Analog Devices ADSP-2186 Specification Sheet page 15

ENVIRONMENTAL CONDITIONS
Ambient Temperature Rating:
T = T – (PD x
AMB CASE
T = Case Temperature in C
CASE
PD = Power Dissipation in W
= Thermal Resistance (Case-to-Ambient)
CA
= Thermal Resistance (Junction-to-Ambient)
JA
= Thermal Resistance (Junction-to-Case)
JC
Package
JA
TQFP 50 C/W
POWER DISSIPATION
To determine total power dissipation in a specific application,
the following equation should be applied for each output:
C
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 V
Total Power Dissipation = P
P = internal power dissipation from Power vs. Frequency
INT
graph (Figure 8).
2
(C V f) is calculated for each output:
DD
# of
Pins C
Address, DMS
8 10 pF
Data Output, WR 9
10 pF
RD
1 10 pF
CLKOUT 1 10 pF
Total power dissipation for this example is PINT + 116.6 mW.
REV. 0
)
CA
JC CA
2 C/W 48 C/W
2
V f
DD
= 5.0 V and t = 30 ns.
DD CK
2
+ (C V f)
INT DD
2
V f
DD
2
5 V 33.3 MHz = 66.6 mW
2
5 V 16.67 MHz = 37.5 mW
2
5 V 16.67 MHz = 4.2 mW
2
5 V 33.3 MHz = 8.3 mW
116.6 mW
2186 POWER, INTERNAL
450
425
400
375
350
330mW
325
300
275
245mW
250
225
200
175mW
175
150
30 32 34
POWER, IDLE
85
80
75
69mW
70
65
60
56mW
55
50
45mW
45
40
35
30
30 32 34
POWER, IDLE n MODES
70
65
60
56mW
55
50
45
40
35
30mW
30
28mW
25
20
28 30 32
VALID FOR ALL TEMPERATURE GRADES.
1
POWER REFLECTS DEVICE OPERATING WITH NO OUTPUT LOADS.
2
IDLE REFERS TO ADSP-2186 STATE OF OPERATION DURING EXECUTION OF IDLE
INSTRUCTION. DEASSERTED PINS ARE DRIVEN TO EITHER V
3
TYPICAL POWER DISSIPATION AT 5.0V V
4
I MEASUREMENT TAKEN WITH ALL INSTRUCTIONS EXECUTING FROM INTERNAL
DD
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.
5
SPECIFICATIONS AT 40MHz ARE PRELIMINARY AT THIS PRINTING.
Figure 8. Power vs. Frequency
–15–
ADSP-2186
1, 3, 4, 5
V = 5.5V
DD
430mW
370mW
325mW
V = 5.0V
DD
275mW
235mW
V = 4.5V
DD
195mW
36 38 40 42
1/f – MHz
CK
1, 2, 3, 5
84mW
76mW
V = 5.5V
DD
67mW
61mW
V = 5.0V
DD
54mW
49mW
V = 4.5V
DD
36 38 40 42
1/f – MHz
CK
3, 5
67mW IDLE
61mW
32mW
34mW
IDLE (16)
32mW
IDLE (128)
30mW
34 36 38 40 42
1/f – MHz
CK
OR GND.
DD
AND T = 25 C EXCEPT WHERE SPECIFIED.
DD A