LG 512W, Service Manual

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3. TECHNICAL BRIEF
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3.4 13MHz Clock
The 13 MHz clock (VC-TCXO-208C) consists of a TCXO (Temperature Compensated Crystal
Oscillator) which oscillates at a frequency of 13 MHz.
It is used within the Si4133G_XM2 Synthesizers, BB Analog chip-set (AD6521), and Digital
(AD6522). The inverter IC, SN74AHC1GU04 buffer the output to AD6521, AD6522 and
Si4133G_XM2.
Figure 3-8. VCTCXO Circuit.
3.5 Power Supplies and Control Signals
There are two regulators used in the phone to provide RF power. One is contained inside of
ADP3408 (U1), power management IC to provide the power for the VCTXO (X302). The other is
used to provide the power for remaining RF circuits.
Table 3-7. Power Supplies
Figure 3-9. Regulator Circuit.
Regulator Voltage Powers Enable Signal
Regulator 1 (U1, 2V7_VTCXO) 2.7 V
± ±
0.5 V VCTXO
Regulator 2 (U309, RF2V8) 2.85 V
± ±
0.5 V RF circuitry VSYNTHEN