LM5118 - Input current control configuration question

Matthew Branchick

Other Parts Discussed in Thread: LM5118, UCC3813-4, TPS40210

Hello,

I am working on an application that requires the switching control be regulated only based on input current or voltage, and I am currently investigating the possible use of the LM5118 for that application. Using the output voltage for control is not an option due to other independent power sources on the output bus. I am wondering if there is a way to reconfigure the vout sense and current sense pins to monitor and regulate the input current into the DC-DC converter to 14A.

Design specs are as follows:

Vin: 5-68V

I_in: 0-14A

I would be open to other IC's as well if someone has a better recommendation. Thanks in advance

over 11 years ago

0 EricLee over 11 years ago

TI__Mastermind 46141 points

Please refer http://www.ti.com/tool/solarmagic-solarpoweroptimizer-ref . LM5118 cannot handle 68V at 14A .

Regards,

0 Matthew Branchick over 11 years ago in reply to EricLee

Prodigy 40 points

Thankyou for the response, the link you provided cannot handle the input voltage requirement though. I should point out I am just looking for a simple way to regulate the duty cycle in a DC-DC converter based on the input current into the converter. Would something like an UCC3813-4 be a better approach?

What can the LM5118 not handle? It is rated for 75V and the 14A would not be flowing through the chip, it just needs to be monitored. I was under the impression that because it was an external switch controller that it was not limited by current so long as the components it is driving are rated to handle the input and output current.

0 EricLee over 11 years ago in reply to Matthew Branchick

TI__Mastermind 46141 points

You are right. It is not limited by current because LM5118 is controller. But practically, converter using LM5118 is designed to handle around 50~100W due to thermal issue.

Regards,

0 John Rice over 11 years ago in reply to Matthew Branchick

TI__Prodigy 430 points

Hi Matthew,

If I understand the question, I think all you need is a high side current shunt monitor on the input feed back into the control loop. A good example of this can be found here.

http://www.ti.com/tool/pmp6572.2

However, as Eric points out, there are practical considerations that limit a particular topology in terms of output power. The UCC3813/TPS40210 are peak-current mode controllers that work well in SEPIC/BOOST/FLYBACK topologies. A higher power topology you might consider is the current feed push-pull based on any number of controllers including this one.

http://www.ti.com/tool/lm5030eval

John Rice

Field Applications

Novi, Michigan

0 Matthew Branchick over 11 years ago in reply to John Rice

Prodigy 40 points

Thanks for all the help everyone, I think this solves my issue.

Power management

Power management forum

LM5118 - Input current control configuration question