DSP56364D Motorola Inc, DSP56364D Datasheet - Page 93

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DSP56364D

Manufacturer Part Number
DSP56364D
Description
24-Bit Audio Digital Signal Processor
Manufacturer
Motorola Inc
Datasheet
4.3
Power dissipation is a key issue in portable DSP applications. Some of the factors which affect current
consumption are described in this section. Most of the current consumed by CMOS devices is alternating
current (ac), which is charging and discharging the capacitances of the pins and internal nodes.
Current consumption is described by the following formula:
The maximum internal current (I
on best-case operation conditions, which is not necessarily a real application case. The typical internal
current (I
For applications that require very low current consumption, do the following:
MOTOROLA
For a Port A address pin loaded with 50 pF capacitance, operating at 3.3 V, and with a 100 MHz
clock, toggling at its maximum possible rate (50 MHz), the current consumption is
All inputs must be terminated (i.e., not allowed to float) using CMOS levels, except for the three pins
with internal pull-up resistors (TMS, TDI, TCK).
Take special care to minimize noise levels on the V
If multiple DSP56364 devices are on the same board, check for cross-talk or excessive spikes on
the supplies due to synchronous operation of the devices.
RESET must be asserted when the chip is powered up. A stable EXTAL signal must be supplied
before deassertion of RESET.
At power-up, ensure that the voltage difference between the 5 V tolerant pins and the chip V
never exceeds 3.95 V.
Set the EBD bit when not accessing external memory.
Minimize external memory accesses and use internal memory accesses.
Minimize the number of pins that are switching.
Minimize the capacitive load on the pins.
Connect the unused inputs to pull-up or pull-down resistors.
Disable unused peripherals.
CCItyp
POWER CONSUMPTION CONSIDERATIONS
where
I
) value reflects the average switching of the internal buses on typical operating conditions.
=
C
V
f
Freescale Semiconductor, Inc.
C = node/pin capacitance
V = voltage swing
f = frequency of node/pin toggle
For More Information On This Product,
I
CCI
=
Example 1 Current Consumption
50
max) value reflects the typical possible switching of the internal buses
DSP56364 Advance Information
Go to: www.freescale.com
10
12
3.3 50
10
CCP
6
=
Power Consumption Considerations
and GND
8.25mA
P
pins.
Design Considerations
CC
4-3

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