4. TROUBLE SHOOTING
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4. TROUBLE SHOOTING
4.11 LTE VCXO Trouble
The reference frequency(19.2MHz) from X200(VCTCXO) is used for system clock. The AFC is calibrated to
generate the 19.2MHz with very low ppm.
The AFC voltage is about 1.4V at R205(TP1) point and VCC voltage is about 2.8V at C201.(TP2)
The 26MHz must be checked at C202.(TP3)
TP1
TP1
TP2 TP3
TP2
TP3
C201
TP1
TP2
R200
C204
Figure 4.2
10n
C205
100n
C200
200K
R203
2V8_TCXO
33
R202
U200
NL17SZ04XV5T2G
3
4
2
5
VCC
GND
2V8_TCXO
10n
C201
100n
C204
33n
C203
100
R200
19.2MHz
X200
TG-5025CG-19_2M
3
2
6
5
4
1
VC
VCC
TP1
TP2
GND
OUT
TCXO_IN
AFC_OUT
REF_CLK_OUT
TP2
TP1
TP3