iC-WT
INCREMENTAL ENCODER
FEATURES
APPLICATIONS
♦ Differential scanning for track A and B
♦ Constant-light-evaluated scanning for the index track Z with
adjustable relative threshold
♦ Photocurrent amplifier with high cut-off frequency
♦ Current comparators with hysteresis
♦ Index track Z selectable gated by tracks A and B
♦ Current-limited and short-circuit-proof push-pull outputs
♦ Outputs TTL compatible
♦ Adjustable LED current control for constant optical receiver
power
♦ Integrated 50mA driver for the transmit LED
♦ LED current monitoring and error message upon violating
the control range
♦ Low current consumption from single 5V power supply
◊ Option: enhanced temperature range -40..125°C
♦ Photocurrent evaluation for
incremental linear or angular
position measuring systems
PACKAGES
SO16N
BLOCK DIAGRAM
+5V
2
VCC
+5V
CODEWHEEL
PHOTODIODES ARRAY
14
DPA
15
DNA
A
DPA
DPB
OUT_A
TRACK A
DNA
LED
3
12
DPB
13
DNB
B
4
Z
5
NERR
6
OUT_B
TRACK B
DNB
iC-WT
11
DZ
DZ
iC-OR
TRACK Z
8
RLR
15kΩ
RZ
15kΩ
ERROR
CLR
10
ILR
9
IZ
16
CLR
10nF
OUT_Z
LED
ERROR
AGND
LED
LED CURRENT CONTROL
7
DRIVER
RLED
68Ω
GND
1
©1997
Rev A0
iC-Haus GmbH
Integrated Circuits
Am Kuemmerling 18, D-55294 Bodenheim
Tel +49-6135-9292-0
Fax +49-6135-9292-192
http://www.ichaus.com
iC-WT
INCREMENTAL ENCODER
Rev A0, Page 2/13
DESCRIPTION
The device iC-WT is an evaluator IC for optical increment linear and rotary motion sensors, e.g. glass
scales or shaft encoders.
A photodiodes array supplies the input signals for the monolithically integrated amplifiers, comparators and
the TTL compatible push-pull output drivers. Two tracks, A and B, are evaluated differentially, the index
track Z as a constant light.
An integrated LED current control with driver stage enables the direct connection of a transmit LED with
series resistor and ensures a constant optical receive power. Two external resistors are used to set the
relative index track comparator threshold and to determine the receive photocurrents.
The internally available logical AND operation of index track Z to tracks A and B can be switched off for
adjustment.
A monitor circuit triggers an error message when the LED current control range is violated. The fault output
designed as an open collector is low active and simultaneously functions as an input to turn off the AND
operation of the index track.
All connections are protected against damage due to ESD. The outputs are short-circuit proof.
PACKAGES SO16N to JEDEC Standard
PIN CONFIGURATION SO16N
(top view)
PIN FUNCTIONS
No. Name Function
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
GND
VCC
A
B
Z
NERR
LED
CLR
IZ
ILR
DZ
DPB
DNB
DPA
DNA
AGND
Ground
+5V Supply Voltage
Track A TTL Output
Track B TTL Output
Track Z TTL Output
Fault Output / AND Gate Disable
Cathode LED
Capacitor for LED Current Control
Threshold for Index Track
Current Control Adjust
Cathode Photodiode Index Track Z
Cathode Photodiode Track B+
Cathode Photodiode Track BCathode Photodiode Track A+
Cathode Photodiode Track ACommon Anode for all photodiodes,
connected to GND internally
iC-WT
INCREMENTAL ENCODER
Rev A0, Page 3/13
ABSOLUTE MAXIMUM RATINGS
Values beyond which damage may occur; device operation is not guaranteed.
Item
Symbol
Parameter
Conditions
Fig.
Unit
Min.
Max.
