iC-LNB 18-BIT OPTO ENCODER
WITH SPI AND SER/PAR INTERFACES
Rev A1, Page 27/35
LED POWER CONTROL
LCSET(5:0)
Addr. 0x06; bit 5:0
Square control
The optical receive power of the sine/cosine sensors
is kept constant by an integrated LED control unit, re-
gardless of the temperature and ageing effects of the
LED. The mode of control can be selected using pa-
rameter LCTYP, the possible options being sum control
or square control. So that the internal interpolator is
always optimally controlled in all operating conditions,
square control should be used. Sum control should be
used for signal conditioning.
Code
Sum control
LCTYP = 1
LCTYP = 0
0.240 Vp
0.243 Vp
0x00
0x01
...
0.140 V
0.142 V
0.24 Vp
0.14 V
1−i·0.0125
1.1 Vp
1−i·0.0125
0.640 V
0x3F
Table 25: LED power control setpoint
LCMOD
Adr 0x01, bit 6
Code
Control mode (LCTYP = 0 or 1)
continuous control
0
1
LCTYP
Addr. 0x06; bit 6
deadband control (approx. 5 % of setpoint)
Code
Control type
0
1
square control (sin2+cos2)
Table 26: LED power control mode
sum control (DC controlled prop. to VR())
Error monitoring
Table 24: LED power control type
iC-LNB’s LED power control is monitored. Should the
LED current exceed its control range, internal error
ERRS (status register) is set to 1. This error signal
is linked to iC-LNB’s ERRP alarm (parity check) and
The setpoint for the control can be configured using output at error output ERR (see the alarm output sec-
parameter LCSET(5:0).
tion).
INTERPOLATOR
ENIPO
Addr. 0x11; bit 4
Description
Interpolator resolution
Code
The resolution of the internal interpolator is set us-
ing RESIPO. The maximum permissible Sin/Cos signal
frequency (RPM speed) is dependent on the selected
resolution. Before changing the interpolator resolution,
the interpolator must be disabled (ENIPO = 0). During
the interpolator is disabled 0 is output as the interpo-
lated position value. Once changes have been made,
the interpolator can be re-enabled (ENIPO = 1).
0
1
Interpolator disabled
Interpolator enabled
Table 28: Interpolator enable
Interpolator filter
The interpolator input signals can be filtered by a low-
pass filter. This filter can be enabled by NENF. The fil-
ter has been designed so that it can be applied across
the entire speed range.
RESIPO
Code
00
Addr. 0x0E; bit 6:5
Interpolator resolution
Max. sin/cos frequency
NENF
Code
0
Addr. 0x07; bit 6
Description
8 bit
50 kHz
100 kHz
200 kHz
-
01
7 bit
10
6 bit
Filter enabled (recommended)
Filter disabled
11
Interpolator deactivated
1
Table 27: Interpolator resolution
Table 29: Interpolator filter
ICHAUS [ IC-HAUS GMBH ]
