IC-LNB_13 Datasheet, PDF (27/35 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
LED POWER CONTROL
Rev A1, Page 27/35
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
output at error output ERR (see the alarm output sec-
tion).
INTERPOLATOR
Interpolator resolution
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).
RESIPO
Code
00
01
10
11
Addr. 0x0E; bit 6:5
Interpolator resolution
8 bit
7 bit
6 bit
Interpolator deactivated
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 fil-
ter 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