56F8346_07 Datasheet, PDF (139/178 Pages) Freescale Semiconductor, Inc – 16-bit Digital Signal Controllers

General Characteristics
Table 10-3 Thermal Characteristics⁶
Characteristic
Comments
Symbol
Value
144-pin LQFP
Unit Notes
Junction to ambient (@1m/sec)
R_θJMA
43.8
°C/W
2
Junction to ambient
Natural convection
Four layer board (2s2p)
R_θJMA
(2s2p)
40.8
°C/W 1,2
Junction to ambient (@1m/sec) Four layer board (2s2p)
R_θJMA
39.2
°C/W 1,2
Junction to case
R_θJC
11.8
°C/W
3
Junction to center of case
Ψ_JT
1
°C/W 4, 5
I/O pin power dissipation
P _I/O
User-determined
W
Power dissipation
P_D
P _D = (I_DD x V_DD + P _I/O)
W
Maximum allowed P_D
P_DMAX
(TJ - TA) / RθJA⁷
W
1. Theta-JA determined on 2s2p test boards is frequently lower than would be observed in an application. Determined on 2s2p ther-
mal test board.
2. Junction to ambient thermal resistance, Theta-JA (R_θJA) was simulated to be equivalent to the JEDEC specification JESD51-2
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_θJC ), was simulated to be equivalent to the measured values using the cold
plate technique with the cold plate temperature used as the "case" temperature. The basic cold plate measurement technique is
described 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. Thermal Characterization Parameter, Psi-JT (Ψ_JT ), is the "resistance" from junction to reference point thermocouple on top cen-
ter of case as defined in JESD51-2. Ψ_JT is a useful value to use to estimate junction temperature in steady-state customer en-
vironments.
5. Junction temperature is a function of 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.
6. See Part 12.1 for more details on thermal design considerations.
7. TJ = Junction temperature
TA = Ambient temperature
Note: The 56F8146 device is guaranteed to 40MHz and specified to meet Industrial requirements only;
CAN is NOT available on the 56F8146 device.
Table 10-4 Recommended Operating Conditions
(V_REFLO = 0V, V_SS = V_{SSA_ADC} = 0V_, V_DDA = V_{DDA_ADC} = V_{DDA_OSC_PLL} )
Characteristic
Symbol
Notes
Min
Typ
Supply voltage
V_{DD_IO}
3
3.3
ADC Supply Voltage
V_{DDA_ADC,}
V_REFH must be less than
3
3.3
V_REFH
or equal to V_{DDA_ADC}
Oscillator / PLL Supply Voltage
V_{DDA_OSC_PLL}
3
3.3
Max
3.6
3.6
3.6
Unit
V
V
V
56F8346 Technical Data, Rev. 15
Freescale Semiconductor
139
Preliminary