LiteOn U170ATA User manual

17-inch LCD Monitor
U170ATA
Service Manual

Circuit Description Index
U170ATA
1. Audio circuit --------------------------------------------------------------------------------------------------------------- 1
1.1 Audio input ------------------------------------------------------------------------------------------------------------ 1
1.2 Audio output ---------------------------------------------------------------------------------------------------------- 1
2. Power supply -------------------------------------------------------------------------------------------------------------- 1
3. Video input circuit -------------------------------------------------------------------------------------------------------- 1
4. Definition converter LSI peripheral circuit ---------------------------------------------------------------------------- 1
5. System reset, LED control circuit --------------------------------------------------------------------------------------- 1
6. E2PROM for PNP --------------------------------------------------------------------------------------------------------- 1
7. E2PROM -------------------------------------------------------------------------------------------------------------------- 2
8. CPU circuit ----------------------------------------------------------------------------------------------------------------- 2
8.1 Dection of POWER switch status ---------------------------------------------------------------------------------- 2
8.2 Display mode identification ----------------------------------------------------------------------------------------- 2
8.3 User control ----------------------------------------------------------------------------------------------------------- 4
8.4 Control of identification converter LSI (IC 14) ------------------------------------------------------------------ 5
8.5 I2C bus control -------------------------------------------------------------------------------------------------------- 5
8.6 Power ON sequence -------------------------------------------------------------------------------------------------- 6
8.7 Power OFF sequence ------------------------------------------------------------------------------------------------- 7
8.8 List of CPU assignments --------------------------------------------------------------------------------------------- 8
Table of Contents

Page 1Circuit Description
U170ATA
1. Audio circuit (Circuit diagrams Main PWB 1/1 JACK PWB 1/1)
1.1 Audio input
The audio signal input received from the audio input terminal (JK011) is applied to the pre-amplifier I006 of
2 (L-CH) and 29 (R-CH) through the low-pass filter consisting of R047, R049, R048, R050, C062 and C063.
In this pre-amplifier, controls of Volume, Balance, Bass, and Treble are conducted. The audio signal controlled
at the pre-amplifier is entered in and amplified at the AMP I007 of 9 (L-CH) and 1 (R-CH). Since then, the signal
is to the output jack.
1.2 Audio output
The audio signal is output from the output terminal (P012) of the jack to the speaker system.
2. Power supply (Circuit daigrams MAIN PWB 8/10, 9/10, 10/10)
1. I322:DC-DC converter
A 5V power supply for LCD module, CPU, and logic is generated from the 19V source.
2. I323:3-terminal regulator
A 3.3V power supply for Scaler IC I315, LVDS IC I319, I320 is generated from the 5V source.
3. I330:3-terminal regulator
A 3.3V power supply for SDRAM IC I316, I317, I318 is generated from the 5V source.
4. I324:3-terminal regulator
A 2.5V power supply for Scaler IC I315 is generated from the 5V source.
Q307, I321 ON/OFF control for LCD Module
ON/OFF control is performed for power ON/OFF and also for the power saving sequence.
3. Video input circuit (Circuit diagram MAIN PWB 4/10)
The AC-coupled video signal is used to clamp the black level at 0V).
4. Definition converter LSI peripheral circuit (Circuit diagram MAIN PWB)
I315 gm5020 is the definition converter LSI.
The analog R, G, B signal input entered from the video input circuit is converted into the digital data of video
signal through the incorporated A/D converter. Based on this conversion, this device performs interpolation
during pixel extension. The source voltage for this device is 3.3V, 2.5V and the system clock frequency is
24MHz. The withstand voltage level for the input signal voltage if I315 is 3.3V and 5V.
5. System reset, LED control circuit (Circuit diagram MAIN PWB 3/10)
5.1 System reset
System reset is performed by detecting the rising and falling of the 5V source voltage at I301.
5.2 LED control circuit
Green / amber is lit with the control signal of the LED GREEN and LED AMBER signal pin 15, 12 from I306
(Circuit diagram MAIN PWB 2/8).
6. E2PROM for PnP (Circuit diagram MAIN PWB 4/10)

