CDB5461 Datasheet, PDF (12/27 Pages) Cirrus Logic – Evaluation Board and Software

CDB5461
2.5.1 Offset / Gain Register
In the Offset and Gain Register boxes, the off-
set and gain registers for both channels are
displayed in hexadecimal and decimal. These
registers can all be modified directly by typing
the desired value in the hexadecimal display
boxes. There are two types of offset registers:
DC offset and AC offset. The AC offset regis-
ters only affect the RMS-register values. The
RMS offset registers only hold positive values
between 0 and +1. The DC offset register is a
two’s complement number whose value rang-
es from -1 to +1.
2.5.2 Performing Calibrations
Offset and gain calibrations can be performed
on both the voltage and current channels of
the CS5461. It is generally a good idea to soft-
ware-reset the CS5461 before running calibra-
tions, because the values in the calibration
registers will affect the results of the calibra-
tion. A software reset will reset these registers
back to the default values of zero offset and
unity gain. Offset calibration should be per-
formed before gain calibration to ensure accu-
rate results.
2.5.2.1. Offset Calibrations:
1) Ground the channel(s) you want to cali-
brate directly at the channel header(s). J13
and J14 for the voltage channel, and J15
and J16 for the current channel. The chan-
nel(s) could also be grounded directly at
the BNC connectors.
2) Press the corresponding AC or DC offset
calibrate button (Cal V, Cal I, or Cal Both)
in the Offset Register boxes.
3) The calibration value(s) will automatically
update when the calibration is completed.
2.5.2.2. Gain Calibrations:
1) Attach an AC or DC calibration signal to the
BNC connector(s), and make sure the cor-
responding channel headers (J13, J14,
J15, and J16) are set to the input position.
2) Press the corresponding AC or DC gain
calibrate button (Cal V, Cal I, or Cal Both)
in the Gain Register box.
3) The calibration value(s) will automatically
update when the calibration is completed.
The Calibration Window also contains the
Power Offset Register display and adjustment.
The user can read and write the value in the
Power Offset Register.
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