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71M6513/71M6513H Demo Board User’s Manual
Page: 57 of 112
©
2005-2006 TERIDIAN Semiconductor Corporation
Revision 5.6
2.4.5 LCD
The 71M6513 has an on-chip LCD controller capable of controlling static or multiplexed LCDs. Figure 2-11
shows the basic connection for LCDs. Note that the LCD module itself has no power connection.
segments
651X
LCD
commons
Figure 2-11: LCD Connections
Figure 2-12 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).
segments
651X
5V LCD
commons
VLCD
V3P3
5VDC
VDRV
segments
651X
5V LCD
commons
VLCD
V3P3
5VDC
VDRV
V3P3
LCD_BSTEN
LCD_FS
LCD_EN
LCD_MODE
Contrast
ON/OFF
LCD type
Figure 2-12: LCD Boost and LCD Control Registers
http://www.datasheetcatalog.com/