iC-MN 25-BIT NONIUS ENCODER
WITH 3-CH. SAMPLING 13-BIT Sin/D INTERPOLATION
Rev D1, Page 28/59
Bias Current Source
required warning temperature Tw, temperature coef-
The calibration of the bias current source in operation ficients TCs and TCth (see Electrical Characteristics,
mode TWIB or TEIB is prerequisite for adherence to Section C) and measurement value VTSw(Tcurr) are
the given electrical characteristics and also instrumen- entered into this calculation:
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.
VTSw(Tcurr) + TCs · (Tw − Tcurr
)
VTth(Tcurr) =
TCth
1 +
· (Tw − Tcurr
)
1+TCth·(T
−T
)
norm
curr
CFGIBP
Code k
0x0
Addr. 0x0D; bit 4:1
31
31−k
IBP ∼
The reference temperature Tnorm is 27 °C. Activation
threshold voltage VTth(Tcurr) 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.
100.00 %
103.3 %
...
0x1
...
0xF
193.7 %
Table 34: Bias current source calibration
CFGTA
Addr. 0x0E; bit 1:0
Addr. 0x0D; bit 7:5
100+5k
100
Code k
0x00
0x01
...
VTth ∼
100 %
105 %
...
i C- M N
IBP
D I R
Pa ra m
TRACMODE
CALMODE
Co d e O p. M o d e
R
5kΩ
0x0
0x5
0x6
V
TWIB
TEIB
0x1F
255 %
G
N
D
A
Table 35: Calibration of temperature monitoring
Signal Noise Filters
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.
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)
Addr. 0x0E; bit 1
Function
Code
0
1
Disabled
Sin/Cos Output driver noise filter activated
Table 36: Noise filter for the output drivers
To set the required warning temperature Tw the tem-
perature sensor voltage VTSw(Tcurr) at which the warn-
ing is generated is first determined. Tcurr 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(Tcurr) is then calculated. The
ENF(1)
Addr. 0x0E; bit 2
Function
Code
0
1
Disabled
S/D Conversion noise filter activated
Table 37: Noise filter for the sine-to-digital converter
ICHAUS [ IC-HAUS GMBH ]
