Energy Metering IC with SPI Interface and Active Power Pulse Output

MCP3909
Energy Metering IC with SPI Interface and Active Power Pulse Output
Features
Description
• Supports IEC 62053 International Energy
Metering Specification
• Digital Waveform Data Access Through SPI
Interface
- 16-bit Dual ADC Output Data Words
- 20-bit Multiplier Output Data Word
• Dual Functionality Pins Support Serial Interface
Access and Simultaneous Active Power Pulse
Output
• Two 16-bit Second Order Delta-sigma Analogto-Digital Converters (ADCs) with Multi-bit DAC
- 81 dB SINAD (typical) on Both Channels
• 0.1% Typical Active Energy Measurement Error
Over 1000:1 Dynamic Range
• PGA for Small Signal Input Supports Low Value
Shunt Current Sensor
• Ultra-low Drift On-chip Reference,15 ppm/°C
(typical)
• Direct Drive for Electromagnetic Mechanical
Counter and Two-phase Stepper Motors
• Low IDD of 4 mA (maximum)
• Tamper Output Pin for Negative Power Indication
• Temperature Ranges:
- Industrial: -40°C to +85°C
- Extended: -40°C to +125°C
The MCP3909 device is an energy-metering IC
designed to support the IEC 62053 international metering standard specification. It supplies a frequency output proportional to the average active real power, with
simultaneous serial access to ADC channels and multiplier output data. This output waveform data is available at up to 14 kHz with 16-bit ADC output and 20-bit
multiplier output words. The 16-bit, delta-sigma ADCs
allow for a wide range of IB and IMAX currents and/or
small shunt (<200 µOhms) meter designs. A no-load
threshold block prevents any current creep measurements for the active power pulse outputs.
The integrated on-chip voltage reference has an
ultra-low temperature drift of 15 ppm per degree C.
This accurate energy metering IC with high field reliability is available in the industry standard 24-lead
SSOP pinout.
Package Type
24-Lead
SSOP
DVDD
HPF
AVDD
NC
CH0+
CH0CH1CH1+
MCLR
REFIN/OUT
AGND
F2/SCK
 2006-2012 Microchip Technology Inc.
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
FOUT0
FOUT1
HFOUT
DGND
NEG/SDO
NC
CLKOUT
CLKIN
G0
G1
F0/CS
F1/SDI
DS22025C-page 1
MCP3909
Functional Block Diagram
HPF
G0 G1
F2/SCK F1/SDI F0/CS NEG/SDO
CH0+
+
PGA
–
CH0-
16-bit
Multi-level
 ADC
4 k
16
HPF1
16
Serial Control
And Output
Buffers
REFIN/OUT
2.4V
Reference
CH1+
+
CH1-
–
16
16-bit
Multi-level
 ADC
SPI
Interface
HFOUT
FOUT0 FOUT1
20
X
DS22025C-page 2
MCLR
16
HPF1
Clock
Sub-system
OSC1 OSC2
Dual Functionality Pin
Control
LPF1
Active Power
DTF
conversion
Stepper Motor
Output Drive
for
Active Power
 2006-2012 Microchip Technology Inc.
MCP3909
1.0
ELECTRICAL
CHARACTERISTICS
† Notice: Stresses above those listed under "Maximum Ratings" may cause permanent damage to the device. This is a
stress rating only and functional operation of the device at
those or any other conditions above those indicated in the
operation listings of this specification is not implied. Exposure
to maximum rating conditions for extended periods may affect
device reliability.
Absolute Maximum Ratings †
VDD...................................................................................7.0V
Digital inputs and outputs w.r.t. AGND ....... -0.6V to VDD +0.6V
Analog input w.r.t. AGND ..................................... ....-6V to +6V
VREF input w.r.t. AGND .............................. -0.6V to VDD +0.6V
Storage temperature .....................................-65°C to +150°C
Ambient temp. with power applied ................-65°C to +125°C
Soldering temperature of leads (10 seconds) ............. +300°C
ESD on the analog inputs (HBM,MM) ................. 5.0 kV, 500V
ESD on all other pins (HBM,MM) ........................5.0 kV, 500V
ELECTRICAL CHARACTERISTICS
Electrical Specifications: Unless otherwise indicated, all parameters apply at AVDD = DVDD = 4.5V to 5.5V,
Internal VREF, HPF turned on (AC mode), AGND, DGND = 0V, MCLK = 3.58 MHz; TA = -40°C to +85°C.
Parameter
Sym
Min
Typ.
Max
Units
Comment
E
—
0.1
—
% FOUT Channel 0 swings 1000:1 range,
FOUT0, FOUT1 Frequency outputs
only, does not apply to serial
interface data. (Note 1, Note 4)
NLT
—
0.0015
—
% FOUT Frequency outputs only, does not
Max
apply to serial interface data.
Disabled when F2, F1, F0 = 0, 1, 1
(Note 5, Note 6)
—
1
5
% FOUT (Note 2, Note 5)
Active Power Measurement Accuracy
Active Energy Measurement
Error
No-Load Threshold/
Minimum Load
System Gain Error
AC Power Supply Rejection
(output frequency variation)
AC PSRR
—
0.01
—
% FOUT F2, F1, F0 = 0, 1, 1 (Note 3)
DC Power Supply Rejection
(output frequency variation)
DC PSRR
—
0.01
—
% FOUT HPF = 1, Gain = 1 (Note 3)
SINAD
—
81
—
dB
Applies to both channels,
VIN = 0 dBFS at 50 Hz
(VIN = Full Scale)
Bandwidth
(Notch Frequency)
—
14
—
kHz
Applies to both channels,
MCLK/256
Phase Delay Between
Channels
—
—
1/MCLK
s
Waveform Sampling
A/D Converter Signal-toNoise and Distortion Ratio
Note 1:
2:
3:
4:
5:
6:
7:
HPF = 0 and 1, < 1 MCLK period
(Note 4, Note 6, Note 7)
Measurement error = (Energy Measured By Device - True Energy)/True Energy * 100%. Accuracy is measured with signal (±660 mV) on Channel 1. FOUT0, FOUT1 pulse outputs. Valid from 45 Hz to 75 Hz. See
typical performance curves for higher frequencies and increased dynamic range. This parameter is not
100% production tested.
Does not include internal VREF. Gain = 1, CH0 = 470 mVDC, CH1 = 660 mVDC, difference between
measured output frequency and expected transfer function.
Percent of HFOUT output frequency variation; Includes external VREF = 2.5V, CH1 = 100 mVRMS @ 50 Hz,
CH2 = 100 mVRMS @ 50 Hz, AVDD = 5V + 1 Vpp @ 100 Hz. DC PSRR: 5V ±500 mV
Error applies down to 60 degree lead (PF = 0.5 capacitive) and 60 degree lag (PF = 0.5 inductive).
Refer to Section 4.0 “Device Overview” for complete description.
Specified by characterization, not production tested.
1 MCLK period at 3.58 MHz is equivalent to less than < 0.005 degrees at 50 or 60 Hz.
 2006-2012 Microchip Technology Inc.
DS22025C-page 3
MCP3909
ELECTRICAL CHARACTERISTICS (CONTINUED)
Electrical Specifications: Unless otherwise indicated, all parameters apply at AVDD = DVDD = 4.5V to 5.5V,
Internal VREF, HPF turned on (AC mode), AGND, DGND = 0V, MCLK = 3.58 MHz; TA = -40°C to +85°C.
Parameter
Sym
Min
Typ.
Max
Units
VOS
—
2
5
mV
—
0.5
—
—
2.4
—
Comment
ADC/PGA Specifications
Offset Error
Gain Error Match
Referred to Input, applies to both
channels
% FOUT (Note 5)
Internal Voltage Reference
Voltage
V
Tolerance
—
±2
—
%
Tempco
—
15
—
ppm/°C
Input Range
2.2
—
2.6
V
Input Impedance
3.2
—
—
kΩ
Input Capacitance
—
—
10
pF
Reference Input
Analog Inputs
Maximum Signal Level
—
—
±1
V
Differential Input Voltage
Range Channel 0
—
—
±470/G
mV
Differential Input Voltage
Range Channel 1
—
—
±660
mV
390
—
—
kΩ
1
—
4
MHz
Input Impedance
CH0+,CH0-,CH1+,CH1- to AGND
G = PGA Gain on Channel 0
Proportional to 1/MCLK
Oscillator Input
Frequency Range
MCLK
Power Specifications
Operating Voltage
AVDD, DVDD
4.5
—
5.5
V
IDD,A
IDD,A
—
2.3
2.8
mA
AVDD pin only
IDD,D
IDD,D
—
0.8
1.2
mA
DVDD pin only
Note 1:
2:
3:
4:
5:
6:
7:
Measurement error = (Energy Measured By Device - True Energy)/True Energy * 100%. Accuracy is measured with signal (±660 mV) on Channel 1. FOUT0, FOUT1 pulse outputs. Valid from 45 Hz to 75 Hz. See
typical performance curves for higher frequencies and increased dynamic range. This parameter is not
100% production tested.
Does not include internal VREF. Gain = 1, CH0 = 470 mVDC, CH1 = 660 mVDC, difference between
measured output frequency and expected transfer function.
Percent of HFOUT output frequency variation; Includes external VREF = 2.5V, CH1 = 100 mVRMS @ 50 Hz,
CH2 = 100 mVRMS @ 50 Hz, AVDD = 5V + 1 Vpp @ 100 Hz. DC PSRR: 5V ±500 mV
Error applies down to 60 degree lead (PF = 0.5 capacitive) and 60 degree lag (PF = 0.5 inductive).
Refer to Section 4.0 “Device Overview” for complete description.
Specified by characterization, not production tested.
1 MCLK period at 3.58 MHz is equivalent to less than < 0.005 degrees at 50 or 60 Hz.
DS22025C-page 4
 2006-2012 Microchip Technology Inc.
MCP3909
TEMPERATURE CHARACTERISTICS
Electrical Specifications: Unless otherwise indicated, VDD = 4.5V to 5.5V, AGND, DGND = 0V.
Parameters
Sym
Min
Typ
Max
Units
Specified Temperature Range
TA
-40
—
+85
°C
Operating Temperature Range
TA
-40
—
+125
°C
Storage Temperature Range
TA
-65
—
+150
°C
JA
—
73
—
°C/W
Conditions
Temperature Ranges
Note
Thermal Package Resistances
Thermal Resistance, 24L-SSOP
Note:
The MCP3909 operates over this extended temperature range, but with reduced performance. In any case,
the Junction Temperature (TJ) must not exceed the Absolute Maximum specification of +150°C.
