LTM4643 datasheet(24/32 Pages) LINER

24 / 32 page

LTM4643

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For more information www.linear.com/LTM4643

APPLICATIONS INFORMATION

Safety Considerations

The LTM4643 modules do not provide galvanic isolation

from VIN to VOUT. There is no internal fuse. If required,

a slow blow fuse with a rating twice the maximum input

current needs to be provided to protect each unit from

catastrophic failure. The device does support thermal

shutdown and overcurrent protection.

Layout Checklist/Example

The high integration of LTM4643 makes the PCB board

layoutverysimpleandeasy.However,tooptimizeitselectri-

cal and thermal performance, some layout considerations

are still necessary.

• Use large PCB copper areas for high current paths,

including VIN1 to VIN4, GND, VOUT1 to VOUT4. It helps to

minimize the PCB conduction loss and thermal stress.

• Place high frequency ceramic input and output capaci-

tors next to the VIN, GND and VOUT pins to minimize

high frequency noise.

• Place a dedicated power ground layer underneath the

unit.

• To minimize the via conduction loss and reduce module

thermal stress, use multiple vias for interconnection

between top layer and other power layers.

• Do not put via directly on the pad, unless they are

capped or plated over.

• Use a separated SGND ground copper area for com-

ponents connected to signal pins. Connect the SGND

to GND underneath the unit.

• For parallel modules, tie the VOUT, VFB, and COMP pins

together. Use an internal layer to closely connect these

pins together. The TRACK/SS pin can be tied a common

capacitor for regulator soft-start.

• Bring out test points on the signal pins for monitoring.

Figure 28givesagoodexampleoftherecommendedlayout.

Figure 28. Recommended PCB Layout

LTM4643 Datasheet(PDF) 24 Page - Linear Technology