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TPS2490: TPS2490 operation as current limiter

Nir Flysher
Expert 3367 points
Part Number: TPS2490

Dear Team,

Please see below question from my customer :

  • I'm using a couple of TPS2490 IC's in my design, as a current limiters (to 5A)
  • My design is very similar to the typical design in the data sheet
  • However, while one of the circuits works flawlessly, the other one fails to operate above 30VDC
  • The failure is in that instead of limiting the current, it turns off the nFET, thus shutting the power to the load
  • I've discovered that if I remove capacitor CIN. the circuit works okay…
  • Questions:
  1. What's the importance of that capacitor ? Is it okay to omit it ?
  2. The data sheet recommends placing RSNS close to the IC; In the faulty circuit this is not the case – How critical is that ? In the faulty circuit, RSNS and the TPS2490 are not so close to each other…

Can anyone on the team please advise ?

Best regards,

Nir.

  • 0
    TI__Expert 5940 points
    Nir,

    Yes, you should follow the DS layout guidelines, always on any device. You are sensing mV level of DM signal in a high voltage environment so treat this as a true analog circuit - where your most critical component is truly the PCB layout. If you ignore the pcb layout, there is usually a price to pay. Place the Rsns, FET and TPS2490 near each other on the same side of the pcb. Keep routes short and run tightly together and kelvin sense. Place Cin on Rsns '+' side (Vin) of the sense point at Rsns (not directly at the TPS2490 Vin). Cin is needed to filter noise and should be small. 0.1uF is good.

    Brian