G001 VCC
Supply Voltage
0
7
V
G002 I(DPx)
I(DNx)
Current in Inputs
DPA, DNA, DPB, DNB
-1
1
mA
G003 V(A,B,Z)
Voltage at Outputs A, B, Z
0
VCC
G004 I(A,B,Z)
Current in Outputs A, B, Z
-4
4
mA
G005 I(DZ)
Current in Input DZ
-1
1
mA
G006 I(ILR)
I(IZ)
Current in ILR, IZ
-6
1
mA
G007 I(CLR)
Current in CLR
-1
1
mA
G008 I(LED)
Current in LED
V(LED)> VCC
-1
1
mA
G009 I(LED)
Current in LED
V(LED)≤ VCC
-1
60
mA
0
VCC
-4
4
mA
V(A,B,Z)< 0V or V(A,B,Z)> VCC
G010 V(NERR) Voltage at NERR
G011 I(NERR)
Current in NERR
V(NERR)< 0 or V(NERR)> VCC
TG1 Tj
Junction Temperature
-30
130
°C
TG2 Ts
Storage Temperature
-30
130
°C
THERMAL DATA
Operating Conditions: VCC= 5V ±10%
Item
Symbol
Parameter
Conditions
Fig.
Unit
Min.
T1
Ta
Operating Ambient Temperature
Range
(extended temperature range on
request)
T2
Rthja
Thermal Resistance
Chip to Ambient
-25
SMD mounting, without special
cooling
All voltages are referenced to ground unless otherwise noted.
All currents into the device pins are positive; all currents out of the device pins are negative.
Typ.
Max.
125
°C
125
K/W
iC-WT
INCREMENTAL ENCODER
Rev A0, Page 4/13
ELECTRICAL CHARACTERISTICS
Operating Conditions: VCC= 5V ±10%, Tj= -25..125°C, unless otherwise noted
Item
Symbol
Parameter
Conditions
Tj
°C
Fig.
Unit
Min.
Typ.
Max.
Total Device
001 VCC
Permissible Supply Voltage
4.5
002 I(VCC)
Supply Current in VCC,
Outputs A, B, Z hi
closed LED control:
R(ILR/AGND)= 15kΩ,
I(LED)≈ 3mA, NERR= hi;
I(A,B,Z)= 0, R(RZ/AGND)= 15kΩ,
I(DZ,DPx)= -400nA,
I(DNx)= -40..0nA, (x= A,B)
003 I(VCC)
Supply Current in VCC,
Outputs A, B, Z lo
closed LED control:
R(ILR/AGND)= 15kΩ,
I(LED)≈ 3mA, NERR= hi;
I(A,B,Z)= 0, R(RZ/AGND)= 15kΩ,
I(DZ,DPx)= -40..0nA
I(DNx)= -400nA
004 fo
Cut-off Frequency
for Tracks A and B
sinusoidal waveform,
I(DPx)= -20..-400nA,
I(DNx)= -400..-20nA
500
kHz
005 fo
Cut-off Frequency
for Index Track Z
rectangular waveform,
I(DZ)= -20..-400nA,
threshold 200nA
250
kHz
006 ∆tp()
Propagation Delay Deviation
track vs.track at A, B, Z
27
5.5
V
10
mA
12
mA
mA
5.5
100
ns
0
nA
Differential Photocurrent Amplifier, Track A and B
101 I(DPx)
I(DNx)
Permissible Sensor Current at
DPA, DNA, DPB, DNB
-600
102 CM(P/N) Common Mode DPA vs. DNA,
DPB vs. DNB
0.85
1
1.15
15
20
25
%
0
nA
10
13
%
Comparator, Track A and B
201 Hys
Hysteresis refered to [I(DPx) +
I(DNx)] / 2
I(DPx,DNx)= -400..0nA
Photocurrent Amplifier, Index Track Z
401 I(DZ)
Permissible Sensor Current at DZ
-600
Comparator, Index Track Z
801 Hys
Hysteresis refered to I(DZ)
I(DZ)= -400..0nA
7
Push-Pull Outputs A, B, Z
301 Vs()hi
Saturation Voltage hi
Vs()hi= VB-V();
I()= -400µA
-25
27
70
125
0.9
0.8
0.75
0.7
1.1
1.0
0.9
0.9
V
V
V
V
302 Vs()hi
Saturation Voltage hi
Vs()hi= VB-V();
I()= -1.6mA
-25
27
70
125
1.2
1.1
1.05
1.05
1.5
1.4
1.3
1.3
V
V
V
V
303 Vs()lo
Saturation Voltage lo
I()= 0.8mA
0.4
V
304 Vs()lo
Saturation Voltage lo
I()= 1.6mA
0.5
V
305 Isc()hi
Short-Circuit Current hi
V()= 0V..2.8V
-1.7
mA
mA
-8
27
-3.5
iC-WT
INCREMENTAL ENCODER
Rev A0, Page 5/13
ELECTRICAL CHARACTERISTICS
Operating Conditions: VCC= 5V ±10%, Tj= -25..125°C, unless otherwise noted
Item
Symbol
Parameter
Conditions
Tj
°C
Fig.
