IC-TW8_13 Datasheet, PDF (41/63 Pages) IC-Haus GmbH – 16-BIT SIN/COS INTERPOLATOR WITH AUTO-CALIBRATION

iC-TW8 16-BIT SIN/COS INTERPOLATOR
Serial Configuration Mode
preliminary
Jan 9, 2013 Page SC14/36
Connecting the ABZ Outputs
The iC-TW8 provides industry-standard quadrature
incremental outputs at OUTA (pin 18) and OUTB
(pin 17). If an index sensor is connected to the
ZERO inputs of the iC-TW8, a Z output synchro-
nous with the AB outputs is also available on OUTZ
(pin 16). These outputs can be directly connected to
an encoder counter such as the iC-TW9.
Alternatively, the ABZ outputs can be connected to
a differential line driver (such as the iC-HD7 or iC-
HX) as shown in Figure 16. When using a line driv-
er it is especially important to isolate the iC-TW8
from external switching noise using a regulator, as
shown.
regulator
3.3V
24V
regulator
5V
line driver
AVDD
DVDD
OUTA
OUTB
OUTZ
AVSS/DVSS
iC-TW8
VCC VB1
VB2
VB3
E1
A1
E3
A2
E5
A3
A4
GNDx A5
A6
iC-HX
Figure 16: Line Driver Connection
Connecting the Serial Ports
The iC-TW8 contains two serial ports that may be
used to access internal registers for configuration.
These are a standard SPI (Serial Peripheral Inter-
face) slave port and a 1-wire port, both of which
utilize the same communication protocol (see Serial
Communication Ports in the Programmer’s Refer-
ence for the protocol definition). Both ports may be
used simultaneously.
The SPI slave port uses a 3-wire or 4-wire full-
duplex interface which operates in CPOL = 0 and
CPHA = 0 mode only. This means that the base
(resting) value of SPI_SCLK (pin 27) is low, SPI_SI
(pin 10) is sampled on the rising edge of
SPI_SCLK, and SPI_SO (pin 9) is changed on the
falling edge of SPI_CLCK.
When using a 4-wire SPI interface, the SPI_xSS
input (pin 14) is used to enable the SPI port when-
ever communication is required. When using a 3-
wire SPI interface, the SPI_xSS input must be tied
to DVSS.
The 1-wire port uses a single bi-directional data line
connected to IR (pin 7) for communication. The bit
stream is pulse-width modulated: a 1-bit is encoded
as a long high level followed by a short low level, a
0-bit is encoded as a short high level followed by a
long low level. A timeout circuit activates a status
bit in the STAT_SP register (see Programmer’s
Reference) in the event of an illegal transaction.
Power-on-Reset
The iC-TW8 contains a built-in power-on-reset
(POR) circuit that controls the safe start-up of the
device. The internal POR can be configured for
two thresholds, 2.7V for use with 3.3V supplies or
4V, which is recommended when operating the
iC-TW8 at 5V. Connect xRST (pin 2) DVDD or
leave it unconnected (xRST has an internal 40kΩ
DVDD
pullup resistor to DVDD) to select a power-on-reset
threshold of 2.7V. Connect xRST to ground through a
68kΩ resistor to select a threshold of 4V. An external
reset source (such as an RC circuit) can also be con-
nected to xRST (pin 2) to directly control the POR
behavior.
Connect xRST to DVSS via 68kΩ
resistor for 4V POR threshold.
xRST
iC-TW8
xRST
68kΩ
Connect xRST to DVDD (or leave
floating) for 2.7V POR threshold.
iC-TW8
DVSS
Figure 17: Setting the Power-On-Reset Threshold
Copyright © 2011–2013 iC-Haus
http://www.ichaus.com