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Revision 1.00

13 - 16

AS1341

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

Diode Selection

The current in the D1 (see Figure 22 on page 10) changes abruptly from zero to its peak value each time the LX switch

turns off. To avoid excessive losses, the diode must have a fast turn-on time and a low forward voltage.

Note: Ensure that the diode peak current rating exceeds the peak current limit set by the current limit (see Setting

Stable Operation

A well-designed system and selection of high-quality external components can eliminate excessive noise on pins OUT,

FB, or GND, which can lead to unstable device operation. Instability typically manifests itself as grouped switching

pulses with large gaps and excessive low-frequency output ripple (motorboating) during no-load or light-load condi-

tions.

Recommended Components

PC Board Layout and Grounding

High switching frequencies and large peak currents make PC board layout an important part of AS1341-based

designs. Good PCB layout can avoid switching noise being introduced into the feedback path, resulting in jitter, insta-

bility, or degraded performance.

- High-power traces (see Figure 22 on page 10) should be as short and wide as possible.

be as short as possible to avoid radiated noise. Connect the ground pins of these power components at a com-

mon node in a star-ground configuration.

- Separate noisy traces, such as the LX node, from the feedback network with grounded copper.

- Keep the extra copper on the PCB and integrate it into a pseudo-ground plane.

- When using external feedback, place the resistors as close to pin FB as possible to minimize noise coupling.

Table 8. Recommended Components

Circuit

Input

Voltage (V)

Output

Voltage (V)

ILIMIT

Inductor

Output Capacitor

1

4.5 to 20

1.25 to 5

High

MSS6132-103ML

LQH66SN-100M03

LQH55DN-150M03

CDRH6D28NP-150

T520V107M010ATE018

A700V826M006ATE018

T520B107M006ATE040

EEFUD0J101R

10TPB100ML

2

4.5 to 12

CDRH5D18NP-4R1

LPS4018-472ML

3

4.5 to 20

1.25 to 5

Low

MSS6132-393ML

CDRH6D28NP-470

LQH66SN-470M03

LQH55DN-470M03

EEFCD0K330R

6TPB47M

T520A336M006ATE070

A700V226M006ATE028

4

4.5 to 12

MSS6132-103ML

LPS4018-223ML

CDRH5D18NP-220

5

6 to 20

High or Low

See Circuit 1-4

510X107M020ATE040