Nokia C2-00, Руководство по обслуживанию

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Baseband electrical interfaces: Audio components
DC blocking capacitors C2102 are inserted to center the audio input around the internal bias level. The
microphone circuit is configured in pseudo-differential mode. VMIC is used for the bias. A low-pass filter
comprising R2100 and C2101 is used to remove any potential noise picked-up by VMIC.
The external microphone for the headset is connected via filtering components to the second differential
microphone input MICP2 and MICN2, and is designed pseudo-differentially for better noise immunity. DC
blocking capacitors C2107 are used. VUMIC for the biasing. A low-pass filter comprising R2105 and C2105
removes any potential noise picked-up by VUMIC.
Figure 66 Earpiece and loudspeaker components
R2511 and R2510 are matching resistor to adapt to high impedance of IHF.
Baseband electrical interfaces: Backlight and illumination
The backlight supply is implemented using the integrated boost converter control circuit of X-Gold213.
The converter circuit is running in the analog feedback control mode, where the on time of the NMOS switch
V7009 is controlled by a comparator triggered by the inductor peak current, while the off time is controlled
by a counter, which resets the NMOS switch when it reaches a pre-programmed value.
RM-704
System Module
Issue 1 COMPANY CONFIDENTIAL Page 5 – 21
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