IC-TW8_13 Datasheet, PDF (17/63 Pages) IC-Haus GmbH – 16-BIT SIN/COS INTERPOLATOR WITH AUTO-CALIBRATION

iC-TW8 16-BIT SIN/COS INTERPOLATOR
Pin Configuration Mode
preliminary
Jan 9, 2013 Page PC5/15
Connecting an Index Sensor (If Used)
The iC-TW8 can interface to a wide range of in-
dex sensors or gating sources to provide an index
or Z output which is synchronized with the AB
outputs. Digital Hall sensors are often used for
this purpose, as shown in Figure 6.
V_DD
iC-TW8
Connecting the EEPROM
The iC-TW8 requires a 24xx02 through 24xx16 fami-
ly I²C EEPROM for storage of sensor calibration data
(offset, gain, etc.). The EEPROM connects directly to
the iC-TW8 via a dedicated I²C communication chan-
nel using SCL (pin 27) and SDA (pin 28) as shown in
Figure 7. No external pull-up resistors are required.
EESEL (pin 4) of the TW8 must also be connected to
DVSS as shown.
V_DD
ZERO+
Digital Hall
active low
ZERO-
Figure 6: Index Sensor Connection
Digital sensors (Hall, MR, and others) typically
provide an active-low signal via an open-drain
output that pulls low in the presence of a magnetic
field. Connect an active-low (open drain) digital
index sensor to the iC-TW8 ZERO– input (pin 48)
and connect the ZERO+ input (pin 47) to a resis-
tive voltage divider set to the midpoint of the in-
dex sensor output voltage swing to provide good
noise rejection. For active-high (open source) dig-
ital index sensors, reverse the ZERO+ and
ZERO– connections.
To guarantee one and only one Z output from the
iC-TW8 over multiple Sin/Cos input cycles, the
ZERO input signal must be roughly centered on
(in phase with) the Cos+ incremental sensor sig-
nal and no larger than 1.5 Sin/Cos input cycles
under all conditions.
DVDD
EESEL
DVSS
SCL
SDA
WP
iC-TW8
VDD
EESEL tied to DVSS.
1µF
SCL VCC
SDA _VSS
WP
EEPROM
24xx
VDD
1µF
Figure 7: EEPROM Connection
In pin configuration mode, the Write Protect (WP)
input of the EEPROM is not controlled by the iC-
TW8. WP must be grounded (disabled) during config-
uration to allow the iC-TW8 to write the auto-adapted
parameters to the EEPROM. In operation, WP can be
left grounded (write protection disabled) as shown in
Figure 7, or connected to DVDD by additional circuit-
ry (such as a jumper) for parameter protection.
If no index (Z) output is required, connect
ZERO+ (pin 47) to ground and ZERO– (pin 48)
to AVDD.
Analog-output index sensors can also be used
with the iC-TW8, but only in SPI/1-wire configu-
ration mode.
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