Only For Training And Service Purposes - LG KP105 Service Manual

3.15.1 FM Tunner
The Si4702 patented digital low-IF architecture reduces external components and eliminates the need
for factory adjustments. The receive (RX) section integrates a low noise amplifier (LNA) supporting the
worldwide FM broadcast band (76 to 108 MHz). An automatic gain control (AGC) circuit controls the
gain of the LNA to optimize sensitivity and rejection of strong interferers.
For two-wire operation, a transfer begins with the START condition. The control word is latched
internally on rising SCLK edges and is eight bits in length, comprised of a seven bit device address
equal to 0010000b and a read/write bit (write = 0 and read = 1). The device acknowledges the address
by setting SDIO low on the next falling SCLK edge. For write operations, the device acknowledge Is
followed by an eight bit data word latched internally on rising edges of SCLK.
The device always acknowledges the data by setting SDIO low on the next falling SCLK edge. An
internal address counter automatically increments to allow continuous data byte writes, starting with
the upper byte of register 02h, followed by the lower byte of register 02h, and onward until the lower
byte of the last register is reached. The internal address counter then automatically wraps around to
the upper byte of register 00h and proceeds from there until continuous writes cease. Data transfer
ceases with the STOP command. After every STOP Command, The internal address counter is reset.
For read operations, the device acknowledge is followed by an eight bit data word shifted out on falling
SCLK edges. An internal address counter automatically increments to allow continuous data byte
reads, starting with the upper byte of register 0Ah, followed by the lower byte of register 0Ah, and
onward until the lower byte of the last register is reached. The internal address counter then
automatically wraps around to the upper byte of register 00h and proceeds from there until continuous
reads cease. After each byte of data is read, the controller IC should return an acknowledge if an
additional byte of data will be requested. Data transfer ceases with the STOP command. After every
STOP command, the internal address counter is reset.
3.15.2 Headphone Amplifier
The LM4809 is a dual audio power amplifier capable of delivering 105mW per channel of continuous
average power into a 16Ω load with 0.1% (THD+N) from a 5V power supply.
Boomer audio power amplifiers were designed specifically to provide high quality output power with a
minimal amount of external components. Since the LM4809 does not require bootstrap capacitors or
snubber networks, it is optimally suited for low-power portable systems.
The unity-gain stable LM4809 can be configured by external gain-setting resistors.
The LM4809 features an externally controlled, active-low, micropower consumption shutdown mode,
as well as an internal thermal shutdown protection mechanism.
Copyright © 2008 LG Electronics. Inc. All right reserved.

Only for training and service purposes

3. TECHNICAL BRIEF
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LGE Internal Use Only