Circuit Descriptions
EN 50
Q552.2L LA
7.
2011-Jul-15
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div. table
7.2
Power Supply
7.2.1
Power Supply Unit
All power supplies are a black box for Service. When defective,
a new board must be ordered and the defective one must be
returned, unless the main fuse of the board is broken. Always
replace a defective fuse with one with the correct
specifications! This part is available in the regular market.
Consult the Philips Service web portal for the order codes of the
boards.
In this manual, no detailed information is available because of
design protection issues.
7.2.2
Connector overview
Table 7-1 Connector overview
7.3
DC/DC Converters
The on-board DC/DC converters deliver the following voltages
(depending on set execution):
•
+3V3-STANDBY, permanent voltage for the Stand-by
controller, LED/IR receiver and controls; connector 1M95
pin 1
•
+12V, input from the power supply for TV550 common
(active mode); connector 1M95 pins 6, 7 and 8
•
+24V, input from the power supply for DVB-S2 (in active
mode); connector 1M09 pins 1 and 2
•
+1V1, core voltage supply for PNX855xx; has to be started
up first and switched "off" last (diagram B03B)
•
+1V2, supply voltage for analogue blocks inside PNX855xx
•
+1V8, supply voltage for DDR2 (diagram B03B)
•
+2V5, supply voltage for analogue blocks inside PNX855xx
(see diagram B03E)
•
+3V3, general supply voltage (diagram B03E)
•
+5V, supply voltage for USB and CAM (diagram B03E)
•
+5V-TUN, supply voltage for tuner (diagram B03E)
•
+V-LNB, input voltage for LNB supply IC (item no. 7T50)
•
+5V-DVBS, input intermediate supply voltage for DVB-S2
(diagram B08A)
•
+3V3-DVBS, clean voltage for silicon tuner and DVB-S2
channel decoder
•
+2V5-DVBS, clean voltage for DVB-S2 channel decoder
•
+1V-DVBS, core voltage for DVB-S2 channel decoder.
A +12 V under-voltage detector
(see diagram B03C) enables
the 12V to 3.3V and 12V to 5V DC/DC converters via the
ENABLE-3V3-5V line, and the 12V to 1.8V DC/DC converter
via the ENABLE-1V8 line. DETECT2 is the signal going to the
Stand-by microcontroller and ENABLE-3V3n is the signal
coming from the Stand-by microcontroller.
Diagram B03D
contains the following linear stabilizers:
•
+2V5 stabilizer, built around item no. 7UCO
•
+5V-TUN stabilizer, built around items no. 7UA6 and 7UA7
•
+1V2 stabilizer, built around items no. 7UA3 and 7UA4.
Diagram B08A
contains the DVB-S2-related DC/DC
converters and -stabilizers:
•
a +24V under-voltage detection circuitry is built around
item no. 7T04
•
the switching frequency of the 24 to 14...20V switched
mode converter is 350 kHz (item no. 7T03 and +V-LNB
lines)
•
the output signal on the +V-LNB line goes to the LNBH23Q
(item no. 7T50)
•
the LNBH23Q (item no. 7T50) sends a feedback signal via
the V0-CNTRL line
•
the switching frequency of the +5V-DVBS to +1-DVBS
switched mode converter is 900 kHz (item no. 7T00)
•
a delay line for the +2V5-DVBS and +1V-DVBS lines is
created with item no. 3T03 (R=10k) and 2T06 (C=100n)
•
a 3.3V to 2.5V linear stabilizer is built around item no. 7T01
•
a 5V to 3.3V linear stabilizer is built around item no. 7T02.
Diagram B08B
contains the DVB-S2 LNB supply:
•
the +V-LNB signal comes from item no. 7T03
•
the V0-CTRL signal goes to item no. 7T03
•
the LNB-RF1 goes to the LNB.
Figures gives a graphical representation of the DC/DC
converters with its current consumptions:
Figure 7-3 DC/DC converters
7.4
Front-End Analogue and DVB-T, DVB-C;
ISDB-T reception
7.4.1
Brazil region
The Front-End for the Brazil region consist of the following key
components:
•
Hybrid Tuner with integrated SAW filter and amplifier
•
External ISDB-T channel decoder covering the Brazilian
digital terrestrial TV standard
•
Bandpass filter
•
Amplifier
•
PNX85500 SoC TV with integrated analogue demodulator.
Below find a block diagram of the front-end application for this
region.
Connector
no.
1308
1316
1M95
Descr.
Mains
to display
to SSB
Pin
CN1
CN2
CN4
1
N
Anode 1
+3V3stdby
2
L
n.c.
Standby
3
-
Cathode 1
GND1
4
-
n.c.
GND1
5
-
Anode 2
+12V
6
-
n.c.
+12V
7
-
Cathode 2
+Vsnd
8
-
n.c.
GND_SND
9
-
Anode 3
BL-ON-OFF
10
-
n.c.
BL-DIM1 (Vsync)
11
-
Cathode 3
BL-I-CTRL
12
-
n.c.
POK
13
-
Anode 4
+24V (AL2_DVBS)
14
-
n.c.
GND1
15
-
Cathode 4
-
1
8
770_226_100127.ep
s
100426
+ 5V 5-T UN
196 m A
+ 5V
+ 5V 5-TUN
+ 5V -TUN
2179 m A
196 m A
+ 12V
+
3
V
3
+
3
V
3
+ 2V 5
2919 m A
2
3
71 m A
450 m A
+ 1V
8
+ 1V
8
+ 1V 2
2450 m A
550 m A
+ 1V 1
5100 m A
+ 1V 1
dc -dc
+ 5V
dc -dc
+ 5V -TUN
s
t
ab
iliz er
+
3
V
3
dc -dc
+ 2V 5
s
t
ab
iliz er
+ 1V
8
dc -dc
+ 1V 2
s
t
ab
iliz er