NSD–1
Disassembly / Troubleshooting Instructions
PAMS Technical Documentation
Page 8
Issue 2 09/00
Nokia Mobile Phones Ltd.
The third regulator is used to power the DSP portion of MAD4. It is en-
abled by Vbb, and difference between the rise times of the DSP regulator
and Vbb should be less than 200usec. This regulator is 2.8V nominal and
can be checked on pin 1, 30, or 115 of the MAD4 ASIC.
Clocks
Sleep Clock
The 32kHz sleep clock is generated by CCONT, and can be checked at
TP26. The 32kHz square wave will be present only after the phone is
turned on. If no signal is present on this line, check the output of the oscil-
lator at R304. This signal should be a 2Vp–p clipped signal riding on 1.5V
DC.
System Clock
The 19.2MHz system clock is generated by the VCTXO in the RF section,
and then squared in CAFE. Check TP20, which should be approximately
a 0.5V sinewave riding on 1.8V DC. Check TP22, which should be a 2.8V
squarewave. This clock is not active during the phone’s sleep mode
(CLK_EN is low during sleep mode).
CDMA clock
The CDMA clock is 9.8MHz and is generated in CAFE with a PLL. This
should be a 2.8V square wave and can be verified at TP21.
Charging Circuit
The charging switch, CHAPS, is controlled by a PWM from CCCONT.
This PWM can be at 1Hz or at 32Hz, with varying duty cycles, and should
only be active when a charger is detected. The frequency should be 1Hz
when an ACP–7 is detected and 32Hz when an ACP–9 is detected. To
verify correct operation of CHAPS, monitor the charging current (ICHAR)
with the service software. When the PWM is off, current should be
approximately 200uA. When the PWM is on, it should be greater than
approximately 300mA.
CAFE
The CAFE ASIC performs various functions with respect to the RF circuit-
ry and audio. It digitizes the analog voice signals from the microphone as
well as converts received digital data to voice signals to be sent to the ear-
piece. This also includes accessory microphones and speakers. It also
generates and decodes I and Q data for CDMA, and demodulates FM
(AMPS) signals. CAFE also acts as a clock squaring circuit and CDMA
clock generator.
Microphones
The internal microphone is biased using transistor V201, which is pow-
ered by VR1_SW (TP11 2.75VDC). Check also the output of V201).
