Analog Devices ADSP-2181 - Manual (Page 18)

ADSP-2181/ADSP-2183
REV. 0 –18–
(C
×
V
DD
2 ×
f ) is calculated for each output:
# of
Pins
×
C
×
V
DD
2 ×
f
Address, DMS 8
×
10 pF
×
3.3 2 V
×
33.3 MHz = 29.0 mW
Data Output, WR 9
×
10 pF
×
3.3 2 V
×
16.67 MHz = 16.3 mW
RD 1
×
10 pF
×
3.3 2 V
×
16.67 MHz = 1.8 mW
CLKOUT 1
×
10 pF
×
3.3 2 V
×
33.3 MHz = 3.6 mW
50.7 mW
Total power dissipation for this example is P
INT
+ 50.7 mW.
1/t CK – MHz
POWER (P
INT
) – mW
200
160
130
22 28 23 24 25 26 27
190
170
150
140
180
120
110
100
POWER, INTERNAL 1,4
V DD = 3.6V
V DD = 3.3V
V
DD
= 3.0V
195mW
160mW
125mW
175mW
140mW
110mW
29 30 31
1/t CK – MHz
34
24
18
22 28 23 24 25 26 27
32
26
22
20
30
28
16
14
12
10
POWER (P
IDLE
) – mW
POWER, IDLE 1,2
V
DD
= 3.6V
V DD = 3.3V
V
DD
= 3.0V
33mW
27mW
21mW
27mW
21mW
17mW
29 30 31
1/t CK – MHz
30
20
14
26 22 23 24 25
28
22
18
16
26
24
12
10
8
6
POWER, IDLE n MODES 3
27mW
13mW
12mW
21mW
12mW
11mW
27 28 29 30
IDLE
IDLE
(16)
IDLE
(128)
POWER (P
IDLE
n
) – mW
31
VALID FOR ALL TEMPERATURE GRADES.
1 POWER REFLECTS DEVICE OPERATING WITH NO OUTPUT LOADS.
2 IDLE REFERS TO ADSP-2183 STATE OF OPERATION DURING EXECUTION OF IDLE
INSTRUCTION. DEASSERTED PINS ARE DRIVEN TO EITHER V
DD
OR GND.
3 TYPICAL POWER DISSIPATION AT 3.3V 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 16. Power vs. Frequency
ADSP-2183
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
NOTES:
1. REFLECTS ADSP-2183 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.
V DD = 3.6V
V
DD
= 3.3V
V DD = 3.0V
Figure 15. 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
= 3.3 V and t
CK
= 34.7 ns.
Total Power Dissipation = P
INT
+ (C
×
V
DD
2 ×
f )
P
INT
= internal power dissipation from Power vs. Frequency
graph (Figure 16).