Datasheet

10
Table 1. Current Requirements at Dierent Brightness Levels
Symbol D
5
D
4
D
3
Brightness 25°C Typ. 25°C Max. Max. over Temp. Units
I
DD
(#) 0 0 0 100% 110 130 160 mA
0 0 1 60% 66 79 98 mA
0 1 0 40% 45 53 66 mA
0 1 1 27% 30 37 46 mA
1 0 0 17% 20 24 31 mA
1 0 1 10% 12 15 20 mA
1 1 0 7% 9 11 15 mA
1 1 1 3% 4 6 9 mA
Figure 3 shows how the Extended Function Disable
(bit D
6
of the Control Register), Master Blank (bit D
2
of
the Control Register), Digit Blank Disable (bit D
1
of the
Attribute RAM), and BL input can be used to blank the
display.
When the Extended Function Disable is a logic 1, the
display can be blanked only with the BL input. When the
Extended Function Disable is a logic 0, the display can be
blanked through the BL input, the Master Blank, and the
Digit Blank Disable. The entire display will be blanked if
either the BL input is logic 0 or the Master Blank is logic
1, providing all Digit Blank Disable bits are logic 0. Those
digits with Digit Blank Disable bits a logic 1 will ignore
both blank signals and remain ON. The Digit Blank Disable
bits allow individual characters to be blanked or ashed
in synchronization with the BL input.
Figure 3. Display blanking truth table.
EFD MB DBD
n
BL
0 0 0 0 Display Blanked by BL
0 0 X 1 Display ON
Display Blanked by BL. Individual characters
0 X 1 0
“ON” based on “1” being stored in DBD
n
0 1 0 X Display Blanked by MB
Display Blanked by MB. Individual characters
0 1 1 1
“ON” based on “1” being stored in DBD
n
1 X X 0 Display Blanked by BL
1 X X 1 Display ON
Dimming
Dimming of the display is controlled through either the
BL input or the Control Register. A pulse width modulated
signal can be applied to the BL input to dim the display.
A three bit word in the Control Register generates an
internal pulse width modulated signal to dim the display.
The internal dimming feature is enabled only if the
Extended Function Disable is a logic 0.
Bits 3-5 in the Control Register provide internal brightness
control. These bits are interpreted as a three bit binary
code, with code (000) corresponding to the maximum
brightness and code (111) to the minimum brightness.
In addition to varying the display brightness, bits 3-5 also
vary the average value of I
DD
. I
DD
can be specied at any
brightness level as shown in Table 1.