TOP221-227
VC
CONTROL
ZC
SHUNT REGULATOR/
ERROR AMPLIFIER
-
+
5.7 V
5.7 V
4.7 V
0
DRAIN
1
INTERNAL
SUPPLY
SHUTDOWN/
AUTO-RESTART
+
-
÷
8
+
-
VI
LIMIT
IFB
THERMAL
SHUTDOWN
POWER-UP
RESET
S
R
Q
Q
OSCILLATOR
DMAX
CLOCK
SAW
CONTROLLED
TURN-ON
GATE
DRIVER
-
+
PWM
COMPARATOR
S
R
Q
Q
LEADING
EDGE
BLANKING
MINIMUM
ON-TIME
DELAY
RE
SOURCE
PI-1935-091696
Figure 2. Functional Block Diagram.
Pin Functional Description
DRAIN Pin:
Output MOSFET drain connection. Provides internal bias
current during start-up operation via an internal switched high-
voltage current source. Internal current sense point.
CONTROL 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.
SOURCE Pin:
Y package – Output MOSFET source connection for high
voltage power return. Primary side circuit
common and reference point.
P and G package – Primary side control circuit common and
reference point.
SOURCE (HV RTN) Pin: (P and G package only)
Output MOSFET source connection for high voltage power return.
Tab Internally
Connected to SOURCE Pin
DRAIN
SOURCE
CONTROL
Y Package (TO-220/3)
SOURCE
1
SOURCE
2
SOURCE
3
CONTROL
4
8
7
6
5
SOURCE (HV RTN)
SOURCE (HV RTN)
SOURCE (HV RTN)
DRAIN
P Package (DIP-8)
G Package (SMD-8)
Figure 3. Pin Configuration.
PI-2084-040401
2
D
7/01
POWERINT [ POWER INTEGRATIONS, INC. ]