TIMING CHARACTERISTICS
Electrical Specifications: Unless otherwise indicated, all parameters apply at AVDD = DVDD = 4.5V to 5.5V,
AGND, DGND = 0V, MCLK = 3.58 MHz; TA = -40°C to +85°C.
Parameter
Sym
Min
Typ
Max
Units
Comment
FOUT0 and FOUT1 Pulse Width
(Logic Low)
tFW
—
275
—
ms
984376 MCLK periods
(Note 1)
HFOUT Pulse Width
tHW
—
90
—
ms
322160 MCLK periods
(Note 2)
Frequency Outputs
FOUT0 and FOUT1 Pulse Period
tFP
Refer to Equation 4-1
s
HFOUT Pulse Period
tHP
Refer to Equation 4-2
s
FOUT0 to FOUT1 Falling-Edge
Time
tFS2
—
0.5 tFP
—
FOUT0 to FOUT1 Minimum Separation
tFS
—
4/MCLK
—
FOUT0 and FOUT1 Output High
Voltage
VOH
4.5
—
—
V
IOH = 10 mA, DVDD = 5.0V
FOUT0 and FOUT1 Output Low
Voltage
VOL
—
—
0.5
V
IOL = 10 mA, DVDD = 5.0V
HFOUT and NEG Output High
Voltage
VOH
4.0
—
—
V
IOH = 5 mA, DVDD = 5.0V
HFOUT and NEG Output Low
Voltage
VOL
—
—
0.5
V
IOL = 5 mA, DVDD = 5.0V
High-Level Input Voltage
(All Digital Input Pins)
VIH
2.4
—
—
V
DVDD = 5.0V
Low Level Input Voltage
(All Digital Input Pins)
VIL
—
—
0.85
V
DVDD = 5.0V
Input Leakage Current
—
0.1
±1
µA
VIN = 0, VIN = DVDD
Pin Capacitance
—
—
10
pF
(Note 3)
Digital I/O
Note 1:
2:
3:
4:
If output pulse period (tFP) falls below 984376*2 MCLK periods, then tFW = 1/2 tFP.
If output pulse period (tHP) falls below 322160*2 MCLK periods, then tHW = 1/2 tHP. When F2, F1, F0
equals 0,1,1, the HFOUT pulse time is fixed at 64 x MCLK periods or 18 µs for MCLK = 3.58 MHz.
Specified by characterization, not production tested.
Serial timings specified and production tested with 180 pF load.
 2006-2012 Microchip Technology Inc.
DS22025C-page 5
MCP3909
TIMING CHARACTERISTICS (CONTINUED)
Electrical Specifications: Unless otherwise indicated, all parameters apply at AVDD = DVDD = 4.5V to 5.5V,
AGND, DGND = 0V, MCLK = 3.58 MHz; TA = -40°C to +85°C.
Parameter
Sym
Min
Typ
Max
Units
ns
Comment
Serial Interface Timings (Note 4)
Data Ready Pulse Width
tDR
Reset Time
tRST
100
—
—
Output Data Rate
fADC
—
MCLK/256
—
Serial Clock Frequency
fCLK
—
20
MHz
4/MCLK
VDD = 5V
Window for serial mode entry
codes
tWINDOW
—
—
32/
MCLK
—
Last bit must be clocked in
before this time.
Window start time for serial
mode entry codes
tWINSET
1/MCLK
—
—
—
First bit must be clocked in
after this time.
Serial Clock High Time
tHI
—
—
25
ns
fCLK= 20 MHz
Serial Clock Low Time
tLO
—
—
25
ns
fCLK= 20 MHz
tSUCS
15
—
—
ns
tSU
10
—
—
ns
CS Fall to First Rising CLK Edge
Data Input Setup Time
Data Input Hold Time
tHD
—
—
10
ns
CS Rise to Output Disable
tDIS
—
—
150
ns
CLK Rise to Output Data Valid
tDO
—
—
30
ns
SDO Rise Time
tR
—
2
—
ns
SDO Fall Time
tF
—
2
—
ns
Note 1:
2:
3:
4:
If output pulse period (tFP) falls below 984376*2 MCLK periods, then tFW = 1/2 tFP.
If output pulse period (tHP) falls below 322160*2 MCLK periods, then tHW = 1/2 tHP. When F2, F1, F0
equals 0,1,1, the HFOUT pulse time is fixed at 64 x MCLK periods or 18 µs for MCLK = 3.58 MHz.
Specified by characterization, not production tested.
Serial timings specified and production tested with 180 pF load.
DS22025C-page 6
 2006-2012 Microchip Technology Inc.
MCP3909
tFP
tFW
FOUT0
tFS
tFS2
FOUT1
tHW
HFOUT
tHP
NEG
FIGURE 1-1:
Output Timings for Active Power Pulse Outputs and Negative Power Pin.
CS
tSUCS
tCLK
tHI
tLO
CLK
tSU
tHD
SDI
tDO
SDO
FIGURE 1-2:
Hi-z
tR
tF
tDIS
Serial Interface Timings showing Output, Rise, Hold, and CS Times.
 2006-2012 Microchip Technology Inc.
DS22025C-page 7
MCP3909
VDD
V
–V

DD
OL
R = -----------------------------------IOL
SPI Data
Output
Pin
FIGURE 1-3:
DS22025C-page 8
180 pF
 VOH 
R = -----------------I
OH
SPI Output Pin Loading Circuit During SPI Testing.
 2006-2012 Microchip Technology Inc.
MCP3909
2.0
TYPICAL PERFORMANCE CURVES
Note:
The graphs and tables provided following this note are a statistical summary based on a limited number of
samples and are provided for informational purposes only. The performance characteristics listed herein
are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified
operating range (e.g., outside specified power supply range) and therefore outside the warranted range.
1
0.8
0.6
0.4
0.2 +25°C
0
-0.2
-0.4
-0.6
-0.8
-1
0.0000
Measurement Error (%)
Measurement Error (%)
Note: Unless otherwise specified, DVDD, AVDD = 5V; AGND, DGND = 0V; VREF = Internal, HPF = 1 (AC mode),
MCLK = 3.58 MHz, CH1 input = 660 mVP-P at 50 Hz, CH0 amplitude sweeps at 50 Hz.
+85°C
-40°C
0.0001
`
0.0010
0.0100
0.1000
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
0.0000
CH0 Vp-p Amplitude (V)
+25°C
- 40°C
0.0010
0.0100
0.1000
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
0.0000
+85°C
- 40°C
0.0100
0.1000
+25°C
1.0000
CH0 Vp-p Amplitude (V)
FIGURE 2-3:
Active Power Measurement
Error (Gain = 2, PF = 1).
 2006-2012 Microchip Technology Inc.
0.0010
0.0100
0.1000
+85°C
+25°C
-40°C
0.0001
0.0010
0.0100
0.1000
FIGURE 2-5:
Active Power Measurement
Error (Gain = 16, PF = 0.5).
Measurement Error (%)
Measurement Error (%)
FIGURE 2-2:
Active Power Measurement
Error (Gain = 16, PF = 1).
0.0010
0.0001
CH0 Vp-p Amplitude (V)
CH0 Vp-p Amplitude (V)
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
0.0001
-40°C
FIGURE 2-4:
Active Power Measurement
Error (Gain = 8, PF = 0.5).
Measurement Error (%)
Measurement Error (%)
+85°C
0.0001
+25°C
CH0 Vp-p Amplitude (V)
FIGURE 2-1:
Active Power Measurement
Error (Gain = 8, PF = 1).
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
0.0000
+85°C
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
0.0001
+85°C
+25°C
-40°C
0.0010
0.0100
0.1000
1.0000
CH0 Vp-p Amplitude (V)
FIGURE 2-6:
Active Power Measurement
Error (Gain =2, PF = 0.5).
DS22025C-page 9
MCP3909
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
0.0001
Measurement Error (%)
Measurement Error (%)
Note: Unless otherwise specified, DVDD, AVDD = 5V; AGND, DGND = 0V; VREF = Internal, HPF = 1 (AC mode),
MCLK = 3.58 MHz, CH1 input = 660 mVP-P at 50 Hz, CH0 amplitude sweeps at 50 Hz.
+85°C
+25°C
- 40°C
0.0010
0.0100
0.1000
1.0000
CH0 Vp-p Amplitude (V)
FIGURE 2-7:
Active Power Measurement
Error (Gain = 1, PF = 1).
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
0.0001
+25°C; PF = 1
+25°C; PF = 0.5
+125°C; PF = 0.5
+125°C; PF = 1
0.001
0.01
0.1
CH1 Vp-p Amplitude (V)
1
FIGURE 2-10:
Measurement Error,
Temperature = +125°C, Gain = 2.
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
0.0001
Measurement Error (%)
Measurement Error (%)
L
+85°C
+25°C
-40°C
0.0010
0.0100
0.1000
1.0000
CH0 Vp-p Amplitude (V)
FIGURE 2-8:
Active Power Measurement
Error (Gain = 1, PF = 0.5).
+25°C; PF = 1
+25°C; PF = 0.5
+125°C; PF = 0.5
+125°C; PF = 1
0.001
0.01
0.1
CH1
V
A lit d Error,
(V)
Measurement
FIGURE 2-9:
Temperature = +125°C, Gain = 1.
1
1
FIGURE 2-11:
Measurement Error,
Temperature = +125°C, Gain = 8.
Measurement Error (%)
Measurement Error (%)
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
0.0001
1
0.8
0.6
+25°C; PF = 1
0.4
+25°C; PF = 0.5
0.2
0
+125°C; PF = 0.5
-0.2
-0.4
-0.6
+125°C; PF = 1
-0.8
-1
0.0001
0.001
0.01
0.1
CH1 Vp-p Amplitude (V)
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
0.0001
+25°C; PF = 1
+25°C; PF = 0.5
+125°C; PF = 0.5
+125°C; PF = 1
0.001
0.01
0.1
CH1 Vp-p Amplitude (V)
1
FIGURE 2-12:
Measurement Error,
Temperature = +125°C, Gain = 16.
DS22025C-page 10
 2006-2012 Microchip Technology Inc.
MCP3909
Note: Unless otherwise specified, DVDD, AVDD = 5V; AGND, DGND = 0V; VREF = Internal, HPF = 1 (AC mode),
MCLK = 3.58 MHz, CH1 input = 660 mVP-P at 50 Hz, CH0 amplitude sweeps at 50 Hz.
1200
3000
1000
O cOccurance
currence
2000
1500
1000
800
16384 Samples
Mean = -1.65 mV
Std. Dev = 16.99 µV
600
400
200
500
FIGURE 2-13:
Channel 0 Offset Error
(DC Mode, HPF off, G = 1, PF = 1).
