LM5165 datasheet(20/52 Pages) TI

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7.4 Device Functional Modes

7.4.1 Shutdown Mode

The EN pin provides ON and OFF control for the LM5165-Q1. When VEN is below approximately 0.6 V, the

device is in shutdown mode. Both the internal LDO and the switching regulator are off. The quiescent current

in shutdown mode drops to 4.6 µA at VIN = 12 V. The LM5165-Q1 also employs internal bias rail undervoltage

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

7.4.2 Standby Mode

The internal bias rail LDO has a lower enable threshold than the regulator itself. When VEN is above 0.6 V and

below the precision enable threshold (1.212 V typically), the internal LDO is on and regulating. The precision

enable circuitry is turned on once the internal VCC is above its UV threshold. The switching action and voltage

regulation are not enabled until VEN rises above the precision enable threshold.

7.4.3 Active Mode in COT

The LM5165-Q1 is in active mode when VEN is above the precision enable threshold and the internal bias rail is

above its UV threshold. In COT active mode, the LM5165-Q1 is in one of three modes depending on the load

current:

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

ripple;

2. Pulse skipping and diode emulation mode (DEM) when the load current is less than half of the peak-to-peak

inductor current ripple in CCM operation. Refer to COT More Light-Load Operation for more detail;

3. Frequency foldback mode to maintain output regulation at low dropout and for improved load-on transient

response. Refer to Low Dropout Operation and 100% Duty Cycle Mode for more detail.

7.4.4 Active Mode in PFM

Similarly, the LM5165-Q1 is in PFM active mode when VEN and the internal bias rail are above the relevant

thresholds, FB has fallen below the lower hysteresis level (VREF1), and boundary conduction mode is recharging

the output capacitor to the upper hysteresis level (VREF2). There is a 4-µs wake-up delay from sleep to active

states.

7.4.5 Sleep Mode in PFM

The LM5165-Q1 is in PFM sleep mode when VEN and the internal bias rail are above the relevant threshold

levels, VFB has exceeded the upper hysteresis level (VREF2), and the output capacitor is sourcing the load

current. In PFM sleep mode, the LM5165-Q1 operates with very low quiescent current.

LM5165-Q1

SNVSAJ3C – MARCH 2016 – REVISED DECEMBER 2022

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LM5165 Datasheet(PDF) 20 Page - Texas Instruments