AS1335 datasheet(16/19 Pages) AMSCO

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AS1335

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

Checking Transient Response

The main loop response can be evaluated by examining the load transient response. Switching regulators normally

take several cycles to respond to a step in load current. When a load step occurs, VOUT immediately shifts by an

amount equivalent to:

VDROP =

ΔILOAD x ESR

(EQ 12)

Where:

ESR is the effective series resistance of COUT.

ΔILOAD also begins to charge or discharge COUT, which generates a feedback error signal. The regulator loop then acts

to return VOUT to its steady-state value. During this recovery time VOUT can be monitored for overshoot or ringing that

would indicate a stability problem.

Layout Considerations

The AS1335 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 FB should be connected directly to the Output Voltage.

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 FB 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.

AS1335 Datasheet(PDF) 16 Page - ams AG