Unit
Min.
Typ.
Max.
Push-Pull Outputs A, B, Z (continued)
306 Isc()lo
Short-Circuit Current lo
V()= 1V..VCC
2
27
13
mA
mA
6
307 Vc()hi
Clamp Voltage hi
Vc()hi= V()-VCC; I()= 4mA
0.4
1.5
V
308 Vc()lo
Clamp Voltage lo
I()=-4mA
-1.5
-0.4
V
-1500
-50
nA
0.1
50
mA
1.2
V
V
1.28
V
LED Current Control, pins CLR, ILR, IZ, LED
601 ISUM
Permissible Total Sensor Current ISUM= I(DPA)+I(DNA) +I(DPB)
at DPA, DNA, DPB, DNB
+I(DNB);
602 I(LED)
Permissible Driver Current in LED
603 Vs(LED)
Saturation Voltage lo at LED
I(LED)= 50mA,
I(ILR)> 5µA, ISUM= 0
0.4
27
0.8
604 V(ILR)
V(IZ)
Voltage at ILR, IZ
I(ILR,IZ)= -150..-5µA
1.15
1.22
606 Isc(ILR)
Isc(IZ)
Short-Circuit Current in ILR, IZ
V(ILR)= 0, V(IZ)= 0
607 CR(ILR)
Current Ratio I(ILR)/ISUM
closed LED control,
ISUM= -800..-50nA
80
100
125
608 CR(IZ)
Current Ratio I(IZ)/I(DZ)
closed LED control,
I(DZ)= -400..-10nA
320
400
500
609 Vc()hi
Clamp Voltage hi
at LED, CLR, ILR, IZ
VCC= 0V, I()= 1mA
0.4
1.0
V
610 Vc()lo
Clamp Voltage lo
at LED, CLR, ILR, IZ
VCC= 0V, I()=-1mA
-1.0
-0.4
V
45
kΩ
1
V
V
0.4
V
V
0.8
V
V
30
mA
mA
-5
27
mA
mA
-2.4
Error Detection, AND Gate Select, Input/Output NERR
501 R(NERR) Internal Pull-Up Resistor
502 Vt()Gate
701 Vs()lo
702 Vs()lo
703 Isc()lo
AND Gate Turn-Off Threshold
Saturation Voltage lo
Saturation Voltage lo
Short-Circuit Current lo
20
Gate disabled if V(NERR)< 0.4V
30
0.4
27
0.5
27
0.15
27
0.25
I(NERR)= 1.6mA
I(NERR)= 5mA
V(NERR)= 2V..VCC
5
27
15
704 Vc()hi
Clamp Voltage hi
Vc()hi= V(NERR)-VCC;
NERR=hi, I(NERR)= 4mA
0.4
1.5
V
705 Vc()lo
Clamp Voltage lo
NERR=lo, I(NERR)=-4mA
-1.5
-0.4
V
iC-WT
INCREMENTAL ENCODER
Rev A0, Page 6/13
APPLICATIONS INFORMATION
Figure 1 illustrates the layout of the entire electronic system of an incremental rotary encoder. The devices
iC-OR (photodiodes array), iC-WT (incremental encoder) and iC-WE (line driver) from iC-Haus are used.
