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AS3715 − Detailed Description – Power Management Functions

Figure 12:

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

DC/DC Buck Dis-Continuous Mode: Shows the DC/DC switching waveforms of SD3 at about 10mA with the

low_noise bit deactivated.

It’s possible to switch between these two modes during

operation.

Power Save Operation (Automatically Controlled):

As soon as the output voltage stays above the desired target

value for a certain time, some internal blocks will be powered

down leaving the output floating to lower the power

consumption. Normal operation starts as soon as the output

drops below the target value for a similar amount of time. To

minimize the accuracy error some internal circuits are kept

powered to assure a minimized output voltage ripple.

Two addition guard bands, based on comparators, are set at

±5% of the target value to react quickly on large

over/under-shoots by immediately turning on the output

drivers without the normal time delays. This ensures a

minimized ripple also in very extreme load conditions.

DVM (Dynamic Voltage Management)

To minimize the over-/undershoot during a change of the

output voltage, the DVM can be enabled. With DVM the output

voltage will ramp up/down with a selectable slope after the new

value was written to the registers. Without DVM the slew rate

of the output voltage is only determined by external

components like the coil and load capacitor as well as the load

current.

DVM can be selected for all step-down converters, but only for

one at a time. (see dvm_time and sd_dvm_select description)

AS3715 Scheda tecnica(PDF) 17 Page - ams-OSRAM AG