ADSP-2196M_15 Datasheet, PDF (55/68 Pages) Analog Devices – DSP Microcomputer

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September 2001 ^{For current information contact Analog Devices at 800/262-5643}
ADSP-2196
72
287387
3,1
S)
Figure 33. Equivalent
Device Loading
for AC
Measurements
(Includes All
Fixtures)
,_2/
,1387
25
287387
9
0.4 V. C_L is the total bus
capacitance (per data line),
and I_L is9the total leakage or
three-state current (per data
line). The hold time will be
Figur3eV4o.ltagReeferencLeevelfsoAr C
MeEansOua9(ubrEetlxpemcu/Deetpinsttasble)
t_DECAY plus the minimum
disable time (i.e., t_DATRWH
for
Example System Hold
the write cycle).
Time Calculation
To determine the data output
h_,2o₊ld time in a particular
system, first calculate t_DECAY
using the equation given in
Figure 31. Choose –V to be
Capacitive Loading
Output delays and holds are
based on standard capacitive
loads: 50 pF on all pins (see
Figure 37). The delay and
hold specifications given
the difference between the _{should be derated by a factor}
ADSP-2196’s output voltage _{of 1.5 ns/50 pF for loads}
and the input threshold for _{other than the nominal value}
the device requiring the hold _{of 50 pF. Figure 35 and}
time. A typical –V will be _{Figure 36 show how output}
rise time varies with capaci-
tance. These figures also
show graphically how output
delays and holds vary with
load capacitance. (Note that
this graph or derating does
not apply to output disable
delays; see Output Disable
Time on page 54.) The
graphs in these figures may
not be linear outside the
ranges shown.





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Figure 35. Typical Output Rise Time (10%–90%,
V_DDEXT =Max) vs. Load Capacitance
Environmental Conditions
The thermal characteristics
in which the DSP is operating
influence performance.
Thermal Characteristics
The ADSP-2196 comes in a
144-lead LQFP or 144-lead
Ball Grid Array (mini-BGA)
package. The ADSP-2196 is
specified for an ambient tem-
perature (T_AMB) as calculated
using the formula in
Figure 38. To ensure that the
T_AMB data sheet specification
is not exceeded, a heatsink
and/or an air flow source may
be used. A heatsink should be
attached to the ground plane
(as close as possible to the
thermal pathways) with a
thermal adhesive.
Where:
• T_AMB = Ambient tempera-
ture (measured near top
surface of package)
• PD = Power dissipation in
W (this value depends
upon the specific applica-
tion; a method for
calculating PD is shown
under Power Dissipation).
• θ_CA = Value from Table 25.
• θ_JB = TBD°C/W
There are some important
things to note about these
T_AMB calculations and the
values in Table 25:
• This represents thermal
resistance at total power of
TBD W.
• For the LQFP package: θ_JC
= 0.96°C/W
For the mini-BGA
package: θ_JC = 8.4°C/W
REV. PrA
This information applies to a product under development. Its characteristics and specifications are subject to change with-
55
out notice. Analog Devices assumes no obligation regarding future manufacturing unless otherwise agreed to in writing.