LTM4602 datasheet(14/24 Pages) LINER

14 / 24 page

LTM4602

4602fa

sinking methods. Thermal models are derived from

several temperature measurements at the bench,

and thermal modeling analysis. Application Note 103

provides a detailed explanation of the analysis for the

thermal models, and the derating curves. Tables 3

and 4 provide a summary of the equivalent θJA for the

noted conditions. These equivalent θJA parameters are

correlated to the measured values, and improve with

air-ﬂow. The case temperature is maintained at 100°C

or below for the derating curves. This allows for 4W

maximum power dissipation in the total module with

top and bottom heat sinking, and 2W power dissipation

through the top of the module with an approximate

θJC between 6°C/W to 9°C/W. This equates to a total

of 124°C at the junction of the device. The θJA values

in Tables 3 and 4 can be used to derive the derating

curves for other output voltages.

Safety Considerations

The LTM4602 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 should be

provided to protect each unit from catastrophic failure.

tion loss is minimized and light load efﬁciency is improved.

The penalty is that the controller may skip cycle and the

output voltage ripple increases at light load.

Paralleling Operation with Load Sharing

Two or more LTM4602 modules can be paralleled to provide

higher than 6A output current. Figure 7 shows the neces-

sary interconnection between two paralleled modules. The

OPTI-LOOP® current mode control ensures good current

sharing among modules to balance the thermal stress.

The new feedback equation for two or more LTM4602s

in parallel is:

VOUT = 0.6V •

100k

+RSET

RSET

where N is the number of LTM4602s in parallel.

Thermal Considerations and Output Current Derating

The power loss curves in Figures 8 and 13 can be used

in coordination with the load current derating curves

in Figures 9 to 12, and Figures 14 to 15 for calculating

approximate θJA for the module with various heat

Figure 7. Parallel Two μModules with Load Sharing

OPTI-LOOP is a registered trademark of Linear Technology Corporation.

VIN

100k

VOUT

VPULLUP

VIN

VOUT

12A MAX

4602 F07

LTM4602

PGOOD

PGND

SGND

COMP VOSET

RSET

VIN

PGOOD

VOUT

LTM4602

PGND

SGND

COMP VOSET

APPLICATIONS INFORMATION

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