Page 2 Circuit Description
U170ATA
7. E2PROM (Circuit diagram MAIN PWB 3/10)
Data transfer between I305 (AT24 C16) and CPU (Circuit diagram MAIN PWB 2/8 (I302) is effected through
the IIC bus SCL (pin 15) and SDA (pin 16) of I302. The data to be transferred to each device are stored in I305.
l I315 control data.
l OSD related setting data.
l Other control data for service menu.
8. CPU circuit (Circuit diagram MAIN PWB 3/10)
I302 (87C51RD2) functions as the CPU.
The source voltage for the device is 5.0V and the system clock frequency is 24MHz.
8.1 Detection of POWER switch status
The CPU identifies the ON status of the two power supplies. The identification is made when the power supply
is turned off. For example, if the power supply is turned off with the POWER switch, the POWER switch must be
turned on when activating the power supply again. If the power supply is turned off by pulling out the power
cord, then this power supply can be turned on by connecting the power cord, without pressing the POWER
switch.
8.2 Display mode identification
8.2.1 Functions
(1) Display mode identification
l The display mode of input signal is identified based on Table 1.
l When the mode has been identified through the measurement of horizontal and vertical frequencies, the total
number of lines is determined with a formula of  Horizontal frequency / Vertical frequency = Total number
of lines. Final identification can be made by examining the coincidence of the obtained figure with the
number of lines for the mode identified from the frequency. The boundary number of lines in each mode is
shown in Table 2.
l When the detected frequency if the sync signal has changed, the total number of lines should be counted even
through it is rge identified frequency in the same mode.
(2) Power save mode.
This power save mode is assumed when the frequency of the horizontal / vertical signal is as specified below.
l Vertical frequency : 50 ~ 86 Hz
l Horizontal frequency : 24 ~ 92 KHz
lVTOTAL : 1200 or more.
(3) Power save mode.
The power save mode is assumed when the horizontal / vertical signals are as specified below.
l If there is no horizontal sync signal input.
l If there is no vertical sync signal input.
l If the horizontal sync signal is outside the measuring range of gm5020.
l If the vertical sync signal is outside the measuring range of gm5020.

Page 3Circuit Description
U170ATA
Table 1
PolarityMode Resolution H-fre
q
(
KHz
)
Band Width
(MHz) HV
1. VGA 720 x 400 70Hz 31.47 28.322 - +
2. VGA 640 x 480 60Hz 31.47 25.175 - -
3. MAC 640 x 480 66Hz 35 32.24 - -
4. VESA 640 X 480 72Hz 37.86 31.5 - -
5. VESA 640 X 480 75Hz 37.5 31.5 - -
6. VESA 640 X 480 85Hz 43.27 36 - -
7. VESA 800 x 600 56Hz 35.16 36 + +
8. VESA 800 x 600 60Hz 37.88 40 + +
9. VESA 800 x 600 75Hz 46.88 49.5 + +
10. VESA 800 x 600 72Hz 48.08 50 + +
11. VESA 800 x 600 85Hz 53.67 56.25 + +
12. MAC 832 x 624 75Hz 49.72 57.283 - -
13. VESA 1024 x 768 60Hz 48.36 65 - -
14. VESA 1024 x 768 70Hz 56.48 75 - -
15. VESA 1024 x 768 75Hz 60.02 78.75 + +
16. VESA 1024 x 768 85Hz 68.68 94.5 + +
17. VESA 1280 x 1024 60Hz 64 108 + +
18. VESA 1280 x 1024 75Hz 80 135 + +
19. VESA 1280 x 1024 85Hz 91.1 157.5 + +
20. VESA 1152 x 864 75Hz 67.5 108 + +
21. VESA 1280 x 960 60Hz 60 108 + +
22. VESA 1280 x 960 85Hz 85.9 148.5 + +

Page 4 Circuit Description
U170ATA
Table 2 the number of the lines, Vsync distinction
9.3 User Control
9.3.1 Related ports of I315 and pin of I302
Indication resolution The number of the
distinction lines
Distinction Vsync The fixed mode
640 x 480 487 < LINE < 607 fV < 63 Hz 2
63 Hz < fV < 68 Hz 3
68 Hz < fV < 74 Hz 4
74 Hz < fV < 78 Hz 5
78 Hz < fV 6
800 x 600 607 < LINE < 777 fV < 58 Hz 7
58 Hz < fV < 63 Hz 8
63 Hz < fV < 73 Hz 10
73 Hz < fV < 78 Hz 9
78 Hz < fV 11
832 x 624 640 < LINE -12
1024 x 768 768 < LINE < 870 fV < 63 Hz 13
68 Hz < fV < 73 Hz 14
73 Hz < fV < 78 Hz 15
78 Hz < fV 16
1152 x 864 870 < LINE < 1031 20
1280 x 960 960 < LINE < 1027 21, 22
1280 x 1024 1027 < LINE 17, 18, 19
9.3.2 Functions
Control is effected for the push-switches to be used when the user changes the parameters, in order to modify the
respective setting values. Whether the switch has been pressed is identified with the switch input level that is
turned L.
Each switch input port is pulled up at outside of ASIC
Each parameter is stored in the EEPROM, the contents of which are updated as required.
.
Port Pin No. I/O Si
g
nal name Function Remarks
GPI04 I315
,
M1 1 MENU EXIT/ENTER switch in
p
ut ENTER/Withdraw
from OSD
GPI05 I315
,
L1 1 DOWN switch input ( ) key
GPI06 I315
,
G18 1 - switch input ( ) key
GPI07 I315
,
G19 1 + switch input ( ) key
GPI0 I302
,
15 1 POWER soft power switch input ( power ) key

