add. 10 mV ripple is a rather strict requirement. You can usually get near that ripple using all ceramic output capacitors. But that is for ripple only. SMPS typically generate switching noise that may also appear on the output along with the normal ripple. If you cannot tolerate that you may require additional post filtering and possibly an RC snubber on the switch node. Another common technique is to regulate to a slightly higher voltage then follow with a low headroom drop out linear regulator for your final 12 V output.
  • 0 in reply to JohnTucker
    Prodigy 30 points
    Thanks John,

    Actually i am working on a defence project, in which they are having restricted area of board. so i am little worried in using 4 ICs.. Can you suggest me ICs, which are having 3 outputs.

    so that for 5V, 3A - I will use one IC and for output2,3,4 - i will use one IC.(12V,2A).

    Please check if you can find out something.
  • 0 in reply to Ashish Sharma69
    TI__Guru**** 191445 points
    I don't think we have any 3 output buck boost. What is driving your need for 3 separate 12 V supplies? You could possibly combine them into a single 6 A output?
  • 0 in reply to JohnTucker
    Prodigy 30 points

    No i dont think so.that will be good option. something with 2 outputs??? 

  • 0 in reply to Ashish Sharma69
    TI__Guru**** 191445 points
    TL1451 may possibly work. I think you can get smaller solution with single solutions in smaller package types though. If you wanted to use an isolated topology, you could get multiple outputs from different windings of the transformer. You are looking at a more complicated solution though. I think you are best off to look at simple single output solutions.