71M6542F MAXIM [Maxim Integrated Products], 71M6542F Datasheet - Page 67

• Manufacturer Part Number: 71M6542F
• Description: 0.1% Accuracy Over 2000:1 Current Range Energy Meter ICs
• Manufacturer: MAXIM [Maxim Integrated Products]

Table 57
The LCD can be driven in static, ½ bias, and 1/3 bias modes.
Note that COM pins that are not required in a specific mode maintain a ‘segment off’ state rather than
GND, VCC, or high impedance.
The segment drivers SEGDIO22 and SEGDIO23 can be configured to blink at either 0.5 Hz or 1 Hz.
The blink rate is controlled by LCD_Y (I/O RAM 0x2400[2]). There can be up to six pixels/segments
connected to each of these driver pins. The I/O RAM fields LCD_BLKMAP22[5:0] (I/O RAM 0x2402[5:0])
and LCD_BLKMAP23[5:0] (I/O RAM 0x2401[5:0]) identify which pixels, if any, are to blink.
LCD_BLKMAP22[5:0] and LCD_BLKMAP23[5:0] are non-volatile.
LCD_VMODE[1:0] 2401[7:6]
Name
LCD_ALLCOM
LCD_BAT
LCD_E
LCD_ON
LCD_BLANK
LCD_RST
LCD_DAC[4:0]
LCD_CLK[1:0]
LCD_MODE[2:0] 2400[6:4]
shows all I/O RAM registers that control the operation of the LCD interface.
240D[4:0]
Location Rst
2400[1:0]
240C[0]
240C[1]
240C[2]
2400[3]
2402[7]
2400[7]
00
0
0
0
0
0
0
0
0
0
Table 57: LCD Configurations
Wk Dir
00
–
–
–
–
–
–
–
–
R/W
R/W Connects the LCD power supply to VBAT in all modes.
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Description
Configures all 6 SEG/COM pins as COM. Has no effect
on pins whose LCD_MAP bit is zero.
Enables the LCD display. When disabled, VLC2,
VLC1, and VLC0 are ground as are the COM and SEG
outputs if their LCD_MAP bit is 1.
LCD_ON = 1 turns on all LCD segments without
affecting the LCD data. Similarly, LCD_BLANK = 1
turns off all LCD segments without affecting the LCD
data. If both bits are set, all LCD segments are turned
on.
Clear all bits of LCD data. These bits affect SEGDIO
pins that are configured as LCD drivers.
This register controls the LCD contrast DAC, which
adjusts the VLCD voltage and has an output range of
2.5 VDC to 5 VDC. The VLCD voltage is
Thus, the LSB of the DAC is 80.6 mV. The maximum
DAC output voltage is limited by V3P3SYS, VBAT, and
whether LCD_BSTE is set.
Sets the LCD clock frequency (1/T). See definition of T
in
The LCD bias and multiplex mode.
This register specifies how VLCD is generated.
LCD_VMODE
Figure 21.
VLCD = 2.5 + 2.5 * LCD_DAC[4:0]/31
11
10
01
00
00-fw/2^9, 01-fw/2^8, 10-fw/2^7, 11-fw/2^6
LCD_MODE
71M6541D/F/G and 71M6542F/G Data Sheet
Figure 21
000
001
010
011
100
101
110
Note: fw = 32768 Hz
Description
External VLCD
LCD boost and LCD DAC
enabled
LCD DAC enabled
No boost and no DAC. VLCD
= VBAT or V3P3SYS
defines the COM waveforms.
Output
4 states, 1/3 bias
3 states, 1/3 bias
2 states, ½ bias
3 states, ½ bias
Static display
5 states, 1/3 bias
6 states, 1/3 bias