DSP56721 Freescale Semiconductor, Inc, DSP56721 Datasheet - Page 10

• Manufacturer Part Number: DSP56721
• Description: Dsp56721 Multi-core Audio Processor
• Manufacturer: Freescale Semiconductor, Inc

2.1.2
For thermal characteristics, see
2.1.3
To prevent high current conditions due to possible improper sequencing of the power supplies, use an external Schottky diode
as shown in
If an external Schottky diode is not used (to prevent a high current condition at power-up), then IO_VDD must be applied ahead
of Core_VDD, as shown in
For correct operation of the internal power-on reset logic, the Core_VDD ramp rate (Tr) to full supply must be less than 10 ms,
as shown in
10
Natural Convection, Junction-to-ambient thermal resistance
Junction-to-case thermal resistance
Notes:
1.
2.
3.
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.
Per SEMI G38-87 and JEDEC JESD51-2 with the single layer board horizontal.
Thermal resistance between the die and the case top surface as measured by the cold plate method
(MIL SPEC-883 Method 1012.1).
Figure
Figure
Thermal Characteristics
Power Requirements
Figure 7. Prevent High Current Conditions by Applying IO_VDD Before Core_VDD
Figure 6. Prevent High Current Conditions by Using External Schottky Diode
6, connected between the DSP56720/DSP56721 IO_VDD and Core_VDD power pins.
8.
Symphony
Characteristic
IO_VDD
Figure
Core_VDD
Table
7.
TM
3
5.
DSP56720 / DSP56721 Multi-Core Audio Processors, Rev. 3
Core_VDD
Table 5. Thermal Characteristics
IO_VDD
1,2
Single layer board
(1s)
Four layer board
(2s2p)
Board Type
—
Schottky
External
Diode
R
R
Symbol
θJC
θJA
or θ
or θ
JA
JC
57 for 80 QFP
49 for 144 QFP
44 for 80 QFP
40 for 144 QFP
10 for 80 QFP
9 for 144 QFP
Freescale Semiconductor
LQFP Values
°
°
°
Unit
C/W
C/W
C/W