Philips 37PF9631D/37 Service Manual page 110

EN 110 9. EJ2.0U LA
9.2.3 DC Protection Circuitry
See figure ""DC protection circuitry" for details.
DC-Protection + Protection Latch
Protection if DC Level
from output is >1V DC
Average =0V
Protection if DC Level
from output is <-1V DC
DC protection in normal operation
During normal operation the output signal of the DC protection
circuitry (PROT-AUDIOSUPPLY) is "low".
DC protection in protection mode
When the circuitry goes into protection, the output of the
circuitry (PROT-AUDIOSUPPLY) will go to "high".
When a DC voltage < -1V or > +1V occurs on one of the inputs,
9.3 Back-end
In this chassis an FPGA (or EPLD or MOP) is used for
AmbiLight processing and for addressing the LCD display.
9.3.1 Display Control
CMOS
MOP2K5
VIPER
Spartan 3
XCF01S
PNX2015
PWM Dimming
To convert PWM to analogue
Figure 9-9 Block diagram display control
The video signal coming from the Viper is directly fed to the
Pacific 3 through an CMOS connection. The FPGA ("Spartan
3") however is used for AmbiLight processing through an I
connection. The signal for Dimming Backlight is coming from
the MOP and can be analogue or pulse-width modulated,
depending on which display is used.
Circuit Descriptions, Abbreviation List, and IC Data Sheets
+1V
3D13
2k7
3D10
2D11
47k
2u2
3D14
220k
3D17
220k
3D18
47k
3D21
2k7
-1V
Figure 9-8 DC protection circuitry
LVDS
Vdisp /+12V
LVDS
PNX2015
CMOS
LVDS
I2C4
Level
AmbiLight
I 2 C Ambi
shift
LCD
MUX
inverter
Analog or PWM Dimming
G_15940_061.eps
3D12
5k6
3D89
22k
7D10-1
3D16
3D15
2k2
47k
2D01
7D11-1
BAS316
BC847BS
7D10-4
3D19
47k
7D11-2
BC847BS
the output of the opamp connected to that input will change
from "high" to "low". Transistor 3D16 will block and 7D11-2 will
conduct resulting line PROT-AUDIOSUPPLY going "high". The
power supply will be switched off and an error code 14 will be
generated causing the LED to blink.
Important: the only way to reset DC protection is by
disconnecting the set from mains!
The signal for Scanning Backlight is an I
Viper. The MOP interfaces:
• CMOS video input.
2
• I C output for driving the AmbiLight unit.
• Additional configuration flash memory.
260506
2
C
Protection
To PNX and Supply
3D20
22k
H = Protection
3D22 2D63
10k 10n
G_15940_062.eps
2
C signal coming from
260506