L6997S datasheet(21/30 Pages) STMICROELECTRONICS

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L6997S

7.2 DEMO BOARD LAYOUT

Real dimensions: 5.7cm x 7.7cm (2.28inch x 3. 08inch)

Figure 18. PCB layout: bottom side

Figure 19. PCB Layout: Top side

Figure 20. Internal ground plane

Figure 21. Power & signal plane

Table 12. PCB Layout guidelines

Goal

Suggestion

To minimize radiation and magnetic

coupling with the adjacent circuitry.

1) Minimize switching current loop areas. (For example placing CIN, High Side

and Low side MOSFETS, Shottky diode as close as possible).

2) Place controller placed as close as possible to the power MOSFETs.

3) Group the gate drive components (Boot cap and diode) near the IC.

To maximize the efficiency.

Keep power traces and load connections short and wide.

To ensure high accuracy in the

current sense system.

Make Kelvin connection for Phase pin and PGND pin and keep them as close

as possible to the Low Side MOSFETS.

To reduce the noise effect on the IC.

1) Put the feedback component (like output divider, integrator network, etc) as

close as possible to the IC.

2) Keep the feedback traces parallel and as close as possible. Moreover they

must be routed as far as possible from the switching current loops.

3) Make the controller ground connection like the figure 8.

L6997S Datasheet(PDF) 21 Page - STMicroelectronics