L6714 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
L6714
STMicroelectronics
'L6714' PDF : 70 Pages View PDF
Embedding L6714 - Based VR
25 Embedding L6714 - Based VR
L6714
When embedding the VRD into the application, additional care must be taken since the
whole VRD is a switching DC/DC regulator and the most common system in which it has to
work is a digital system such as MB or similar. In fact, latest MB has become faster and
powerful: high speed data bus are more and more common and switching-induced noise
produced by the VRD can affect data integrity if not following additional layout guidelines.
Few easy points must be considered mainly when routing traces in which high switching
currents flow (high switching currents cause voltage spikes across the stray inductance of
the trace causing noise that can affect the near traces):
Keep safe guarding distance between high current switching VRD traces and data buses,
especially if high-speed data bus to minimize noise coupling.
Keep safe guard distance or filter properly when routing bias traces for I/O sub-systems that
must walk near the VRD.
Possible causes of noise can be located in the PHASE connections, MOSFET gate drive
and Input voltage path (from input bulk capacitors and HS drain). Also PGND connections
must be considered if not insisting on a power ground plane. These connections must be
carefully kept far away from noise-sensitive data bus.
Since the generated noise is mainly due to the switching activity of the VRM, noise
emissions depend on how fast the current switches. To reduce noise emission levels, it is
also possible, in addition to the previous guidelines, to reduce the current slope by properly
tuning the HS gate resistor and the PHASE snuber network.
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