L6710

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are turned off, the FAULT pin is driven high and the device stops working. Cycle the power supply to re-

start operation.

The maximum average current during the Constant-Current behavior results:

In this particular situation, the switching frequency results reduced. The ON time is the maximum allowed

(TonMAX) while the OFF time depends on the application:

threshold is fixed, to modify the percentage with respect to the load value, it can be simply considered that,

Figure 5. Constant Current operation

INTEGRATED DROOP FUNCTION

The device uses a droop function to satisfy the requirements of high performance microprocessors, re-

ducing the size and the cost of the output capacitor.

This method "recovers" part of the drop due to the output capacitor ESR in the load transient, introducing

a dependence of the output voltage on the load current: the regulated voltage decrease as the load in-

crease with a precise relationship.

As shown in figure 6, the ESR drop is present in any case, but using the droop function the total deviation

a resistor between FB and GND allowing to exploit the all tolerance interval available. This additional re-

sistor is not required in application such as VRD10 since the nominal value is already set by the VID* and

the load regulation fixed by the specs.

Since the device has an average current mode regulation, the information about the total current delivered

I

MA X,TOT

2I

MA X

2I

OCPx

I peak

I

OCPx

–

2

--------------------------------------

+





⋅

=

⋅

=

T

OFF

L

I peak

I

OCPx

–

V

OU t

--------------------------------------

f

1

T

ONm ax

T

OFF

+

-----------------------------------------

=

⋅

=

TonMAX

TonMAX

Ipeak

Vout

Iout

µA)

µA)

UVP

Droop effect

a) Maximum current for each phase

b) Output Characteristic