71M6545 Datasheet, PDF (79/134 Pages) Maxim Integrated Products – Four-Quadrant Metering, Phase Metrology Processors Flash/RAM Size

PDS_6545_009
Data Sheet 71M6545/H
For the 71M6545H (±0.1% energy accuracy), coefficients specific to each individual device can be
calculated from values read from additional on-chip fuses that characterize the VREF behavior of each
individual part across industrial temperatures (see 4.5.3 Temperature Coefficients for the 71M6545H).
The resulting tracking of the reference VREF voltage is within ±10 ppm/°C.
4.6 Connecting I²C EEPROMs
I²C EEPROMs or other I²C compatible devices should be connected to the DIO pins DIO2 and DIO3, as
shown in Figure 29.
Pull-up resistors of roughly 10 kΩ to V3P3D should be used for both SDCK and SDATA signals. The
DIO_EEX (I/O RAM 0x2456[7:6]) field must be set to 01 in order to convert the DIO pins DIO2 and DIO3 to
I²C pins SCL and SDATA.
10 kΩ
V3P3D
10 kΩ
DIO2
DIO3
EEPROM
SDCK
SDATA
71M6545/H
Figure 29: I²C EEPROM Connection
4.7 Connecting Three-Wire EEPROMs
µWire EEPROMs and other compatible devices should be connected to the DIO pins DIO2 and DIO3, as
described in 2.5.11 EEPROM Interface on page 57.
4.8 UART (TX/RX)
The UART0 RX pin should be pulled down by a 10 kΩ resistor and additionally protected by a 100 pF
ceramic capacitor, as shown in Figure 30.
71M6545/H
100 pF 10 kΩ
RX
RX
TX
TX
Figure 30: Connections for the UART
4.9 Connecting the Reset Pin
Even though a functional meter does not necessarily need a reset switch, it is useful to have a reset
pushbutton for prototyping as shown in Figure 31, left side. The RESET signal may be sourced from
V3P3SYS.
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