Rev. B 09/15

2

LYT2002-2005

www.power.com

Pin Functional Description

DRAIN (D) Pin:

Power MOSFET drain connection. It also provides internal

operating current during start-up and in steady-state operation.

BYPASS (BP) Pin:

Connection point for the external 1 mF bypass capacitor connected to

the internally generated 6 V supply.

FEEDBACK (FB) Pin:

Controls switching of the power MOSFET during normal opera-

tion. This pin senses the AC voltage on the bias winding.

Input is used to regulate both the output voltage in CV mode

and output current in CC mode based on voltage across the

bias winding in the flyback portion of the switching cycle. The

internal inductance correction circuit uses voltage on the bias

winding during forward part of the switching cycle to sense the

bulk capacitor voltage.

SOURCE (S) Pin:

Connected to the MOSFET source and is used for high-voltage

power and control circuit common returns.

Figure 2. Functional Block Diagram.

Figure 3. Pin Configuration.

PI-7302-061214

SOURCE

(S)

LEADING

EDGE

BLANKING

+

-

+

-

+

-

DRAIN

(D)

REGULATOR

6 V

BYPASS

(BP)

FEEDBACK

(FB)

SOURCE

(S)

FB

OUT

Reset

6 V

5 V

t

SAMPLE-OUT

t

SAMPLE-INPUT

V

ILIMIT

I

LIM

V

TH

t

SAMPLE-INPUT

t

SAMPLE-OUT

V

ILIMIT

6.5 V

Drive

I

LIM

DC

MAX

DC

MAX

FB

Current Limit

Comparator

STATE

MACHINE

SAMPLE

DELAY

THERMAL

SHUTDOWN

OSCILLATOR

FAULT

AUTO-RESTART

OPEN-LOOP

INDUCTANCE

CORRECTION

CONSTANT

CURRENT

D Q

12 S

11 S

10 S

9 S

8 S

7 S

FB 1

BP 2

NC 3

NC 4

D 6

PI-6906-051614

Exposed Pad

(On Back Side)

Internally

Connected to

SOURCE Pin

1

E Package

(eSIP-7C)

K Package

(eSOP-12B)

Exposed Pad (On Bottom)

Internally Connected to

SOURCE Pin

2 3 4 5 7

D Package (SO-8C)

FB 1

BP 2

D 4

8 S

7 S

6 S

5 S