600
2000
500
O cOccurance
currence
O cOccurance
currence
-1.59
-1.60
-1.61
-1.62
FIGURE 2-15:
Channel 0 Offset Error
(DC Mode, HPF off, G = 8, PF = 1).
16384 Samples
Mean = -1.20 mV
Std. Dev. = 25.1 µV
2500
-1.64
Bin (mV)
Bin (mV)
3000
-1.65
-1.50
-1.66
-1.59
-1.67
-1.68
-1.68
-1.77
-1.69
-1.72
0
0
-1.70
O cOccurance
currence
2500
16,384 Samples
Mean = -1.62 mV
Std. Dev = 54.6 µV
1500
1000
500
16384 Samples
Mean = - 17.91 mV
Std. Dev = - 1.22 µV
400
300
200
100
-1.11
-1.13
-1.16
-1.18
-1.20
-1.22
-1.25
-1.27
-1.30
0
Bin (mV)
FIGURE 2-14:
Channel 0 Offset Error
(DC Mode, HPF off, G = 2, PF = 1).
 2006-2012 Microchip Technology Inc.
0
-1.30
-1.25
-1.23
-1.20
-1.17
Bin (mV)
FIGURE 2-16:
Channel 0 Offset Error
(DC Mode, HPF Off, G = 16, PF = 1).
DS22025C-page 11
MCP3909
Note: Unless otherwise specified, DVDD, AVDD = 5V; AGND, DGND = 0V; VREF = Internal, HPF = 1 (AC mode),
MCLK = 3.58 MHz, CH1 input = 660 mVP-P at 50 Hz, CH0 amplitude sweeps at 50 Hz.
0.3
0.2
Measurement Error (%)
Measurement Error (%)
0.3
0.25
VDD=5.0V
0.15
0.1
VDD=4.5V
0.05
VDD=5.25V
0
VDD=4.75V
-0.05
VDD=5.5V
-0.1
-0.15
0.0001
0.0010
0.0100
0.1000
0.2
0.1
-0.2
FIGURE 2-17:
Active Power Measurement
Error over VDD , Internal VREF (G = 16, PF = 1).
Measurement Error (%)
Measurement Error (%)
0.15
VDD=4.5V
VDD=4.75V
0.05
VDD=5.0V
VDD=5.25V
-0.05
VDD=5.5V
-0.1
0.0001
0.0010
0.0100
0.1000
1.0000
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
0.0001
PF = 0.5
PF = 1
50
55
60
65
70
75
Frequency (Hz)
FIGURE 2-19:
Active Power Measurement
Error vs. Input Frequency (G = 16).
DS22025C-page 12
1.0000
+85°C
+25°C
-40°C
0.0010
0.0100
0.1000
1.0000
FIGURE 2-21:
Active Power Measurement
Error with External VREF (G = 1, PF = 0.5).
Measurement Error (%)
% Error
FIGURE 2-18:
Active Power Measurement
Error over VDD, External VREF (G = 1, PF = 1).
45
0.1000
CH1 Vp-p Amplitude (V)
CH0 Vp-p Amplitude (V)
0.5
0.4
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
0.0100
FIGURE 2-20:
Active Power Measurement
Error with External VREF (G = 1, PF = 1).
0.2
0
0.0010
CH0 Vp-p Amplitude (V)
CH0 Vp-p Amplitude (V)
0.1
+25°C
- 40°C
-0.1
-0.3
0.0001
1.0000
+85°C
0
0.5
0.4
0.3
0.2
0.1
0 +25°C
-0.1
-0.2
-0.3
-0.4
-0.5
0.0001
+85°C
- 40°C
0.0010
0.0100
0.1000
1.0000
CH0 Vp-p Amplitude (V)
FIGURE 2-22:
Active Power Measurement
Error with External VREF (G = 2, PF = 1).
 2006-2012 Microchip Technology Inc.
MCP3909
+85°C
-40°C
0.0100
0.1000
1
0.8
0.6
0.4
0.2
0
-0.2 - 40°C
-0.4
-0.6
-0.8
-1
0.0000
1.0000
+85°C
-40°C
0.0010
0.0100
0.1000
1
0.8
0.6
0.4
0.2 +25°C
0
-0.2
-0.4
-0.6
-0.8
-1
0.0000
+85°C
-40°C
0.0010
0.0100
0.1000
CH1 Vp-p Amplitude (V)
FIGURE 2-25:
Active Power Measurement
Error with External VREF (G = 8, PF = 0.5).
 2006-2012 Microchip Technology Inc.
0.0100
0.1000
-40°C
+85°C
0.0001
0.0010
0.0100
0.1000
FIGURE 2-27:
Active Power Measurement
Error with External VREF (G =16, PF = 0.5).
SINAD (dBFS)
Measurement Error (%)
FIGURE 2-24:
Active Power Measurement
Error with External VREF (G = 8, PF = 1).
0.0001
0.0010
CH1 Vp-p Amplitude (V)
CH1 Vp-p Amplitude (V)
1
0.8
0.6
0.4
0.2 +25°C
0
-0.2
-0.4
-0.6
-0.8
-1
0.0000
0.0001
FIGURE 2-26:
Active Power Measurement
Error with External VREF (G = 16, PF = 1).
Measurement Error (%)
Measurement Error (%)
FIGURE 2-23:
Active Power Measurement
Error with External VREF (G = 2, PF = 0.5).
0.0001
+25°C
CH1 Vp-p Amplitude (V)
CH1 Vp-p Amplitude (V)
1
0.8
0.6
0.4
0.2
+25°C
0
-0.2
-0.4
-0.6
-0.8
-1
0.0000
+85°C
100
90
80
70
60
50
40
30
20
10
0
0.0001
100
90
80
SINAD (dBFS)
70
60
SINAD(dB)
50
40
30
20
10
SINAD (dB)
1
0.8
0.6
0.4
0.2
0
-0.2
+25°C
-0.4
-0.6
-0.8
-1
0.0001
0.0010
Measurement Error (%)
Measurement Error (%)
Note: Unless otherwise specified, DVDD, AVDD = 5V; AGND, DGND = 0V; VREF = Internal, HPF = 1 (AC mode),
MCLK = 3.58 MHz, CH1 input = 660 mVP-P at 50 Hz, CH0 amplitude sweeps at 50 Hz.
0
0.0010
0.0100
0.1000
1.0000
CH0 Vp-p Amplitude (V)
FIGURE 2-28:
Signal-to-Noise and
Distortion Ratio vs. Input Signal Amplitude
(G = 1).
DS22025C-page 13
MCP3909
100
100
90
90
80
80
SINAD (dBFS)
70
70
60
60
50
50
40
40
30
30
SINAD (dB)
20
20
10
10
0
0
0.000010 0.000100 0.001000 0.010000 0.100000
CH0 Vp-p Amplitude (V)
CH0 Vp-p Amplitude (V)
SINAD (dBFS)
SINAD (dB)
0.0001
0.001
0.01
0.1
CH0 Vp-p Amplitude (V)
FIGURE 2-30:
Signal-to-Noise and
Distortion Ratio vs. Input Signal Amplitude
(G = 8).
DS22025C-page 14
0
-20
Amplitude (dB)
100
90
80
70
60
50
40
30
20
10
0
FIGURE 2-31:
Signal-to-Noise and
Distortion Ratio vs. Input Signal Amplitude
(G = 16).
SINAD (dB)
SINAD (dBFS)
FIGURE 2-29:
Signal-to-Noise and
Distortion Ratio vs. Input Signal Amplitude
(G = 2).
100
90
80
70
60
50
40
30
20
10
0
0.00001
SINAD (dB)
SINAD (dBFS)
100
100
90
90
SINAD (dBFS)
80
80
70
70
60
60
50
50
SINAD (dB)
40
40
30
30
20
20
10
10
0
0
0.000100 0.001000 0.010000 0.100000 1.000000
SINAD (dB)
SINAD (dBFS)
Note: Unless otherwise specified, DVDD, AVDD = 5V; AGND, DGND = 0V; VREF = Internal, HPF = 1 (AC mode),
MCLK = 3.58 MHz, CH1 input = 660 mVP-P at 50 Hz, CH0 amplitude sweeps at 50 Hz.
-40
-60
-80
-100
-120
-140
-160
0
2000
4000
6000
Frequency (Hz)
FIGURE 2-32:
Frequency Spectrum,
50 Hz Input Signal.
 2006-2012 Microchip Technology Inc.
MCP3909
3.0
PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 3-1.
TABLE 3-1:
MCP3909
PIN FUNCTION TABLE
Symbol
Description
SSOP
3.1
1
DVDD
Digital Power Supply Pin
2
HPF
High-Pass Filters Control Logic Pin
3
AVDD
Analog Power Supply Pin
4
NC
5
CH0+
Non-Inverting Analog Input Pin for Channel 0 (Current Channel)
6
CH0-
Inverting Analog Input Pin for Channel 0 (Current Channel)
7
CH1-
Inverting Analog Input Pin for Channel 1 (Voltage Channel)
8
CH1+
Non-Inverting Analog Input Pin for Channel 1 (Voltage Channel)
9
MCLR
Master Clear Logic Input Pin
10
REFIN/OUT
11
AGND
Analog Ground Pin, Return Path for internal analog circuitry
12
SCK / F2
Serial Clock or Frequency Control for HFOUT Logic Input Pin
13
SDI / F1
Serial Data Input or Frequency Control for FOUT0/1 Logic Input Pin
14
CS / F0
Chip Select or Frequency Control for FOUT0/1 Logic Input Pin
15
G1
Gain Control Logic Input Pin
16
G0
Gain Control Logic Input Pin
17
OSC1
Oscillator Crystal Connection Pin or Clock Input Pin
18
OSC2
Oscillator Crystal Connection Pin or Clock Output Pin
19
NC
20
SDO / NEG
21
DGND
Digital Ground Pin, Return Path for Internal Digital Circuitry
22
HFOUT
High-Frequency Logic Output Pin (Intended for Calibration)
23
FOUT1
Differential Mechanical Counter Logic Output Pin
24
FOUT0
Differential Mechanical Counter Logic Output Pin
No Connect
Voltage Reference Input/Output Pin
No Connect
Serial Data Out or Negative Power Logic Output Pin
Digital VDD (DVDD)
DVDD is the power supply pin for the digital circuitry
within the MCP3909 device.
This pin requires appropriate bypass capacitors and
should be maintained to 5V ±10% for specified
operation. Refer to Section 6.0 “Applications
Information”.
 2006-2012 Microchip Technology Inc.
