WM8958 Datasheet, PDF (365/377 Pages) Wolfson Microelectronics plc – Multi-Channel Audio Hub CODEC for Smartphones

Pre-Production
WM8958
Figure 87 Digital Microphone Connection
The MICBIAS generators can each operate as a voltage regulator or in bypass mode. See “Analogue
Input Signal Path” for details of the MICBIAS generators.
In Regulator mode, the MICBIAS regulators are designed to operate without external decoupling
capacitors. It is important that parasitic capacitances on the MICBIAS1 or MICBIAS2 pins do not
exceed the specified limit in Regulator mode (see “Electrical Characteristics”).
If the capacitive load on MICBIAS1 or MICBIAS2 exceeds the specified limit (eg. due to a decoupling
capacitor or long PCB trace), then the respective generator must be configured in Bypass mode.
The maximum output current is noted in the “Electrical Characteristics”. This limit must be observed
on each MICBIAS output, especially if more than one microphone is connected to a single MICBIAS
pin. Note that the maximum output current differs between Regulator mode and Bypass mode. The
MICBIAS output voltage can be adjusted using register control in Regulator mode.
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PP, August 2012, Rev 3.4
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