IC-LNG_14 Datasheet, PDF (27/30 Pages) IC-Haus GmbH – 16-BIT OPTO ENCODER

iC-LNG 16-BIT OPTO ENCODER ^preliminary
WITH SPI AND SERIAL / PARALLEL OUTPUTS
LED CURRENT CONTROL
Rev B1, Page 27/30
The optical receive power of the sine/cosine sensors
is kept constant by the integrated LED control unit, re-
gardless of the temperature and ageing effects of the
LED. The type of control can be selected using param-
eter LCSET(6), 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(6)
0
1
Add. 0x06, bit 6
Square control (sum of the amplitude squares)
Sum control (DC control prop. to VR())
Table 28: Control mode
The setpoint for the control can be configured using
parameter LCSET(5:0).
LCSET(5:0)
Add. 0x06, bit 5:0
Code
LCSET(6) = 0
0x00
0.240 Vp
0x01
...
0x3F
0.243 Vp
0.24 Vp
1−i ·0.0125
1.1 Vp
LCSET(6) = 1
0.140 V
0.142 V
0.14 V
1−i ·0.0125
0.640 V
Table 29: Control Setpoint
Error Monitoring
iC-LNG’s LED current control range is monitored.
Should the LED current control exit its control range,
internal error ERRS is set to 1. This error signal is or-
gated with iC-LNG’s ERRP alarm (parity check) and
output at error output ERR (cf. section on the alarm
output).
ALARM OUTPUT
iC-LNG has an alarm or error output to indicate exist-
ing errors. If an error occurs, pin ERR is set to 1.
iC-LNG’s LED current control range is monitored.
Should the LED current control exit its control range,
internal error ERRS is set to 1.
If the parity check signals an error in the RAM area,
internal error ERRP is set to 1.
ERROR MESSAGE VDD
ERRS
³1
ERRP
ERR
GND
Figure 19: Alarm output