Minimum power supply for my charger with uc3906

Stachiotti Fernando

I have read the aplication note U-104 and in Figure 13 is used as the minimum input voltage of 9 volts for Voc = 7.5 V. my question is, what should be my minimum supply voltage for my charger with Voc = 29V?

thanks for your help

best regards

over 12 years ago

0 Charles Mauney over 12 years ago

TI__Mastermind 31120 points

There charger will take at least one voltage higher than the bulk battery voltage. For a six cell it would be ~2.4x6 = 14.4V bulk regulation and need a 15.4V or higher supply....would probably use 16V.

0 Stachiotti Fernando over 12 years ago in reply to Charles Mauney

Prodigy 80 points

Thank you very much for your reply.

I have 2 batteries of 12V each, so 12 cells in total.
I have set my voltage VOC = 28.8 volt, 12 cells of 2.4 volts each.
What should be the limit of my power, 30 volt? What should be the minimum value of Vin?

Best Regards

0 Charles Mauney over 12 years ago in reply to Stachiotti Fernando

TI__Mastermind 31120 points

I would say 30V as a minimum.

I always like to do a bench test and find the minimum voltage on one EVM where operation starts to be erratic and then make the minimum voltage at least 0.5V higher.

This is a higher voltage application that I am used to so do not have much experienced with the quirks at this higher voltage; thus the margin.

0 Stachiotti Fernando over 12 years ago in reply to Charles Mauney

Prodigy 80 points

Thank for the reply, just tried it with 31v and doing very well. I'll try to 30V.

Best Regards

Fernando

0 Charles Mauney over 12 years ago in reply to Stachiotti Fernando

TI__Mastermind 31120 points

Great!

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Minimum power supply for my charger with uc3906