Datasheet

LTM4602
14
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 θ
JA
for the
noted conditions. These equivalent θ
JA
parameters are
correlated to the measured values, and improve with
air-fl ow. 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
θ
JC
between 6°C/W to 9°C/W. This equates to a total
of 124°C at the junction of the device. The θ
JA
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 V
IN
to
V
OUT
. 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 effi ciency 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:
V
OUT
= 0.6V •
100k
N
+ R
SET
R
SET
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
an
approximate θ
JA
for the module with various heat
Figure 7. Parallel Two μModules with Load Sharing
OPTI-LOOP is a registered trademark of Linear Technology Corporation.
V
IN
100k
V
OUT
V
PULLUP
V
IN
V
OUT
12A MAX
4602 F07
LTM4602
PGOOD
PGND SGNDCOMP V
OSET
R
SET
V
IN
PGOOD
V
OUT
LTM4602
PGND
SGNDCOMP V
OSET
APPLICATIONS INFORMATION