Page 5Circuit Description
U170ATA
8.4.2 Functions
Major function of I315 are as follows:
(1) Expansion of the display screen.
(2) Timing control for various signal types.
(3) Power-supply sequence (LCD panel).
8.5 I2C bus control
8.5.1 Related ports of I302
Port Pin No. I/O Si
g
nal name Function
P3.5 17 I IICCLK IIC bus clock
P3.4 16 I/O IICDATA IIC bus data
8.5.2 I2C-controlled functions
The following functional controls are effected by I2C.
(1) Control of EEPROM I305f for parameter setting.
(2) Control of audio preamplifier.
8.4 Control of definition converter LSI I315
Pin No. I/O Si
g
nal name Function
R3 I IRQ gmZan1 interrupt signal
P1 O HCLK gmZan1 serial clock
P3, P4,
R1
,
R2
I/O HDATA gmZan1 serial data
P2 O HFS gmZan1 serial select
8.4.1 Ports related to control

Page 6 Circuit Description
U170ATA
8.6 Power ON sequence
When the POWER switch is pressed, the POWER OFF signal is turned H. When this H potential is detected,
the CPU begins to establish the respective power supplies according to the sequence shown below.
POWER
LED
LVCC
(Audio_EN)
Panel_VCC
PCLK/DATA
Backlight_EN

Page 7Circuit Description
U170ATA
8.7 Power OFF sequence
When the POWER switch is pressed while the power supply is ON, the POWER ON signal is turned H. When
this H potential is detected, the CPU begins to turn off the respective power supplies according to the sequence
shown below.
POWER
LED
LVCC
(Audio_EN)
Panel_VCC
PCLK/DATA
Backlight_EN

Page 8 Circuit Description
U170ATA
Port Pin No. Signal Name Initial Setting Function Remark
~ 1NC ~ ~
P1.0 2HDATA0 ~ gm5020 4bit interface data
P1.1 3HDATA1 ~ gm5020 4bit interface data
P1.2 4HDATA2 ~ gm5020 4bit interface data
P1.3 5HDATA3 ~ gm5020 4bit interface data
P1.4 6HCLK ~ gm5020 4bit interface Clock
P1.5 7HFS ~ gm5020 data enable
P1.6 8Bank ~ ~
P1.9 9PWM ~ Pulse width modulation
~10 RST L Reset CPU Active H
P3.0 11 RXD H Receive data
~12 NC ~ ~
P3.1 13 TXD H Transmit data
P3.2 14 IRQ ~ gm5020 interrupt signal
P3.3 15 PWR_SW ~ ON/OFF monitor power
P3.4 16 SDA H IIC Bus Data
P3.5 17 SCL ~ IIC Bus Data Active L
P3.6 18 P3.6 H External Memor
y
Write Enable
P3.7 19 DDC_GND L Detect Dsub cable plug-in
~20 XTAL2 ~ Crystal signal out
~21 XTAL ~ Crystal signal in
~22 GND ~ ~
~23 NC ~ ~
P2.0 24 A8 ~ High-order address byte
P2.1 25 A9 ~ High-order address byte
P2.2 26 A10 ~ High-order address byte
P2.3 27 A11 ~ High-order address byte
P2.4 28 A12 ~ High-order address byte
P2.5 29 A13 ~ High-order address byte
P2.6 30 A14 ~ High-order address byte
P2.7 31 A15 ~ High-order address byte
~32 PSEN# H Program store enable
~33 ALE ~ Address latch enable
~34 NC ~ ~
~35 EA# H External Access Enable
P0.7 36 D7(USB_ON) H USB HUB
p
ower Enable
(
o
p
tion
)
P0.6 37 D6(MUTE) H Audio MUTE Enable
P0.5 38 D5(LVCC) L Audio suspend Enable
P0.4 39 D4(LEDGRN) H LED Green ON
P0.3 40 D3
(
LEDAMBER
)
L LED AMBER ON
P0.2 41 D2(BKLT_EN) ~ Inverter Back light Enable
P0.1 42 D1
(
LVDS ON
)
H LVDS IC Enable
P0.0 43 D0
(
PANEL EN
)
H Panel power Enable
~44 VCC ~ VCC
8.8 List of CPU Pin Assignments