TOP412/414

A

4/99

2

PI-1746-011796

SHUTDOWN/

AUTO-RESTART

PWM

COMPARATOR

CLOCK

SAW

OSCILLATOR

CONTROLLED

TURN-ON

GATE

DRIVER

INTERNAL

SUPPLY

5.7 V

4.7 V

SOURCE

S

R

Q

Q

DMAX

-

+

CONTROL

-

+

5.7 V

IFB

RE

ZC

VC

MINIMUM

ON-TIME

DELAY

+

-

VI

LIMIT

LEADING

EDGE

BLANKING

POWER-UP

RESET

R

S

Q

Q

÷ 8

0

1

THERMAL

SHUTDOWN

EXTERNALLY

TRIGGERED

SHUTDOWN

SHUNT REGULATOR/

ERROR AMPLIFIER

+

-

DRAIN

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. Trigger input for latching

shutdown. It is also used as the supply bypass and auto-restart/

compensation capacitor connection point.

SOURCE Pin:

Output MOSFET source connection.

Primary-side circuit

common, power return, and reference point.

Figure 3. Pin Configuration.

PI-2208-120798

CONTROL

8

5

7

6

DRAIN

SOURCE (HV RTN)

SOURCE

SOURCE

1

4

2

3

SOURCE (HV RTN)

SOURCE (HV RTN)

SOURCE

G Package (SMD-8)