L6711 datasheet(23/50 Pages) STMICROELECTRONICS

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L6711

Remote voltage sense

23/50

Remote voltage sense

The device embeds a Remote Sense Buffer to sense remotely the regulated voltage without

any additional external components. In this way, the output voltage programmed is

regulated between the remote buffer inputs compensating motherboard or connector

losses. The very low-offset amplifier senses the output voltage remotely through the pins

FBR and FBG (FBR is for the regulated voltage sense while FBG is for the ground sense)

and reports this voltage internally at VSEN pin with unity gain eliminating the errors.

Keeping the FBR and FBG traces parallel and guarded by a power plane results in common

mode coupling for any picked-up noise.

If remote sense is not required, it is enough connecting the resistor RFB directly to the

regulated voltage: VSEN becomes not connected and still senses the output voltage

through the remote buffer. In this case the FBG and FBR pins must be connected anyway to

the regulated voltage (See Figure 8).

Warning:

The remote buffer is included in the trimming chain in order

to achieve ±0.5% accuracy (0.6% for the Hammer DAC) on the

output voltage when the RB is used: eliminating it from the

control loop causes the regulation error to be increased by

the RB offset worsening the device performances!

Figure 8.

Remote buffer connections

RB used (up to ±0.5% Accuracy)

RB Not Used (Precision worsened)

VID

COMP

VSEN

64k

FBR

FBG

64k

RFB

To Vcore

(Remote Sense)

VID

COMP

VSEN

64k

FBR

FBG

64k

RFB

To Vcore

L6711 Datasheet(PDF) 23 Page - STMicroelectronics

L6711 Datasheet(HTML) 23 Page - STMicroelectronics

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