7.3 Feature Description

The LM7311 eFuse is a compact, feature rich power management device that provides detection, protection and

indication in the event of system faults. .

7.3.1 Undervoltage Lockout (UVLO and UVP)

The LM7311 implements undervoltage protection on IN in case the applied voltage becomes too low for the

system or device to properly operate. The undervoltage protection has a default lockout threshold of VUVP

which is fixed internally. Apart from that, the UVLO comparator on the EN/UVLO pin allows the undervoltage

Protection threshold to be externally adjusted to a user defined value. The Figure 7-1 and Equation 1 below

show how a resistor divider can be used to set the UVLO set point for a given voltage supply

IN

EN/UVLO

GND

Power

Supply

R1

R2

Figure 7-2. Adjustable Undervoltage Protection

VIN(UV)  = VUVLO(F) × R1 + R2R2 

(1)

7.3.2 Overvoltage Lockout (OVLO)

The LM7311 implements a fixed overvoltage lockout to protect the load from input overvoltage conditions. Once

the voltage at the VIN pin crosses the OVLO rising threshold VOV(R), the device turns off the power to the

output after tOVLOdeb debounce time.

Once the device turns off its latched off till a EN cycle is applied for it to start again

The device employs additional protection mechanism of VDS CLAMP in the event of the device VIN voltage

exceeding the VDSCLAMP activation threshold. Here the device partially turns on to protect itself from VDS

(VIN-VOUT) absmax violation by charging the output to VOCLAMP voltage. This protection helps the device

self-protect during transient surges if the TVS diode is unable to clamp the surge below the device VDS absmax.

7.3.3 Inrush Current, Overcurrent, and Short Circuit Protection

LM7311 incorporates four mechanisms to handle overcurrent:

1. Adjustable slew rate (dVdt) for inrush current control durint start-up.

2. Fixed Current limit (ILIM) during overcurrent in start-up.

3. Fixed threshold (ISFT) for fast-trip response to quickly protect against hard output short-circuits during

startup.

4. Fixed threshold (IFFT) for fast-trip response to quickly protect against hard output short-circuits during steady-

state.

7.3.3.1 Slew Rate (dVdt) and Inrush Current Control

During hot-plug events or while trying to charge a large output capacitance at start-up, there can be a large

inrush current. If the inrush current is not managed properly, it can damage the input connectors and/or cause

the system power supply to droop leading to unexpected restarts elsewhere in the system. The inrush current

during turn on is directly proportional to the load capacitance and rising slew rate.

LM7311

SLVSKK8 – AUGUST 2026

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