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 congured 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 sufcient 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
congured 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.
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