The rotary encoder requires the supply voltages VCC= +5V and VB= +5V to +30V (line driver) and supplies the
conditioned signals of tracks A and B and index track Z at the outputs. It’s possible to transmit these signals
over directly connected lines of 100m length. The system’s upper cut-off frequency is 500kHz for track A/B.
Internal monitoring functions are available for the chip temperature of the line driver, for the supply voltages and
for the LED current control. The ERROR port provides an error message signal which can be logically linked
to other, external error signals by simple connection.
Fig. 1: Incremental rotary encoder
DESCRIPTION OF FUNCTIONS
The photodiodes array iC-OR comprises two diodes each for tracks A and B (differential evaluation) and one
diode for track Z (index pulse for constant-light evaluation) in the layout typical for an incremental encoder. A
reference diode is not required since the threshold for the index signal is generated from the signals of tracks
A and B. It is also possible to use the iC-Haus device iC-WS or the Siemens device KOM 2100.
The incremental encoder iC-WT evaluates the currents of the photodiodes and generates TTL-compatible
information. The zero pulse is logically linked to the tracks A and B with an AND operation. This operation can
be cancelled for adjustment purposes by applying a low level to the error message output NERR (combined
input and output).
An integrated transmit-current drive circuit makes the adjustment to a constant summation photoelectric current
at inputs A/B which is specified as the reference current at ILR by means of the external resistor RLR. The
external capacitor CLR stabilizes this adjustment. Using a further reference current at IZ which is set with RZ
it is possible to specify the constant-light evaluation threshold for the zero pulse at a controlled and,
consequently, constant illuminance. With identical geometries and homogeneous illumination of all photodiodes,
ILR and IZ can operate on a common resistor.
The resistor RLED limits the maximum possible current through the LED. The transmit-current control features
an error detector which sets the output NERR to LOW (open collector) when the permissible working area is
exited. The error message detector is activated, for example, in case of a defect of the LED, when the code
discs are dirty or steamed, or in the case of excessive influence of lights from an external source.
iC-WT
INCREMENTAL ENCODER
Rev A0, Page 7/13
The line driver iC-WE possesses short-circuit-proof push-pull output stages for the tracks A, B and Z. The
drivers typically supply 300mA at VB= 24V and are internally adapted for a characteristic impedance of 75Ω.
The outputs can be inverted via input INV (active-high). Consequently, when two line drivers are used, a
balanced activation of the line is also possible. Tri-state switching of the output stages is possible to support bus
systems (input TRI). An error detector monitors the chip temperature as well as the supply voltages VCC and
VB. In the event of a fault, the open-collector output NER is switched low and the output stages are switched
to high impedance to prevent destruction. The error signal of the incremental encoder iC-WT can be switched
through to the output NER via the error input TNER.
