DSPIC33FJ128GP706A-I/MR Microchip Technology, DSPIC33FJ128GP706A-I/MR Datasheet - Page 19

• Manufacturer Part Number: DSPIC33FJ128GP706A-I/MR
• Description: IC DSPIC MCU/DSP 128K 64-QFN
• Manufacturer: Microchip Technology
• Series: dsPIC™ 33Fr

Specifications of DSPIC33FJ128GP706A-I/MR

• Core Processor: dsPIC
• Core Size: 16-Bit
• Speed: 40 MIPs
• Connectivity: CAN, I²C, IrDA, LIN, SPI, UART/USART
• Peripherals: AC'97, Brown-out Detect/Reset, DMA, I²S, POR, PWM, WDT
• Number Of I /o: 53
• Program Memory Size: 128KB (128K x 8)
• Program Memory Type: FLASH
• Ram Size: 16K x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 3.6 V
• Data Converters: A/D 18x10b/12b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-VFQFN, Exposed Pad
• Product: DSCs
• Processor Series: DSPIC33F
• Core: dsPIC
• 3rd Party Development Tools: 52713-733, 52714-737, 53276-922, EWDSPIC
• Development Tools By Supplier: PG164130, DV164035, DV244005, DV164005, PG164120, DM240001, DV164033
• Core Frequency: 40MHz
• Core Supply Voltage: 3.3V
• Embedded Interface Type: I2C, SPI, UART
• No. Of I/o's: 53
• Flash Memory Size: 128KB
• Supply Voltage Range: 3V To 3.6V
• Rohs Compliant: No
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

© 2009 Microchip Technology Inc.
2.2.1
The high precision class 0.2S requirement for the energy meter makes it crucial to
select proper burden resistors for the output of the current transformers.
Metal film resistors with low inherent noise and temperature coefficient are ideal. Given
that the secondary current of the CT is I, then the input voltage of the MCP3909 device
is U = IR, where R is the resistance of R
If the temperature varies by ΔT, and the temperature coefficient of sampling resistor R
is β ppm/°C, then the output voltage is:
EQUATION 2-1:
The voltage variation is:
EQUATION 2-2:
This relationship shows that the output voltage variation caused by temperature
variation is in proportion to the temperature coefficient of the burden resistor.
In addition, a smaller temperature coefficient benefits meter start stabilization after
startup. It takes a longer time for resistors with larger temperature coefficient to
stabilize. Therefore, accurate measurements would require a longer wait after
power-up. This affects the efficiency, or speed of meter calibration.
Burden Resistor Temperature Coefficient
ΔU
=
U' U
–
U'
=
=
I
×
I R
(
ΔT β
125
+
×
Δ
and R
Hardware Description
T
×
×
R
β
126
×
=
R
U
)
(Using Phase A as an example).
×
ΔT
×
β
DS51723A-page 19