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Axelite Confidential Materials, do not copy or distribute without written consent.

Rev.1.1 Nov.01, 2019

AX3704

Output Capacitor Selection

An output capacitor is required to obtain a stable output voltage. To minimize the output voltage

ripple, ceramic capacitors should be used, and the ripple voltage can be estimated as:

If electrolytic or tantalum capacitors are used, the ESR will dominate the output voltage ripple:

PCB Layout Recommendation

The physical design of the PCB is the final stage in the design of power converter. If designed

improperly, the PCB could radiate excessive EMI and contribute instability to the power converter.

Therefore, following the PCB layout guidelines below can ensure better performance of AX3704.

(1). The loop (Vin-SW-L-Cout-GND) indicates a high current path. The traces within the loop

should be kept as wide and short as possible to reduce parasitic inductance and

high-frequency loop area. It is also good for efficiency improvement.

(2). Input capacitor as close as possible to the IC Pins (Vin and GND) and the input loop area

should be as small as possible to reduce parasitic inductance, input voltage spike and noise

emission.

(3). Feedback components (R1, R2 and CFF) should be routed as far away from the inductor and

the SW Pin as possible to minimize noise and EMI issue.

DFN3x3-10L

Top Layer

Bottom Layer