DIMENSIONING
Adjusting the LED current control
Since the photodiodes DPA to DNA and DPB to DNB have anti-phase illumination, the following applies for the
control parameter ISUM as a function of the photocurrent peak value Iph,max. of a photodiode:
ISUM
I(DPA)
I(DNA)
I(DPB)
I(DNB)
2 ×Iph,max
Multiplied by the current transmission factor of the LED current control CR(ILR), the current to be set at ILR is
(see electrical characteristics, No.607):
IILR
ISUM ×CR(ILR)
2 ×Iph,max ×CR(ILR)
This current can be set with a resistor RLR connected to AGND. Due to the reference voltage V(ILR) being
applied to pin ILR, this produces:
RLR
V(ILR)
I(ILR)
V(ILR)
2 ×Iph,max ×CR(ILR)
Example: As a setpoint, the photodiodes should be illuminated so brightly that it conducts a photocurrent Iph,max=
400nA at a maximum. With the electrical characteristics No.604 for V(ILR) and No.607 for CR(ILR) the result
is:
RLR
1.22
2 ×400nA ×100
15.25kΩ
Adjusting the index track comparator threshold
The comparator threshold for the index signal is defined via a further reference current. The photocurrent Iph,max
is also obtained as the maximum for the photodiode DZ in the event of homogeneous illumination and same
photodiodes for track A/B and track Z. The maximum signal-to-noise ratio is attained with the constant-light
evaluation threshold:
Ith
Iph,max
2
Analogue to the calculation of RLR, it follows that:
IIZ
RZ
Ith × CR(IZ)
V(IZ)
I(IZ)
V(IZ)
Ith ×CR(IZ)
Example: As a setpoint, the threshold Ith should be 200nA. With the electrical characteristics No.604 for V(IZ)
and No.608 for CR(IZ) the result is:
RZ
1.22V
200nA ×400
15.25kΩ
iC-WT
INCREMENTAL ENCODER
Rev A0, Page 8/13
If the current from ILR is the same as the current from IZ, a common resistor with the value RLR,Z= RLR / 2 = RZ
/ 2 can be utilized (in the example, 15.25 kΩ / 2 = 7.625 kΩ). ILR is connected directly to IZ.
Limiting the current for the transmit LED
The resistance RLED limits the maximum current through the LED. It is calculated with the minimum forward
voltage Vfw,min of the LED used for illumination, the minimum saturation voltage of the LED pin Vs(LED)
(electrical characteristics No.603) and the permissible transmit current for the driver output I(LED)max (electrical
characteristics No.602):
RLED
VCCmax
Vfw,min
Vs(LED)min
I(LED)max
Example: RLED= (5.5V - 1.2V - 0.4V) / 50mA = 78Ω
The lowest value for the current limiting is obtained by inserting the maximum saturation voltage of the LED pin
Vs(LED)max and the maximum LED forward voltage Vfw,max:
I(LED)lim≥
VCCmin
Vfw,max
Vs(LED)max
RLED
Example: I(LED)lim= (4.5V - 1.5V - 1.2) / 78Ω ≈ 19mA
The limiting value inserted for the saturation voltage Vs(LED)max of 1.2V is not achieved by currents under
50mA. The real minimum value for current limiting is therefore a little higher.
Capacitor at CLR
The value of capacitor CLR is not critical. The bottom of the permissible value range is restricted by the stability
of control. The following applies:
CLR,min
1nF × 15kΩ
RLR
Upwardly, the value is limited by the dead time τ of the LED current control after switching on the supply
voltage:
CLR,max
0.25 × τ
RLR
Example: τ= 100ms, RLR= 15kΩ: CLR,max= (0.25 × 100ms) / 15kΩ ≈ 1.5µF
PRINTED CIRCUIT BOARD LAYOUT
The following aspects should be noted when creating the PCB layout:
-
Short connections between photodiodes array and iC-WT to minimize couplings and interference on the
small photocurrents.
Short-circuit the anodes of the photodiodes to pin AGND of the iC-WT. The connection to GND is made
exclusively inside the chip.
Switch RLR, RZ, CLR to AGND too.
Do not run the printed conductors of the outputs of iC-WT and iC-WE in the vicinity of the connections
between photodiodes array and iC-WT or decouple by means of a GND conductor between them.
Connecting point of a metal reticle for the photodiodes array is GND on the iC-WT.
iC-WT
INCREMENTAL ENCODER
Rev A0, Page 9/13
DEMO BOARD
The demonstration board provides a survey over the properties of the iC-WT simply and easily. The encoder
IC is already connected to the necessary external components. In addition, the board contains subunits which
can be utilized to have measurements performed - even without a rotary encoder. Figures 2 to 4 show the
wiring as well as the top and bottom layout of the test PCB.
