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TPS92515HV: Peak inductor current limitation

Kai Nomiyama
Expert 5545 points
Part Number: TPS92515HV
Other Parts Discussed in Thread: TPS92515

Hi Team,

I have a question about TPS92515HV peak inductor current.

TPS92515HV supports constant average current up to 2A so peak inductor current(ILave+⊿ILpp/2) should be higher than 2A.

Question here is what is the limitation of that peak inductor current?
limited by 150C abso max junction temperature or any current limit value?

Regards,
Kai

  • 0
    TI__Mastermind 28655 points

    Hello Kia,

    This depends on the application not the peak current.  The TPS92515 cannot provide 2A for all applications, see section 8,1 in the datasheet.  Things that limit the current in the design:

    What is your Vin range including maximum?

    What is you Vled range including maximum?

    What maximum switching frequency are you looking at using?

    How well will the TPS92515 have heatsinking?  FR4, metal core, multi layer FR4 with multiple ground and thermal vias?

    What is the maximum ambient for the board?

    Best Regards,

  • 0 in reply to Irwin Nederbragt
    TI__Expert 5545 points

    Hi Irwin,

    Here is requirement for TPS92515HV.

    #1: What is your Vin range including maximum?

    →38V-42V

    #2: What is you Vled range including maximum?

    →15V

    #3: What maximum switching frequency are you looking at using?

    →330kHz

    #4: How well will the TPS92515 have heatsinking?  FR4, metal core, multi layer FR4 with multiple ground and thermal vias?

    →FR4_6 layer, no heatsink on TPS92515HV, thermal via under TPS92515HV thermal pad.　

    #5: What is the maximum ambient for the board?

    →85℃

    TPS92515HV_timing.zip

    Regards,

    Kai

  • 0 in reply to Kai Nomiyama
    TI__Mastermind 28655 points

    Hello,

    This will take a little time.  I will get back to you soon.

    Best Regards,

  • 0 in reply to Irwin Nederbragt
    TI__Expert 5545 points

    Hi Irwin,

    Do you have any update for this?

    Regards,

    Kai

  • 0 in reply to Kai Nomiyama
    TI__Mastermind 28655 points

    Hello Kai,

    Sorry about the delay:

    So you asked about 2A however the picture shows 2.7A average with 3A peak during the PWM on-time.  This should still work at the PWM duty cycle, 3.9%, input voltage and led voltage:

    Vin 42 V 38V - 42V
    Vled 15 V  
    Fsw 330000 Hz  
    Ipeak 3 A  
    Iave 2.7 A  
    didt 0.6 Apkpk  
    Voff 1 V  
    Vcs 0.2486 V  
    Rcs 0.082866667 ohm  
    Coff 4.7E-10 F  
    duty 0.357142857    
    toff 1.94805E-06 sec  
    ton 1.08225E-06 sec  
    Lind 4.87013E-05 Hz choose 47 uH
    Roff 60075.6468 ohm choose 57.6 Kohm
    dutypwm 0.038461538    
    Iequiv 0.529513565 Aequiv equivalent DC current

    I chose a slightly lower Roff because the standard inductor value is slightly lower than calculated.

    Best Regards,

  • +1 in reply to Irwin Nederbragt
    TI__Expert 5545 points

    Thanks Irwin,

    I close this thread and if I have additional question, I post another one.

    Regards,

    Kai