IC-MN_16 Datasheet, PDF (28/62 Pages) IC-Haus GmbH – 25-BIT NONIUS ENCODER WITH 3-CH. SAMPLING 13-BIT Sin/D INTERPOLATION

iC-MN 25-BIT NONIUS ENCODER
WITH 3-CH. SAMPLING 13-BIT Sin/D INTERPOLATION
Rev F2, Page 28/62
Bias Current Source
The calibration of the bias current source in operation
mode TWIB or TEIB is prerequisite for adherence to
the given electrical characteristics and also instrumen-
tal in the determination of the chip timing (e.g. SCL
clock frequency). For the calibration of source IBP to
its target value of 200 µA the voltage across the 5 kΩ
measurement resistor has to be adjusted to 1 V.
CFGIBP
Code k
0x0
0x1
...
0xF
Addr. 0x0D; bit 4:1
IBP
∼
31
31−k
100.00 %
103.3 %
...
193.7 %
Table 34: Bias current source calibration
iC-MN
IBP
DIR
Param
TRACMODE
CALMODE
Code
0x0
0x5
0x6
Op. Mode
TWIB
TEIB
R
5kÙ
V
GNDA
warning temperature T_w, temperature coefficients TCs
and TCth (see Electrical Characteristics, Section C)
and measurement value VTS_w(T_curr) are entered into
this calculation:
VTth(T _curr)
=
VTS_w(T _curr) + TCs · (Tw − T _curr)
1
+
TCth
1+TCth·(T_curr −T_norm)
·
(Tw
−
T_curr )
The reference temperature T_norm is 27 °C. Activation
threshold voltage VTth(T_curr) is provided for a high
impedance measurement (10 MΩ) at output pin T0 and
must be set by programming CFGTA(4:0) to the calcu-
lated value.
CFGTA
Code k
0x00
0x01
...
0x1F
Addr. 0x0E; bit 1:0
Addr. 0x0D;
VTth
∼
100+5k
100
100 %
bit 7:5
105 %
...
255 %
Table 35: Calibration of temperature monitoring
Figure 10: Measurement circuit
Temperature Sensor
As regards temperature two settings can be made; ei-
ther a temperature threshold for an excessive temper-
ature warning or an excessive temperature error can
be set. The excessive temperature error and warning
are coupled to one another (see Characteristics C07).
Calibration of the excessive temperature warning in
calibration mode TWIB is described by way of example.
To set the required warning temperature T_w the temper-
ature sensor voltage VTS_w(T_curr) at which the warning
is generated is first determined. T_curr is the actual tem-
perature. To this end a voltage ramp from VDD towards
GND is applied to pin T1 until pin NERR indicates the
error message. The necessary activation threshold
voltage VTth(T_curr) is then calculated. The required
Signal Noise Filters
iC-MN has a noise filter for both the analog output
drivers and the sine-to-digital converter. These filters
can be activated by ENF.
ENF(0)
Code
0
1
Addr. 0x0E; bit 1
Function
Disabled
Sin/Cos Output driver noise filter activated
Table 36: Noise filter for the output drivers
ENF(1)
Code
0
1
Addr. 0x0E; bit 2
Function
Disabled
S/D Conversion noise filter activated
Table 37: Noise filter for the sine-to-digital converter