3.2
High-Pass Filter Input Logic Pin
(HPF)
HPF controls the state of the high-pass filter in both
input channels. A logic ‘1’ enables both filters, removing any DC offset coming from the system or the
device. A logic ‘0’ disables both filters allowing DC
voltages to be measured.
DS22025C-page 15
MCP3909
3.3
Analog VDD (AVDD)
AVDD is the power supply pin for the analog circuitry
within the MCP3909.
This pin requires appropriate bypass capacitors and
should be maintained to 5V ±10% for specified
operation. Refer to Section 6.0 “Applications
Information”.
3.4
Current Channel (CH0-, CH0+)
CH0- and CH0+ are the fully differential analog voltage
input channels for the current measurement, containing
a PGA for small-signal input, such as shunt current
sensing. The linear and specified region of this channel
is dependant on the PGA gain. This corresponds to a
maximum differential voltage of ±470 mV/G and maximum absolute voltage, with respect to AGND, of ±1V.
Up to ±6V can be applied to these pins without the risk
of permanent damage.
Refer to Section 1.0 “Electrical Characteristics”.
3.5
Voltage Channel (CH1-,CH1+)
CH1- and CH1+ are the fully differential analog voltage
input channels for the voltage measurement. The linear
and specified region of these channels have a maximum differential voltage of ±660 mV and a maximum
absolute voltage of ±1V, with respect to AGND. Up to
±6V can be applied to these pins without the risk of permanent damage.
Refer to Section 1.0 “Electrical Characteristics”.
3.6
Master Clear (MCLR)
MCLR controls the reset for both delta-sigma ADCs, all
digital registers, the SINC filters for each channel and
all accumulators post multiplier. The MCLR pin is also
used to change pin functionality and enter the serial
interface mode. A logic ‘0’ resets all registers and holds
both ADCs in a Reset condition. The charge stored in
both ADCs is flushed and their output is maintained to
0x0000h. The only block consuming power on the
digital power supply during Reset is the oscillator
circuit.
3.7
Reference (REFIN/OUT)
REFIN/OUT is the output for the internal 2.4V reference. This reference has a typical temperature coefficient of 15 ppm/°C and a tolerance of ±2%. In addition,
an external reference can also be used by applying
voltage to this pin within the specified range. This pin
requires appropriate bypass capacitors to AGND, even
when using the internal reference only.
3.8
Analog Ground (AGND)
AGND is the ground connection to internal analog circuitry (ADCs, PGA, band gap reference, POR). To
ensure accuracy and noise cancellation, this pin must
be connected to the same ground as DGND, preferably
with a star connection. If an analog ground plane is
available, it is recommended that this device be tied to
this plane of the PCB. This plane should also reference
all other analog circuitry in the system.
3.9
Serial Clock Input or F2 Frequency
Control Pin
This dual function pin can act as either the serial clock
input for SPI communication or the F2 selection for the
high-frequency output and low-frequency output pin
ranges, changing the value of the constants FC and
HFC used in the device transfer function. FC and HFC
are the frequency constants that define the period of
the output pulses for the device.
3.10
Serial Data Input or F1 Frequency
Control Pin
This dual function pin can act as either the serial data
input for SPI communication or the F1 selection for the
high-frequency output and low-frequency output pin
ranges, changing the value of the constants FC and
HFC used in the device transfer function. FC and HFC
are the frequency constants that define the period of
the output pulses for the device.
3.11
Chip Select (CS) or F0 Frequency
Control Pin
This dual function pin can act as either the chip select
for SPI communication or the F0 selection for the highfrequency output and low-frequency output pin ranges
by changing the value of the constants FC and HFC
used in the device transfer function. FC and HFC are
the frequency constants that define the period of the
output pulses for the device.
3.12
Gain Control Logic Pins (G1, G0)
G1 and G0 select the PGA gain (G) on Channel 0 from
four different values: 1, 2, 8 and 16.
Refer to Section 6.0 “Applications Information”.
DS22025C-page 16
 2006-2012 Microchip Technology Inc.
MCP3909
3.13
Oscillator (OSC1, OSC2)
OSC1 and OSC2 provide the master clock for the
device. A resonant crystal or clock source with a similar
sinusoidal waveform must be placed across these pins
to ensure proper operation. The typical clock frequency
specified is 3.579545 MHz. However, the clock frequency can be within the range of 1 MHz to 4 MHz
without disturbing measurement error. Appropriate
load capacitance should be connected to these pins for
proper operation.
A full-swing, single-ended clock source may be connected to OSC1 with proper resistors in series to
ensure no ringing of the clock source due to fast
transient edges.
3.14
Serial Data Output or Negative
Power Output Logic Pin (NEG)
This dual function pin can act as either the serial data
output for SPI communication or NEG. NEG detects the
phase difference between the two channels and will go
to a logic ‘1’ state when the phase difference is greater
than 90° (i.e., when the measured real power is negative). The output state is synchronous with the rising
edge of HFOUT and maintains the logic ‘1’ until the real
power becomes positive again and HFOUT shows a
pulse.
3.15
3.16
High-Frequency Output (HFOUT)
HFOUT is the high-frequency output of the device and
supplies the instantaneous real-power information. The
output is a periodic pulse output, with its period proportional to the measured real power, and to the HFC constant defined by F0, F1 and F2 pin logic states. This
output is the preferred output for calibration due to
faster output frequencies, giving smaller calibration
times. Since this output gives instantaneous real
power, the 2 ripple on the output should be noted.
However, the average period will show minimal drift.
3.17
Frequency Output (FOUT0, FOUT1)
FOUT0 and FOUT1 are the frequency outputs of the
device that supply the average real-power information.
The outputs are periodic pulse outputs, with its period
proportional to the measured real power, and to the FC
constant, defined by F0 and F1 pin logic states. These
pins include high-output drive capability for direct use
of electromechanical counters and 2-phase stepper
motors. Since this output supplies average real power,
any 2 ripple on the output pulse period is minimal.
Ground Connection (DGND)
DGND is the ground connection to internal digital
circuitry (SINC filters, multiplier, HPF, LPF,
digital-to-frequency converter and oscillator). To
ensure accuracy and noise cancellation, DGND must be
connected to the same ground as AGND, preferably
with a star connection. If a digital ground plane is
available, it is recommended that this device be tied to
this plane of the Printed Circuit Board (PCB). This
plane should also reference all other digital circuitry in
the system.
 2006-2012 Microchip Technology Inc.
DS22025C-page 17
MCP3909
4.0
DEVICE OVERVIEW
4.1
Active Power
The instantaneous power signal contains the active
power information; it is the DC component of the
instantaneous power. The averaging technique can be
used with both sinusoidal and non-sinusoidal 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.
The MCP3909 is an energy metering IC that serves two
distinct functions that can operate simultaneously:
- Active Power Pulse Output
- Waveform Output via SPI Interface
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.
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 FOUT0 and FOUT1 outputs are designed to drive
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
HFOUT output has a higher frequency setting and less
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 FOUT0/1 and HFOUT
Output Frequencies”).
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 represents the simplified block diagram of
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.
MCP3909
CH0+
+
CH0-
PGA
??A
? DC
ANALOG
HPF
X
DIGITAL
..0101...
LPF
CH1+
+
CH1-
-
Frequency
Content
?
0
Input Signal with
System offset and line
frequency
FIGURE 4-1:
DS22025C-page 18
DTF
HPF
??A
? DC
0
FOUT0
FOUT1
HFOUT
?
ADC Output code
contains System and
ADC offset
0
?
DC Offset
removed by
HPF
0
?
?
0
?
INSTANTANEOUS
POWER
?
?
?
INSTANTANEOUS
REAL POWER
Active Power Signal Flow with Frequency Contents.
 2006-2012 Microchip Technology Inc.
MCP3909
Analog Inputs
The MCP3909 analog inputs can be connected directly
to the current and voltage transducers (such as shunts
or current transformers). Each input pin is protected by
specialized ESD structures that are certified to pass
5 kV HBM and 500V MM contact charge. These structures also allow up to ±6V continuous voltage to be
present at their inputs without the risk of permanent
damage.
Both channels have fully differential voltage inputs for
better noise performance. The absolute voltage at each
pin relative to AGND should be maintained in the ±1V
range during operation in order to ensure the measurement error performance. The common-mode signals
should be adapted to respect both the previous conditions and the differential input voltage range. For best
performance, the common-mode signals should be
referenced to AGND.
The current channel comprises a PGA on the front-end
to allow for smaller signals to be measured without
additional signal conditioning. The maximum differential voltage specified on Channel 0 is equal to ±470 mV/
Gain (see Table 4-1). The maximum peak voltage
specified on Channel 1 is equal to ±660 mV.
TABLE 4-1:
GAIN SELECTIONS
G1
G0
CH0 Gain
Maximum
CH0 Voltage
0
0
1
1
0
1
0
1
1
2
8
16
±470 mV
±235 mV
±60 mV
±30 mV
4.3
16-Bit Delta-Sigma A/D Converters
The ADCs used in the MCP3909 for both current and
voltage channel measurements are delta-sigma ADCs.
They comprise a second-order, delta-sigma modulator
using a multi-bit DAC and a third-order SINC filter. The
delta-sigma architecture is very appropriate for the
applications targeted by the MCP3909 because it is a
waveform-oriented converter architecture that can offer
both high linearity and low distortion performance
throughout a wide input dynamic range. It also creates
minimal requirements for the anti-aliasing filter design.
The multi-bit architecture used in the ADC minimizes
quantization noise at the output of the converters
without disturbing the linearity.
 2006-2012 Microchip Technology Inc.
Each ADC has a 16-bit resolution, allowing wide input
dynamic range sensing. The oversampling ratio of both
converters is 64. Both converters are continuously converting during normal operation. When the MCLR pin is
low, both converters will be in Reset and output code
0x0000h. If the voltage at the inputs of the ADC is
larger than the specified range, the linearity is no longer
specified. However, the converters will continue to produce output codes until their saturation point is
reached. The DC saturation point is around 700 mV for
Channel 0 and 1V for Channel 1, using internal voltage
reference. The output code will be locked past the saturation point to the maximum output code.
The clocking signals for the ADCs are equally distributed between the two channels in order to minimize
phase delays to less than 1 MCLK period (see
Section 3.2 “High-Pass Filter Input Logic Pin
(HPF)”). The SINC filters main notch is positioned at
MCLK/256 (14 kHz with MCLK = 3.58 MHz), allowing
the user to be able to measure wide harmonic content
on either channel. The data ready signals used for synchronization of the part with a MCU will come at a rate
of MCLK/256 and a pipeline delay of 3 data readys is
required to settle the SINC 3rd order digital filter. The
magnitude response of the SINC filter is shown in
Figure 4-2.
