8.4 Device Functional Modes

8.4.1 Shutdown Mode

EN/UVLO provides ON and OFF control for the LM5013. When VEN/UVLO is below approximately 1.1 V,

the device is in shutdown mode. Both the internal linear regulator and the switching regulator are off. The

quiescent current in shutdown mode drops to 3.1 µA at VIN = 24 V. The LM5013 also employs internal bias rail

undervoltage protection. If the internal bias supply voltage is below the UV threshold, the regulator remains off.

8.4.2 Standby Mode

The LM5013 enter standby mode during light or no-load on the output. The LM5013 enters standby mode

to prevent draining the input power supply. All internal controller circuits are turned off to reduce the current

consumption. The quiescent current in standby mode is 25 μA (typical).

8.4.3 Active Mode

The LM5013 is in active mode when VEN/UVLO is above the precision enable threshold and the internal bias rail

is above its UV threshold. In COT active mode, the LM5013 is in one of three modes depending on the load

current:

• CCM with fixed switching frequency when load current is above half of the peak-to-peak inductor current

ripple

• The LM5013 enters discontinuous conduction mode when the load current is less than half of the peak-to-

peak inductor current in CCM operation.

• Current limit CCM with peak current limit protection when an overcurrent condition is applied at the output

8.4.4 Sleep Mode

During discontinuous conduction mode, the load current is lower than half of the peak-to-peak inductor current

ripple and the switching frequency decreases when the load is further decreased in pulse skipping mode. A

switching pulse is set when VFB drops below 1.2 V.

As the frequency of operation decreases and VFB remains above 1.2 V (VREF) with the output capacitor sourcing

the load current for greater than 15 µs, the converter enters an ultra-low IQ sleep mode to prevent draining

the input power supply. The input quiescent current (IQ) required by the LM5013 decreases to 10 µA in sleep

mode, improving the light-load efficiency of the regulator. In this mode, all internal controller circuits are turned

off to ensure very low current consumption by the device. Such low IQ renders the LM5013 as the best option to

extend operating lifetime for off-battery applications. The FB comparator and internal bias rail are active to detect

when the FB voltage drops below the internal reference VREF and the converter transitions out of sleep mode

into active mode. There is a 9-µs wake-up delay from sleep to active states.

LM5013

SNVSCB3 – OCTOBER 2022

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