Datasheet
LTM8028
18
8028fa
For more information www.linear.com/LTM8028
1V at 5A Regulator with 2% Transient Response
Transient Response from 0.5A to 5A, 1µs
Load Current Rise and Fall Time, 12V
IN
LOAD
CURRENT
2A/DIV
V
OUT
20mV/DIV
1µs/DIV
8028 TA03
Typical applicaTions
Given these definitions, it should now be apparent that none
of these thermal coefficients reflects an actual physical
operating condition of a µModule regulator. Thus, none
of them can be individually used to accurately predict the
thermal performance of the product. Likewise, it would
be inappropriate to attempt to use any one coefficient to
correlate to the junction temperature vs load graphs given
in the product’s data sheet. The only appropriate way to
use the coefficients is when running a detailed thermal
analysis, such as FEA, which considers all of the thermal
resistances simultaneously.
A graphical representation of these thermal resistances
is given in Figure 6:
The blue resistances are contained within the µModule
regulator, and the green are outside.
The die temperature of the LTM8028 must be lower than
the maximum rating of 125°C, so care should be taken in
the layout of the circuit to ensure good heat sinking of the
LTM8028. The bulk of the heat flow out of the LTM8028
is through the bottom of the module and the LGA pads
into the printed circuit board. Consequently a poor printed
circuit board design can cause excessive heating, result
-
ing in impaired performance or reliability. Please refer to
the PCB Layout section for printed cir
cuit board design
suggestions.
applicaTions inForMaTion
8028 F06
µMODULE DEVICE
JUNCTION-TO-CASE (TOP)
RESISTANCE
JUNCTION-TO-BOARD RESISTANCE
JUNCTION-TO-AMBIENT RESISTANCE (JESD 51-9 DEFINED BOARD)
CASE (TOP)-TO-AMBIENT
RESISTANCE
BOARD-TO-AMBIENT
RESISTANCE
JUNCTION-TO-CASE
(BOTTOM) RESISTANCE
JUNCTION
AMBIENT
CASE (BOTTOM)-TO-BOARD
RESISTANCE
Figure 6. Thermal Model of µModule
+
LINEAR
REGULATOR
V
IN
V
OUT
SENSEP
BKV
RUN
402k
V
IN
6V TO 36V
165k
0.01µF
MARGA
IMAX
SS PGOOD
100µF
RT
GND
V
OB
V
O0
V
O1
V
O2
470µF
*137µF = 4.7µF + 10µF + 22µF +100µF IN PARALLEL
8028 TA02
137µF*
V
OUT
1V
5A
SYNC
LTM8028
10µF