Fig. 2: Schematic diagram of the Demo Board
Fig. 3: Demo Board (components side)
Fig. 4: Demo Board (solder dip side)
iC-WT
INCREMENTAL ENCODER
Rev A0, Page 10/13
MEASUREMENTS WITH THE DEMO BOARD
The iC-WT can be examined at three different levels:
1. Static wiring of the sensor inputs with constant currents (using DIP switches)
2. Dynamic wiring of the sensor inputs using function generator and current mirror circuit
3. Dynamic wiring of the sensor inputs using a rotary encoder with photodiodes array
A regulated power supply of +5V dc must be applied between VCC and GND for all measurements. Since the
iC-WT operates with very low sensor currents, the work surface should possess an insulated screen (e.g. a
single sided copper-clad plate) which is connected to GND. AGND is pulled down to GND inside the iC-WT and
should not be interconnected externally. The transmit LED of the rotary encoder can be connected between
LED and VCC. For the visual check in case of measurements without rotary encoder a colored LED is
recommended.
1.1 Static function of A, B and Z
Shut off the AND operation of index signal Z with A and B by connecting the combined input/output NERR to
ground; the red control LED will light up. The two trimming potentiometers should be in the middle position
initially, the DIP switches opened.
Closing a DIP switch of No.4 to No.8 connects the corresponding sensor input to AGND via a resistor (R4 to
R8). Since each input is at constant (but temperature-dependent!) voltage potential V(T), a constant current
results of the magnitude:
I= V(T) / R.
The result at room temperature is about:
I= 1.8V / 4.3MΩ = 420nA
This current is supposed to simulate the photocurrent of an illuminated photodiode. An open switch simulates
a diode which is not illuminated (I= 0).
The tracks A and B are evaluated differentially. The corresponding output is high (low) when current is only
flowing from the P(ositive) (N(egative)) input. If the two inputs are conducting no current or the same current,
the output remains in its old state due to hysteresis.
Track Z is compared to a current threshold set using the trimmer RZ. If the input current is higher, the output
Z is high. The current flowing from IZ is specified with RZ:
IIZ= V(IZ) / RZ
The current threshold set is obtained with the aid of the current transmission factor CR(IZ) as:
Ith= V(IZ) / (CR(IZ) × RZ)
When the trimmer is at the middle setting, the following applies:
Ith= 1.22V / (400 × 12.5kΩ) = 244nA
The resistance value set with RZ can be measured after removing the jumper JZ.
1.2 LED current control and error output
The function of the current control can be checked with an LED connected between LED and VCC. The voltage
at NERR is displayed by the red LED on the demo board. It lights up when NERR is active, i.e. low.
The setpoint of the receive power is set at pin ILR by using trimmer RLR. The resistance value can be
measured after removing the jumper JLR. The receive power is defined as the sum of the currents at the input
pins DPA, DNA, DPB and DNB. The setpoint ISUM is:
ISUM= V(ILR) / (RLR × CR(LR))
or:
RLR= V(ILR) / (ISUM × CR(LR))
iC-WT
INCREMENTAL ENCODER
Rev A0, Page 11/13
If two of the DIP switches No.4 to No.7 are closed, the actual value of ISUM is:
ISUM= 2 × 420nA = 840nA,
Correspondingly, for the resistance RLR:
RLR= 1.22V / (840nA × 100) = 14.5kΩ
If the resistance set with the trimmer RLR is smaller, the result is a setpoint which is larger than the actual
value. The control attempts to compensate for this by increasing the transmit LED current. Since the control
loop is not closed, the control moves to the top stop and the transmit LED lights up brightly.
If the resistance set with the trimmer RLR is smaller, the result is a setpoint smaller than the actual value. The
control attempts to compensate for this by reducing the transmit LED current. Since the control loop is not
closed, the control moves to the bottom stop and the transmit LED is extinguished.
Between these extremes is a linear range in which the transmit LED is operated with a current proportional to
the control difference. In this range the output NERR is moved to VCC potential via a pull-up resistor inside the
IC and the error display is not lit. If the control is at a stop, NERR is low and the error LED is lit.
