iC-TW8 16-BIT SIN/COS INTERPOLATOR
Pin Configuration Mode
Jan 9, 2013 Page PC4/15
Connecting the Incremental Sensor
The iC-TW8 connects directly to magnetic (such
as the iC-SM2L or iC-SM5L) or optical sensors
providing differential Sin/Cos outputs as shown in
Figure 3. Signal amplitude (A) from all four sen-
sor channels must be in the range of 5 – 350mV as
shown in Figure 4 for proper operation with the
iC-TW8.
Single-ended Sin/Cos inputs can also be connected to
the iC-TW8 by connecting the SIN– and COS– pins to
the proper bias voltage as shown in Figure 5. Since the
iC-TW8 provides high-impedance signal inputs, a
simple resistive voltage divider can be used to gener-
ate the required bias voltage. For AMR sensors, it is
recommended that the resistors of the bias generator
match the AMR sensor bridge resistance to improve
power supply noise rejection. No decoupling capacitor
should be used.
VDD
SIN+
AVDD
Sensor Bridge 0
SIN+
SIN-
Sensor Bridge 0
COS+
COS+
Sensor Bridge 1
Sensor Bridge 1
COS-
iC-TW8
SIN-
COS-
Figure 3: Differential Sensor Connection
iC-TW8
Resistive Bias
Generator
SIN+
A
Figure 5: Single-ended Sensor Connection
Differential inputs should be used whenever possible
to reject common mode distortions and provide in-
creased signal amplitude and improved signal to noise
ratio (SNR).
5mV ≤ A ≤ 350mV
0 (VDD/2)
–A
Regardless of input configuration, the auto-calibration
feature of the iC-TW8 is sufficient in most cases to
compensate for any signal offset, gain, and phase dis-
tortions without requiring any additional external
components.
SIN-
0°
180°
360°
Figure 4: Differential Sensor Signal Inputs
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