Datasheet

LPC12D27 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2011. All rights reserved.
Product data sheet Rev. 1 — 20 September 2011 18 of 46
NXP Semiconductors
LPC12D27
32-bit ARM Cortex-M0 microcontroller
9. Thermal characteristics
9.1 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 6. Thermal characteristics
V
DD
= 3.0 V to 3.6 V; T
amb
=  40  C to +85  C unless otherwise specified.
Symbol Parameter Conditions Min Typ Max Unit
R
th(j-a)
thermal resistance from
junction to ambient
JEDEC test board; no
air flow
LQFP64 package
-61- C/W
LQFP48 package 86 - C/W
R
th(j-c)
thermal resistance from
junction to case
JEDEC test board
LQFP64 package
-19- C/W
LQFP48 package 36 - C/W
T
j(max)
maximum junction
temperature
--150 C