1.3 AND-operation of index track Z with A and B
The measuring set-up is identical to the one in 1.2. The LED current control is set as the normal operating
condition such that it operates in the linear range, i.e. NERR is high. The AND-operation of index track Z with
A and B is now activated. With RZ at the middle setting the output Z can only be switch high via DIP switch
No.8 if A and B are also high (DIP switches No.5 and 7 closed, 4 and 6 open). If A or B or both are low, the
high state of Z is only advanced to its output if the combined input/output NERR is connected to GND (AND
gate disabled). This situation also exists if an error condition of the LED current control exists. In actual
operation this situation is insignificant, since the condition of tracks A and B are undefined anyway in the event
of an error.
2.1 Dynamic activation
To check the dynamic operation, inputs must be stimulated with a function generator. Tracks A and B are
identical in construction, so only A and Z have to be studied. The signal is injected for track A at the Demo
Board via pin ACA. A function generator connected between ACA and AGND should generate a delta or
sinusoidal signal of variable frequency. DIP switches No.2 and 3 are closed, and No.4 and 5 are opened. Via
R3 the ACA signal reaches a current mirror consisting of two NPN transistors, IC2A and IC2E, which prepare
the input signal for the differential activation.
With VACA as the input voltage, the following applies for the current through R3 and consequently the current
from DPA:
IDPA= (VACA - VBE) / R3
The result for the current from DNA is:
IDNA= (VDNA - VACA) / R2
With R2= R3, the input currents assume the same value for a symmetrical activation via VACA as the medium
voltage between VDNA and VBE:
VACA = (VDNA + VBE) / 2 ≈ 1.16V
IDPA = {(VDNA + VBE) / 2 - VBE} / R3
= {VDNA / 2 - VBE / 2} / R3
= {1.8V / 2 - 0.52V / 2} / 3MΩ
= 213nA
IDNA = {VDNA - (VDNA + VBE) / 2} / R2
= {VDNA / 2 - VBE / 2} / R2
= {1.8V / 2 - 0.52V / 2} / 3MΩ
= 213nA
iC-WT
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Modulating ACA around its mean value functions like a linear differential activation of the inputs DPA and DNA.
The modulation limits are VBE and BDNA.
An appropriate rectangular signal can be picked off at output A with an oscilloscope. For a pulse duty factor of
1:1 it may be necessary to readjust the temperature-dependent medium voltage at ACA. In addition, at high
frequencies over 200kHz the parasitic capacities of the test circuit affect the activation and thus the output
signal.
Index track Z can be measured by closed DIP switch No.1 and opening No.8. The signal is injected via ACZ,
R1 and the 1:1 current mirror IC2B, IC2D. The specifications for track A apply appropriately.
The comparison threshold is set at RZ (no differential activation). If the AND operation is activated, outputs A
and B must be high in order for output Z to switch.
3.1 Activation with rotary encoder
The demonstration board can be activated by a rotary encoder with a photodiodes array. The connection
between encoder and Demo Board can be made using a shielded cable. After the DIP switch is removed, the
plug supplied can be installed. Figures 5 and 6 show the connection.
Fig. 5: Connector configuration
Fig. 6: Connecting a photodiodes array
iC-WT
INCREMENTAL ENCODER
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ORDERING INFORMATION
Type
Package
Order designation
iC-WT
WT Demo Board
SO16N
iC-WT-SO16N
WT Demo Board
For information about prices, terms of delivery, options for other case types, etc., please contact:
iC-Haus GmbH
Am Kuemmerling 18
D-55294 Bodenheim
GERMANY
Tel +49-6135-9292-0
Fax +49-6135-9292-192
http://www.ichaus.com
This specification is for a newly developed product. iC-Haus therefore reserves the right to modify data without further notice. Please contact
us to ascertain the current data. The data specified is intended solely for the purpose of product description and is not to be deemed
guaranteed in a legal sense. Any claims for damage against us - regardless of the legal basis - are excluded unless we are guilty of
premeditation or gross negligence.
We do not assume any guarantee that the specified circuits or procedures are free of copyrights of third parties.
Copying - even as an excerpt - is only permitted with the approval of the publisher and precise reference to source.