ic-wt iC-Haus, ic-wt Datasheet - Page 11

• Manufacturer Part Number: ic-wt
• Description: Incremental Encoder
• Manufacturer: iC-Haus

If two of the DIP switches No.4 to No.7 are closed, the actual value of I
Correspondingly, for the resistance RLR:
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 V
from DPA:
The result for the current from DNA is:
With R2= R3, the input currents assume the same value for a symmetrical activation via V
voltage between V
iC-WT
INCREMENTAL ENCODER
I
RLR= 1.22V / (840nA
I
I
V
I
I
SUM
DPA
DNA
DPA
DNA
ACA
= (V
= (V
ACA
= 2
= (V
= {(V
= {V
= {1.8V / 2 - 0.52V / 2} / 3M
= 213nA
= {V
= {V
= {1.8V / 2 - 0.52V / 2} / 3M
= 213nA
as the input voltage, the following applies for the current through R3 and consequently the current
ACA
DNA
420nA = 840nA,
DNA
DNA
DNA
DNA
DNA
- V
- V
+ V
/ 2 - V
- (V
/ 2 - V
+ V
BE
ACA
DNA
) / R3
BE
DNA
) / R2
BE
) / 2
and V
) / 2 - V
BE
BE
+ V
/ 2} / R3
/ 2} / R2
BE
100) = 14.5k
BE
) / 2} / R2
1.16V
:
BE
} / R3
SUM
is:
Rev A0, Page 11/13
ACA
as the medium