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no image Wednesday, August 23, 2017 by Bhargav Jani

DC-DC Power supply design in Automotive

Hello All,

Currently, working on project, in which i have to design A DC-DC Power supply for automotive. I am currently stuck at selecting the IC (after looking for many like TPS40170, LT8390A, LM25117-Q1) all being the 4 switch buck-boost topology IC.

I have attached a diagram to show, how the system appears to be, I am using s dsPIC 30F4011, to control the IC (Digitally PWM) . Thus IC needs to have digital input pins or it can be done via Digi POT ...(not a major issue)

The input req will be from 5V to 48V (nominal battery voltage) , Vout - (from 0.5V to 40V) and Iout (upto 7A) depending on the loads attached to the ECU

The ECU Kl30 is a pos pin through which the current will flow through to the ECU to KL31

The KL31 pin also has a inverting power supply (neg input voltage or neg currents ) to the other system comp in automotive or other ECU-s for that matter.

I need your suggestions regarding LM5170.Q1 (Multiphase controller) attached. It has a dual battery system controller.

I am not sure, whether I can use this IC or look for other IC (and if it can be used as buck-boost controller in the application.

Is the diagram lacking some circuitry.

Suggestions, changes, review welcomed#




  • by  Neil Mula (edited)
    Hi Bhargav, Specifically it is stated as automotive 48-V and 12-V dual battery systems, therefore it good to have this voltage rating in order to optimized its operation. Also " regulates the average current flowing between the high voltage and low voltage ports...." , this specify its application and if you have that IC then, try to have some test with your designed circuitry. Hope it helps. Best, Neil

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