8.4 Device Functional Modes

8.4.1 Shutdown Mode

below its UVLO threshold 3.25 V, the converter is turned off.

8.4.2 Active Mode

simplest way to enable the LMR50410-Q1 is to connect the EN pin to VIN pin. This allows self-start-up when the

input voltage is in the operating range of 4.0 V to 36 V. See Section 8.3.3 for details on setting these operating

levels.

In Active Mode, depending on the load current, the LMR50410-Q1 is in one of four modes:

1. Continuous conduction mode (CCM) with fixed switching frequency when load current is greater than half of

the peak-to-peak inductor current ripple

2. Discontinuous conduction mode (DCM) with fixed switching frequency when load current is less than half of

the peak-to-peak inductor current ripple

3. Pulse frequency modulation mode (PFM) when switching frequency is decreased at very light load

8.4.3 CCM Mode

Continuous Conduction Mode (CCM) operation is employed in the LMR50410-Q1 when the load current is

greater than half of the peak-to-peak inductor current. In CCM operation, the frequency of operation is fixed,

output voltage ripple is at a minimum in this mode and the maximum output current of 1 A can be supplied by the

LMR50410-Q1.

8.4.4 Light-Load Operation (PFM Version)

For PFM version, when the load current is lower than half of the peak-to-peak inductor current in CCM, the

LMR50410-Q1 operates in Discontinuous Conduction Mode (DCM), also known as Diode Emulation Mode

typical) to improve efficiency. Both switching losses and conduction losses are reduced in DCM, compared to

forced PWM operation at light load.

During light load operation, Pulse Frequency Modulation (PFM) mode is activated to maintain high efficiency

switching frequency is decreased by the control loop to maintain output voltage regulation when load current

reduces. Switching loss is further reduced in PFM operation due to a significant drop in effective switching

frequency.

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LMR50410-Q1

SLUSDW4 – JULY 2020

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