Datasheet

( )
tL
I
( )
tOUT
V
1
L
1
D
1
Q
1
C
IN
V
LM2735
SNVS485F –JUNE 2007–REVISED APRIL 2013 www.ti.com
• PCB variables (copper weight, thermal via’s, layers component placement).
It would be wrong to assume that the top case temperature is the proper temperature when calculating R
θJC
value. The R
θJC
value represents the thermal impedance of all six sides of a package, not just the top side. This
document will refer to a thermal impedance called R
ψJC
. R
ψJC
represents a thermal impedance associated with
just the top case temperature. This will allow one to calculate the junction temperature with a thermal sensor
connected to the top case.
LM2735 Thermal Models
Heat is dissipated from the LM2735 and other devices. The external loss elements include the Schottky diode,
inductor, and loads. All loss elements will mutually increase the heat on the PCB, and therefore increase each
other’s temperatures.
Figure 28. Thermal Schematic
18 Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated
Product Folder Links: LM2735