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Original question:

TPS40210: TPS40210

TPS40210: TPS40210

Steven Barnett41
Prodigy 30 points
Part Number: TPS40210
Other Parts Discussed in Thread: LM3481

I'm trying to power a pulsed load (several milliseconds @ ~ 25W) using this controller: Vin = VDD = 6VDC; fsw = 500K. The transient rise of current appears to reach the current limit of ~ 7 Amps.

I've generated a Matlab model using the paper "...Under the Hood of a DC/DC Boost Converter..." by Brian Lynch.

Any help appreciated!

  • 0
    TI__Mastermind 21720 points
    Hi Steven,

    Can you please share the application specifications and schematic? If current limit is being triggered the easiest way to resolve the issue is to decrease the current sense resistor.

    Thanks,

    Garrett
  • 0 in reply to Garrett Roecker
    Prodigy 30 points

    Garrett,

    Thanks for responding.

    I tried reducing the current sense resistor. The specs are 6VDC in; 24VDC out @ a pulsed power (several milliseconds) of 25W and approximately 10% of that as average power. Switching frequency is 500K; inductor is 4.7uh; output capacitance is ~ 90uF w/10 milliohms ESR; Sense resistor .010 ohms.

    Please let me know if you think these components are acceptable.

    Steve 

  • 0 in reply to Steven Barnett41
    TI__Mastermind 21720 points
    Hi Steven,

    Please be aware that the TPS40210 has hiccup mode. This means when the current limit is tripped the device pulls the SS pin low, stopping switching. There is no way to disable this for this device.

    Based on the initial post it sounds like the output load step is from 0% to 100%. The hiccup mode of the TPS40210 is probably not conducive to this as the inductor current can rise quickly triggering the peak current limit and placing in the device in hiccup mode. A better choice might be to select a device with simple cycle-by-cycle peak current limiting. A device that does this would be the LM3481.

    Thanks,

    Garrett
  • 0 in reply to Garrett Roecker
    Prodigy 30 points

    Garrett,

    Thanks very much. That could be the problem. I'll look into it and let you know my findings.

    Thanks,

    Steve