HD66727 Datasheet, PDF (69/97 Pages) Hitachi Semiconductor – Low-Power Dot-Matrix Liquid Crystal Display Controller/Driver with Key Scan Function

HD66727
Segment Display and Annunciator Display
The HD66727 provides both segment display, which is driven by the multiplexing method, and annunciator
display, which is driven statically. Annunciator display is driven at a logic operating voltage (V_CC –
AGND) and is thus also available while the LCD drive power supply is turned off. Accordingly,
annunciator display is suitable for displaying marks during system standby, when it is desirable to reduce
current consumption. It is available in the sleep mode, where internal multiplexing operations for character
or segment display are halted. If an alternating signal is supplied to the EXM pin, it is also available in the
standby mode, where the internal R-C oscillator is halted. Here, AGND must be equal to or above the GND
level.
Note that annunciator display cannot share character display drivers SEG and COM but require special
drivers ASEG and ACOM that require long routing.
Tables 31 to 34 compare segment display to annunciator display. Figure 40 shows annunciator drive output
waveforms in two modes.
Table 31 Comparison between Segment Display and Annunciator Display
Item
Number of driven elements
Blinking
Segment drivers
Common drivers
LCD power supply
Normal mode display
Sleep mode display
Standby mode display
(without oscillation)
Segment Display
40 each by 5-dot font width
48 each by 6-dot font width
Impossible
SEG1–SEG60
(shared with character display)
COMS1, COMS2
V_CC – V5
(LCD power supply necessary)
Possible together with
character display by multiplexing
drive
Impossible
(SEG and COM output V_CC)
Impossible
(SEG and COM output V_CC)
Annunciator Display
12
Possible
ASEG1–ASEG12
(independent of character display)
ACOM
V_CC – AGND
(LCD power supply unnecessary)
Possible by static drive
Possible by static drive
Possible by supplying alternating
signal to the EXM pin
69