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5.1
Failure Diagnosis of IC8
Overview:
VCO/PLL IC (IC8) This is a flowchart for checking the problem.
Parts information:
QFN (Quad Flat Non-lead package)
When exchanging parts, it is recommended to use QFN replacement equipment.
● Check power supply voltage <1>
Checking voltage
VIN IC2(4pin)
● Check power supply voltage <2>
Points to be checked
VDD IC8(28pin)
● Check for reset and power down
Points to be checked
PDN IC8(21pin)
RSTN IC8(20pin)
● Check serial control signal
Points to be checked
CSN IC8(1pin)
Points to be checked
SCLK IC8(2pin)
Points to be checked
SDATAI IC8(3pin)
Measurement condition:
Receive standby
oscilloscope
4us/div 1V/div
Band 100 MHz or more is recommended
● Check the reference clock
Voltage check
Points to be checked
REFCKIN IC8(35pin)
Frequency check
Points to be checked
REFCKIN IC8(35pin)
Measurement condition:
Receive standby
oscilloscope: 10ns/div 500mV/div
Band 100 MHz or more is recommended.
● CV Checking voltage
Points to be checked
Test land TL27
Measurement condition:
PTT ON
Digital multi meter
● Check RF signal output
Points to be checked
RF out B IC8(17pin)
Measurement condition:
PTT ON
Spectrum analyzer or power meter
Failure other than IC8.
1-32 (No.RA066<Rev.001>)
SECTION 5
TROUBLESHOOTING
Regular voltage
Fail
3.8V
Pass
Regular voltage
Fail
3V
Pass
Regular voltage
3V
Fail
3V
Pass
Regular voltage waveform
3Vp-p
Regular voltage waveform
Fail
3Vp-p
Regular voltage waveform
3Vp-p
Pass
Regular voltage waveform
Fail
0.2Vp-p or more
Regular frequency
50.4MHz
Fail
Pass
Regular voltage
1.2V
Fail
Pass
Regular power
-10dBm or more
Fail
Pass
When pin 4 of VIN IC2 is irregular voltage, it is a failure other
than IC8.
If VDD is irregular voltage, remove R25 and check 3MS
voltage. Even if R25 is removed, in case of irregular voltage,
failure other than IC8.
· When PDN is irregular voltage, connection failure between
PDN-IC7 (MCU) and IC7 error. Remove R25 and check the
voltage on IC7 side. When the IC7 side becomes regular
voltage, failure of R25 or connection failure with IC8. If there is
no abnormality in these, failure of IC8.
· When RSTN is irregular voltage, connection failure between
RSTN - IC7 (MCU) or IC7 failure . Remove R60 and check the
voltage of pin 46 of IC7. If the IC7 side becomes regular
voltage, failure of R60 or poor connection with IC8. If it is still
irregular voltage, failure of C73. If there is no abnormality in
these, failure of IC8.
· If CSN is irregular voltage waveform, it is a connection failure
with IC7 (MCU) or IC7 failure. Remove R50 and check the
voltage of IC7 pin 44. When the IC7 side becomes regular
voltage, it is a failure of R50 or a connection failure with IC8. If
there is no abnormality in these failure of IC8.
· If SCLK is irregular voltage waveform, it is a connection
failure with IC7 (MCU) or IC7 failure. Remove R52 and check
the voltage of IC7 45 pin. When the IC7 side becomes regular
voltage, fail of R 52 or C 61 or connection failure with IC8. If
there is no abnormality in these, failure of IC8.
· If SDATAI is irregular voltage waveform, it is a connection
failure with IC7 (MCU) or IC7 failure. Remove R53 and check
the voltage at pin 43 of IC7.When IC7 side becomes normal
voltage failure of R53 or C68 or connection failure with IC8 . If
there is no abnormality in these, failure of IC8.
When REFCKIN is irregular voltage waveform, failure other
than IC8.
If REFCKIN is irregular frequency, failure other than IC8.
When TL 27 is 0 V, the circuit failure around LOOP FILTER.
If RF OUT B is irregular power, remove C 108, C 109. When it
is still irregular power, exchange in order of L16, R79, L14,
R73. If there is no abnormality in these, a failure of IC8.
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