TOP232-234
DRAIN (D)
0
1
CONTROL (C)
V
C
Z
C
INTERNAL
SUPPLY
SHUNT REGULATOR/
ERROR AMPLIFIER
+
-
SOFT START
5.8 V
4.8 V
-
5.8 V
+
INTERNAL UV
COMPARATOR
I
FB
V
I (LIMIT)
CURRENT
LIMIT
ADJUST
-
÷ 8
ON/OFF
+
SHUTDOWN/
AUTO-RESTART
V
+ V
BG
T
CURRENT LIMIT
COMPARATOR
HYSTERETIC
THERMAL
SHUTDOWN
MULTI-
FUNCTION (M)
V
BG
CONTROLLED
TURN-ON
GATE DRIVER
STOP
SOFT-
OV/UV
DC
START
D
LINE
SENSE
MAX
DC
MAX
MAX
CLOCK
SAW
S
R
Q
Q
HALF
-
LEADING
EDGE
BLANKING
FREQUENCY
FREQUENCY (F)
(Y Package Only)
+
OSCILLATOR WITH JITTER
PWM
COMPARATOR
R
E
SOURCE (S)
PI-2535-083099
Figure 2. Functional Block Diagram.
The switching frequency is internally set for 132 kHz only
operation in P and G packages.
Pin Functional Description
DRAIN (D) Pin:
SOURCE (S) Pin:
Output MOSFET source connection for high voltage power
return. Primary side control circuit common and reference point.
High voltage power MOSFET drain output. The internal start-
up bias current is drawn from this pin through a switched high-
voltage current source. Internal current limit sense point for
drain current.
Tab Internally
Connected to SOURCE Pin
CONTROL (C) Pin:
Error amplifier and feedback current input pin for duty cycle
control. Internal shunt regulator connection to provide internal
bias current during normal operation. It is also used as the
connection point for the supply bypass and auto-restart/
compensation capacitor.
7 D
5 F
4 S
3 M
1 C
Y Package (TO-220-7B)
MULTI-FUNCTION (M) Pin:
Input pin for OV, UV, line feed forward with DCMAX reduction,
externalsetcurrentlimit,remoteON/OFFandsynchronization.
A connection to SOURCE pin disables all functions on this pin
and makes TOPSwitch-FX operate in simple three terminal
mode (like TOPSwitch-II).
1
2
M
S
8
S
7 S
3
S
C 4
5 D
FREQUENCY (F) Pin: (Y package only)
Inputpinforselectingswitchingfrequency:132 kHzifconnected
to SOURCE pin and 66 kHz if connected to CONTROL pin.
P Package (DIP-8B)
G Package (SMD-8B)
PI-2501-031901
Figure 3. Pin Configuration.
B
7/01
3
PAM [ POWER ANALOG MICOELECTRONICS ]
