LTM8042EV-1PBF LINER [Linear Technology], LTM8042EV-1PBF Datasheet - Page 27

• Manufacturer Part Number: LTM8042EV-1PBF
• Description: ?Module Boost LED Driver and Current Source
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
The most appropriate way to use the coefficients is when
running a detailed thermal analysis, such as FEA, which
considers all of the thermal resistances simultaneously.
None of them can be individually used to accurately pre-
dict the thermal performance of the product, so it would
be inappropriate to attempt to use any one coefficient to
correlate to the junction temperature versus load graphs
given in the LTM8042/LTM8042-1 data sheet.
A graphical representation of these thermal resistances
is given in Figure 5.
The blue resistances are contained within the μModule
regulator, and the green are outside.
TYPICAL APPLICATIONS
JUNCTION
μMODULE DEVICE
11.6V TO 19V
(BOTTOM) RESISTANCE
V
JUNCTION-TO-CASE
IN
JUNCTION-TO-AMBIENT RESISTANCE (JESD 51-9 DEFINED BOARD)
Boost Operation, Driving 6 White LEDs at 1A
JUNCTION-TO-BOARD RESISTANCE
JUNCTION-TO-CASE (TOP)
4.7μF
RESISTANCE
CASE (BOTTOM)-TO-BOARD
V
RUN
BSTIN/BKLED
PWM
SYNC
TGEN
SS
RT
CC
22.6k
f
SW
Figure 5
LTM8042
= 750kHz
RESISTANCE
BSTOUT/BKIN
–
The die temperature of the LTM8042/LTM8042-1 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 LTM8042/LTM8042-1. The bulk of the
heat flow out of the LTM8042/LTM8042-1 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, resulting in impaired
performance or reliability. Please refer to the PCB Layout
section for printed circuit board design suggestions.
GND CTL
LED
TG
+
4.7μF
CASE (TOP)-TO-AMBIENT
LTM8042/LTM8042-1
BOARD-TO-AMBIENT
RESISTANCE
RESISTANCE
UP TO 20.6V
80421 TA02
1A
80421 F05
A t
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80421fa