DSP56002RC40 Motorola Inc, DSP56002RC40 Datasheet - Page 104

• Manufacturer Part Number: DSP56002RC40
• Description: 24-BIT DIGITAL SIGNAL PROCESSOR
• Manufacturer: Motorola Inc

Design Considerations
Power Consumption
POWER CONSUMPTION
4-4
Equation 3:
Equation 4:
Power dissipation is a key issue in portable DSP applications. The following describes
some factors which affect current consumption. Current consumption is described by
the formula:
where:
For example, for an address pin loaded with a 50 pF capacitance and operating at 5.5
V with a 40 MHz clock, toggling at its maximum possible rate (which is 10 MHz), the
current consumption is:
The maximum internal current value (I
when running the code given below. This represents “typical” internal activity, and is
included as a point of reference. Some applications may consume more or less current
depending on the code used. The typical internal current value (I
what is typically seen when running the given code.
The following steps are recommended for applications requiring very low current
consumption:
1. Minimize external memory accesses; use internal memory accesses instead.
2. Minimize the number of pins that are switching.
3. Minimize the capacitive load on the pins.
4. Connect the unused inputs to pull-up or pull-down resistors.
C = node/pin capacitance
V = voltage swing
f = frequency of node/pin toggle
I
I
=
=
C V f
50 10
–
12
5.5 10 10
DSP56002/D, Rev. 3
6
=
2.75mA
CCI
-max), reflects the maximum I
CCI
-typ) reflects
MOTOROLA
CC
expected