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LM25117: Constant Current Mode

B K
Prodigy 10 points
Part Number: LM25117
Other Parts Discussed in Thread: LM5190

Tool/software:

Is there a calculator or simulator for constant current configuration of LM25117? I am trying to set up a stable 6.5A CC output. I am using 24V, 200W power supply for Vin. I can successfully achieve 6.5A at output, but current starts to drop when output voltage nears 19V. I have verified the power supply is not derating. My switching frequency is set to 150KHz, so my output duty cycle should max out at roughly 94%. This means my maximum output voltage should be 22.56V (24Vin * 94%) before current starts to drop off if I am understanding correctly? I would like to know if there is a calculator so I can plug in values and see why output current drops before hitting the max output duty cycle.

Thank you, 

BK

  • 0
    TI__Guru 58691 points

    Hello BK 

    Unfortunately, there is no dedicated tool available for CC mode. Please measure the inductor current and check if peak current limiting is triggered when VOUT is near 19V. 

    Also, if not too late, please consider using LM5190 (https://www.ti.com/product/LM5190) which is capable of CCCV regulation with integrated dual-loop. Please create a new post if you have any question about LM5190 device. 

    -EL