Datasheet

LPC540xx All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2018. All rights reserved.
Product data sheet Rev. 1.8 — 22 June 2018 87 of 168
NXP Semiconductors
LPC540xx
32-bit ARM Cortex-M4 microcontroller
9. Thermal characteristics
The average chip junction temperature, T
j
(C), can be calculated using the following
equation:
(1)
• T
amb
= ambient temperature (C),
• R
th(j-a)
= the package junction-to-ambient thermal resistance (C/W)
• P
D
= sum of internal and I/O power dissipation
The internal power dissipation is the product of I
DD
and V
DD
. The I/O power dissipation of
the I/O pins is often small and many times can be negligible. However it can be significant
in some applications.
Table 11. Thermal resistance
Symbol Parameter Conditions Max/Min Unit
LQFP208 Package
R
th(j-a)
thermal resistance from
junction to ambient
JEDEC (4.5 in  4 in); still air 33 15 % C/W
Single-layer (4.5 in  3 in); still air 41 15 % C/W
R
th(j-c)
thermal resistance from
junction to case
16 15 % C/W
LQFP100 Package
R
th(j-a)
thermal resistance from
junction to ambient
JEDEC (4.5 in  4 in); still air 48 15 % C/W
Single-layer (4.5 in  3 in); still air 65 15 % C/W
R
th(j-c)
thermal resistance from
junction to case
19 15 % C/W
TFBGA180 Package
R
th(j-a)
thermal resistance from
junction to ambient
JEDEC (4.5 in  4 in); still air 41 15 % C/W
8-layer (4.5 in  3 in); still air 33 15 % C/W
R
th(j-c)
thermal resistance from
junction to case
14 15 % C/W
TFBGA100 Package
R
th(j-a)
thermal resistance from
junction to ambient
JEDEC (4.5 in  4 in); still air 69 15 % C/W
8-layer (4.5 in  3 in); still air 60 15 % C/W
R
th(j-c)
thermal resistance from
junction to case
10 15 % C/W
T
j
T
amb
P
D
R
th j a–
+=