ade7953 Analog Devices, Inc., ade7953 Datasheet - Page 21

• Manufacturer Part Number: ade7953
• Description: Single Phase, Multifunction Metering Ic With Neutral Current Measurement Ade7953
• Manufacturer: Analog Devices, Inc.

VOLTAGE CHANNEL ADC
Figure 41 shows the ADC signal path and signal processing for
the voltage channel input, which is accessed through the VP and
VN pins. The ADC output is a twos complement, 24-bit data-
word that is available at a rate of 6.99 kSPS (thousand samples
per second). With the specified full-scale analog input of ±500 mV
and a PGA_V gain setting of 1, the ADC produces its maximum
output code. The ADC output swings between −6,500,000 LSBs
(decimal) and +6,500,000 LSBs. Note that this output varies
from part to part.
As shown in Figure 41, there is a high-pass filter (HPF) in the
voltage channel signal path. The HPF is enabled by default and
removes any dc offset in the ADC output. It is highly recom-
mended that this filter be enabled at all times, but it can be
disabled by clearing the HPFEN bit (Bit 2) in the CONFIG
register (Address 0x102). Clearing the HPFEN bit disables the
filters in both current channels and in the voltage channel.
V
IN
VP
VN
×1, ×2, ×4, ×8, ×16
PGA_V BITS
PGA
Figure 41. Voltage Channel ADC and Signal Path
REFERENCE
ADC
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DSP
VGAIN
HPFEN BIT
CONFIG[2]
REFERENCE CIRCUIT
The ADE7953 has an internal voltage reference of 1.2 V nominal,
which appears on the REF pin. This reference voltage is used by
the ADCs in the ADE7953. The REF pin can be overdriven by
an external source, for example an external 1.2 V reference. The
voltage of the ADE7953 internal reference drifts slightly over
temperature (see the Specifications section). The value of the tem-
perature drift may vary slightly from part to part. A drift of x% in
the reference results in a 2x% deviation in meter accuracy. The
reference drift is typically minimal and is usually much smaller
than the drift of other components in the meter. By default, the
ADE7953 is configured to use the internal reference. If Bit 0 of
the EX_REF register (Address 0x800) is set to 1, an external
voltage reference can be applied to the REF pin.
HPF
VOLTAGE PEAK,
OVERVOLTAGE,
SAG DETECTION
VOLTAGE RMS (VRMS)
CALCULATION
V WAVEFORM
SAMPLING REGISTER
ACTIVE AND REACTIVE
POWER CALCULATION
LPF1
ZX DETECTION
ADE7953