Normal Mode Rejection (dB)
4.2
0
-20
-40
-60
-80
-100
-120
0
5
10
15
20
25
30
Frequency (kHz)
FIGURE 4-2:
SINC Filter Magnitude
Response (MCLK = 3.58 MHz).
DS22025C-page 19
MCP3909
Ultra-Low Drift VREF
The MCP3909 contains an internal voltage reference
source specially designed to minimize drift over temperature. This internal VREF supplies reference voltage
to both current and voltage channels ADCs. The typical
value of this voltage reference is 2.4V ±100 mV. The
internal reference has a very low typical temperature
coefficient of ±15 ppm/°C, allowing the output frequencies to have minimal variation with respect to temperature since they are proportional to (1/VREF)².
The output pin for the voltage reference is REFIN/OUT.
Appropriate bypass capacitors must be connected to
the
REFIN/OUT
pin
for
proper
operation
(see Section 6.0 “Applications Information”). The
voltage reference source impedance is typically 4 kΩ
which enables this voltage reference to be overdriven
by an external voltage reference source.
If an external voltage reference source is connected to
the REFIN/OUT pin, the external voltage will be used
as the reference for both current and voltage channel
ADCs. The voltage across the source resistor will then
be the difference between the internal and external
voltage. The allowed input range for the external voltage source goes from 2.2V to 2.6V for accurate measurement error. A VREF value outside of this range will
cause additional heating and power consumption due
to the source resistor, which might affect measurement
error.
4.5
Power-On Reset (POR)
The MCP3909 contains an internal POR circuit that
monitors analog supply voltage AVDD during operation.
This circuit ensures correct device startup at system
power-up and system power-down events. The POR
circuit has built-in hysteresis and a timer to give a high
degree of immunity to potential ripple and noise on the
power supplies, allowing proper settling of the power
supply during power-up. A 0.1 µF decoupling capacitor
should be mounted as close as possible to the
AVDD pin, providing additional transient immunity
(see Section 6.0 “Applications Information”).
The threshold voltage is typically set at 4V, with a tolerance of about ±5%. If the supply voltage falls below this
threshold, the MCP3909 will be held in a Reset condition (equivalent to applying logic ‘0’ on the MCLR pin).
The typical hysteresis value is approximately 200 mV
in order to prevent glitches on the power supply.
Once a power-up event has occurred, an internal timer
prevents the part from outputting any pulse for approximately 1s (with MCLK = 3.58 MHz), thereby preventing potential metastability due to intermittent resets
caused by an unsettled regulated power supply.
Figure 4-3 illustrates the different conditions for a
power-up and a power-down event in the typical
conditions.
DS22025C-page 20
AVDD
5V
4.2V
4V
1s
0V
DEVICE
MODE
RESET
NO
PULSE
OUT
FIGURE 4-3:
4.6
Time
PROPER
OPERATION
RESET
Power-On Reset Operation.
High-Pass Filters and Multiplier
The active real-power value is extracted from the DC
instantaneous power. Therefore, any DC offset component present on Channel 0 and Channel 1 affects the
DC component of the instantaneous power and will
cause the real-power calculation to be erroneous. In
order to remove DC offset components from the instantaneous power signal, a high-pass filter has been introduced on each channel. Since the high-pass filtering
introduces phase delay, identical high-pass filters are
implemented on both channels. The filters are clocked
by the same digital signal, ensuring a phase difference
between the two channels of less than one MCLK
period. Under typical conditions (MCLK = 3.58 MHz),
this phase difference is less than 0.005°, with a line frequency of 50 Hz. The cut-off frequency of the filter
(4.45 Hz) has been chosen to induce minimal gain
error at typical line frequencies, allowing sufficient settling time for the desired applications. The two highpass filters can be disabled by applying logic ‘0’ to the
HPF pin.
Normal Mode Rejection (dB)
4.4
0
-5
-10
-15
-20
-25
-30
-35
-40
0.1
1
10
100
1000
Frequency (Hz)
FIGURE 4-4:
HPF Magnitude Response
(MCLK = 3.58 MHz).
 2006-2012 Microchip Technology Inc.
MCP3909
The multiplier output gives the product of the two
high-pass filtered channels, corresponding to instantaneous real power. Multiplying two sine wave signals by
the same ω frequency gives a DC component and a 2ω
component. The instantaneous power signal contains
the real power of its DC component, while also containing 2ω components coming from the line frequency
multiplication. These 2ω components come for the line
frequency (and its harmonics) and must be removed in
order to extract the real-power information. This is
accomplished using the low-pass filter and DTF
converter.
4.7
Active Power Low-Pass Filter and
DTF Converter
For the active power signal calculation, the MCP3909
uses a digital low-pass filter. This low-pass filter is a
first-order IIR filter, which is used to extract the active
real-power information (DC component) from the
instantaneous power signal. The magnitude response
of this filter is detailed in Figure 4-5. Due to the fact that
the instantaneous power signal has harmonic content
(coming from the 2 components of the inputs), and
since the filter is not ideal, there will be some ripple at
the output of the low-pass filter at the harmonics of the
line frequency.
Normal Mode Rejection (dB)
The cut-off frequency of the filter (8.9 Hz) has been
chosen to have sufficient rejection for commonly-used
line frequencies (50 Hz and 60 Hz). With a standard
input clock (MCLK = 3.58 MHz) and a 50 Hz line frequency, the rejection of the 2ω component (100 Hz) will
be more than 20 dB. This equates to a 2ω component
containing 10 times less power than the main DC component (i.e., the average active real power).
The output of the low-pass filter is accumulated in the
digital-to-frequency converter. This accumulation is
compared to a different digital threshold for FOUT0/1
and HFOUT, representing a quantity of real energy measured by the part. Every time the digital threshold on
FOUT0/1 or HFOUT is crossed, the part will output a
pulse (See Section 4.8 “Active Power FOUT0/1 and
HFOUT Output Frequencies”).
The equivalent quantity of real energy required to output a pulse is much larger for the FOUT0/1 outputs than
the HFOUT. This is such that the integration period for
the FOUT0/1 outputs is much larger. This larger integration period acts as another low-pass filter so that the
output ripple due to the 2ω components is minimal.
However, these components are not totally removed,
since realized low-pass filters are never ideal. This will
create a small jitter in the output frequency. Averaging
the output pulses with a counter or a MCU in the application will then remove the small sinusoidal content of
the output frequency and filter out the remaining 2
ripple.
HFOUT is intended to be used for calibration purposes
due to its instantaneous power content. The shorter
integration period of HFOUT demands that the 2ω component be given more attention. Since a sinusoidal signal average is zero, averaging the HFOUT signal in
steady-state conditions will give the proper real energy
value.
0
-5
-10
-15
-20
-25
-30
-35
-40
0.1
1
10
100
1000
Frequency (Hz)
FIGURE 4-5:
LPF1 Magnitude Response
(MCLK = 3.58 MHz).
 2006-2012 Microchip Technology Inc.
DS22025C-page 21
MCP3909
4.8
Active Power FOUT0/1 and HFOUT
Output Frequencies
The thresholds for the accumulated energy are different for FOUT0/1 and HFOUT (i.e., they have different
transfer functions). The FOUT0/1 allowed output frequencies are quite low in order to allow superior integration time (see Section 4.7 “Active Power LowPass Filter and DTF Converter”). The FOUT0/1 output
frequency can be calculated with the following
equation:
EQUATION 4-1:
Where:
FOUT FREQUENCY
OUTPUT EQUATION
8.06  V 0  V1  G  F C
F OUT  Hz  = ---------------------------------------------------------2
 VREF 
V0
=
the RMS differential voltage on
Channel 0
V1
=
the RMS differential voltage on
Channel 1
G
=
the PGA gain on Channel 0 (current
channel)
FC
=
the frequency constant selected
VREF
=
the voltage reference
For a given DC input V, the DC and RMS values are
equivalent. For a given AC input signal with amplitude
of V, the equivalent RMS value is V/ sqrt(2), assuming
purely sinusoidal signals. Note that since the real
power is the product of two RMS inputs, the output frequencies of AC signals are half of the DC inputs ones,
again assuming purely sinusoidal AC signals. The
constant FC depends on the FOUT0 and FOUT1 digital
settings. Table 4-2 shows FOUT0/1 output frequencies
for the different logic settings.
TABLE 4-2:
ACTIVE POWER OUTPUT FREQUENCY CONSTANT FC FOR FOUT0/1 (VREF = 2.4V)
F1
F0
FC (Hz)
FC (Hz)
(MCLK = 3.58 MHz)
FOUT Frequency (Hz)
with Full-Scale
DC Inputs
FOUT Frequency (Hz)
with Full-Scale
AC Inputs
0
0
MCLK/221
1.71
0.74
0.37
0
1
20
MCLK/2
3.41
1.48
0.74
1
0
MCLK/219
6.83
2.96
1.48
1
18
13.66
5.93
2.96
1
MCLK/2
The high-frequency output HFOUT has lower integration times and, thus, higher frequencies. The output frequency value can be calculated with the following
equation:
DS22025C-page 22
 2006-2012 Microchip Technology Inc.
MCP3909
EQUATION 4-2:
ACTIVE POWER HFOUT
FREQUENCY OUTPUT
EQUATION
8.06  V 0  V 1  G  HF C
HF OUT  Hz  = ----------------------------------------------------------------2
 V REF 
Where:
V0
=
the RMS differential voltage on
Channel 0
V1
=
the RMS differential voltage on
Channel 1
G
=
the PGA gain on Channel 0
(current channel)
HFC
=
the frequency constant selected
VREF
=
the voltage reference
The constant HFC depends on the FOUT0 and FOUT1
digital settings with the Table 4-3.
The detailed timings of the output pulses are described
in the Timing Characteristics table (see Section 1.0
“Electrical Characteristics” and Figure 1-1).
TABLE 4-3:
4.8.1
MINIMAL OUTPUT FREQUENCY
FOR NO-LOAD THRESHOLD
The MCP3909 also includes, on each output frequency, a no-load threshold circuit that will eliminate
any creep effects in the meter. The outputs will not
show any pulse if the output frequency falls below the
no-load threshold. This threshold only applies to the
pulse outputs and does not gate any serial data coming
from either the A/D output or the multiplier output. The
minimum output frequency on FOUT0/1 and HFOUT is
equal to 0.0015% of the maximum output frequency
(respectively FC and HFC) for each of the F2, F1 and F0
selections (see Table 4-2 and Table 4-3); except when
F2, F1, F0 = 011. In this last configuration, the no-load
threshold feature is disabled. The selection of FC will
determine the start-up current load. In order to respect
the IEC standards requirements, the meter will have to
be designed to allow start-up currents compatible with
the standards by choosing the FC value matching
these requirements. For additional applications information on no-load threshold, startup current and other
meter design points, refer to AN994, "IEC Compliant
Active Energy Meter Design Using The MCP3905/6”,
(DS00994).
