TPS22981RGPR datasheet(12/19 Pages) TI

12 / 19 page

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Short Resistance - Ω

Load

Current

Output

Voltage

OC Limit

tLIM delay

TPS22981

SLVSBM6 – DECEMBER 2012

www.ti.com

OVER-CURRENT LIMIT AND SHORT CIRCUIT PROTECTION

When the load at OUT attempts to draw more current than the limit set by the external RSET resistors for the

V3P3 switch and VHV switch (for both S0 and S3 modes), the device will operate in a constant current mode

while lowering the output voltage. Figure 10 shows the delay, tLIM, which occurs from the instance an over-

current fault is detected until the output current is lowered to ILIMHV tolerances for VHV or ILIM3V3 tolerances for

V3P3 shown in Figure 6. Figure 11 shows the response time versus a resistance shorted across the output.

Figure 10. Overcurrent Output Response

Figure 11. Overcurrent Response Time vs Short Resistance

All short circuit conditions are treated as over-current conditions. In the event of a short circuit, the device will

limit the output current to the corresponding RSET value and continue to do so until thermal shutdown is

encountered or the short circuit condition is removed.

REVERSE CURRENT PROTECTION

Reverse current protection for the V3P3 supply to OUT triggers at IREV3P3 causing the V3P3 supply switch to

open. When the HV_EN signal is not asserted and reverse current protection is triggered, a discharge current

source is turned on to bring the output voltage to near the V3P3 voltage.

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