Analog Devices ADSP-2181 - Manual (Page 14)

ADSP-2181/ADSP-2183
REV. 0 –14–
ADSP-2181
ENVIRONMENTAL CONDITIONS
Ambient Temperature Rating:
T
AMB
= T
CASE
– (PD
× θ
CA
)
T
CASE
= Case Temperature in
°
C
PD = Power Dissipation in W
θ
CA
= Thermal Resistance (Case-to-Ambient)
θ
JA
= Thermal Resistance (Junction-to-Ambient)
θ
JC
= Thermal Resistance (Junction-to-Case)
Package
θ
JA
θ
JC
θ
CA
TQFP 50
°
C/W 2
°
C/W 48
°
C/W
PQFP 41
°
C/W 10
°
C/W 31
°
C/W
TEMPERATURE –
°
C
CURRENT (LOG SCALE) – µA
1000
100
0
–5 85 25 55
10
V
DD
= 5.5V
V
DD
= 5.0V
V
DD
= 4.5V
NOTES:
1. REFLECTS ADSP-2181 OPERATION IN LOWEST POWER MODE.
(SEE "SYSTEM INTERFACE" CHAPTER OF THE ADSP-2100 FAMILY
USER'S MANUAL FOR DETAILS.)
2. CURRENT REFLECTS DEVICE OPERATING WITH NO OUTPUT LOADS.
Figure 8. Power-Down Supply Current (Typical)
POWER DISSIPATION
To determine total power dissipation in a specific application,
the following equation should be applied for each output:
C
×
V
DD
2 ×
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 V
DD
= 5.0 V and t
CK
= 30 ns.
Total Power Dissipation = P
INT
+ (C
×
V
DD
2 ×
f )
P
INT
= internal power dissipation from Power vs. Frequency
graph (Figure 9).
(C
×
V
DD
2 ×
f ) is calculated for each output:
# of
Pins
×
C
×
V
DD
2 ×
f
Address, DMS 8
×
10 pF
×
5 2 V
×
33.3 MHz = 66.6 mW
Data Output, WR 9
×
10 pF
×
5 2 V
×
16.67 MHz = 37.5 mW
RD 1
×
10 pF
×
5 2 V
×
16.67 MHz = 4.2 mW
CLKOUT 1
×
10 pF
×
5 2 V
×
33.3 MHz = 8.3 mW
116.6 mW
Total power dissipation for this example is P
INT
+ 116.6 mW.
1/t
CK
– MHz
POWER (P
INT
) – mW
570
450
360
28 34 29 30 31 32 33
550
480
420
390
530
510
330
300
270
240
2181 POWER, INTERNAL
V DD = 5.5V
V
DD
= 5.0V
V
DD
= 4.5V
550mW
425mW
330mW
490mW
365mW
275mW
1/f
CK
– MHz
95
60
45
28 34 29 30 31 32 33
90
65
55
50
85
75
80
70
40
POWER, IDLE 1, 2
POWER (P
IDLE
) – mW
90mW
70mW
54mW
47mW
60mW
75mW
V DD = 5.5V
V
DD
= 5.0V
V DD = 4.5V
1/f
CK
– MHz
75
40
30
28 34 29 30 31 32 33
70
45
35
65
55
60
50
25
POWER, IDLE n MODES 3
70mW
35mW
33mW
29mW
31mW
60mW
IDLE;
IDLE (16)
IDLE (128)
POWER (P
IDLE
n
) – mW
VALID FOR ALL TEMPERATURE GRADES.
1 POWER REFLECTS DEVICE OPERATING WITH NO OUTPUT LOADS.
2 IDLE REFERS TO ADSP-2181 STATE OF OPERATION DURING EXECUTION OF IDLE
INSTRUCTION. DEASSERTED PINS ARE DRIVEN TO EITHER V
DD
OR GND.
3 TYPICAL POWER DISSIPATION AT 5.0V V DD DURING EXECUTION OF IDLE n
INSTRUCTION (CLOCK FREQUENCY REDUCTION).
4 I DD 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.
Figure 9. Power vs. Frequency