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LM25061 high current limit

Khoi Nguyen83
Expert 1180 points
Other Parts Discussed in Thread: LM25061, LM5069, CSD16415Q5, LM25069

Is it possible to design LM25061 for high current 25-30A limit shutoff with 10A average current.

  • 0
    TI__Expert 5940 points

    Khoi,

    Yes, that isn't a problem with this part.  Great care must be taken in selecting a good SOA FET and please pay close attention to the Layout Recommendations (as well as apps section). 

    Brian

  • 0 in reply to Brian Daugherty
    Expert 1180 points

    I pick Vishay SIR662DP. Typical current draw for motor is around 10-15A and peak is 25A when stalling.

    I''m not sure how to pick based on SOA. I figure low Rs 0.002 and FET Rds(on) = 0.0048 max, so I only need 20W and so I pick R_pwr=10K.

    Can I send the schematic for quick review since I need to go to layout tomorrow?

  • 0 in reply to Khoi Nguyen83
    Expert 1180 points
    btw, Looking at the datasheet, LM5069 (higher input range 9 to 80V) has almost the same footprint and function except for pin 4 OVLO instead of FB on LM25061. I would have to do some tunning but either one work work correct?
  • 0 in reply to Khoi Nguyen83
    TI__Expert 5940 points
    Khoi,

    The SIR662DP has a decent SOA curve and should be workable. At 4.4mohm 'hot' Rdson, it will be good for 10A steady state. A better SOA FET, if you have any trouble is the TI CSD16415Q5, which is ~ 1.4mohm "hot' so it will run cooler SS and has ~ 2x the SOA window. Recommend you visit to www.ti.com/hotswap and review the Tech Docs & Tools+Software tabs. In particular, 'Robust Hotswap Design', TVS doc, and Transients doc. The LM5069 calculator tool is on there. The LM25061 calculator is on the standard www.ti.com product page for that device. These calculators make design much easier.

    LM25061 = LM25069 with differences in how PG is done. LM25061 omits OVLO and has an adjustable PG vs the LM25069. The LM5069 is a higher voltage rated version of the LM25069, but does have different gate and timer currents along with a 9v min operation (PORs are different) so adjustments in design are needed.

    Brian
  • 0 in reply to Brian Daugherty
    Expert 1180 points
    Thanks for the suggestion. I need FET to handle high current motor current 15A continuous, 25A peak pulse so I will look at TI one.

    Couple more questions:

    1) Does the device handle reverse polarity?

    2) the motor back emf will cause the current to run in reverse direction and it can charge the battery at the input when the FET is on, would there be an issue with hotswap chip?