iC-LNB 18-BIT OPTO ENCODER
WITH SPI AND SER/PAR INTERFACES
Rev A1, Page 26/35
VDDAH. This signal is available in test mode at pin The signal path of the Sin/Cos tracks is shown in Fig-
NCOS. The offset of signal NCOS must then be cali- ure 18 with the conditioning unit.
brated to the calibrated offset of signal PCOS.
OCP
Code
0x00
0x01
...
Addr. 0x04; bit 6:0
Offset values
3Meg
0.45 · VDDA
GS
GS
-
VPSI
+
-
NSIN
-
0.4508 · VDDA
Vref
+
DPSIN
(0.45 + OCP·0.1 ) · VDDA
VDDA
+
127
+
-
GR
0x7F
0.55 · VDDA
OSN
Vref
VREFNS
VDDA
Table 22: PCOS offset
+
-
VREFPS
OSP
3Meg
OCN
Code
0x00
0x01
...
Addr. 0x05; bit 6:0
Offset values
GS
-
VNSI
+
-
+
-
PSIN
Vref
+
DNSIN
0.45 · VDDA
GS
GR
0.4508 · VDDA
Vref
(0.45 + OCN·0.1 ) · VDDA
127
0x7F
0.55 · VDDA
3Meg
GC
GC
-
VPCO
+
-
NCOS
-
Table 23: NCOS offset
Vref
+
DPCOS
+
VDDA
+
-
GR
OCN
Square control
Vref
VREFNC
VREFPC
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).
VDDA
+
-
OCP
3Meg
GC
-
VNCO
+
-
+
-
PCOS
Vref
+
DNCOS
GC
GR
Vref
Figure 18: Sin/Cos signal path
ICHAUS [ IC-HAUS GMBH ]
