Samsung SCH-570 Service Manual page 7

5-1-3 Baseband Part
MOBILE STATION MODEM (MSM)
The MSM equipped with the INTEL 80186 CPU
core is an important component of the CDMA
cellular phone. The MSM comes in a 176 pins
TQFP package.
MICROPROCESSOR INTERFACE
The interface circuitry consists of reset circuit,
address bus (A0-A19), data bus (AD0-AD15), and
memory controls (ALE, DT_R, HWR/, LWR/,
RAM_CS/, ROM_CS etc).
INPUT CLOCK
CPU clock: 27 MHz
TCXO/4 (pin 34): 4.92 MHz. This clock signal
from the BBA is the reference clock for the MSM
except in CDMA mode.
CHIPX8 : 9.8304 MHz. The reference clock used
during the CDMA mode.
BBA INTERFACE
CDMA, FM Data Interface
TXIQDATA0-7 (pins 24-32) : TX data bus used
during both CDMA and FM mode but it is used
only for CDMA mode at this phone.
Clock
TC_CLK (pin 22), TX_CLK/(pin 23) : Digital to
Anolog Converter (DAC) reference clock used in
CDMA TX mode.
CHIPX8 : ADC reference clock used in CDMA
RX mode.
ADC Interface
ADC_CLK (pin 3), ADC_ENABLE (pin 1) and
ADC_DATA (pin 2) are required to control the
internal ADC in the BBA.
Data Port Interface
Includes the UART. Also, supports Diagnostic
Monitor (DM), HP equipment interface, down
loading, and data service.
CODEC Interface
The MSM sends 2.048 MHz PCM_CLK (pin 19)
and 8 KHz PCM_SYNC (pin 16, 20) to the CODEC
(U117). The voice PCM data from the MSM (U101)
PCM_DIN (pin 135) is compressed into 8 KHz, by
QCELP algorithm in the CDMA mode.
RF Interface
TX : TX_AGC_ADJ (pin 35) port is used to control
the TX power level and PA_ON (pin 44) signal is
used to control the power amplifier. This signal
depends on the TX vocoder rate.
RX : AGC_REF (pin 36) port is used to control the
RX gain and TRK_LO_ADJ (pin 45) is used to
compensate the TCXO clock.
General Purpose I/O Register Pins
Input/output ports to control external devices.
Power Down Control
When the IDLE/ signal turns to LOW, only the TX
sections will be disabled. If both the IDLE/ and
SLEEP/ change to LOW, all the pins except for the
TCXO and 27MHz clock are disabled.
5-2