Philips MX3550D/37S - Page 57

POWER BOARD
TABLE OF CONTENTS
Internal IC Diagram........................................................10-1
Circuit Diagram ..............................................................10-2
PCB Layout.....................................................................10-3
Electrical Parts List..........................................................10-4
10-1
ANODE
REF
CATHODE
2.4 k

7.2 k

3.28 k

20 pF
4 k

1 k

800 

800 

800 

20 pF
150 

10 k

TL431 EQUIVALENT SCHEMATIC
TOP249 BLOCK DIAGRAM
10-1
SHUTDOWN/
AUTO-RESTART
PWM
COMPARATOR
CLOCK
SAW
HALF
FREQ.
CONTROLLED
TURN-ON
GATE DRIVER
CURRENT LIMIT
COMPARATOR
INTERNAL UV
COMPARATOR
INTERNAL
SUPPLY
5.8 V
4.8 V
SOURCE (S)
S
R
Q
D
MAX
STOP
SOFT-
START
-
+
CONTROL (C)
LINE-SENSE (L)
EXTERNAL
CURRENT LIMIT (X)
FREQUENCY (F)
-
+
5.8 V
1 V
I
FB
R
E
Z
C
V
C
+
-
LEADING
EDGE
BLANKING
÷ 8
1
HYSTERETIC
THERMAL
SHUTDOWN
SHUNT REGULATOR/
ERROR AMPLIFIER
+
-
DRAIN (D)
ON/OFF
SOFT
START
DC
MAX
V
BG
DC
MAX
V
BG
+ V
T
0
OV/UV
V
I (LIMIT)
CURRENT
LIMIT
ADJUST
LINE
SENSE
SOFT START
LIGHT LOAD
FREQUENCY
REDUCTION
STOP LOGIC
OSCILLATOR WITH JITTER