MSC8101DS Motorola / Freescale Semiconductor, MSC8101DS Datasheet - Page 112

• Manufacturer Part Number: MSC8101DS
• Description: MSC8101 Network Digital Signal Processor
• Manufacturer: Motorola / Freescale Semiconductor

4.3
The internal power dissipation consists of three components:
The power dissipation depends on the operating frequency of the different portions of the chip. The numbers
given in Table 4-1 refer to 300 MHz core frequency, 150 MHz CPM frequency, and 100 MHz SIU frequency.
To determine the power dissipation at a given frequency, the following equations should be applied:
Where f is the operating frequency in MHz and all power numbers are in mW.
To determine a total power dissipation in a specific application, the following equation should be applied for
each I/O output pin:
Where: P = power in mW, C = load capacitance in pF, f = output switching frequency in MHz.
Example:
For an application in which external data memory is used in a 32-bit single bus mode and no other outputs are
active, the core runs at 200 MHz, the CPM runs at 100 MHz and the SIU runs at 50 MHz, power dissipation is
calculated as follows:
Assumptions:
Since the address pins switch once at every second cycle, the address pins frequency is a quarter of the bus
frequency (i.e., 25 MHz).
For the same reason the data pins frequency is 3.125 MHz.
Calculating internal power:
4-2
Data, HRD, HRW
Total P
CLKOUT
Address
Power Considerations
P
P
P
P
External data memory is accessed every second cycle with 10% of address pins switching.
External data memory writes occurs once every eight cycles with 50% of data pins switching.
Each address and data pin has a 30 pF total load at the pin.
The application operates at VDDH = 3.3 V.
Pins
INT
CORE
SIU
CPM
Equation 2: P = C
(f) = ((P
= P
I/O
(f) = ((P
(f) = ((P
CORE
SIU
CPM
+ P
CORE
– P
SIU
switching
# of pins
– P
LSI
– P
34
+ P
LCP
4
1
)/100) f + P
LCO
CPM
V
)/150)
DDH
)/300)
2
Table 4-1. Power Dissipation
MSC8101 Technical Data
f + P
f
LSI
f + P
10
LCP
30
30
30
C
–3
LCO
V
3.3
3.3
3.3
DDH
2
2
2
2
3. 125
12.5
50
f
10
10
10
–3
10
–3
–3
–3
Power in mW
16.25
34.75
16
67