General Characteristics
6
Table 10-3 LQFP Package Thermal Characteristics
Value
(LQFP)
Characteristic
Symbol
Unit
Notes
Comments
Junction to ambient
Natural convection
Single layer board
(1s)
RθJA
41
34
°C/W
°C/W
2
Junction to ambient
Natural convection
Four layer board
(2s2p)
RθJMA
1, 2
Junction to ambient
(@200 ft/min)
Single layer board
(1s)
RθJMA
34
29
°C/W
°C/W
2
Junction to ambient
(@200 ft/min)
Four layer board
(2s2p)
RθJMA
1, 2
Junction to board
RθJB
RθJC
ΨJT
24
8
°C/W
°C/W
°C/W
4
3
5
Junction to case
Junction to package top
Natural Convection
2
1. Theta-JA determined on 2s2p test boards is frequently lower than would be observed in an application. Determined on 2s2p
thermal test board.
2. Junction to ambient thermal resistance, Theta-JA (R ), was simulated to be equivalent to the JEDEC specification JESD51-2
θJA
in a horizontal configuration in natural convection. Theta-JA was also simulated on a thermal test board with two internal planes
(2s2p, where “s” is the number of signal layers and “p” is the number of planes) per JESD51-6 and JESD51-7. The correct name
for Theta-JA for forced convection or with the non-single layer boards is Theta-JMA.
3. Junction to case thermal resistance, Theta-JC (R ), was simulated to be equivalent to the measured values using the cold plate
θJC
technique with the cold plate temperature used as the “case” temperature. The basic cold plate measurement technique is de-
scribed by MIL-STD 883D, Method 1012.1. This is the correct thermal metric to use to calculate thermal performance when the
package is being used with a heat sink.
4. Junction to board thermal resistance, Theta-JB (R ), is a metric of the thermal resistance from the junction to the printed circuit
θJB
board determined per JESD51-8. Board temperature is measured on the top surface of the board near the package.
5. Thermal Characterization Parameter, Psi-JT (Y ), is the “resistance” from junction to reference point thermocouple on top center
JT
of case as defined in JESD51-2. Y is a useful value to use to estimate junction temperature in steady state customer
JT
environments.
6. Junction temperature is a function of die size, on-chip power dissipation, package thermal resistance, mounting site (board)
temperature, ambient temperature, air flow, power dissipation of other components on the board, and board thermal resistance.
7. See Section 12.1 for more details on thermal design considerations.
Table 10-4 Recommended Operating Conditions
(V
= 0V, V
= 0V, V = 0V)
REFL x
SSA SS
Characteristic
Supply voltage
Symbol
Notes
Min
Typ
Max
Unit
VDD,
3
3.3
3.6
V
VDDA
ADC Reference Voltage High
VREFHx
3.0
VDDA
V
56F8025 Data Sheet, Rev. 3
Freescale Semiconductor
Preliminary
119
FREESCALE [ Freescale ]
