EVAL-AD1940EB View Datasheet(PDF) - Analog Devices
Part Name
Description
MFG CO.
'EVAL-AD1940EB' PDF : 32 Pages View PDF
AD1940/AD1941
1.0
0.8
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
–1.0
0
5
10
15
20
25
30
35
TIME (ms)
Figure 16. Slew RAM—Linear Update Decreasing Ramp
Constant dB and RC Type (Exponential) Update Math
Exponential math is accomplished by shifts and adds with a
range from 6.1 ms to 1.27 s (–60 dB relative to 0 dB full scale).
When the ramp type is set to 01 (constant dB), each step size is
set to the current value in the slew data. When the ramp type
bits are set to 10 (RC type), the step sizes are equal to the
difference between the values in the target RAM and slew RAM.
Figure 17 and Figure 18 show examples of this type of
target/slew RAM ramping. A decreasing ramp of both the
constant dB and RC type ramps is a mirror image of the
constant dB increasing ramp, and is show in Figure 19.
1
0.8
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
–1
0
5
10
15
20
25
TIME (ms)
30
35
Figure 17. Slew RAM—Constant dB Update Increasing Ramp
1
0.8
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
–1
0
5
10
15
20
25
30
35
TIME (ms)
Figure 18. Slew RAM—RC Type Update Increasing Ramp
1.0
0.8
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
–1.0
0
5
10
15
20
25
30
35
TIME (ms)
Figure 19. Slew RAM—Constant dB and RC Type
Update Decreasing Ramp, Full Scale
1
0.8
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
–1
0
5
10
15
20
25
30
35
TIME (ms)
Figure 20. Slew RAM—Constant Time Update Increasing Ramp, Full Scale
Rev. A | Page 22 of 36
Share Link: 
