IC-MN Datasheet, PDF (28/59 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 D1, Page 28/59
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
5kΩ
V
GNDA
required warning temperature T_w, temperature coef-
ficients 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; bit 7:5
VTth
∼
100+5k
100
100 %
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 tempera-
ture warning or an excessive temperature error can be
set. The excessive temperature error and warning are
coupled to one another (see Characteristics C07). Cal-
ibration of the excessive temperature warning in cali-
bration mode TWIB is described by way of example.
To set the required warning temperature T_w the tem-
perature sensor voltage VTS_w(T_curr) at which the warn-
ing is generated is first determined. T_curr is the actual
temperature. To this end a voltage ramp from VDD
towards GND is applied to pin T1 until pin NERR in-
dicates the error message. The necessary activation
threshold voltage VTth(T_curr) is then calculated. The
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