OUTPUT FREQUENCY CONSTANT HFC FOR HFOUT (VREF = 2.4V)
F2
F1
F0
HFC
HFC (Hz)
HFC (Hz)
(MCLK = 3.58 MHz)
HFOUT Frequency (Hz) with
full scale AC Inputs
0
0
0
64 x FC
MCLK/215
109.25
27.21
32 x FC
MCLK/215
109.25
27.21
16 x FC
MCLK/215
109.25
27.21
0
0
0
1
1
0
0
1
1
2048 x FC
MCLK/27
27968.75
6070.12
1
0
0
128 x FC
MCLK/216
219.51
47.42
64 x FC
MCLK/216
219.51
47.42
32 x FC
MCLK/216
219.51
47.42
16 x FC
MCLK/216
219.51
47.42
1
1
1
0
1
1
1
0
1
 2006-2012 Microchip Technology Inc.
DS22025C-page 23
MCP3909
5.0
5.1
SERIAL INTERFACE
DESCRIPTION
DVDD
HPF
AVDD
NC
CH0+
CH0CH1CH1+
Dual Functionality Pin And Serial
Interface Overview
The MCP3909 device contains three serial modes that
are accessible by changing the pin functionality of the
NEG, F2, F1, and F0 pins to SDO, SCK, SDI and CS,
respectively.
These modes are entered by giving the MCP3909
device a serial command on these pins during a time
window after device reset or POR. During this window
of time, F2 acts as SCK, F1 acts as SDI and F0 acts
as CS. Once a serial mode has been entered, the
device must be reset to disable mode functionality, or
change to another serial mode. This is done by using
MCLR pin or power on reset event.
MCLR
REFIN/OUT
AGND
F2/SCK
FIGURE 5-1:
the MCP3909.
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
FOUT0
FOUT1
HFOUT
DGND
NEG/SDO
NC
CLKOUT
CLKIN
G0
G1
F0/CS
F1/SDI
Dual Functionality Pins for
During serial mode entry and the three serial modes,
data is clocked into the device on the rising edge of
SCK and out of the device on the falling edge of SCK.
The SPI data can be access at up to 20 MHz. This
speed enables quick data retrieval in between conversion times. For 3-phase metering applications with
multiple ADCs, this fast communication is essential to
allow for power calculation windows between conversions, as shown in Figure 5-3.
After a serial mode has been entered, all blocks of the
MCP3909 device are still operational. The PGA, A/D
converters, HPF, multiplier, LPF, and other digital sections are still functional, allowing the device to have
true dual functionality in energy metering systems.
IRQ
tSAMPLE
tLINE_CYC
IRQ
Phase A,B,C I & V Data
SDO DR
16 bits
x 6 ADCs
DR
tSAMPLE
FIGURE 5-2:
DS22025C-page 24
Data Access between Data Ready Pulses using SPI Interface for a 3-phase System.
 2006-2012 Microchip Technology Inc.
MCP3909
MCLR
tWINDOW
tWINSET
1
2
3
4
5
6
7
8
F2 / SCK
F0 / CS
F1 / SDI
D7 D6 D5 D4 D3 D2
FIGURE 5-3:
5.2
D1 D0
Dual Functionality Pin Serial Mode Entry Protocol.
Serial Mode Entry Codes
The MCP3909 devices contains three different serial
modes with data presented in 2's complement coding.
• Multiplier Output
• Dual Channel Output
• Filter Input
After entering any of these modes the active power
calculation block is still functional and presents output
pulses on FOUT0, FOUT1, and HFOUT. For this reason,
the F2, F1, F0 output frequency selection constant can
be changed with multiple command bytes for serial
mode entry.
The command bytes to enter these modes are
described in Table 5-1.
TABLE 5-1:
ENTRY CODES
Internal State of F2, F1, F0 Constants Frequency
Selection During Serial Mode (1)
Command
D7......D0
Serial Mode
1 0 1 0 0 0 0 1
Multiplier Output
0
F1 pin
1
1 0 1 0 1 0 0 1
Multiplier Output
1
F1 pin
1
1 0 1 0 0 1 0 0
Dual Channel Output Pre HPF1
0
F1 pin
1
1 0 1 0 1 1 0 0
Dual Channel Output Post HPF1
1
F1 pin
1
1 0 1 0 1 0 1 0
Filter Input
1
0
F0 pin
1 0 1 0 1 1 1 0
Filter Input
1
1
F0 pin
1 0 1 0 0 0 1 0
Filter Input
0
0
F0 pin
1 0 1 0 0 1 1 0
Filter Input
0
1
F0 pin
Note 1:
F2
F1
F0
The active power frequency outputs FOUT0, FOUT1, and HFOUT remain active after serial mode entry. Leaving the SDI (F1) and CS (F0) pins at a known state after serial communication will control the frequency
selection. The HPF pin controls the state of the HPF for the multiplier mode output and the output pulses
from the active power D to F block.
 2006-2012 Microchip Technology Inc.
DS22025C-page 25
MCP3909
5.3
Multiplier Output Mode
Multiplier mode allows the user to retrieve the output
of the multiplier on the MCP3909 device. Data is presented in a 20 bit (19 bit + sign) protocol, MSB first. A
data ready flag (DR) is output for every MCLK/256
clock cycles and a new multiplier output value is ready.
If the multiplier value is not clocked out of the device it
will be over-written. Data is clocked out on the rising
edge of SCK.
EQUATION 5-1:
+
–
+
–
 CH0 – CH0   CH1 – CH1 
Multiplier Code = ----------------------------------------------------------------------------------  524288  8.06  G
VREF 2
TABLE 5-2:
MULTIPLIER OUTPUT MODE CODING
Binary
Decimal
0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
+524287
0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0
+524286
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
-1
1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1
-524287
1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
-524288
F0 / CS
1
2
3
4
X 20
17 18
19 20
F2 / SCK
X 20
NEG / SDO
Hi-z
DR
D19 D18 D17 D16
SIGN MSB
F1 / SDI
FIGURE 5-4:
DS22025C-page 26
D3
Hi-z
D2
D1
0
D0
Hi-z
LSB
Multiplier Output Mode.
 2006-2012 Microchip Technology Inc.
MCP3909
5.4
Dual Channel Output Mode
This mode allows the user to retrieve the individual
channel information from the ADC outputs. The ADC
outputs of both channels are synchronized together
and their data ready is represented by the data ready
pulse on SDO. If the ADC output values are not clocked
out of the device, they will be over-written. A 32-bit data
word is given, each channel is 16 bits (15 bits + sign),
presented in 2's complement coding. Channel 1 comes
first then channel 0.
A data ready flag (DR) is output for every MCLK / 256
clock cycles and a new filter output value is ready. If the
dual channel output values are not clocked, and is not
clocked out of the device, they will be over-written.
The following formulas relate the channel input voltages to their respective output code. The code locks to
+32767 on the positive side, and to -32768 on the
negative side.
EQUATION 5-2:
  VIN+ – V IN- 
0.66
Channel 0 Code =  ------------------------------------  32768   8.06  -----------  PGA

V
0.47


REF
V
–V 
IN+
IN0.47
Channel 1 Code = ------------------------------------  32768   8.06  -----------

V
0.66
REF
TABLE 5-3:
CHANNEL OUTPUT MODE
CODING
Binary
0
0
0
1
1
1
111
111
000
111
000
000
5.5
1111
1111
0000
1111
0000
0000
1111
1111
0000
1111
0000
0000
Decimal
1111
1110
0000
1111
0001
0000
+ 32,767
+ 32,766
0
-1
- 32,767
- 32,768
High-Pass Filter Control
There are two options for the channel output data. The
first options collects the channel data pre-high pass
filter, or the output of the SINC filter of the delta sigma
modulator. The second option collects the channel data
post high pass filter. It is important to note that the
HPF pin controls the state of the high pass filter for this
second option. If the HPF pin is low, the post high pass
filter mode will output all zero's. This HPF pin must be
high to access the post HPF data in the channel output
mode.
 2006-2012 Microchip Technology Inc.
DS22025C-page 27
MCP3909
F0 / CS
1
2
X 32
X 16
15 16
X 16
17 18 31 32
F2 / SCK
X 16
NEG / SDO
Hi-z
DR
D15 D14 D1
D31 D30 D17 D16
Hi-z
Hi-z
F1 / SDI
5.6
D0
Channel 0
Channel 1
FIGURE 5-5:
X 16
X 32
Dual Channel Output Mode.
Filter Input Mode
The filter input mode allows the user to feed the
MCP3909 device an input to the LPF1. Data is
received MSB first. The MCP3909 will treat this data
as if it were the output of the multiplier and will LPF
and D-F the result as normal, giving the resulting output frequency on HFOUT, FOUT0 and FOUT1. See
Tables 4-2 and 4-3 for transfer functions of the output
frequencies.
When using filter input mode, the user must wait for
the data ready flag (DR) to appear on SDO before
attempting to clock in data to the device. The user can
not access either the multiplier output or the dual
channel output while in this mode.
F0 / CS
X 20
1
2
3
4
17 18
19 20
D3
D1
F2 / SCK
X 20
F1 / SDI
NEG / SDO
FIGURE 5-6:
DS22025C-page 28
D19
Hi-z
D18 D17 D16
D2
D0
Hi-z
DR
Filter Input Mode.
 2006-2012 Microchip Technology Inc.
MCP3909
5.7
Using the MCP3909 with
Microcontroller (MCU) SPI Ports
With microcontroller SPI ports, it is required to send
groups of eight bits. It is also required that the microcontroller SPI port be configured to clock out data on
the falling edge of clock and latch data in on the rising
edge, or vice versa depending on the mode.
5.7.1
SPI MODE DEFINITIONS
The following table represents the standard SPI mode
terminology, the respective PIC bit settings, and a
description of compatibility for the MCP3909 device.
The MCP3909 works in SPI mode 0,1 mode, that is the
data is clocked out of the part on the rising edge and
clocked in on the falling edge of SCK.
TABLE 5-4:
Standard SPI
Mode
Terminology
SPI MODE COMPATIBILITY
PIC Control Bits
State
MCP3909
Compatibility
Description
CKP
CKE
0,0
0
1
—
Idle state for clock is low level, transmit (from PIC)
occurs from active to idle clock state
0,1
0
0
√
Idle state for clock is low level, transmit (from PIC)
occurs from idle to active clock state
1,0
1
1
—
Idle state for clock is high level, transmit (from PIC)
occurs from active to idle clock state
1,1
1
0
—
Idle state for clock is high level, transmit (from PIC)
occurs from idle to active clock state
 2006-2012 Microchip Technology Inc.
