Philips LC4.5E Service Manual page 68

EN 68 9. LC4.5E AA
9.8.4 Audio: Lip Sync (Optional)
A "lip sync" circuit with an audio delay can be added (not for all
models/regions), in order to synchronise with video delay due
to the complexity of the display processing. This video delay is
significant, due to memory based processing. For instance, the
"frame rate conversion" causes a delay of two frames, while the
LCD panel response also causes a delay.
The circuit is a (16 bit) FIFO based digital delay. E.g.: the
memory size required for a 80 ms delay (with a data clock of
1.024 MHz) can be calculated with: Memory size = delay time
* f_clk. This gives: 80 ms * 1.024 MHz = 81920 bits.
To calculate the memory size for a 16 bits mode I
audio stream we must use the following data:
• f_s = 32 kHz, 16 bits, stereo
• Data clock = 32 kHz * 16 * 2 = 1.024 MHz
• Memory size for 1 ms delay = 1 ms * 1.024 MHz = 1024 bits
= 1 kbit
So, the delay time of 80 ms can be built with five steps of 16
ms, which is close to the frame rate. Therefore, a 128 kbit
SRAM (16 x 8) is chosen.
9.9.2 Block Diagram
The block diagram of the Micro Controller application is shown
below.
Sound
Sound_Enable
HREC
127
RST P1.4
Sel IF/
114
SDM P2.3
116
ADC1
Status1
115
ADC0
Light
Sense
123
P2.5
97
INT0
P50_LINE_ITV_IR_SW
RC
MUX
EXT_MUTE
TV_IR
Circuit Descriptions, Abbreviation List, and IC Data Sheets
2
S digital
Tuner
ComPair
NVM
Amp
NVM_WP
111 104
P2.0 P0.2
SDA 109
SCL 108
HERCULES
INT1 98
P1.1 99
ADC3 120
126
102 122 128
INT2
P0.4 P2.4 P1.5
Standby
POWER
DOWN
Figure 9-5 Micro controller block diagram
Note that above described calculation is just an example,
values in the set can deviate.
9.9 Control
9.9.1 Hercules
The System Board has two main micro-controllers on board.
These are:
• On-chip x86 micro-controller (OCM) from Genesis LCD TV/
Monitor Controller.
• On-chip 80C51 micro-controller from Philips
Semiconductor UOCIII (Hercules) series.
Each micro-controller has it own I
internal devices.
The Hercules is integrated with the Video and Audio Processor.
For dynamic data storage, such as SMART PICTURE and
SMART SOUND settings, an external NVM IC is being used.
Another feature includes an optional Teletext/Closed Caption
decoder with the possibility of different page storage depending
on the Hercules type number.
IIC BUS1
IIC BUS 2
93
92
NVRAM
NVRAM
_SDA
_SCL
SDA
78 DDC_SDA_VGA
SCL
77 DDC_SCL_VGA
TV_IRQ
82 GPIO1
TV_SC_COM
81 GPIO0
Keyboard
POWER_DOWN
90 GPIO7
111
103 106 107 108
GPIO23
+3V3STBY
HIGH or
LOW
level input
2
C bus which host its own
GPROBE for Debug
or ComPair(Scaler)
NVM
1407
1406
1405
NVM_WP
83 72
71
194 193 187
PC_DET
GPIO2
85
(GPIO4)
SD_PCHD_SEL
88
(GPIO5)
89
PC_HD_SEL
(GPIO6)
68
LAMP_ON_OFF
(PBIAS)
SCALER
PANEL_PWR_CTL
67
(PPWR)
HD_FILTER
99
(PWM1)
98 BACK_LIGHT_ADJ1
(GPIO11/
PWM0)
ROM_DATA0-7
5 6 7 ROM_ADD0-17
Flash ROM
+3V3STBY
E_14490_062.eps
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