iC-TW8 16-BIT SIN/COS INTERPOLATOR
Pin Configuration Mode
Jan 9, 2013 Page PC8/15
Pin Configuration
In pin configuration mode, the iC-TW8 is config-
ured by applying different voltages to configura-
tion inputs C0, C1, C2, and C3 (pins 30, 31, 32,
and 33 respectively). Each configuration input rec-
ognizes 12 different voltage levels which together
select one of 124 = 20,736 separate operational
configurations for the device.
Table 1 shows the recommended resistor values for
setting the configuration levels. The resistors must
be 1% (or better) tolerance to guarantee reliable
operation under all conditions.
Configuration
Divider
Ratio
0.87
0.80
0.73
0.67
0.60
0.54
0.46
0.40
0.33
0.27
0.20
0.13
Rx1
[k]
0.00
3.01
4.02
4.99
6.04
6.98
8.06
9.09
10.0
11.0
12.1
∞
Rx2
[k]
∞
Level
11
10
9
8
7
6
5
4
3
12.1
11.0
10.0
9.09
8.06
6.98
6.04
4.99
4.02
3.01
0.00
The desired voltage levels are typically set using a
resistive voltage divider on each of the configura-
tion inputs as shown in Figure 11. Thus, only 8
resistors are required to completely configure the
iC-TW8.
VDD
AVDD
R01
2
1
0
C0
R02
VDD
iC-TW8
Table 1: Pin Configuration Resistor Values
R11
C1
An open circuit is shown as infinite (∞) resistance
and a short circuit is shown as zero resistance in
Table 1.
R12
Do not use
decoupling caps!
VDD
R21
C2
R22
VDD
R31
C3
R32
1% resistors as close to iC-TW8
configuration pins as possible.
Figure 11: Pin Configuration Resistors
The resistors should be located as close to the con-
figuration input pins as possible and no decoupling
capacitors should be used.
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