LG ID2750 Service Manual page 26

LG-ID2750
MIC signals are inputted into the audio codec, and amplified with programmable gain, and converted
into digital signals(PCM). Then, they are inputted into MSM6000.
In addition, digital audio signals(PCM) outputted from MSM6000 are converted into analog signals
after going through the audio codec. These signals are amplified with programmable gain on codec's
internal AMP and external MIDI Synthesizer, transferred to the ear-piece.
2.3.3 Memory Part
The memory part consists of a 32Mbits Flash Memory and a 16Mbits SRAM. On the Flash Memory,
there are programs used for the operation of a mobile station and the non-volatile data of the mobile
station such as a ESN(Electronic Serial Number) are stored. The programs can be changed through
down loading after the assembling of mobile stations. On the SRAM, data generated during the
operation of a mobile station are stored temporarily.
2.3.4 Power Supply Part
When the battery voltage (+4.2V) is fed and the PWR key of keypad is pressed, the power-up circuitry
in PM (power management) IC (U401) is activated by the PWR_ON_SW/ signal, and then the LDO
regulators embedded in PMIC for MSM are operated and +1.90V_MSMC, +2.85V_MSMP and
+2.6V_MSMA are generated.
The Rx part regulator (+2.6V_RX) is operated by the SBI(Seiral Bus Interface) control signal from
MSM6000. The Tx part regulator (+2.6V_TX) is operated by SBI(Seiral Bus Interface) control signal
from MSM6000.
The block diagram of power management IC is shown in [Figure 3-2].
[Figure 3-2] Block Diagram Of Power Management IC
LGE
LG Electronics Inc.
24/26