ADSP2186 Datasheet, PDF (15/32 Pages) Analog Devices – DSP Microcomputer

ENVIRONMENTAL CONDITIONS
Ambient Temperature Rating:
T_AMB =
T_CASE =
PD =
θ_CA =
θ_JA
=
θ_JC
=
T_CASE – (PD x θ_CA)
Case Temperature in °C
Power Dissipation in W
Thermal Resistance (Case-to-Ambient)
Thermal Resistance (Junction-to-Ambient)
Thermal Resistance (Junction-to-Case)
Package
TQFP
␪_JA
50°C/W
␪_JC
2°C/W
␪_CA
48°C/W
POWER DISSIPATION
To determine total power dissipation in a specific application,
the following equation should be applied for each output:
C × V_DD2 × 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_DD² × f)
P_INT = internal power dissipation from Power vs. Frequency
graph (Figure 8).
(C × V_DD² × f) is calculated for each output:
# of
Pins ؋ C
؋ V_DD2 ؋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
× 33.3 MHz = 66.6 mW
× 16.67 MHz = 37.5 mW
× 16.67 MHz = 4.2 mW
× 33.3 MHz = 8.3 mW
116.6 mW
Total power dissipation for this example is PINT + 116.6 mW.
ADSP-2186
450
425
400
375
350
325
300
275
250
225
200
175
150
30
85
80
75
70
65
60
55
50
45
40
35
30
30
70
65
60
55
2186 POWER, INTERNAL^{1, 3, 4, 5}
V_DD = 5.5V
370mW
430mW
330mW
245mW
175mW
V_DD = 5.0V
275mW
325mW
V_DD = 4.5V
195mW
235mW
32
34
36
38
1/f_CK – MHz
POWER, IDLE^{1, 2, 3, 5}
69mW
76mW
V_DD = 5.5V
56mW
45mW
61mW
V_DD = 5.0V
49mW
V_DD = 4.5V
40
42
84mW
67mW
54mW
32
34
36
38
40
42
1/f_CK – MHz
POWER, IDLE n MODES^{3, 5}
61mW
67mW IDLE
56mW
50
45
40
35
30mW
30
25
28mW
32mW
30mW
34mW _{IDLE (16)}
32mW _{IDLE (128)}
20
28
30
32
34
36
38
40
42
1/f_CK – MHz
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_DD OR GND.
3_{TYPICAL POWER DISSIPATION AT 5.0V VDD AND TA = 25°C EXCEPT WHERE SPECIFIED.}
4_{IDD 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.
5_{SPECIFICATIONS AT 40MHz ARE PRELIMINARY AT THIS PRINTING.}
Figure 8. Power vs. Frequency
REV. 0
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