Equation 2 can be used to find the slew rate (SR) required to limit the inrush current (IINRUSH) for a given load

capacitance (COUT):

IINRUSH (mA) = COUT (µF) × SRON (V/ms)

(2)

A capacitor can be connected to the dVdt pin to control the rising slew rate and lower the inrush current during

turn on. The required CdVdt capacitance to produce a given slew rate can be calculated using the equation:

SRON(V/ms) = GDVDT(V/V)xIDVDT(uA)

CDVDT(uF)

(3)

The fastest output slew rate is achieved by leaving the dVdt pin open.

7.3.3.2 Short-Circuit Protection

During certain system faults, the current through the device can increase very rapidly. In such events, the device

provides fast-trip response with a fixed thresholds IFFT during steady state and ISFTduring start-up. Once the

current exceeds the thresholds, the HFET is turned off completely within tSC. Thereafter, the devices tries to

turn the HFET back on after a short de-glitch interval (30μs) in a current limited manner instead of a dVdt limited

manner. This ensures that the HFET has a faster recovery after a transient overcurrent event and minimizes

the output voltage droop. However, if the fault is persistent, the device stays in current limit causing the junction

temperature to rise and eventually enter thermal shutdown. See Overtemperature Protection (OTP) section for

details on the device response to overtemperature.

7.3.3.3 Current Limit in Start-up

The LM7311x responds to overcurrent condition in start-up by limiting the current to a fixed limit of ILIM if the

output current set by the DVDT capacitor exceeds ILIM but stays below the ISFT(2 x ILIM). The current limit

circuit employs a foldback mechanism. The current limit threshold in the foldback region (0V < VOUT < VFB) is

lower than the startup-up current limit threshold (ILIM). During this period if the resulting device power dissipation

results in the internal device temperature (TJ to exceed the thermal shutdown threshold(TSD), the device shuts

off due to TSD fault. The FLTb pin is asserted during the TSD fault. In the latched off version it will stay

latched off or restart after the fixed delay (tTSD,RST) once the device cools down sufficiently below the TSD

Hysterisis(TSDHYS) level.

7.3.4 Analog Load Current Monitor

The device allows the system to accurately monitor the output load current by providing an analog current sense

output on the IMON pin which is proportional to the current through the FET. The user can sense the voltage

(VIMON) across the RIMON to get a measure of the output load current.

ILOAD (A) =  VIMON (µV)

RILM (Ω) × GIMON (µA/A)

(4)

www.ti.com

LM7311

SLVSKK8 – AUGUST 2026

Copyright © 2026 Texas Instruments Incorporated

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