wm8400 Wolfson Microelectronics plc, wm8400 Datasheet - Page 206

• Manufacturer Part Number: wm8400
• Description: Wolfson Audioplustm Hi-fi Audio Codec And Power Management Unit For Mobile Multimedia
• Manufacturer: Wolfson Microelectronics plc

WM8400
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Figure 108 EMI Reduction Techniques
POWER MANAGEMENT (DC-DC / LDO CONNECTIONS)
The tracking and component layout associated with the DC Converters and LDO Regulators is
particularly important, as the ripple currents in these circuits can be prone to coupling into other
circuits.
Ripple current can flow from a DC-DC converter input capacitor, through the WM8400 to the output
capacitor and back to the input through the ground trace. It is therefore advisable to keep all such
tracking loops as small as possible.
A single load connection point should be used at the output of each DC Converter or LDO Regulator.
A ‘star’ connection point should be provided for the ground connection to each DC Converter or LDO
Regulator; these should connect to the main system ground as close to the chip as possible.
High current PCB tracks for the Power Management circuits should be short and wide, as far as
possible. All Power Management tracks should be kept on the component side of the PCB in order to
avoid impedance through vias.
PP, April 2009, Rev 3.0
Pre-Production
206