IC-LNB_16 Datasheet, PDF (28/37 Pages) IC-Haus GmbH – 18-BIT OPTO ENCODER

iC-LNB 18-BIT OPTO ENCODER ^preliminary
WITH SPI AND SER/PAR INTERFACES
LED POWER CONTROL
Rev B2, Page 28/37
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.
LCSET(5:0)
Addr. 0x06; bit 5:0
Code
Square control
LCTYP = 0
Sum control
LCTYP = 1
0x00
0.240 Vp
0.140 V
0x01
...
0x3F
0.243 Vp
0.24 Vp
1−i·0.0125
1.1 Vp
0.142 V
0.14 V
1−i·0.0125
0.640 V
Table 25: LED power control setpoint
LCTYP
Code
0
1
Addr. 0x06; bit 6
Control type
square control (sin²+cos²)
sum control (DC controlled prop. to VR())
LCMOD
Code
0
1
Adr 0x01, bit 6
Control mode (LCTYP = 0 or 1)
continuous control
deadband control (approx. 5 % of setpoint)
Table 26: LED power control mode
Table 24: LED power control type
The setpoint for the control can be configured using
parameter LCSET(5:0).
Error monitoring
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 out-
put at error output ERR (see the alarm output section).
INTERPOLATOR
Interpolator resolution
The resolution of the internal interpolator is set using
RESIPO. The maximum permissible Sin/Cos signal fre-
quency (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).
RESIPO Addr. 0x0E; bit 6:5
Code
Interpolator resolution
00
8 bit
01
7 bit
10
6 bit
11
Interpolator deactivated
*) Dependent on elec. char. no.: F01
Max. sin/cos frequency*
50 kHz
100 kHz
200 kHz
-
ENIPO
Code
0
1
Addr. 0x11; bit 4
Description
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 filter
has been designed so that it can be applied across the
entire speed range.
NENF
Code
0
1
Addr. 0x07; bit 6
Description
Filter enabled (recommended)
Filter disabled
Table 27: Interpolator resolution
Table 29: Interpolator filter