IC-LNB_13 Datasheet, PDF (26/35 Pages) IC-Haus GmbH – 18-BIT OPTO ENCODER WITH SPI AND SER/PAR INTERFACES

iC-LNB 18-BIT OPTO ENCODER ^preliminary
WITH SPI AND SER/PAR INTERFACES
Rev A1, Page 26/35
VDDAH. This signal is available in test mode at pin
NCOS. The offset of signal NCOS must then be cali-
brated to the calibrated offset of signal PCOS.
The signal path of the Sin/Cos tracks is shown in Fig-
ure 18 with the conditioning unit.
OCP
Code
0x00
0x01
...
0x7F
Addr. 0x04; bit 6:0
Offset values
0.45 · VDDA
0.4508 · VDDA
(0.45
+
OCP ·0.1
127
)
·
VDDA
0.55 · VDDA
Table 22: PCOS offset
OCN
Code
0x00
0x01
...
0x7F
Addr. 0x05; bit 6:0
Offset values
0.45 · VDDA
0.4508 · VDDA
(0.45
+
OCN ·0.1
127
)
·
VDDA
0.55 · VDDA
Table 23: NCOS offset
Square control
After all parameters (gain and offset) have been cali-
brated, it is recommended that the square control func-
tion in the LED power control be enabled (see the LED
power control section on page 27) in order to keep the
optical receive power of the sine/cosine sensors con-
stant, regardless of temperature and LED ageing ef-
fects. To this end the device is switched to normal
mode (TA = 0x0) and square control enabled (LCTYP =
0). The LED power control setpoint is adjusted to the
set target amplitude with parameter LCSET(5:0).
DPSIN
- ^3Meg
+
+ ^Vref
-
GR
Vref
VPSI
DNSIN
- ^3Meg
+
+ ^Vref
-
GR
Vref
VNSI
GS
-
+
GS
VREFNS
VREFPS
GS
+
-
GS
NSIN
+
VDDA
-
OSN
+
VDDA
-
OSP
PSIN
DPCOS
- ^3Meg
+
+ ^Vref
-
GR
Vref
VPCO
DNCOS
- ^3Meg
+
+ ^Vref
-
GR
Vref
VNCO
GC
-
+
GC
VREFNC
VREFPC
GC
+
-
GC
NCOS
+
VDDA
-
OCN
+
VDDA
-
OCP
PCOS
Figure 18: Sin/Cos signal path