ADSP-2196MKSTZ-160 Datasheet, PDF (54/68 Pages) Analog Devices – DSP Microcomputer

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September 2001 ^{For current information contact Analog Devices at 800/262-5643}
ADSP-2196
The P_EXT equation is calculated for each class of pins that
can drive as shown in Table 24.
Table 24. P_EXT Calculation
Pin Type # of Pins
% Switching
؋C
Address 15
50
MSx
1
0
WR
1
—
Data
16
50
CLKOUT 1
—
TBD pF
TBD pF
TBD pF
TBD pF
TBD pF
؋f
؋25.0 MHz
؋25.0 MHz
؋25 MHz
؋25.0 MHz
؋100 MHz
؋ V_DD²
؋10.9 V
؋ 10.9 V
؋10.9 V
؋10.9 V
؋10.9 V
= P_EXT
=TBD W
=TBD W
=TBD W
=TBD W
=TBD W
P_EXT=TBD W
A typical power consumption can now be calculated for
these conditions by adding a typical internal power dissipa-
tion with the formula in Figure 30.
P_TOTAL= P_EXT + P_INT
The output disable time t_DIS is the difference between
t_MEASURED and t_DECAY as shown in Figure 32. The time
t_MEASURED is the interval from when the reference signal
switches to when the output voltage decays –V from the
measured output high or output low voltage. The t_DECAY is
calculated with test loads C_L and I_L, and with –V equal to
0.5 V.
Figure 30. P_TOTAL (Typical) Calculation
Where:
• P_EXT is from Table 24
• P_INT is I_DDINT ؋ 2.5V, using the calculation I_DDINT listed in
Power Dissipation on page 52
Note that the conditions causing a worst-case P_EXT are
different from those causing a worst-case P_INT. Maximum
P_INT cannot occur while 100% of the output pins are
switching from all ones to all zeros. Note also that it is not
common for an application to have 100% or even 50% of
the outputs switching simultaneously.
Test Conditions
The DSP is tested for output enable, disable, and hold time.
Output Disable Time
Output pins are considered to be disabled when they stop
driving, go into a high impedance state, and start to decay
from their output high or low voltage. The time for the
voltage on the bus to decay by – V is dependent on the
capacitive load, C_L and the load current, I_L. This decay time
can be approximated by the equation in Figure 31.
t_DECAY
=
C_-----L---∆_----V_---
I_L
Figure 31. Decay Time Calculation
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Figure 32. Output Enable/Disable
Output Enable Time
Output pins are considered to be enabled when they have
made a transition from a high impedance state to when they
start driving. The output enable time t_ENA is the interval
from when a reference signal reaches a high or low voltage
level to when the output has reached a specified high or low
trip point, as shown in the Output Enable/Disable diagram
(Figure 32). If multiple pins (such as the data bus) are
enabled, the measurement value is that of the first pin to
start driving.
REV. PrA
This information applies to a product under development. Its characteristics and specifications are subject to change with-
54
out notice. Analog Devices assumes no obligation regarding future manufacturing unless otherwise agreed to in writing.