DS22025C-page 29
MCP3909
F0 / CS
MCU latches data from
Device on falling edges of SCK
F2 / SCK
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Data is clocked out
on rising edges of SCK
F1 / SDI
Don’t Care
NEG / SDO
D19 D18 D17 D16 D15 D14 D13
MCU Transmit Buffer
MCU Receive Buffer
X
X
X
X
X
X
X
D11 D10 D9 D8 D7 D6 D5 D4
D12
X
X
X
X
X
X
X
X
X
D19 D18 D17 D16 D15 D14 D13 D12
D11 D10 D9 D8 D7 D6 D5 D4
Data is stored into the MCU
receive register after transmission
of the first 8 bits
Data is stored into the MCU
receive register after transmission
of the second 8 bits
F0 / CS
F2 / SCK
17
18
F1 / SDI
19
20
21
22
23
24
Don’t Care
D3 D2 D1 D0
NEG / SDO
MCU Transmit Buffer
X
MCU Receive Buffer
D3 D2 D1 D0
X
X
X
X
X
X
X
0
0
0
0
X = Don’t Care Bits
Data is stored into the MCU
receive register after transmission
of the third 8 bits
FIGURE 5-7:
SCK idles low).
DS22025C-page 30
N = Null Bits
Multiplier Output Mode 1 SPI Communication using 8-bit segments (Mode 0,1:
 2006-2012 Microchip Technology Inc.
MCP3909
F0 / CS
MCU latches data from
Device on falling edges of SCK
1
F2 / SCK
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Data is clocked out
on rising edges
F1 / SDI
Don’t Care
CHANNEL 0
NEG / SDO
D15 D14 D13 D12 D11 D10 D9 D8
MCU Transmit Buffer
X
MCU Receive Buffer
X
X
X
X
X
X
D6 D5 D4 D3 D2 D1 D0
D7
X
X
X
X
X
X
X
X
X
D15 D14 D13 D12 D11 D10 D9 D8
D7 D6 D5 D4 D3 D2 D1 D0
CH0 Data is stored into the MCU
receive register after transmission
of the first 8 bits
CH0 Data is stored into the MCU
receive register after transmission
of the second 8 bits
F0 / CS
MCU latches data from
Device on falling edges of SCK
F2 / SCK
17
18
20
19
21
22
23
24
25
26
27
28
29
30
31
32
Data is clocked out
on rising edges
F1 / SDI
Don’t Care
CHANNEL 1
NEG / SDO
MCU Transmit Buffer
MCU Receive Buffer
D15 D14 D13 D12 D11 D10 D9 D8
X
X
X
X
X
X
X
X
D15 D14 D13 D12 D11 D10 D9 D8
CH1 Data is stored into the MCU
receive register after transmission
of the third 8 bits
D7
X
D6 D5 D4 D3 D2 D1 D0
X
X
X
X
X
X
X
D7 D6 D5 D4 D3 D2 D1 D0
CH1 Data is stored into the MCU
receive register after transmission
of the fourth 8 bits
FIGURE 5-8:
Dual Channel Output Mode SPI Communication using 8-bit segments
(Mode 0,1: SCK idles low).
 2006-2012 Microchip Technology Inc.
DS22025C-page 31
MCP3909
6.0
APPLICATIONS INFORMATION
The following application figures represent meter
designs using the MCP3909 device. Some of these
applications ideas are available as fully function meter
reference designs and demo boards. For complete
schematic and for fully function meter designs, visit
Microchip’s web page for demo board and reference
design availability.
6.1
Performing RMS, Apparent Power,
and Active Power using MCP3909
Waveform Data
Output registers for the power quantities and calibration registers for phase, offset, gain, and LSB adjustment are available through a serial interface to the PIC
microcontroller. See Microchip’s web page for firmware
solution and demo board.
The example signal flow here shows 4 output power
quantities and 6 calibration registers. For a 60 Hz
design that is using 128 samples per line cycle for the
power calculation the MCP3909 would have a new
data ready pulse every 130 µs. The SPI communication to gather 16-bits x 2 channels at 10 MHz is approximately 3.2 µs, leaving ~125 µs for the power
calculations before the next sample is ready.
Figure 6-1 represents power calculations from waveform data based on a PIC MCU and MCP3909 device.
The PIC MCU accomplishes the following energy
meter calculation outputs per phase, per line cycle:
-
RMS Current
RMS Voltage
Active Power
Apparent Power
.
MCP3909
PIC Microcontroller
RMS Current
ADC
CURRENT
X
S
X2
PHA_I_RMS_OFF:16
X
S
X
X
Apparent Power
PHA_VA_GAIN:16
Active Power
VOLTAGE
ADC
PHA_DELAY:8 PHA_W_GAIN:16
PHA_W_OFF:32
PHA_V_RMS_OFF:16
F
X2
S
RMS Voltage
FIGURE 6-1:
Power Calculations from Waveform Sampling Using a PIC MCU. Register names
shown are used on MCP3909 Energy Meter Reference Design.
DS22025C-page 32
 2006-2012 Microchip Technology Inc.
MCP3909
6.2
Achieving Line Cycle Sampling
with Zero Blind Cycles
A simpler lower cost option would be to choose a frequency that would give an integer number of line cycles
for exactly 50 Hz (or 60 Hz). This is possible using a
39.3216 MHz crystal for the PIC18F device.
In most energy meter applications, it will be necessary
to have 2N samples for each 50 or 60 Hz line cycle,
where N is typically 64, 128 or 256. Controlling the
MCLK of the MCP3909 allows you to control the sample rate and ultimately the data ready (DR) pulses for
coherent waveform sampling.
Figure 6-2 shows example clock frequencies to
achieve 128 samples for each line cycle, 1.63 MHz for
a 50 Hz line, or 1.96 MHz for a 60 Hz line. The
MCP3909 clock can operate from 1 MHz to 4 MHz.
Using this approach, the PIC MCU can gather the
waveform data immediately after the data ready pulse,
at up to 10 MHz. The remainder of the time can be used
to calculate the power measurements to achieve true
line cycle sampling with zero blind cycles.
The following scheme shows how the TIMER and
COMPARATOR modules of the PIC MCU can be used
to generate the clock for the MCP3909 from either a
PLL internal MCLK. For class 0.2 or class 0.1 meter
designs that require harmonic analysis using a PLL is
recommended to shift sample rate with line cycle drift,
e.g. line cycle changes from 60 Hz to 59.1 Hz. This is
shown as option 1 in Figure 6-2.
For more information and firmware, see the Microchip
web page for demo board information.
128 samples/line cycle
X1
Phase A || B || C
50 (or 60 Hz)
39.3216 MHz
(50 or 60 Hz)
1.63 MHz (50)
PLL Circuit
x 32768
1.96 MHz (60)
3.579 MHz
PIC MCU
CCP2 / 32768
Option 1
Option 2
MCLK input
SDO
SDO
IRQ
To PIC MCU
IRQ
MCP3909
SDO
MCP3909
MCP3909
DR Pulse
tSAMPLE
tLINE_CYC
IRQ
Phase A,B,C I & V Data
SDO DR
16 bits
x 6 ADCs
DR
tSAMPLE
FIGURE 6-2:
Using the PIC device to control the MCP3909 MCLK to achieve 2N samples per line
cycle, 3-phase sampling shown with 6 ADCs.
 2006-2012 Microchip Technology Inc.
DS22025C-page 33
MCP3909
N
L
PHA_W:16
ENERGY_W:64
ENERGY_VA_GLSB:16
PHA_I_RMS:16
PHA_V_RMS:16
kW
kWhr
kVAhr
A
V
CH1+
CH1-
MCP3909
AGND,DGND
SCK
SDI
SDO
CS
Power Supply
Circuitry
RC3/SCK
RC5/SDO
RC4/SDI
RA0/ANO
...
RB7
RC1/CCP2
OSC1
40 MHZ
Resistor Divider
AVDD,DVDD CLKIN
PIC MCU
CH0+
CH0-
RB0
LCD
OSC2
RX/RC6
TX/RC7
GND
FIGURE 6-3:
6.3
RS-232
To PC or
Calibration
Equipment
Simplified MCU Based Energy Meter.
Meter Calibration
To achieve meter calibration the MCP3909 waveform
samples are adjusted during the power calculations on
the PIC MCU. In Figure 6-3, this interface is shown via
RS-232 on the PIC microcontroller. This process is
streamlined using calibration software available from
the Microchip’s web site.
6.4
Analog Meter Design Tips
For analog design tips and PCB layout recommendations, refer to AN994, "IEC Compliant Active Energy
Meter Design Using The MCP390X” (DS00994). This
application note includes all required energy meter
design information, including the following:
•
•
•
•
•
•
•
•
•
•
•
•
Meter rating and current sense choices
Shunt design
PGA selection
F2, F1, F0 selection
Meter calibration
Anti-aliasing filter design
Compensation for parasitic shunt inductance
EMC design
Power supply design
No-Load threshold
Start-up current
Accuracy testing results from MCP390X-based
meter
• EMC testing results from MCP390X-based meter
DS22025C-page 34
 2006-2012 Microchip Technology Inc.
MCP3909
7.0
PACKAGING INFORMATION
7.1
Package Marking Information
24-Lead SSOP
Examples:
XXXXXXXXXXXX
XXXXXXXXXXXX
YYWWNNN
MCP3909
e3
I/SS^^
1140256
MCP3909
e3
E/SS^^
1140256
Legend: XX...X
Y
YY
WW
NNN
e3
*
Note:
Customer-specific information
Year code (last digit of calendar year)
Year code (last 2 digits of calendar year)
Week code (week of January 1 is week ‘01’)
Alphanumeric traceability code
Pb-free JEDEC designator for Matte Tin (Sn)
This package is Pb-free. The Pb-free JEDEC designator ( e3 )
can be found on the outer packaging for this package.
In the event the full Microchip part number cannot be marked on one line, it will
be carried over to the next line, thus limiting the number of available
characters for customer-specific information.
 2006-2012 Microchip Technology Inc.
