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L6712A L6712

then implemented allowing the device to recover if the over load cause has been removed.

The maximum duty cycle is fixed and constant with the delivered current. The device works in constant

current operation once the OCP threshold has overcome. Refer to the above Constant Current section in

which only the different value in the maximum duty has to be considered as follow:

All the above reported relationships about the deliverable current once in quasi-constant current and con-

stant current are still valid in this case.

3.5 REMOTE SENSE AMPLIFIER

Remote Sense Amplifier is integrated in order to recover from losses across PCB traces and wiring in high

current DC/DC converter remote sense of the regulated voltage is required to maintain precision in the

regulation. The integrated amplifier is a low-offset error amplifier; external resistors are needed as shown

in Figure 11 to implement a differential remote sense amplifier.

Figure 11. Remote Sense Amplifier Connections

Equal resistors give to the resulting amplifier a unity gain: the programmed reference will be regulated

across the remote load.

To regulate output voltages different from the available references, the Remote Amplifier gain can be ad-

justed simply changing the value of the external resistors as follow (see Figure 11):

to regulate a voltage double of the reference, the above reported gain must be equal to ½.

Modifying the Remote Amplifier Gain (in particular with values higher than 1) allows also to regulate volt-

ages lower than the programmed reference.

Since this Amplifier is connected as a differential amplifier, when calculating the offset introduced

in the regulated output voltage, the "native" offset of the amplifier must be multiplied by the term

the offset.

comes not connected and still senses the output voltage through the remote amplifier. In this case the use

of the external resistors R1 and R2 becomes optional and the Remote Sense Amplifier can simply be con-

nected as a "buffer" to keep VSEN at the regulated voltage (See Figure 11). Avoiding use of Remote Am-

plifier saves its offset in the accuracy calculation but doesn't allow remote sensing.

I

peak

I

OCPx

V

IN

Vout

min

–

L

-------------------------------------- Ton

MAX

I

OCPx

V

IN

Vout

MIN

–

L

--------------------------------------- 0.85 T

⋅⋅

+

=

⋅

+

=

Reference

REMOTE

AMPLIFIER

ERROR

AMPLIFIER

DROOP

FB

COMP

VSEN

FBG

FBR

Remote

Ground

Remote

R2

R2

R1

R1

Reference

REMOTE

AMPLIFIER

ERROR

AMPLIFIER

DROOP

FB

COMP

VSEN

FBG

FBR

RB used

RB Not Used

RA_Gain

V

VSEN

Remote_V

OUT

Remote_GND

–

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

=

R2

R1

--------

=