TPS2480PW datasheet(18/60 Pages) TI2

18 / 60 page

TPS2480

TPS2481

SLUS939B – APRIL 2010 – REVISED DECEMBER 2010

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The TPS2480/81 responds rapidly to the short circuit as seen in Figure 15. The falling OUT voltage is the result

of the external FET and CO currents through the short circuit impedance. The internal GATE clamp causes the

GATE voltage to follow the output voltage down and subsequently limits the negative VDS to 1.2 V. The rapidly

rising fault current overdrives the GATE amplifier causing it to overshoot and rapidly turn the external FET off by

sinking current to ground. The external FET slowly turns back on as the GATE amplifier recovers; the external

FET then settles to an equilibrium operating point determined by the power limiting circuit.

Figure 15. Current Limit Onset

Minimal input voltage overshoot appears in Figure 15 because a local 100-mF bypass capacitor and very short

input leads were used. The input voltage would overshoot as the input current abruptly drops in a typical

application due to the stored energy in the input distribution inductance. The exact waveforms seen in an

application depend upon many factors including parasitics of the voltage distribution, circuit layout, and the short

itself.

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TPS2480PW Datasheet(PDF) 18 Page - Texas Instruments