LM5008A for split rail power supply

Denis Kotlar

Other Parts Discussed in Thread: TPS54060, LM5008A, LM5019, LM5018, LM5017, LM5118, LM5008

I need split a rail power supply for generate Vout1=+15V and Vout2=-15V. Vin=48VAC what after rectifying could be up to +68VDC. Application note SLVA369 use TPS54060 that can go up to +60VDC. Therefore I'd like to use LM5008A to be on the safe side. My question is: can I use LM5008A when main rail is inverted (negative) and positive rail is derived from coupled inductor? If not, what is an alternative?

over 10 years ago

0 Vijay86929 over 10 years ago

TI__Genius 11490 points

Hi Denis,

LM5017 / LM5018 / LM5019 family of parts (100V) can be used to generate +/- voltages in Fly-Buck configuration. The primary side can be positive (like a buck converter) or negative (inverting buck-boost). See the following links for more information.

http://e2e.ti.com/blogs_/b/powerhouse/archive/2014/11/08/should-you-use-buck-or-inverting-topology-for-fly-buck.aspx

http://www.ti.com/lit/an/snva674b/snva674b.pdf

Thanks and regards

Vijay

0 Denis Kotlar over 10 years ago in reply to Vijay86929

Intellectual 820 points

Thanks Vijay for quick response and mentioned references. I presume that LM5008 is out of game according to the criteria to provide split rails but also because it does not have a SYNC pin. I'd like to add converter to the board which already has LM5118 on it and think that sychronization will be right thing to do. That makes my requirement even more complex, but please let me know if TI has a solution for split rail from high input voltage (70VDC) and in the same time synchronization capability. Thanks once again.

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LM5008A for split rail power supply