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TPS40345: TPS40345 and TPS40345EVM-353

Yuval Izhaki
Prodigy 190 points
Part Number: TPS40345

Hi

I would like to use the TPS40345 in a new design ,

the new design is a high power LED driver 7V@10A and 4.5V@10A

I plan to test this design using the TPS40345EVM-353 with some modification to the feedback resistor 

Can you please let me know whether this part can provide the required power or recommend another part (EVB) who can provide

(we plan to build 1000 to 5000 unit of each design 7V and 4.5V)

Best regards

Yuval Izhaki

  • 0
    TI__Guru 52785 points

     

    Yes, the TPS40345, with properly selected MOSFETS can support 4.5V and 7V @ 10A each.

    However, I have a few notes:

    1) The output capacitors used in the TPS40345EVM-353 are rated for 6.3V.  Even at 4.5V, they will suffer from sever DC bias capacitance loss which could compromise the output stability with the existing compensation.  To modify the EVM, you should expect to change the Output Capacitors (C8, C9, and C10) and Compensation Components  (R1, R2, C4, C5, and C6) as well as the Feedback Bias resistor (R6) 

    2) The existing 380nH inductor used on the TPS40345EVM-353 will have 12.8A peak to peak inductor current ripple at 12V to 7V and 12.3A pk-pk ripple at 12 to 4.5.  Both of those are very high inductor ripple current for a 10A load.  In addition to changing the output capacitors, you may want to consider increasing the inductor to reduce the cycle by cycle ripple current.  Typically, designs recommend peak to peak ripple current approximately 20-40% of the full load current, which would require about 1.2μH for 12V to 7V @ 10A with a 600kHz switching frequency.

    3)  With output voltages greater than 4V, it is recommended that the Enable pin be used to hold the TPS40345 in the disabled state until the input voltage is high enough to support the output voltage to prevent the TPS40345 from experiencing repeated starts and failing to reach output voltage regulation.