3

4712B–AUTO–10/05

U2008B

2.

Pin Configuration

Figure 2-1.

Pinning

2.1

Mains Supply, Pin 5

The integrated circuit U2008B, which also contains voltage limiting, can be connected via D

R

Pin 5, is smoothed by C

The series resistance R1 can be calculated as follows:

where:

Operation with externally stabilized DC voltage is not recommended.

1

2

3

4

8

7

6

5

ISENSE

C

ϕ

CONTROL

GND

OUTPUT

VSYNC

R

ϕ

- VS

U2008B

Table 2-1.

Pin Description

Pin

Symbol

Function

1

ISENSE

Load current sensing

2C

ϕ

Ramp voltage

3

CONTROL

Control input/compensation output

4

GND

Ground

5

-VS

Supply voltage

6R

ϕ

Ramp current adjustment

7

VSYNC

Voltage synchronization

8

OUTPUT

Trigger output

V

M

= Mains voltage

V

Smax

= Maximum supply voltage

I

tot

= I

I

Smax

= Maximum current consumption of the IC

I

x

= Current consumption of the external components

R

1max

0.85

V

M

V

Smax

–

2I

tot

×

------------------------------

×

=