AS3715 datasheet(16/159 Pages) AMSOSRAM

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[v1-03] 2015-Aug-10

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AS3715 − Detailed Description – Power Management Functions

Only in the case the load current gets so small that less than the

minimum ON-time of the PMOS would be needed to keep the

loop in regulation the regulator will enter low power mode

operation and skip pulses during this time. The crossover point

is about ~1% of the DCDC current limit.

Figure 10:

DC/DC Buck Dis-Continuous & Low Power Mode

DC/DC Buck Dis-Continuous & Low Power Mode: Shows the DC/DC switching waveforms of SD3 at about

10mA.

High Efficiency Operation (Default Setting)

Bit settings: sdX_low_noise=0

In this mode there is a minimum coil current necessary before

switching OFF the PMOS. As a result there are less pulses

necessary at low output loads, and therefore the efficiency at

low output load is increased. As drawback this mode increases

the ripple at lower output currents.

The crossover point to low power mode is already reached at

reasonable high output currents (~10% of the DCDC current

limit).

Figure 11:

DC/DC Buck Dis-Continuous Mode & High Efficiency 1/2

DC/DC Buck Dis-Continuous Mode: Shows the DC/DC switching waveforms of SD3 at about 60mA with the

low_noise bit deactivated.

AS3715 Datasheet(PDF) 16 Page - ams-OSRAM AG