LTM4603HVEV-PBF View Datasheet(PDF) - Linear Technology

Part Name

Description

MFG CO.

LTM4603HVEV-PBF

6A, 28VIN DC/DC µModule with PLL, Output Tracking and Margining

Linear Technology 

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LTM4603HV

APPLICATIO S I FOR ATIO

Safety Considerations

The LTM4603HV modules do not provide 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.

Layout Checklist/Example

The high integration of LTM4603HV makes the PCB board

layout very simple and easy. However, to optimize its electri-

cal and thermal performance, some layout considerations

are still necessary.

• Use large PCB copper areas for high current path, in-

cluding VIN, PGND and VOUT. It helps to minimize the

PCB conduction loss and thermal stress.

• Place high frequency ceramic input and output capaci-

tors next to the VIN, PGND 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 vias directly on pads.

• If vias are placed onto the pads, the the vias must be

capped.

• Interstitial via placement can also be used if necessary.

• Use a separated SGND ground copper area for com-

ponents connected to signal pins. Connect the SGND

to PGND underneath the unit.

Figure 17 gives a good example of the recommended

layout.

Frequency Adjustment

The LTM4603HV is designed to typically operate at 1MHz

across most input conditions. The fSET pin is typically left

open or decoupled with an optional 1000pF capacitor. The

switching frequency has been optimized for maintaining

constant output ripple noise over most operating ranges.

The 1MHz switching frequency and the 400ns minimum

off time can limit operation at higher duty cycles like 5V to

3.3V, and produce excessive inductor ripple currents for

lower duty cycle applications like 28V to 5V. The 5V and

3.3V drop out curves are modified by adding an external

resistor on the fSET pin to allow for wider input voltage

operations.

VIN

CIN CIN

GND

SIGNAL

GND

COUT

COUT

VOUT

4603HV F17

Figure 17. Recommended Layout

4603hvf

18

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