EL7530IY(2004) データシートの表示（PDF） - Intersil

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EL7530IY
(Rev.:2004)

Monolithic 600mA Step-Down Regulator with Low Quiescent Current

Intersil 

EL7530

Output Voltage Selection

Users can set the output voltage of the variable version with

a resister divider, which can be chosen based on the

following formula:

VO

=

0.8

×



1



+

R-R----21- 

Component Selection

Because of the fixed internal compensation, the component

choice is relatively narrow. For a regulator with fixed output

voltage, only two capacitors and one inductor are required.

We recommend 10µf to 22µF multi-layer ceramic capacitors

with X5R or X7R rating for both the input and output

capacitors, and 1.5 to 2.2µH for the inductor.

The RMS current present at the input capacitor is decided by

the following formula:

IINRMS

=

-----V----O------×----(---V----I--N-----–-----V----O----)-

VIN

×

IO

This is about half of the output current IO for all the VO. This

input capacitor must be able to handle this current.

The inductor peak-to-peak ripple current is given as:

∆IIL

=

(---V----I--N------–----V-----O----)----×-----V----O--

L × VIN × fS

L is the inductance

fS the switching frequency (nominally 1.4MHz)

The inductor must be able to handle IO for the RMS load

current, and to assure that the inductor is reliable, it must

handle the 2A surge current that can occur during a current

limit condition.

Layout Considerations

The layout is very important for the converter to function

properly. The following PC layout guidelines should be

followed:

1. Separate the Power Ground ( ) and Signal Ground

( i); connect them only at one point right at the pins

2. Place the input capacitor as close to VIN and PGND pins

as possible

3. Make the following PC traces as small as possible:

4. from LX pin to L

5. from CO to PGND

6. If used, connect the trace from the FB pin to R1 and R2

as close as possible

7. Maximize the copper area around the PGND pin

8. Place several via holes under the chip to additional

ground plane to improve heat dissipation

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

outline. Please refer to the EL7530 Application Brief.

10

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