MCP3909-I/SS Microchip Technology, MCP3909-I/SS Datasheet - Page 34

• 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

MCP3909 / dsPIC33F 3-Phase Energy Meter Reference Design
DS51723A-page 34
The energy pulse processing program only begins when the level is close to outputting
pulse level. To simplify the process and shorten the ISR execution time, a counter is
used in place of the energy accumulation function for each pulse and to determine if a
pulse will be outputted. When the count is greater than the threshold of pulse output,
an energy pulse will be outputted, and the appropriate amount of energy will be sub-
tracted from the energy accumulating register. Output toggling will then be processed.
Once the width of the output pulse exceeds 80 ms, the pulse output will be turned off.
The program flow chart is shown in Figure 3-4.
FIGURE 3-4:
IC1 Interrupt Service Routine.
ICI Interrupt Service
Call MCP3909 data
reactive energy?
falling edge of
active energy?
active energy?
active energy?
rising edge of
falling edge of
rising edge of
read program
Processing
Processing
Processing
Processing
routine
Return
No
No
No
No
Yes
Yes
Yes
Yes
Update pulse width
counter, if pulse
width > 80 ms, toggle
pulse output level.
End pulse output
process.
Update pulse width
counter, if counter >
flip threshold, output
pulse and update
energy accumulation
register.
Update pulse width
counter, if pulse
width > 80 ms, toggle
pulse output level.
End pulse output
process.
Update pulse width
counter, if counter >
flip threshold, output
pulse and update
energy accumulation
register.
© 2009 Microchip Technology Inc.