CDB5463U Cirrus Logic Inc, CDB5463U Datasheet - Page 38

• Manufacturer Part Number: CDB5463U
• Description: BOARD EVAL & SOFTWARE CS5463 ADC
• Manufacturer: Cirrus Logic Inc
• Type: A/Dr

Specifications of CDB5463U

• Main Purpose: Power Management, Energy/Power Meter
• Embedded: Yes, MCU, 8-Bit
• Utilized Ic / Part: CS5463
• Primary Attributes: 1-Phase, Energy-to-Frequency Output
• Secondary Attributes: GUI, USB, SPI Interfaces
• Product: Data Conversion Development Tools
• Maximum Clock Frequency: 4 MHz
• Interface Type: USB
• Supply Voltage (max): 5 V
• Supply Voltage (min): 3.3 V
• For Use With/related Products: CS5463
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant
• Other names: 598-1553

each instantaneous measurement to nullify the DC
component present in the system during conversion
commands.
7.1.2.2 AC Offset Calibration Sequence
Corresponding offset registers I
should be cleared prior to initiating AC offset calibra-
tions. Initiate an AC offset calibration.The AC offset reg-
isters are updated with an offset value that reflects the
RMS output level. Upon completion of the AC offset cal-
ibration the AC offset is stored in the corresponding AC
offset register. The AC offset register value is subtract-
ed from each successive V
7.1.3 Gain Calibration Sequence
When performing gain calibrations, a reference signal
should be applied to the VIN ± pins of the voltage and
IIN ± pins of the current channels that represents the de-
sired maximum signal level. Figure 14 shows the basic
setup for gain calibration.
For gain calibrations, there is an absolute limit on the
RMS voltage levels that are selected for the gain cali-
bration input signals. The maximum value that the gain
registers can attain is 4. Therefore, if the signal level of
the applied input is low enough that it causes the
CS5463 to attempt to set either gain register higher than
4, the gain calibration result will be invalid and all
CS5463 results obtained while performing measure-
ments will be invalid.
If the channel gain registers are initially set to a gain oth-
er then 1.0, AC gain calibration should be used.
7.1.3.1 AC Gain Calibration Sequence
The corresponding gain register should be set to 1.0,
unless a different initial gain value is desired. Initiate an
AC gain calibration. The AC gain calibration algorithm
computes the RMS value of the reference signal applied
to the channel inputs. The RMS register value is then di-
vided into 0.6 and the quotient is stored in the corre-
sponding
measurement will be multiplied by its corresponding AC
gain value.
38
R eference
Signal
CM + -
Figure 14. System Calibration of Gain.
+
-
External
Connections
gain
IN+
IN-
register.
RMS
+
-
and I
Each
XG AIN
ACoff
RMS
and/or V
instantaneous
calculation.
+
-
ACoff
A typical rms calibration value which allows for reason-
able over-range margin would be 0.6 or 60% of the volt-
age and current channel’s maximum input voltage level.
Two examples of AC gain calibration and the updated
digital output codes of the channel’s instantaneous data
registers are shown in Figures 15 and 16. Figure 16
shows that a positive (or negative) DC-level signal can
be used even though an AC gain calibration is being ex-
ecuted.
DC Signal
Sinewave
Sinewave
DC Signal
SIGNAL
After AC Gain Calibration (Vgain Register changed to approx. 0.65217)
SIGNAL
INPUT
INPUT
SIGNAL
SIGNAL
After AC Gain Calibration (Vgn Register changed to approx. 0.9223)
INPUT
INPUT
Figure 15. Example of AC Gain Calibration
Figure 16. Example of AC Gain Calibration
-250 mV
-250 mV
250 mV
230 mV
Before AC Gain Calibration (Vgain Register = 1)
250 mV
230 mV
-230 mV
-250 mV
-230 mV
-250 mV
250 mV
230 mV
250 mV
230 mV
0 V
0 V
0 V
0 V
Before AC Gain Calibration (Vgn Register = 1)
V
RMS
V
V
V
RMS
RMS
RMS
Register =
Register = 0.600000
Register =
Register = 0.600000
230
/
√2
230
250
x
1
= 0.92
/
250
≈ 0.65054
-0.84853
-0.92231
-1.0000...
0.92231
0.84853
0.9999...
-0.92
0.92
-0.65217
-1.0000...
0.65217
0.9999...
0.92
0.6000
Instantaneous Voltage
Instantaneous Voltage
Instantaneous Voltage
CS5463
Instantaneous Voltage
Register Values
Register Values
Register Values
Register Values
DS678F2