DRX-1
DRX-1
72
7251
7200
6240
6230
6220
2220
2220
2235
6231
2222
6221
7220
6215
6210
6211
6200
6201
5131
7125
7140
7141
7143
7142
6142
6144
6143
2151
6140
2125
Regulation
EMI
FILTER
MAINS
Vi
33Vstby
+12Vstby
+3V9
Lightning
Protection
Rectifier
Overload
protection
Control
feed forward
Power
switch
Overvoltage
protection
Rsense
4
2
8
7
-5Nstby
5.2Vstby
-Vgnstby
2260
2210
2214
2240
2211
2241
+ Vb
-Vreg
3141
2140
2146
2141
+12Vreg
+12Vreg
FLYB
■
CIRCUIT DESCRIPTION
1. Multi-Mode SOPS 50PS203
1.1. Why Multi-Mode SOPS?
Using ordinary SOPS results in a decrease of the
efficiency at low output loads due to the increase of the
switching frequency.
The Multi-Mode SOPS will reduce the switching frequency
at low loads but still preserves valley switching.
1.2. Block Diagram
1.3. Circuit Description
Input Circuit
The input circuit consists of a lightning protection circuit
and an EMI filter.
The lightning protection comprises R3120, sparkgaps
1124 and 1125. D6128, 6129, C2127 and R3129 are
optional.
L5110, L5115, C2120 and L5120 form the EMI filter. It
prevents inflow of noises into the mains.
Primary Rectifier/smoothing Circuit
The AC input is rectified by diodes 6151,6152, 6153, 6154
and smoothed into C2125. The voltage over C2125 is
approximately 300V. It can vary from 200V to 390V.
Start Circuit
This circuit is formed by R3125, 3126, R3141, C2140 and
R3132.
When the power plug is connected to the mains voltage,
the MOSFET 7125 will start conducting as soon as the
gate voltage reaches a treshold value. A current starts to
flow in primary winding 2-4. The MOSFET will be fed
forward via winding 7-8, R3150 and C2146.
+Vb Supply and Negative Regulation Voltage
The positive part of the voltage over winding 7-8 will be
rectified via R3150, D6140 and charged via R3140 into
C2140. The voltage over C2140 has a value of +30 till
+40V. This value depends on the value of the mains
voltage Vi and the load.
The negative part of the voltage over winding 7-8 will be
rectified via R3150, D6142 and charged into C2151. The
voltage over C2151 has a value of -15V and is used as
regulation voltage.
Fig. 1
Summary of Contents for DRX-1
Page 99: ...DRX 1 DRX 1 99 TMP93C071 IC7803 ...
Page 100: ...DRX 1 DRX 1 100 STV5348 IC7990 UDA1334TS IC7506 ...
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Page 134: ...2 A B C D E F G H I J 1 3 4 5 7 DRX 1 6 134 PRINTED CIRCUIT BOARD DVIO P C B Part 2 Top View ...
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