LM76005 datasheet(20/51 Pages) TI2

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7.4.6 Light Load Mode

At light output current loads, PFM is activated for the highest efficiency possible. When the inductor current does

not reach IPEAK_MIN during a switching cycle, the on-time is increased, and the switching frequency reduces as

needed to maintain proper regulation. The on-time has a maximum value of 8 µs to avoid large output voltage

ripple in dropout conditions. Efficiency is greatly improved by reducing switching and gate-drive losses. During

light-load mode of operation, the LM76005 operates with a minimum quiescent current of 10 to 15 µA (typical).

7.4.7 Foldback Mode

Foldback protection modes are entered when the duty cycle exceeds the minimum on- and off-times of the

device. At very high duty cycles, where the minimum off-time is not satisfied, the frequency folds back to allow

more time for the peak current command to be reached. The maximum on-time is 8 µs, which limits the

maximum duty cycle in dropout to 98%. At very low duty cycles when the minimum on-time is reached, the

device maintains regulation by dropping the frequency to allow more time for the inductor current to discharge

the output capacitor. Foldback mode is exited once the minimum on-time and off-times are satisfied.

7.4.8 Forced Pulse-Width-Modulation Mode

FPWM is employed when the FPWM pin is pulled high, or the device is synchronized to an external clock. In this

mode, diode emulation is turned off, and the device remains in CCM over the full load range. In FPWM

operation, the frequency of operation is constant and fixed unless the minimum tON or tOFF are exceeded, which

cause the device to enter foldback mode. In these cases, PWM operation is still maintained, but the frequency of

operation is folded back (reduced) to maintain proper regulation. DC accuracy is highest in FPWM mode.

LM76005

SNVSBK5A – FEBRUARY 2020 – REVISED JULY 2020

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LM76005 Datasheet(PDF) 20 Page - Texas Instruments