2

LNK562-564

F

10/05

Figure 2. Functional Block Diagram.

Pin Functional Description

DRAIN (D) Pin:

The power MOSFET drain connection provides internal

operating current for both start-up and steady-state operation.

BYPASS (BP) Pin:

A 0.1

µF external bypass capacitor for the internally generated

5.8 V supply is connected to this pin.

FEEDBACK (FB) Pin:

During normal operation, switching of the power MOSFET is

controlled by this pin. MOSFET switching is disabled when a

current greater than 70

µA flows into this pin.

SOURCE (S) Pin:

This pin is the power MOSFET source connection. It is also the

ground reference for the BYPASS and FEEDBACK pins.

LinkSwitch-LP Functional

Description

LinkSwitch-LP comprises a 700 V power MOSFET switch with

a power supply controller on the same die. Unlike conventional

PWM (pulse width modulation) controllers, it uses a simple

ON/OFF control to regulate the output voltage. The controller

consists of an oscillator, feedback (sense and logic) circuit, 5.8 V

regulator, BYPASS pin under-voltage circuit, over-temperature

PI-3491-111903

FB

D

S

BP

S

S

S

P Package (DIP-8B)

G Package (SMD-8B)

8

5

7

1

4

2

3

Figure 3. Pin Configuration.

protection, frequency jittering, current limit circuit, and leading

edge blanking.

Oscillator

The typical oscillator frequency is internally set to an average

of 66/83/100 kHz for the LNK562, 563 & 564 respectively.

Two signals are generated from the oscillator: the maximum

duty cycle signal (DC

the beginning of each switching cycle.

PI-3958-092905

CLOCK

JITTER

AUTO-RESTART

COUNTER

FAULT

PRESENT

OSCILLATOR

5.8 V

4.85 V

SOURCE

(S)

S

R

Q

DC

MAX

ADJ

BYPASS

(BP)

+

-

VI

LIMIT

LEADING

EDGE

BLANKING

THERMAL

SHUTDOWN

+

-

DRAIN

(D)

BYPASS PIN

UNDER-VOLTAGE

CURRENT LIMIT

COMPARATOR

FEEDBACK

(FB)

OPEN LOOP

PULLDOWN

Q

6.3 V

1.69 V -V

TH

0.8 V

REGULATOR

5.8 V

RESET