AS1324 datasheet(16/20 Pages) AMSCO

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AS1324

Data Sheet - A p p l i c a t i o n I n f o r m a t i o n

For best overall efficiency use an inductor with a rating of 720mA or greater and less than 0.2

Ω series resistance. CIN

will require an RMS current rating of at least 0.3A

≅ ILOAD(MAX)/2, whereas COUT will require an ESR of less than

0.25

Ω. In most cases, a ceramic capacitor will satisfy this requirement.

For the feedback resistors, select the value for R1 = 375k

Ω. R2 can then be calculated from (EQ 7) to be:

R2 = (VOUT/0.6 - 1)375k = 1000k

Layout Considerations

The AS1324 requires proper layout and design techniques for optimum performance.

The power traces (GND, SW, and VIN) should be kept as short, direct, and wide as is practical.

Pin VFB (AS1324 only) should be connected directly to the feedback resistors (R1 and R2). A potentiometer as

replacement for R1 and R2 should be avoided to minimize the output voltage ripple and to maintain the stability of

the regulator.

The resistive divider (R1/R2) must be connected between the positive plate of COUT and ground.

The positive plate of CIN should be connected as close to VIN as is practical since CIN provides the AC current to

the internal power MOSFETs.

Switching node SW should be kept far away from the sensitive VFB node.

The negative plates of CIN and COUT should be kept as close to each other as is practical. A starpoint to Ground is

recommended.

Figure 29. AS1324 Basic PCB Layout

Figure 30. AS1324 Basic Diagram

AS1324

Via to GND

Via to VOUT

VOUT

GND

VIN

Via to VIN

COUT

CIN

CFWD

AS1324

VIN

VFB

GND

CIN

CFWD

High Current Path

VIN

COUT

VOUT

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