TOP232-234
0
DRAIN (D)
INTERNAL
SUPPLY
CONTROL (C)
ZC
VC
1
SHUNT REGULATOR/
ERROR AMPLIFIER
-
+
+
5.8 V
4.8 V
SOFT START
-
5.8 V
INTERNAL UV
COMPARATOR
VI
(LIMIT)
IFB
CURRENT
LIMIT
ADJUST
ON/OFF
÷
8
SHUTDOWN/
AUTO-RESTART
-
+
VBG + VT
CURRENT LIMIT
COMPARATOR
MULTI-
FUNCTION (M)
VBG
STOP
DCMAX
SOFT-
START
DMAX
CLOCK
HYSTERETIC
THERMAL
SHUTDOWN
CONTROLLED
TURN-ON
GATE DRIVER
OV/UV
LINE
SENSE
DCMAX
HALF
FREQUENCY SAW
FREQUENCY (F)
(Y Package Only)
-
+
PWM
COMPARATOR
S
R
Q
Q
OSCILLATOR WITH JITTER
LEADING
EDGE
BLANKING
RE
SOURCE (S)
PI-2535-083099
Figure 2. Functional Block Diagram.
Pin Functional Description
DRAIN (D) Pin:
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.
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.
MULTI-FUNCTION (M) Pin:
Input pin for OV, UV, line feed forward with DC
MAX
reduction,
external set current limit, remote ON/OFF and synchronization.
A connection to SOURCE pin disables all functions on this pin
and makes
TOPSwitch-FX
operate in simple three terminal
mode (like
TOPSwitch-II).
FREQUENCY (F) Pin: (Y package only)
Input pin for selecting switching frequency: 132 kHz if connected
to SOURCE pin and 66 kHz if connected to CONTROL pin.
The switching frequency is internally set for 132 kHz only
operation in P and G packages.
SOURCE (S) Pin:
Output MOSFET source connection for high voltage power
return. Primary side control circuit common and reference point.
Tab Internally
Connected to SOURCE Pin
7D
5F
4S
3M
1C
Y Package (TO-220-7B)
M
1
S
2
S
3
C
4
8
S
7
S
5
D
P Package (DIP-8B)
G Package (SMD-8B)
Figure 3. Pin Configuration.
PI-2501-031901
B
7/01
3
PAM [ POWER ANALOG MICOELECTRONICS ]
