ADSP-2184BST-160 Просмотр технического описания (PDF) - Analog Devices
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ADSP-2184BST-160 Datasheet PDF : 31 Pages
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ADSP-2184
OUTPUT DRIVE CURRENTS
Figure 20 shows typical I-V characteristics for the output drivers
of the ADSP-2184. The curves represent the current drive
capability of the output drivers as a function of output voltage.
60
VDD = 5.0V @ +25؇C
40
20
VDD = 4.5V @ +85؇C
0
VOH
VDD = 5.5V @ –40؇C
–20
VOL
–40
VDD = 4.5V @ +85؇C
VDD = 5.0V @ +25؇C
–60
0
VDD = 5.5V @ –40؇C
10
20
30
40
50
60
SOURCE VOLTAGE – V
Figure 20. Typical Drive Currents
POWER DISSIPATION
To determine total power dissipation in a specific application,
the following equation should be applied for each output:
C × VDD2 × f
C = load capacitance, f = output switching frequency.
Example
In an application where external data memory is used and no
other outputs are active, power dissipation is calculated as follows:
Assumptions
• External data memory is accessed every cycle with 50% of the
address pins switching.
• External data memory writes occur every other cycle with
50% of the data pins switching.
• Each address and data pin has a 10 pF total load at the pin.
• The application operates at VDD = 5.0 V and tCK = 25 ns.
Total Power Dissipation = PINT + (C × VDD2 × f)
PINT = internal power dissipation from Power vs. Frequency
graph (Figure 21).
(C × VDD2 × f) is calculated for each output:
# of
Pins ؋ C
؋ VDD2 ؋f
Address, DMS 8
Data Output, WR 9
RD
1
CLKOUT
1
× 10 pF × 52 V
× 10 pF × 52 V
× 10 pF × 52 V
× 10 pF × 52 V
× 40 MHz = 80 mW
× 20 MHz = 45 mW
× 20 MHz = 5 mW
× 40 MHz = 10 mW
140 mW
Total power dissipation for this example is PINT + 40 mW.
2184 POWER, INTERNAL1, 2, 3
400
385mW
375
VDD = 5.5V
350
325
330mW
300
275
VDD = 5.0V
300mW
250
250mW
225
VDD = 4.5V
225mW
200
180mW
175
150
33.33
40
1/tCYC – MHz
POWER, IDLE1, 2, 4
95
90
VDD = 5.5V
91.52mW
85
82.28mW
80
75
70
65
62.1mW
60
VDD = 5.0V
70.55mW
55
50
VDD = 4.5V
51.705mW
45
44.73mW
40
33.33
40
1/tCYC – MHz
POWER, IDLE n MODES2
75
70
70.55mW
IDLE
65
62.1mW
60
55
50
45
40
34.7mW
35
30
32.8mW
36.6mW
34.3mW
IDLE (16)
IDLE (128)
25
33.33
40
1/tCYC – MHz
VALID FOR ALL TEMPERATURE GRADES.
1POWER REFLECTS DEVICE OPERATING WITH NO OUTPUT LOADS.
2IDD MEASUREMENT TAKEN WITH ALL INSTRUCTIONS EXECUTING FROM INTERNAL
MEMORY. 50% OF THE INSTRUCTIONS ARE MULTIFUNCTION (TYPES 1, 4, 5, 12, 13, 14)
30% ARE TYPE 2 AND TYPE 6, AND 20% ARE IDLE INSTRUCTIONS.
3IDLE REFERS TO ADSP-2184 STATE OF OPERATION DURING EXECUTION OF IDLE
INSTRUCTION. DEASSERTED PINS ARE DRIVEN TO EITHER VDD OR GND.
4TYPICAL POWER DISSIPATION AT 5.0V VDD AND TA = 25؇C EXCEPT WHERE SPECIFIED.
Figure 21. Power vs. Frequency
–26–
REV. 0
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