ADSP-2109 AD [Analog Devices], ADSP-2109 Datasheet - Page 14

• Manufacturer Part Number: ADSP-2109
• Description: Low Cost DSP Microcomputers
• Manufacturer: AD [Analog Devices]

ADSP-2104/ADSP-2109
SPECIFICATIONS (ADSP-2104/ADSP-2109)
POWER DISSIPATION EXAMPLE
To determine total power dissipation in a specific application,
the following equation should be applied for each output:
C = load capacitance, f = output switching frequency.
Example:
In an ADSP-2104 application where external data memory is
used and no other outputs are active, power dissipation is
calculated as follows:
Assumptions:
•
•
•
•
P
(C
Output
Address, DMS 8
Data, WR
RD
CLKOUT
Total power dissipation for this example = P
ENVIRONMENTAL CONDITIONS
Ambient Temperature Rating:
Package
PLCC
INT
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
T
T
PD = Power Dissipation in W
CA
JA
JC
AMB
CASE
= internal power dissipation (from Figure 7).
V
= Thermal Resistance (Junction-to-Ambient)
= Thermal Resistance (Junction-to-Case)
DD
= Thermal Resistance (Case-to-Ambient)
Total Power Dissipation = P
= T
= Case Temperature in C
2
CASE
f ) is calculated for each output:
# of
Pins
9
1
1
– (PD
27 C/W
JA
10 pF
10 pF
10 pF
10 pF
C
C
CA
)
V
DD
DD
2
INT
= 5.0 V and t
5
5
5
5
V
2
2
2
2
DD
V
V
V
V
f
+ (C
16 C/W
2
JC
f
20 MHz = 40.0 mW
10 MHz = 22.5 mW
10 MHz = 2.5 mW
20 MHz = 5.0 mW
INT
V
DD
+ 70.0 mW.
CK
2
= 50 ns.
f )
70.0 mW
11 C/W
CA
–14–
Figure 9. Typical Output Valid Delay or Hold vs. Load
Capacitance, C
CAPACITIVE LOADING
Figures 8 and 9 show capacitive loading characteristics.
Figure 8. Typical Output Rise Time vs. Load Capacitance, C
(at Maximum Ambient Operating Temperature)
–1
–2
–3
L
8
7
6
5
4
3
2
1
0
5
4
3
2
1
0
(at Maximum Ambient Operating Temperature)
0
0
25
25
50
50
V
75
75
C
C
DD
L
L
V
DD
– pF
– pF
= 4.5V
100 125
100
= 4.5V
125
150
150
175
175
REV. 0
L