Only For Training And Service Purposes - LG GB220 Service Manual

▪ Microphone Supply
X-GOLD™213 has a single ended power-supply concept for electric microphones:
For both modes a minimal load capacitance of t.b.d. nF is necessary to guarantee stable operation of the
buffer.
The maximal load capacitance must not exceed t.b.d. nF.
2 microphone supplies VMIC and VUMIC are available. The supply VUMIC has a ultra-low-power mode, where
the current consumption is minimum, whilst at the same time the noise performance is reduced.
Configuration can be done with AFE_AUDIOINCTRL, DIGMIC_CONTROL2.For this purpose the VUMIC is
directly supplied out of the VMIC regulator, the Mic-Buffer can be switched off and only the quiescent current
of the VMIC regulator is present. This mode can be used to supply a headset and allow accessory detection
with highly reduced current consumption For normal operation the supply can be switched to normal
operation mode with improved noise performance. The supply voltage can be chosen with
AFE_AUDIOINCTRL.VMICSEL. In case of an digital microphone VMIC can be used for supplying this
microphone.
Figure 3.12.5 Typical Microphone Supply Generation (alternative)
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Copyright © 2007 LG Electronics. Inc. All right reserved.
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3. TECHNICAL BRIEF
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