DS22025C-page 35
MCP3909
/HDG3ODVWLF6KULQN6PDOO2XWOLQH66±PP%RG\>6623@
1RWH
)RUWKHPRVWFXUUHQWSDFNDJHGUDZLQJVSOHDVHVHHWKH0LFURFKLS3DFNDJLQJ6SHFLILFDWLRQORFDWHGDW
KWWSZZZPLFURFKLSFRPSDFNDJLQJ
D
N
E
E1
1 2
NOTE 1
b
e
c
φ
A2
A
A1
L
L1
8QLWV
'LPHQVLRQ/LPLWV
1XPEHURI3LQV
0,//,0(7(56
0,1
1
120
0$;
3LWFK
H
2YHUDOO+HLJKW
$
±
%6&
±
0ROGHG3DFNDJH7KLFNQHVV
$
6WDQGRII
$
±
±
2YHUDOO:LGWK
(
0ROGHG3DFNDJH:LGWK
(
2YHUDOO/HQJWK
'
)RRW/HQJWK
/
)RRWSULQW
/
5()
/HDG7KLFNQHVV
F
±
)RRW$QJOH
ƒ
ƒ
ƒ
/HDG:LGWK
E
±
1RWHV
3LQYLVXDOLQGH[IHDWXUHPD\YDU\EXWPXVWEHORFDWHGZLWKLQWKHKDWFKHGDUHD
'LPHQVLRQV'DQG(GRQRWLQFOXGHPROGIODVKRUSURWUXVLRQV0ROGIODVKRUSURWUXVLRQVVKDOOQRWH[FHHGPPSHUVLGH
'LPHQVLRQLQJDQGWROHUDQFLQJSHU$60(<0
%6& %DVLF'LPHQVLRQ7KHRUHWLFDOO\H[DFWYDOXHVKRZQZLWKRXWWROHUDQFHV
5() 5HIHUHQFH'LPHQVLRQXVXDOO\ZLWKRXWWROHUDQFHIRULQIRUPDWLRQSXUSRVHVRQO\
0LFURFKLS 7HFKQRORJ\ 'UDZLQJ &%
DS22025C-page 36
 2006-2012 Microchip Technology Inc.
MCP3909
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
 2006-2012 Microchip Technology Inc.
DS22025C-page 37
MCP3909
NOTES:
DS22025C-page 38
 2006-2012 Microchip Technology Inc.
MCP3909
APPENDIX A:
REVISION HISTORY
Revision C (March 2012)
The following is the list of modifications:
1.
2.
3.
4.
Added the extended temperature option to the
features list.
Updated Section 2.0 “Typical Performance
Curves” with new extended temperature
graphs.
Added the package markings information for the
extended temperature option.
Updated the Product Identification System
page.
Revision B (April 2009)
Updated EDS information and Timing Characteristics
in Section 1.0 “Electrical Characteristics”.
Revision A (December 2006)
Original release of this document.
 2006-2012 Microchip Technology Inc.
DS22025C-page 39
MCP3909
NOTES:
DS22025C-page 40
 2006-2012 Microchip Technology Inc.
MCP3909
PRODUCT IDENTIFICATION SYSTEM
To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.
PART NO.
-X
/XX
Device
Temperature
Range
Package
Device:
a)
MCP3909-I/SS:
b)
Industrial Temperature,
24LD SSOP.
MCP3909T-I/SS: Tape and Reel,
Industrial Temperature,
24LD SSOP.
c)
MCP3909-E/SS:
d)
Extended Temperature,
24LD SSOP.
MCP3909T-E/SS: Tape and Reel,
= -40°C to +85°C
= -40°C to +125°C
SS = Plastic Shrink Small Outline (209 mil Body),
24-lead
 2006-2012 Microchip Technology Inc.
Energy Metering IC
Energy Metering IC
MCP3909: Energy Metering IC
MCP3909T: Energy Metering IC
(Tape and Reel)
Temperature Range: I
E
Package:
Examples:
Energy Metering IC
Energy Metering IC
Extended Temperature,
24LD SSOP.
DS22025C-page 41
MCP3909
NOTES:
DS22025C-page 42
 2006-2012 Microchip Technology Inc.
Note the following details of the code protection feature on Microchip devices:
•
Microchip products meet the specification contained in their particular Microchip Data Sheet.
•
Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the
intended manner and under normal conditions.
•
There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.
•
Microchip is willing to work with the customer who is concerned about the integrity of their code.
•
Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not
mean that we are guaranteeing the product as “unbreakable.”
Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.
Information contained in this publication regarding device
applications and the like is provided only for your convenience
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
MICROCHIP MAKES NO REPRESENTATIONS OR
WARRANTIES OF ANY KIND WHETHER EXPRESS OR
IMPLIED, WRITTEN OR ORAL, STATUTORY OR
OTHERWISE, RELATED TO THE INFORMATION,
INCLUDING BUT NOT LIMITED TO ITS CONDITION,
QUALITY, PERFORMANCE, MERCHANTABILITY OR
FITNESS FOR PURPOSE. Microchip disclaims all liability
arising from this information and its use. Use of Microchip
devices in life support and/or safety applications is entirely at
the buyer’s risk, and the buyer agrees to defend, indemnify and
hold harmless Microchip from any and all damages, claims,
suits, or expenses resulting from such use. No licenses are
conveyed, implicitly or otherwise, under any Microchip
intellectual property rights.
Trademarks
The Microchip name and logo, the Microchip logo, dsPIC,
KEELOQ, KEELOQ logo, MPLAB, PIC, PICmicro, PICSTART,
PIC32 logo, rfPIC and UNI/O are registered trademarks of
Microchip Technology Incorporated in the U.S.A. and other
countries.
FilterLab, Hampshire, HI-TECH C, Linear Active Thermistor,
MXDEV, MXLAB, SEEVAL and The Embedded Control
Solutions Company are registered trademarks of Microchip
Technology Incorporated in the U.S.A.
Analog-for-the-Digital Age, Application Maestro, chipKIT,
chipKIT logo, CodeGuard, dsPICDEM, dsPICDEM.net,
dsPICworks, dsSPEAK, ECAN, ECONOMONITOR,
FanSense, HI-TIDE, In-Circuit Serial Programming, ICSP,
Mindi, MiWi, MPASM, MPLAB Certified logo, MPLIB,
MPLINK, mTouch, Omniscient Code Generation, PICC,
PICC-18, PICDEM, PICDEM.net, PICkit, PICtail, REAL ICE,
rfLAB, Select Mode, Total Endurance, TSHARC,
UniWinDriver, WiperLock and ZENA are trademarks of
Microchip Technology Incorporated in the U.S.A. and other
countries.
SQTP is a service mark of Microchip Technology Incorporated
in the U.S.A.
All other trademarks mentioned herein are property of their
respective companies.
© 2006-2012, Microchip Technology Incorporated, Printed in
the U.S.A., All Rights Reserved.
Printed on recycled paper.
ISBN: 978-162076-064-2
QUALITY MANAGEMENT SYSTEM
CERTIFIED BY DNV
== ISO/TS 16949 ==
 2006-2012 Microchip Technology Inc.
Microchip received ISO/TS-16949:2009 certification for its worldwide
headquarters, design and wafer fabrication facilities in Chandler and
Tempe, Arizona; Gresham, Oregon and design centers in California
and India. The Company’s quality system processes and procedures
are for its PIC® MCUs and dsPIC® DSCs, KEELOQ® code hopping
devices, Serial EEPROMs, microperipherals, nonvolatile memory and
analog products. In addition, Microchip’s quality system for the design
and manufacture of development systems is ISO 9001:2000 certified.
DS22025C-page 43
Worldwide Sales and Service
AMERICAS
ASIA/PACIFIC
ASIA/PACIFIC
EUROPE
Corporate Office
2355 West Chandler Blvd.
Chandler, AZ 85224-6199
Tel: 480-792-7200
Fax: 480-792-7277
Technical Support:
http://www.microchip.com/
support
Web Address:
www.microchip.com
Asia Pacific Office
Suites 3707-14, 37th Floor
Tower 6, The Gateway
Harbour City, Kowloon
Hong Kong
Tel: 852-2401-1200
Fax: 852-2401-3431
India - Bangalore
Tel: 91-80-3090-4444
Fax: 91-80-3090-4123
India - New Delhi
Tel: 91-11-4160-8631
Fax: 91-11-4160-8632
Austria - Wels
Tel: 43-7242-2244-39
Fax: 43-7242-2244-393
Denmark - Copenhagen
Tel: 45-4450-2828
Fax: 45-4485-2829
India - Pune
Tel: 91-20-2566-1512
Fax: 91-20-2566-1513
France - Paris
Tel: 33-1-69-53-63-20
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Tel: 81-66-152-7160
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Mississauga, Ontario,
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Tel: 905-673-0699
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Tel: 61-2-9868-6733
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Tel: 86-10-8569-7000
Fax: 86-10-8528-2104
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Tel: 86-28-8665-5511
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Tel: 86-23-8980-9588
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Netherlands - Drunen
Tel: 31-416-690399
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Tel: 82-53-744-4301
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Tel: 82-2-554-7200
Fax: 82-2-558-5932 or
82-2-558-5934
China - Hong Kong SAR
Tel: 852-2401-1200
Fax: 852-2401-3431
Malaysia - Kuala Lumpur
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Fax: 86-25-8473-2470
Malaysia - Penang
Tel: 60-4-227-8870
Fax: 60-4-227-4068
China - Qingdao
Tel: 86-532-8502-7355
Fax: 86-532-8502-7205
Philippines - Manila
Tel: 63-2-634-9065
Fax: 63-2-634-9069
China - Shanghai
Tel: 86-21-5407-5533
Fax: 86-21-5407-5066
Singapore
Tel: 65-6334-8870
Fax: 65-6334-8850
China - Shenyang
Tel: 86-24-2334-2829
Fax: 86-24-2334-2393
Taiwan - Hsin Chu
Tel: 886-3-5778-366
Fax: 886-3-5770-955
China - Shenzhen
Tel: 86-755-8203-2660
Fax: 86-755-8203-1760
Taiwan - Kaohsiung
Tel: 886-7-536-4818
Fax: 886-7-330-9305
China - Wuhan
Tel: 86-27-5980-5300
Fax: 86-27-5980-5118
Taiwan - Taipei
Tel: 886-2-2500-6610
Fax: 886-2-2508-0102
China - Xian
Tel: 86-29-8833-7252
Fax: 86-29-8833-7256
Thailand - Bangkok
Tel: 66-2-694-1351
Fax: 66-2-694-1350
UK - Wokingham
Tel: 44-118-921-5869
Fax: 44-118-921-5820
China - Xiamen
Tel: 86-592-2388138
Fax: 86-592-2388130
China - Zhuhai
Tel: 86-756-3210040
Fax: 86-756-3210049
DS22025C-page 44
Italy - Milan
Tel: 39-0331-742611
Fax: 39-0331-466781
Japan - Yokohama
Tel: 81-45-471- 6166
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11/29/11
 2006-2012 Microchip Technology Inc.
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