RT6310CSLASHCH datasheet(44/54 Pages) RICHTEK

44 / 54 page

RT6310

is a registered trademark of Richtek Technology Corporation.

www.richtek.com

DS6310-04

August 2023

Figure 20. De-rating Curve of Maximum Power

Dissipation

Layout Considerations

Printed circuit board (PCB) layout design for switch-

mode power supply IC is critical and important.

Improper PCB layout brings lots of problems on power

supply, such as poor output voltage regulation,

switching jitter, bad thermal performance, excessively

radiate noise and reducing component reliability. To

avoid those issues, designers have to understand

current trace and signal flow in the switching power

supply. The following are design considerations of PCB

layout for switching power supply.



For suppressing phase ring and extra power losses

that affect device reliability, the input capacitor has to

be placed close to VIN pin to reduce the influence of

parasitic inductor.



For

thermal

stress

and

power

consumption

considerations, the current paths of VIN and VOUT has

to be as short and wide as possible to decrease the

trace impedance.



Since the LX node voltage swings from VIN to 0V with

very fast rising and falling times, switching power

supply suffers quite serious EMI issues. To eliminate

EMI problems, the inductor must be put as close as

possible to IC to narrow the LX node area. Besides,

the LX node should be arranged in the same plate to

reduce coupling noise path caused by parasitic

capacitance.



For system stability and coupling noise elimination,

the sensitive components and signals, such as

control signal and feedback loop, should be kept

away from LX node.



For enhancing noise immunity on VCC pin, the

decoupling capacitor must be connected from VCC to

AGND, and the capacitor should be placed close to

IC.



The feedback signal path from VOUT to IC should be

wide and kept away from high switching path.



The trace width and numbers of via should be

designed based on application current. Make sure the

switching

power

supply

has

great

thermal

performance and good efficiency.

An example of PCB layout guides are shown in Figure

21 to Figure 23 for reference.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

100

125

Ambient Temperature (°C)

four-layer Richtek EVB

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