Datasheet

71M6513/71M6513H
3-Phase Energy Meter IC
DATA SHEET
SEPTEMBER 2011
© 2005-2011 Teridian Semiconductor Corporation Page: 43 of 104
A Maxim Integrated Products Brand
LCD Drivers
The 71M6513 contains 24 dedicated LCD segment drivers and 18 multi-purpose pins which may be configured as additional
LCD segment drivers (see I/O RAM register LCD_NUM). The 71M6513/6513H is capable of driving between 96 to 168 pixels
of LCD display with 25% duty cycle. At seven segments per digit, the LCD can be designed for 13 to 24 digits for display.
Since each pixel is addressed individually, the LCD display can be a combination of alphanumeric digits and enunciator
symbols. The information to be displayed is written into the lower four bits of I/O RAM registers LCD_SEG0 through
LCD_SEG41. Bit 0 corresponds to the segment selected when COM0 pin is active while bit 1 is allocated to COM1.
The LCD driver circuitry is grouped into 4 common outputs (COM0 to COM3) and up to 42 segment outputs (see Table 55).
The typical LCD map is shown below.
SEG0 SEG1 SEG2 SEG3 … SEG27 … SEG41
COM0
P0 P4 P8 P12 ... P108 ... P164
COM1
P1 P5 P9 P13 … P109 ... P165
COM2
P2
P6
P10
P14
...
P110
...
P166
COM3
P3
P7
P11
P15
...
P111
...
P167
Table 55: Liquid Crystal Display Segment Table (Typical)
Note: P0, P1, … Represent the pixel/segment numbers on the LCD.
A charge pump suitable for driving VLCD is included on-chip. This circuit creates 5V from the 3.3V supply. A contrast DAC is
provided that permits the LCD full-scale voltage to be adjusted between VLCD and 70% of VLCD. The LCD_NUM register
defines the number of dual purpose pins used for LCD segment interface.
LCD Voltage Boost Circuitry
A voltage boost circuit may be used to generate 5V from the 3.3V supply to support low-power 5V devices, such as LCDs.
Figure 10 shows a block diagram of the voltage boost circuitry including the voltage regulators for V2P5 and V2P5NV. When
activated using the I/O RAM register LCD_BSTEN (0x2020[7]), the boost circuitry provides an AC voltage at the VDRV output
pin (see the Applications section for details).
Figure 10: LCD Voltage Boost Circuitry
GNDD
V3P3D
VBAT
VOLT
REG
0.1V
V2P5
VLCD
VDRV
VOLTAGE
BOOST
LCD_BSTEN
LCD_IBST
GNDD
GNDD
GNDD
V2P5
V3P3D
V2P5NV