MCP3909-I/SS Microchip Technology, MCP3909-I/SS Datasheet - Page 19

• Manufacturer Part Number: MCP3909-I/SS
• Description: IC POWER METERING-1 PHASE 24SSOP
• Manufacturer: Microchip Technology

Specifications of MCP3909-I/SS

• Package / Case: 24-SSOP (0.200", 5.30mm Width)
• Input Impedance: 390 KOhm
• Measurement Error: 0.1%
• Voltage - I/o High: 2.4V
• Voltage - I/o Low: 0.85V
• Current - Supply: 2.3mA
• Voltage - Supply: 4.5 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Meter Type: Single Phase
• Operating Temperature Range: - 40 C to + 85 C
• Mounting Style: SMD/SMT
• Supply Voltage Range: 4.5V To 5.5V
• Digital Ic Case Style: SSOP
• No. Of Pins: 24
• Interface Type: Serial, SPI
• Supply Voltage Max: 5.5V
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: MCP3909EV-MCU16 - EVALUATION BOARD FOR MCP3909MCP3909RD-3PH1 - REF DESIGN MCP3909 3PH ENGY MTR
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

4.0
The MCP3909 is an energy metering IC that serves two
distinct functions that can operate simultaneously:
For the active power output, the device supplies a
frequency output proportional to active (real) power,
and higher frequency output proportional to the
instantaneous power for meter calibration.
For the waveform output, it can be used serially to
gather 16-bit voltage channel and current channel A/D
data, or 20-bit wide multiplier output data. Both
channels use 16-bit, second-order, delta-sigma ADCs
that oversample the input at a frequency equal to
MCLK/4, allowing for wide dynamic range input signals.
A Programmable Gain Amplifier (PGA) increases the
usable range on the current input channel (Channel 0).
Figure 4-1
the MCP3909, detailing its main signal processing
blocks.
Two digital high-pass filters cancel the system offset on
both channels such that the real-power calculation
does not include any circuit or system offset. After
being high-pass filtered, the voltage and current signals
are multiplied to give the instantaneous power signal.
This signal does not contain the DC offset components,
such that the averaging technique can be efficiently
used to give the desired active-power output.
FIGURE 4-1:
© 2009 Microchip Technology Inc.
- Active Power Pulse Output
- Waveform Output via SPI Interface
CH0+
CH0-
CH1+
CH1-
Frequency
Content
DEVICE OVERVIEW
represents the simplified block diagram of
+
+
System offset and
-
-
Input Signal with
PGA
line frequency
0
Active Power Signal Flow with Frequency Contents.
ANALOG
ADC
ADC
ADC Output code
DIGITAL
contains System
and ADC offset
0
HPF
HPF
removed by HPF
0
DC Offset
X
4.1
The instantaneous power signal contains the active-
power information; it is the DC component of the
instantaneous power. The averaging technique can be
used
waveforms, as well as for all power factors. The
instantaneous power is thus low-pass filtered in order
to produce the instantaneous real-power signal.
A digital-to-frequency converter accumulates the
instantaneous active real power information to produce
output pulses with a frequency proportional to the
average real power. The low-frequency pulses present
at the F
electromechanical counters and two-phase stepper
motors displaying the real-power energy consumed.
Each pulse corresponds to a fixed quantity of real
energy, selected by the F2, F1 and F0 logic settings. The
HF
integration period such that it can represent the
instantaneous real-power signal. Due to the shorter
accumulation time, it enables the user to proceed to
faster calibration under steady load conditions (see
Section 4.8 “Active Power F
Output Frequencies”).
OUT
INSTANTANEOUS
with
output has a higher frequency setting and less
0
OUT0
Active Power
POWER
LPF
and F
both
OUT1
sinusoidal
INSTANTANEOUS
MCP3909
REAL POWER
0
outputs are designed to drive
..
0
DTF
1
MCP3909
0
1
...
and
OUT0/1
DS22025B-page 19
non-sinusoidal
and HF
HF
F
F
OUT0
OUT1
OUT
OUT