2
DragonBall Power Management
Motorola
DragonBall Power Modes
Content Organization
Please refer to the following list for a description of this application note’s contents.
“DragonBall Common Reference Platform”.......................................................................................... 1
“Content Organization”.................................................................................................................... 2
“DragonBall Power Modes”................................................................................................................... 2
“Burst Mode”................................................................................................................................... 3
“DOZE Mode”................................................................................................................................. 3
“Sleep Mode”................................................................................................................................... 4
“Power Consumption Test”.................................................................................................................... 4
“Test Hardware Set-Up”.................................................................................................................. 4
“Normal Mode Test”........................................................................................................................ 4
“Burst Mode Test”........................................................................................................................... 5
“DOZE Mode Test”......................................................................................................................... 5
“Sleep Mode Test”........................................................................................................................... 6
“Conclusions”......................................................................................................................................... 7
DragonBall Power Modes
Based on application needs, the DragonBall can operate in any of four modes: normal mode, burst
mode, DOZE mode, and sleep mode. Properly applied, power-saving techniques can result in minimal
power consumption for the entire system and can thus extend battery life. The current consumption
values specified in the DragonBall user’s manual represent the maximum normal mode value as well
as a sleep mode value. In real-world applications, DOZE mode is used most of the time the system is
up and running.
The DragonBall processors acheive power savings by minimizing bus activity while optimizing
system and CPU clock frequencies. Figure 2 shows the clock tree model of the internal phase lock
loop (PLL) and power management circuit.
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Figure 2.
Clock Tree Model of Internal PLL
Please refer to the following list for a description of the elements of Figure 2.
External clock input—Both 32.768KHz and 38.4KHz crystals can be used as the PLL input
frequency. A frequency of 32.768KHz is recommended. Throughout this application note,
32.768KHz, or simply 32KHz, will be assumed as the input reference.
Voltage-controlled oscillator (VCO)—This is the output frequency of the PLL’s VCO. Its
default output frequency, for a 32KHz input, is 16.58MHz. The VCO frequency can be
changed from approximately 9MHz to 23 MHz through programming of the P and Q values of
Frequency
Select
Sysclk
Divider
CPU Clock
Burst Control
Pixclk
Divider
Sysclk
VCO
Peripheral Modules
Pixel Clock
CPU Clock
External
Clock Input
AA1913