26 Mhz Clock (Vctcxo, X400); Power Supplies For Rf Circuits (Rf Ldo, U403) - LG KG245 Service Manual
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- User manual (225 pages) ,
- User manual (165 pages) ,
- User manual (84 pages)
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3. TECHNICAL BRIEF
3.3 26 MHz Clock (VCTCXO, X400)
The 26 MHz clock(X400) consists of a VCTCXO(Temperature Compensated Crystal Oscillator) which
oscillates at a frequency of 26 MHz. It is used within the Si4205, analog base band chipset (U101,
AD6537B), digital base band chipset (U102, AD6527)
3.4 Power Supplies for RF Circuits (RF LDO, U403)
Two regulators are used for RF circuits. One is MIC5255 (U403), and the other is one port of AD6537B
(U101). MIC5255 (U403) supplies power to transceiver (SI4210, U401). One port of AD6537B supplies
power to VVCXO (X400). Main power (VBAT) from battery is used for PAM (SKY77328, U400) because
PAM requires high power.
Supplier
U403(RF)
U102(VVCXO)
Battery(VBAT)
2V75_VVCXO
R416
100
C442
C443
2.2u
NA
Figure 3-5 VCTCXO CIRCUIT DIAGRAM
Voltage
2.85 V
2.75 V
3.4 ~ 4.2 V
Table 3-2 RF POWER SUPPLIERS
X400
R417
3
1
OUT
VCONT
15K
4
2
VCC
GND
26MHz
C441
1000p
PowersPowers
U401
X400
U400, U403
- 20 -
AFC
enabled signal
CLKON
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