LM5000

Hi Kevin,

The peak current requirement of your application exceeds the capability of LM5000. LM5000  has 1.35A min (2A typical) switch current limit, and 1.35 A min should be used for worse case.

Assuming 30% peak to peak current ripple and 90% efficiency, the required peak switch current of your application will be 48*1.5/(0.9*0.85*12)=7.8A, which is way higher than 1.35 peak current limit of LM5000.

We can put it in another way, the max output current LM5000 can support for 12V to 48V boost is around

12*1.35*0.9/(1.15*48)=0.26A.

I would recommend you to take a look at boost controllers LM5020 or LM5022.

Thanks.

Haifeng   

How about if I use TPS40210? Can it be used to drive +48V/1.5A from +12V input?

Yes, the TPS40210 controller also can do the job.