IC-MQ_15 Datasheet, PDF (38/43 Pages) IC-Haus GmbH – Sin/Cos INTERPOLATION IC WITH RS422 DRIVER

iC-MQ PROGRAMMABLE 9-BIT
Sin/Cos INTERPOLATION IC WITH RS422 DRIVER
Offset Quick Check
During normal operation with an interpolation factor
of one iC-MQ comparates the sine and cosine zero
crossing.
Connecting a DC voltmeter to the complementary out-
puts (P versus N output) indicates directly deviations of
the duty cycle. Offset-free signals lead to a duty cycle
of 50 % and thus to a measurement value of zero Volts
ideally.
This measurement method can also be used when line
drivers are connected for 24 V applications; just sensi-
tivity is increased.
To obtain stable readings a minimal signal frequency
must be selected, what may depend on the voltmeter
model.
Mode ABZ
normal operation
ACO Control OFF
SELRES
0x00E0
resolution 4
interpolation factor x1
Mode ABZ
Rev F3, Page 38/43
no
V(PA) – V(NA)
=0V?
minimized
OF1
up / down
no
V(PB) – V(NB)
=0V?
OF2
up / down
minimized
quick offset calibration
Figure 25: Offset quick check during normal opera-
tion with interpolation factor x1.
Signal Conditioning Example 1:
Photodiode array connected to current inputs, LED supply with constant current source
Step
1.
Operating Mode
2.
Calibration 2
3.
Calibration 2
4.
System Test
5.
Calibration 2
6.
System Test
Calibration and Signal
Presets
VOS12= 0x3, GF1= 0x40, VDC1= 0x20, OF1= 0x0, GF2= 0x10, VDC2= 0x20, OF2= 0x0
Example: LED current approx. 6.25 mA
ADJ(8)= 1 (constant current source), ADJ(6:5)= 11 (range 50 mA), ADJ(4:0)= 0x04 (value 12.5)
Calibration of Channel 1:
Parameter GR12: Adjust diff. signal at PA vs. NA to approx. 500 mV amplitude
Parameter GF1: Adjust diff. signal at PA vs. NA to exactly 500 mV amplitude
Parameter VDC1: Minimization of VDC1 AC fraction at output PZ (ripple < 10 mVpeak)
Parameter OR1, OF1: Calibration of DC fraction to zero for diff. signal PA vs. NA (< 5 mVdc)
Calibration of Channel 2:
Parameter GF2: Adjust diff. signal at PB vs. NB to exactly 500 mV amplitude
Parameter VDC2: Minimization of VDC2 AC fraction at ouput NZ (ripple < 10 mVpeak)
Parameter OR2, OF2: Calibration of DC fraction to zero for diff. signal PB vs. NB (< 5 mVdc)
1. Iteration, Calibration of Channel 1 vs. Channel 2:
Parameter OF1: Adjust duty ratio of A₄ at PA to 50 %
Parameter OF2: Adjust duty ratio of B₄ at PB to 50 %
Parameter PH12: Adjust duty ratio of A₈ at NA to 50 %
Parameter GF1: Adjust duty ratio of B₈ at NB to 50 %
Repeated Adjustment of Intermediate Voltages, VDC1 and VDC2:
Parameter VDC1: Minimization of VDC1 AC fraction at ouput PZ
Parameter VDC2: Minimization of VDC2 AC fraction at ouput NZ
2. Iteration, Calibration of Channel 1 vs. Channel 2:
Parameter OF1: Adjust duty ratio of A₄ at PA to 50 %
Parameter OF2: Adjust duty ratio of B₄ at PB to 50 %
Parameter PH12: Adjust duty ratio of A₈ at NA to 50 %
Parameter GF1: Adjust duty ratio of B₈ at NB to 50 %
Table 64: Conditioning example 1