71M6513/71M6513H
3-Phase Energy Meter IC
A Maxim Integrated Products Brand
DATA SHEET
AUGUST 2011
For best rejection of electromagnetic interference, connect the crystal body and the ground terminals of the two
crystal capacitors to GNDD through a ferrite bead. No external resistor should be connected across the crystal,
since the oscillator is self-biasing.
Connecting LCDs
The 71M6513 has a LCD controller on-chip capable of controlling static or multiplexed LCDs. Figure 33 shows the basic
connection for a LCD.
71M6513
LCD
segments
commons
Figure 33: Connecting LCDs
Figure 34 shows how 5V LCDs can be operated even when a 5V supply is not available. Setting the I/O RAM register
LCD_BSTEN to 1 starts the on-chip boost circuitry that will output an AC frequency on the VDRV pin. Using a small coupling
capacitor, two general-purpose diodes and a reservoir capacitor, a 5VDC voltage is generated which can be fed back into the
VLCD pin of the 71M6513. The LCD drivers are enabled with the I/O register LCD_ON; I/O register LCD_FS is used to adjust
contrast, and LCD_MODE selects the operation mode (LCD type).
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