DSP56156FV40 MOTOROLA [Motorola, Inc], DSP56156FV40 Datasheet - Page 65

• Manufacturer Part Number: DSP56156FV40
• Description: 16-bit Digital Signal Processor
• Manufacturer: MOTOROLA [Motorola, Inc]

60
Design Considerations
Heat Dissipation
Power, Ground, and Noise
Heat Dissipation
The average chip junction temperature, T
Where:
For most applications P
be neglected. An appropriate relationship be-
tween P
Solving equations (1) and (2) for K gives:
Where K is a constant pertaining to the partic-
ular package. K can be determined from
equation (2) by measuring P
um) for a known T
values of P
ing equations (1) and (2) iteratively for any
value of T
package (
ponents,
to heat flow from the semiconductor junction
to the package (case) surface (
the case to the outside ambient (
terms are related by the equation:
Design Considerations
C, can be obtained from:
P
K = P
T
T
P
P
P
D
A
J
D
INT
I/O
JA
JA
= T
= K/(T
=
D
= ambient temperature, C
= package thermal resistance,
= P
= I
= power dissipation on input and
D
A
and T
A
JC
D
+ (P
. The total thermal resistance of a
junction-to-ambient, C/W
power
output pins — user determined
JA
JC
CC
(T
INT
and
and T
) can be separated into two com-
+
J
A
+ 273)
D
J
+ P
V
+ 273) + P
(if P
CA
CC
A
J
CA
I/O
. Using this value of K, the
can be obtained by solv-
JA
watts — chip internal
I/O
, representing the barrier
)
I/O
is neglected) is:
Freescale Semiconductor, Inc.
D
< P
For More Information On This Product,
D
INT
(at equilibri-
DSP56156 Data Sheet
JA
JC
) and from
and P
CA
). These
Go to: www.freescale.com
I/O
(2)
(3)
(4)
J
can
, in
(1)
enced by the user. However,
pendent and can be minimized by such
thermal management techniques as heat
sinks, ambient air cooling, and thermal con-
vection. Thus, good thermal management on
the part of the user can significantly reduce
Substitution of
result in a lower semiconductor junction
temperature. Values for thermal resistance
presented in this document, unless estimat-
ed, were derived using the procedure de-
scribed in Motorola Reliability Report 7843,
“Thermal Resistance Measurement Method
for MC68XX Microcomponent Devices”, and
are provided for design purposes only. Ther-
mal measurements are complex and depen-
dent on procedure and setup. User-derived
values for thermal resistance may differ.
Power, Ground, and
Noise
Each DSP56156 V
with a low-impedance path to +5 volts. Each
DSP56156 GND pin should likewise be pro-
vided with a low-impedance path to ground.
The power supply pins drive distinct groups
of logic on chip as shown in Table 26.
passed to GND ground using at least six
0.01 – 0.1 µF bypass capacitors located ei-
ther underneath the chip’s socket or as close
as possible to the four sides of the package.
The capacitor leads and the associated
printed circuit traces connecting to chip V
and GND should be kept to less than 0.5” per
JC
CA
The V
is device-related and cannot be influ-
so that
CC
power supply should be by-
JA
approximately equals
JC
CC
for
pin should be provided
JA
in equation (1) will
CA
is user-de-
MOTOROLA
JC
.
CC