prel
imin
ary
prel
imin
ary
iC-TW29
26-BIT ENCODER PROCESSOR
WITH INTERPOLATION AND BiSS INTERFACE
Rev C1, Page 6/28
PIN FUNCTIONS
No. Name
I/O
Function
Description
1
SIN+
Analog in
Sine Input +
Differential sine signal input. For single ended sensors SIN– must be
biased to an appropriate DC level.
2
SIN–
Analog in
Sine Input –
3
AVDD
Supply
Analog Power Supply
+3.1 V to +3.6 V supply voltage input for analog circuitry. AVDD should
be tied together with DVDD and IOVDD and supplied from a clean
source.
4
COS+
Analog in
Cosine Input +
Differential cosine signal input. For single ended sensors COS– must
be biased to an appropriate DC level.
5
COS–
Analog in
Cosine Input –
6
AVSS
Ground
Analog Ground
AVSS must be tied to high quality ground, usually a solid PCB plane.
7
ZERO+
Analog in
Zero Input +
Differential Zero Gating Input.
If single ended signal sources are used, the unused terminal (either
ZERO+ or ZERO–) must be tied to an appropriate DC bias.
8
ZERO–
Analog in
Zero Input –
9
VREF
Analog out
Bias Output
Decouple with 100 nF capacitor to AVSS. Do not inject noise into this
pin as it directly impacts ADC conversion quality.
10 VC
Analog out
Bias Output
Decouple with 100 nF capacitor to AVSS. Do not inject noise into this
pin as it directly impacts ADC conversion quality.
11
Reserved
Digital in
Test Input
Reserved pins; must be connected to DVSS for normal operation.
12 Reserved
Digital in
Test Input
13 GPIO
Digital in/out
General-Purpose I/O
Connect to AVSS if not used.
14 xRST
Digital in,
active low
Reset Input
The device is held in reset (low power mode) as long as xRST is low.
15 xCALIB
Digital in,
active low
Calibration Control
Device enters calibration mode on falling edge of CALIB. This pin must
be tied high if not used.
16 xIRQ
Digital out,
active low
or input
IRQ or Fault Output or IRQ
input
Interrupt request output to external micro controller or interrupt re-
quest input. Output can also be used to directly drive a fault LED
in stand-alone applications. Can be configured as push-pull or
open-drain.
17 Z–
Digital/RS422 out Z– or W– Output
In ABZ output modes these are the differential Z outputs.
In UVW output modes these are the W outputs.
In
BiSS mode
(BISSEN pin high), pin Z+ is the data input SLI. If daisy
chaining is not required, Z+ can be grounded (IOVSS).
In other modes, these are multifunction I/O.
18 Z+
Digital/RS422 out Z+ or W+ Output
19 IOVSS
Ground
I/O Ground
All ground pins must be connected to a high quality ground, usually a
solid PCB plane.
20 B–
Digital/RS422 out B– or V– Output
In ABZ output modes these are the differential B outputs.
In UVW output modes these are the V outputs.
In
BiSS mode
(BISSEN pin high), pin B+ is the data output SLO.
In other modes, these are multifunction I/O.
In
Z test mode
these show the Z gating window.
21 B+
Digital/RS422 out B+ or V+ Output
22 IOVDD
Supply
Output Drivers
Power Supply
+3.1 V to +3.6 V voltage terminal supplying all pin output drivers includ-
ing the RS422 drivers and LED current.
IOVDD and DVDD must be the same voltage level. IOVDD can require
up to 100mA depending on loads. It is usually sufficient to tie IOVDD to
the same supply as AVDD and DVDD.
23 A–
Digital/RS422 out A– or U– Output
In ABZ output modes these are the differential Z outputs.
In UVW output modes these are the W outputs.
In
BiSS mode
(BISSEN pin high), pin A+ is the clock input MA.
In other modes, these are multifunction I/O.
In
Z test mode
these show the un-gated Z signal once per input period.
With
Encoder Link
active, A+ is the ELCLK input and A– is ELIN input
or ELOUT output.
24 A+
Digital/RS422 out A+ or U+ Output
25 DVDD
Supply
Digital Power Supply
+3.1 V to +3.6 V supply voltage terminal for digital circuits. DVDD
should be tied together with AVDD and IOVDD to a high quality supply.
26 LED
Digital input
or output
LED PWM Output
Used to supply the illumination LED of optical sensors to maintain
constant intensity and constant Sin/Cos sensor amplitude. Can be
configured as push-pull or open-drain. If not required for LED control, it
is a general purpose I/O.
27 DVSS
Ground
Digital Ground
Pin must tied to high quality ground, usually a solid PCB plane.
28 SO
Digital out
SPI Slave Output
Connect to SPI master MI pin.
