ADE9000 Technical Reference Manual
UG-1098
Rev. 0 | Page 9 of 86
MEASUREMENTS
CURRENT CHANNEL MEASUREMENT UPDATE
RATES
Table 5 indicates the registers that hold current channel
measurements and the rate at which they update.
Table 5. Current Channel Measurement Update Rates
Register
Name
Description
Update
Rate
AI_SINC_DAT IA sinc4 filter output
32 ksps
BI_SINC_DAT IB sinc4 filter output
32 ksps
CI_SINC_DAT IC sinc4 filter output
32 ksps
NI_SINC_DAT IN sinc4 filter output
32 ksps
AI_LPF_DAT
IA sinc4 + IIR LPF filter output
f
DSP
= 8 ksps
BI_LPF_DAT
IB sinc4 + IIR LPF filter output
f
DSP
= 8 ksps
CI_LPF_DAT
IC sinc4 + IIR LPF filter output
f
DSP
= 8 ksps
NI_LPF_DAT
IN sinc4 + IIR LPF filter output
f
DSP
= 8 ksps
AI_PCF
Instantaneous current on IA
f
DSP
= 8 ksps
BI_PCF
Instantaneous current on IB
f
DSP
= 8 ksps
CI_PCF
Instantaneous current on IC
f
DSP
= 8 ksps
NI_PCF
Instantaneous current on IN
f
DSP
= 8 ksps
AIRMS
Filtered-based total rms of IA
f
DSP
= 8 ksps
BIRMS
Filtered-based total rms of IB
f
DSP
= 8 ksps
CIRMS
Filtered-based total rms of IC
f
DSP
= 8 ksps
NIRMS
Filtered-based total rms of IN
f
DSP
= 8 ksps
ISUMRMS
Filtered rms of vector sum (
CI_PCF ± NI_PCF); see the
Neutral Current RMS, Vector Current
Sum section
f
DSP
= 8 ksps
IPEAK
Peak current channel sample; see the
Peak Detection section
f
DSP
= 8 ksps
ANGLx_xxx
Voltage to current or current to
current phase angle; see the Angle
Measurement section
CLKIN/24 =
1024 ksps
ADC_REDIRECT Multiplexer
The
provides a multiplexer that allows any ADC
output to be redirected to any digital processing datapath.
By default, each modulator is mapped to its corresponding
datapath. For example, the IAP and IAN pins go into the IA
modulator, which is mapped to the IA digital processing
datapath. Write to the ADC_REDIRECT register to change the
ADC to digital channel mapping.
The redirection can be useful to simplify layout, depending on if
the
is on the top or bottom of the PCB, by redirecting
the IA ADC output to the IC digital datapath and the IC ADC
output to the IA digital datapath. To redirect the IA and IC
ADC outputs, write IA_DIN = 010 and IC_DIN = 000 in the
ADC_REDIRECT register.
Alternatively, the VA voltage channel output can be used for all
three datapaths by writing VB_DIN = 101 and VC_DIN = 101
in the ADC_REDIRECT register.
The neutral current channel does not offer a zero-crossing output
or angle measurements. To calibrate the phase of the neutral
current NI_PCF signal, direct the neutral current ADC output
to, for example, the Phase B digital current channel and check
how its angles correspond to Phase A by writing IA_DIN = 111.
REFERENCE
Σ-Δ
MODULATOR
V
IN
IA_DIN[2:0]
AI_SINC_DAT
AI_LPF_DAT
IA MODULATOR
IA DIGITAL DATAPATH
IA_MOD
011
IB_MOD
IC_MOD
IN_MOD
VA_MOD
VB_MOD
VC_MOD
IA_MOD
000
001
010
100
101
110
111
15523-
010
Figure 10. ADC_REDIRECT Modulator to Digital Datapath Multiplexing
Current Channel Gain, xIGAIN
There are many sources of gain error in an energy metering
system. The current sensor, including current transformer
burden resistors, may have some error. There is part to part gain
error in the
device itself, and the voltage reference
may have some variation (see the data sheet for the device
specifications).
The
provides a current gain calibration register so
that each metering device has the same current channel scaling.
The current channel gain varies with xIGAIN as shown in the
following equation:
+
=
27
2
1
xIGAIN
Gain
Channel
Current
Use this equation to calculate the xIGAIN value for a given
current channel gain:
xIGAIN
= ROUND((
Current Channel Gain
− 1) × 2
27
The current channel gain can be positive or negative.
For example, to gain the current channel up by 10% to 1.1,
xIGAIN
= ROUND((1.1 − 1) × 2
27
= 13421773 =
0x00CC_CCCD
To gain it down by 10% to 0.9,
xIGAIN
= ROUND((0.9 − 1) × 2
27
= −1 × 10
7
=
0xFF33_3333
It is also possible to use the current channel gain register to
change the sign of the current channel, which can be useful if
the current sensor was installed backwards. To compensate for
this, use current channel gain = −1.
xIGAIN
= ROUND((−1 − 1) × 2
27
= −268435456 =
0xF000_0000
If the multipoint phase and gain feature is used, it is recommended
to use the xIGAIN for the main correction, done at the nominal
current for the meter (see the Multipoint Phase/Gain Calibration
section for more information).