Datasheet

LPC84x All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2018. All rights reserved.
Product data sheet Rev. 1.7 — 27 February 2018 44 of 97
NXP Semiconductors
LPC84x
32-bit Arm Cortex-M0+ microcontroller
10. 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.
T
j
T
amb
P
D
R
th j a–
+=
Table 10. Thermal resistance
Symbol Parameter Conditions Max/min Unit
HVQFN33 package
R
th(j-a)
thermal resistance from junction-to-ambient JEDEC (4.5 in  4 in); still air 40  15 % C/W
single-layer (4.5 in  3 in); still air 114  15 % C/W
R
th(j-c)
thermal resistance from junction-to-case 20  15 % C/W
HVQFN48 package
R
th(j-a)
thermal resistance from junction-to-ambient JEDEC (4.5 in  4 in); still air 35  15 % C/W
single-layer (4.5 in  3 in); still air 85  15 % C/W
R
th(j-c)
thermal resistance from junction-to-case 9  15 % C/W
LQFP48 package
R
th(j-a)
thermal resistance from junction-to-ambient JEDEC (4.5 in  4 in); still air 82  15 % C/W
single-layer (4.5 in  3 in); still air 115  15 % C/W
R
th(j-c)
thermal resistance from junction-to-case 30  15 % C/W
LQFP64 package
R
th(j-a)
thermal resistance from junction-to-ambient JEDEC (4.5 in  4 in); still air 59  15 % C/W
single-layer (4.5 in  3 in); still air 82  15 % C/W
R
th(j-c)
thermal resistance from junction-to-case 18  15 % C/W