MCP3909-I/SS Microchip Technology, MCP3909-I/SS Datasheet - Page 23

• 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

© 2009 Microchip Technology Inc.
2.4.1
The UART and SPI1 interfaces are multiplexed. Through the UART or SPI1 interface,
the host MCU can communicate with the metering front-end to perform calibration or
obtain metering results. The SPI interface may also be used if high-speed data transfer
is desired. In this case, the SPI interface of the dsPIC device works in the slave mode.
The UART and SPI1 share a common pin, so only one of the two interfaces can be
used at a time. Since the reference design uses a PC to simulate the host MCU, the
UART interface is chosen as the communication interface. SPI and RS232 interfaces
are not isolated from the PC. A general-purpose transceiver device, MAX232, is used
for the UART interface.
2.4.2
Three sets of outputs for energy measurement pulses are available in this design,
corresponding to the I/O pins of RD1-RD3. Two of them, output total active energy and
total reactive energy, respectively, and the other is not yet specified. Outputs are
isolated by a photo-electronic coupling device, U
active when corresponding I/O pin is high.
In addition, the design also provides two sets of LED outputs for energy meter calibra-
tion. The output pins for these LEDs are RC13 and RC14. The LED is on when the
output is low. Figure 2-4 is the circuit of energy pulse output interface.
FIGURE 2-4:
Energy Pulse Output Interface
RD3
RD1
UART and SPI1 Interface
RD2
RC13
RC14
Energy Output Pulse Configuration.
1 kΩ
R
1 kΩ
R
1 kΩ
R
301
301
301
R
470Ω
R
470Ω
314
310
Hardware Description
3.3V
3.3V
3
. The photo-electronic coupler is
D303
D302
Total Reactive
(not used)
Total Active
Total Reactive
Total Active
DS51723A-page 23