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[v1-11] 2016-Dec-14

AS3701 − Detailed Description – Power Management Functions

Figure 15:

Output Voltage Ripple Measurement at Operating Point 5

Operating Point 5: These graphs show the switching behavior referring to the operating point 5 from figure10.

Here the load current is 100mA and high enough to keep the DCDC always in a continuous switching operation

regardless of the mode setting.

Low Power Mode 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/undershoots by immediately turning ON the output

drivers without the normal time delays. This ensures a

minimized ripple also in very extreme load conditions.

Dynamic Voltage Management

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

output voltage, the DVM can be enabled with dvm_enable [SD_

control2]. With DVM the output voltage will ramp up/down with

a selectable slope after the new value was written to the

registers. The DVM time can be chosen between 8

μs and 16μs

by setting the bit dvm_time [SD_control2]. 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.

AS3701 데이터시트(PDF) 15 Page - ams-OSRAM AG