11

FN7333.5

April 5, 2006

where:

D = MOSFET turn-on ratio:

The following table gives typical maximum Iout values for

1.2MHz switching frequency and 22µH inductor:

Thermal Performance

The EL7516 uses a fused-lead package, which has a

reduced

on a two-layer board. Maximizing copper around the ground

pins will improve the thermal performance.

This device also has internal thermal shut-down set at

around 130°C to protect the component.

Layout Considerations

To achieve highest efficiency, best regulation and most

stable operation, a good printed circuit board layout is

essential. It is strongly recommended that the demoboard

layout to be followed as closely as possible. Use the

following general guidelines when laying out the print circuit

board:

supply bypass capacitor of the device.

possible.

4. High current traces should be short and as wide as

possible.

5. Place feedback resistor close to the FB pin to avoid noise

pickup.

6. Place the compensation network close to the COMP pin.

The demo board is a good example of layout based on these

principles; it is available upon request.

TABLE 1.

2.5

5

570

2.5

9

325

2.5

12

250

3.3

5

750

3.3

9

435

3.3

12

330

5

9

650

5

12

490

ΔI

L

V

IN

V

O

V

DIODE

+

() V

IN

–

[]

×

LV

O

(

V

F

S

×

+

×

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

=

I

L-AVG

I

OUT

1D

–

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

=

D1

V

IN

V

OUT

V

DIODE

+

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

–

=

EL7516