L6711TR datasheet(46/50 Pages) STMICROELECTRONICS

46 / 50 page

Layout guidelines

L6711

46/50

18.3

Current sense connections.

Remote Buffer: The input connections for this component must be routed as parallel nets

from the FBG/FBR pins to the load in order to compensate losses along the output power

traces and also to avoid the pick-up of any common mode noise. Connecting these pins in

points far from the load will cause a non-optimum load regulation, increasing output

tolerance.

Current Reading: The Rg resistors have to be placed as close as possible to the CSx- and

CSx+ pins in order to limit the noise injection into the device; this is still valid also for the

Rg(RC)-Cg network used when sensing current across the inductor. The PCB traces

connecting these resistors to the reading point must use dedicated nets, routed as parallel

traces in order to avoid the pick-up of any common mode noise.

Figure 24.

Device orientation (left) and sense nets routing (right: red for Lsense,

black for LSsense)

It's also important to avoid any offset in the measurement and, to get a better precision, to

connect the traces as close as possible to the sensing elements. Symmetrical layout is also

suggested.

Small filtering capacitor can be needed between VOUT and SGND on the CSx- line, placed

near the controller, allowing higher layout flexibility in the current sense connection.

VCCDR

L6711TR Datasheet(PDF) 46 Page - STMicroelectronics