MSC8126 Datasheet, PDF (44/48 Pages) Freescale Semiconductor, Inc – Quad Digital Signal Processor

Ordering Information
3.5 Thermal Considerations
An estimation of the chip-junction temperature, T_J, in °C can be obtained from the following:
T_J = T_A + (R_θJA × P_D)
Eqn. 1
where
T_A = ambient temperature near the package (°C)
R_θJA = junction-to-ambient thermal resistance (°C/W)
P_D = P_INT + P_I/O = power dissipation in the package (W)
P_INT = I_DD × V_DD = internal power dissipation (W)
P_I/O = power dissipated from device on output pins (W)
The power dissipation values for the MSC8126 are listed in Table 2-3. The ambient temperature for the device is the air
temperature in the immediate vicinity that would cool the device. The junction-to-ambient thermal resistances are JEDEC
standard values that provide a quick and easy estimation of thermal performance. There are two values in common usage: the
value determined on a single layer board and the value obtained on a board with two planes. The value that more closely
approximates a specific application depends on the power dissipated by other components on the printed circuit board (PCB).
The value obtained using a single layer board is appropriate for tightly packed PCB configurations. The value obtained using a
board with internal planes is more appropriate for boards with low power dissipation (less than 0.02 W/cm² with natural
convection) and well separated components. Based on an estimation of junction temperature using this technique, determine
whether a more detailed thermal analysis is required. Standard thermal management techniques can be used to maintain the
device thermal junction temperature below its maximum. If T_J appears to be too high, either lower the ambient temperature or
the power dissipation of the chip. You can verify the junction temperature by measuring the case temperature using a small
diameter thermocouple (40 gauge is recommended) or an infrared temperature sensor on a spot on the device case that is painted
black. The MSC8126 device case surface is too shiny (low emissivity) to yield an accurate infrared temperature measurement.
Use the following equation to determine T_J:
T_J = T_T + (θ_JA × P_D)
Eqn. 2
where
Note:
T_T = thermocouple (or infrared) temperature on top of the package (°C)
θ_JA = thermal characterization parameter (°C/W)
P_D = power dissipation in the package (W)
See MSC8102, MSC8122, and MSC8126 Thermal Management Design Guidelines (AN2601/D).
4 Ordering Information
Consult a Freescale Semiconductor sales office or authorized distributor to determine product availability and place an order.
Part
Package Type
MSC8126 Flip Chip Plastic Ball Grid Array (FC-PBGA)
Spheres
Lead-free
Lead-bearing
Lead-free
Lead-bearing
Core
Voltage
1.2 V
Operating
Temperature
Core
Frequency
(MHz)
–40° to 105°C
400
0° to 90°C
500
Order Number
MSC8126TVT6400
MSC8126TMP6400
MSC8126VT8000
MSC8126MP8000
MSC8126 Quad Digital Signal Processor Data Sheet, Rev. 13
44
Freescale Semiconductor