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AS1323

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

9 Application Information

Figure 20. Typical Application

Inductor Selection

The control scheme of the AS1323 allows for a wide range if inductor values. A 10µH inductor should be sufficient for

most applications (see Figure 20).

Smaller inductance values typically offer smaller physical size for a given series resistance, allowing the smallest over-

all circuit dimensions. Applications using larger inductance values may startup at lower battery voltages, provide higher

efficiency and exhibit less ripple, but they may reduce the maximum output current. This occurs when the inductance is

expires (see Electrical Characteristics on page 4).

For maximum output current, the inductor value should be chosen such that the controller reaches the current-limit

before the maximum on-time is triggered:

The inductor’s incremental saturation current rating should be greater than the peak switching current. However, it is

generally advisable to bias the inductor into saturation by as much as 20%, although this will slightly reduce efficiency.

Maximum Output Current

η) as indicated in

AS1323

3

SHDNN

1

VBATT

4

VOUT

5

LX

10µF

2

VSS

10µF

10µH

L

⋅

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

>

(EQ 1)

⋅

L

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

=

(EQ 2)

1

2

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

⎝⎠

⎛⎞ η

⋅⋅

⋅

=

(EQ 3)